JP5742204B2 - Photoelectric conversion element, solar cell and solar cell module - Google Patents

Description

  The present invention relates to a photoelectric conversion element using a fullerene compound as a semiconductor material. In particular, the present invention relates to an organic photoelectric conversion element suitable for use in an organic solar battery, a solar battery using the same, and a solar battery module.

As organic thin-film solar cells, those using a coating-type high-molecular organic semiconductor layer or a vapor-deposited low-molecular-weight organic semiconductor layer are conventionally known. An organic thin-film solar cell using the above has been proposed (Patent Document 1, Non-Patent Document 1).
As a coating type polymer organic thin film solar cell, polyhexylthiophene (P3HT), which is a conjugated polymer soluble in a p-type semiconductor, or a derivative having increased solubility of fullerene, such as PCBM, is used in an n-type semiconductor. Many. In most cases, the layer structure of the semiconductor layer is composed of only a bulk hetero layer in which molecules of a p-type semiconductor and an n-type semiconductor coexist.

The evaporation-based low molecular organic thin film solar cell, phthalocyanines in p-type semiconductor, pentacene, oligothiophene is, C ₆₀ to n-type semiconductor is often used. As a layer structure of the semiconductor layer, in addition to a p layer made of a p-type semiconductor and an n layer made of an n-type semiconductor, an i-layer in which a p-type semiconductor and an n-type semiconductor coexist is introduced at a pn junction interface. There may be an n-layer structure (Non-patent Document 2).

As a coating conversion type low molecular organic thin film solar cell, tetrabenzoporphyrin or the like is used for a p-type semiconductor, and a fullerene compound or the like is used for an n-type semiconductor. The layer structure of the semiconductor layer is the same as that of the low molecular vapor deposition system (Patent Document 1, Non-Patent Document 1).
Fullerene compounds are attracting attention as n-type semiconductor materials, and fullerene compounds having substituents are particularly attracting attention because they facilitate film formation.

The fullerene compound having a substituent _{group, [6,6] -Phenyl-C 61} -Butyric Acid Methyl Ester ( phenyl _{C 61} butyric acid methyl ester, PCBM) but have been generally used, further improvement in photoelectric conversion efficiency Has been desired. Recently, it has been reported that fullerene compounds having a silylmethyl group as a substituent can be produced at low cost (Patent Documents 2 and 3). In addition, it has been reported that an organic thin-film solar cell that is a photoelectric conversion element using the fullerene compound achieves higher conversion efficiency than PCBM (Patent Document 4).

International Publication No. 2007/126102 JP 7-89972 A International Publication No. 2008/059771 International Publication No. 2009/008323

Matsuo, Y. et al. et al. J. et al. Am. Chem. Soc. 2009, 131, 16048. Hiramoto, M.M. et al. Appl. Phys. Lett. 1991, 58, 1062.

  According to the study by the present inventors, the fullerene compounds described in Patent Documents 1 and 4 have low thermal stability, and when the entire device is subjected to heat treatment after all layers of the photoelectric conversion device are laminated, It has been found that the photoelectric conversion efficiency of the abruptly decreases. Especially in solar cell applications, durability under high-temperature conditions is required. Therefore, a decrease in photoelectric conversion efficiency due to heat treatment of the entire device is expected to lead to lack of durability under high-temperature conditions. It will be a challenge. Moreover, when this fullerene compound was used, the subject that the open circuit voltage (Voc) was not necessarily enough also became clear.

  On the other hand, although the organic thin film solar cell having a polymer-coated semiconductor layer has a relatively excellent photoelectric conversion efficiency of about 5%, it has been found that there is a problem in durability as a photoelectric conversion element. In addition, there is a concern that high-purity purification of the polymer material is essential and that it is difficult to stably supply the material in terms of controlling the molecular weight and molecular weight distribution.

In view of the above-described conventional situation, the present inventors have a fullerene compound that is excellent in thermal stability and can provide a high open-circuit voltage, a high-purity purification and mass synthesis of materials, and low thermal stability. It has been found that a photoelectric conversion element having excellent performance when used in a solar cell can be obtained by combining with a molecular organic semiconductor compound, and the present invention has been completed.
That is, the gist of the present invention is as follows.
[1] A photoelectric conversion element including at least an active layer and a pair of electrodes, wherein the active layer contains a fullerene compound obtained by condensing a fullerene with a ring having four or more members and a low molecular organic semiconductor compound. The photoelectric conversion device , wherein the fullerene compound is the following fullerene compound A or the following fullerene compound B.

[2] The photoelectric conversion element according to [1], wherein the low-molecular organic semiconductor compound has crystallinity.
[3] The photoelectric conversion element according to [1], wherein the low-molecular organic semiconductor compound is a phthalocyanine compound and a metal complex thereof, and a porphyrin compound and a metal complex thereof.

[4] The photoelectric conversion element according to any one of [1] to [3], wherein the photoelectric conversion element further includes a buffer layer.
[5] A solar cell comprising the photoelectric conversion element according to any one of [1] to [4].
[6] A solar cell module comprising the solar cell according to [5].

  According to the present invention, it is possible to obtain a photoelectric conversion element that has high thermal stability, high open-circuit voltage, excellent photoelectric conversion efficiency, and excellent durability, and a solar cell and a solar cell module using the photoelectric conversion device. .

It is sectional drawing which shows typically the structure of the photoelectric conversion element as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell module as one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
The description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified in these contents unless it exceeds the gist of the present invention.
<Photoelectric conversion element>
The photoelectric conversion device according to the present invention includes at least an active layer and a pair of electrodes sandwiching the active layer, and the active layer contains a fullerene compound formed by condensation of a ring structure of four or more members and a low molecular organic semiconductor. To do. Moreover, it is preferable that the photoelectric conversion element of this invention has a buffer layer further. The buffer layer is usually disposed between the electrode and the active layer.

  FIG. 1 shows an example of the configuration of a photoelectric conversion element used in a general organic thin film solar cell. A photoelectric conversion element 109 according to an embodiment of the present invention includes a cathode (transparent electrode) 101, a hole extraction layer 102, an active layer 108 (a p-type semiconductor compound layer 103, a p-type semiconductor compound and an n-type semiconductor) on a substrate 100. A compound mixed layer 104 and an n-type semiconductor compound layer 105), an electron extraction layer 106, and an anode (counter electrode) 107 are sequentially formed.

<Active layer 108>
In the photoelectric conversion element according to the present invention, the active layer 108 includes a p-type semiconductor compound and an n-type semiconductor compound. When the photoelectric conversion element 109 receives light, the light is absorbed by the active layer 108, electricity is generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound, and the generated electricity is extracted from the electrodes 101 and 107.

As the layer structure of the active layer, a thin film laminated structure in which a p-type semiconductor compound and an n-type semiconductor compound are laminated, or a thin film laminated type comprising a p-type semiconductor compound layer 103 and an n-type semiconductor compound layer 105 as shown in FIG. Examples of the intermediate layer include a pin stack structure including a layer (i layer) 104 in which a p-type semiconductor compound and an n-type semiconductor compound are mixed.
<N-type semiconductor compound>
In the present invention, as an n-type semiconductor compound, one of the characteristics is to use a fullerene compound represented by the following general formula (1), which is formed by condensing a fullerene with a 4-membered ring or more.

In the formula, ring A is formed by combining a fullerene (hereinafter sometimes referred to as FLN) with a divalent substituent R having 2 or more carbon atoms, and the substituent R and two or more carbons in fullerene. It is a 4 or more membered ring. For the sake of brevity, in the present invention, this state is referred to as “a fullerene is condensed with a ring of four or more membered rings”.
The substituent R may be bonded to the fullerene in any manner. For example, as shown in the following formula, the substituent R may be bonded to two adjacent carbon atoms on the fullerene ring to form a ring A. In addition, the substituent R may be bonded to two carbon atoms located on the fullerene ring with one carbon atom interposed therebetween to form a ring A. Further, the substituent R may be bonded to two carbon atoms located on the fullerene ring with two or more carbon atoms sandwiched therebetween to form a ring A. In addition, the substituent R is preferably bonded to the same five-membered ring or six-membered ring in the fullerene skeleton. Furthermore, it is particularly preferable that the substituent R is bonded to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton.

  Ring A is a 4-membered ring or more, preferably a 5-membered ring or more. Ring A is preferably a 10-membered ring or less, more preferably a 7-membered ring or less, and still more preferably a 6-membered ring or less. Ring A may be an aliphatic ring or an aromatic ring, but is preferably an aliphatic ring. Further, ring A may be an aliphatic hydrocarbon ring or an aliphatic heterocyclic ring containing a nitrogen atom, an oxygen atom or a sulfur atom. More preferably, it is an aliphatic hydrocarbon ring.

Specific examples of ring A include aliphatic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, bicyclo [2,2,1] heptane, and bicyclo [2,2,2] octane. Ring; pyrrolidine, piperidine, piperazine, tetrahydrofuran, morpholine, azabicyclo [2,2,1] heptane,
Aliphatic heterocycles such as oxabicyclo [2,2,1] heptane, thiabicyclo [2,2,1] heptane or diazabicyclo [2,2,2] octane.

Among them, preferred is cyclopentane, cyclohexane or bicyclo [2,2,1] heptane, and more preferred is cyclopentane or cyclohexane.
m represents an integer and is usually 1 or more, preferably 2 or more. On the other hand, m is usually 10 or less, preferably 6 or less. When m is 2 or more, each ring A may be the same or different. These rings may further form a ring directly or via a substituent. When m is 2 or more, an isomer may exist depending on the condensation position of ring A. However, as the fullerene compound of the present invention, a single isomer or a mixture of a plurality of isomers may be used. May be.

The fullerene according to the present invention is a carbon cluster having a closed shell structure. The carbon number of fullerene is usually an even number of 60 to 130. Examples of fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ and higher carbon clusters having more carbon than these. Among these, C ₆₀ or C ₇₀ is preferable, and C ₆₀ is more preferable.

In the present invention, fullerenes may have broken carbon-carbon bonds on some fullerene rings. Some carbon atoms may be replaced with other atoms. Further, a metal atom, a non-metal atom, or an atomic group composed of these may be included in the fullerene cage.
In the fullerene compound of the present invention, it is preferable that ring A is further condensed with another ring. Among these, fullerene compounds represented by the following general formula (2) are preferable.

In the general formula (2), ring A is condensed with ring B. Ring B may be an aliphatic ring or an aromatic ring, but is preferably an aromatic ring. The aromatic ring may be an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Moreover, the number of atoms which form a ring structure is 5-20 normally, Preferably the number of atoms is 5-18, More preferably, the number of atoms is 5-12.
Specific examples of the aliphatic hydrocarbon ring related to ring B include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, and cyclodecane. Among them, preferred is cyclopentane or cyclohexane.

Specific examples of the aliphatic heterocyclic ring related to ring B include piperidine, piperazine, tetrahydrofuran or morpholine. Of these, piperidine or morpholine is preferable.
Specific examples of the aromatic hydrocarbon ring according to ring B include benzene, naphthalene, fluorene, anthracene, or pyrene. Of these, benzene is preferred. Furthermore, specific examples of the aromatic heterocyclic ring which may be condensed include furan, thiophene, pyrrole, oxazole, thiazole, imidazole, pyrazole, pyridine, pyridazine, pyrimidine, pyrazine, quinoline or quinoxaline. Among them, furan or thiophene is preferable.

Ring A and ring B described above may have another substituent. When there are a plurality of substituents, each substituent may be the same or different.
The substituent for ring A and ring B is not particularly limited as long as it does not impair the object of the present invention. Specific examples include a halogen atom, a hydroxyl group, a cyano group, an amino group, an ester group, a carboxyl group, a carbonyl group. Group, acetyl group, sulfonyl group, silyl group, boryl group, nitrile group, alkyl group, alkenyl group, alkynyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group or aromatic group.

The alkyl group preferably has 1 to 20 carbon atoms, and specific examples include methyl, ethyl, i-propyl, n-propyl, n-butyl, t-butyl, n-hexyl or cyclohexyl. Groups and the like.
The alkenyl group preferably has 2 to 20 carbon atoms, and specific examples thereof include a vinyl group, a styryl group, and a diphenylvinyl group.

As the alkynyl group, those having 2 to 20 carbon atoms are preferable, and specific examples include a methylethynyl group, a phenylethynyl group, a trimethylsilylethynyl group, and the like.
The alkoxy group is preferably one having 1 to 20 carbon atoms, and specific examples include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group or t-butoxy group. Can be mentioned.

The aryloxy group preferably has 2 to 20 carbon atoms, and specific examples include a phenoxy group.
The alkylthio group preferably has 1 to 20 carbon atoms, and specific examples thereof include a methylthio group and an ethylthio group.
The arylthio group is preferably one having 2 to 20 carbon atoms, and specific examples thereof include a phenylthio group.

Specific examples of the amino group include alkylamino groups such as dimethylamino group, diethylamino group or diisopropylamino group; arylamino groups such as diphenylamino group, ditolylamino group or carbazoyl group.
Specific examples of the silyl group include alkylsilyl groups such as a trimethylsilyl group; arylsilyl groups such as a dimethylphenyl group or a triphenylsilyl group.

Specific examples of the boryl group include a dimethylboryl group substituted with an aryl group.
As an aromatic group, phenyl group, naphthyl group, phenanthryl group, biphenylenyl group, triphenylene group, anthryl group, pyrenyl group, fluorenyl group, azulenyl group, acenaphthenyl group, fluoranthenyl group, naphthacenyl group, perylenyl group, pentacenyl group, Aromatic hydrocarbon group such as triphenylenyl group or quarterphenyl group; pyridyl group, thienyl group, furyl group, pyrrole group, oxazole group, thiazole group, oxadiazole group, thiadiazole group, pyrazyl group, pyrimidyl group, pyrazoyl group, imidazoyl Group, benzothienyl group, dibenzofuryl group, dibenzothienyl group, phenylcarbazoyl group, phenoxathienyl group, xanthenyl group, benzofuranyl group, thiantenyl group, indolizinyl group, phenoxazinyl group, phenoxy group Thiazinyl group, acridinyl group, phenanthridinyl group, quinolyl group, isoquinolyl group, an aromatic heterocyclic group such as indolyl, or quinoxalinyl group. Among them, the aromatic hydrocarbon group is preferably a phenyl group, a naphthyl group, a phenanthryl group, a triphenylene group, an anthryl group, a pyrenyl group, a fluorenyl group, an acenaphthenyl group, a fluoranthenyl group, a perenylenyl group, or a triphenylenyl group. As the heterocyclic group, pyridyl group, pyrazyl group, pyrimidyl group, pyrazoyl group, quinolyl group, isoquinolyl group, imidazolyl group, acridinyl group, phenanthridinyl group, quinoxalinyl group, dibenzofuryl group, dibenzothienyl group, phenylcarbazoyl group Group, xanthenyl group or phenoxazinyl group.

  Particularly preferred as the fullerene compound of the present invention is a fullerene compound represented by the following general formula (3) or (4).

In general formula (3) and (4), X is an oxygen atom, a sulfur atom, an amino group, an alkylene group, or an arylene group. The alkylene group preferably has 1 to 2 carbon atoms. As an arylene group, C5-C12 is preferable, for example, is a phenylene group.
The amino group may be substituted with an alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group.

The alkylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or an aromatic complex having 2 to 20 carbon atoms. It may be substituted with a cyclic group.
The arylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or an aromatic complex having 2 to 20 carbon atoms. It may be substituted with a cyclic group.

Ar ¹ has the same meaning as in the case of ring B being an aromatic ring. Preferred ranges and examples are also the same as in ring B.
n represents an integer and is usually 1 or more, preferably 2 or more. On the other hand, n is usually 10 or less, preferably 6 or less. When n is 2 or more, each ring structure formed by condensation with fullerene may be the same or different. These rings may further form a ring directly or via a substituent. When n is 2 or more, an isomer may exist depending on the condensation position of the ring structure. However, as the fullerene compound of the present invention, a single isomer or a mixture of a plurality of isomers may be used. May be.

In addition, in the fullerene compound of this invention, when the ring A, the ring B, and those substituents have the coordination ability to a metal, the metal complex may be formed through the coordinate bond with a metal atom.
The fullerene compound according to the present invention preferably has a partial structure represented by the following general formula (n1) or (n2).

In the general formulas (n1) and (n2), FLN represents fullerene. In the general formula (n1), —R ¹ and — (CH ₂ ) _L are respectively added to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. In the general formula (n2), —C (R ⁵ ) (R ⁶ ) is added to two adjacent carbon atoms on the same 5-membered or 6-membered ring in the fullerene skeleton to form a 3-membered ring. It becomes. d and e are each independently an integer, and the sum of d and e is usually 1 or more, and usually 5 or less, preferably 3 or less. L is an integer and is usually 1 or more, while it is usually 8 or less, preferably 4 or less. L is more preferably 1 or 2.

R ¹ in the general formula (n1) has an optionally substituted alkyl group having 1 to 14 carbon atoms, an optionally substituted alkoxy group having 1 to 14 carbon atoms, or a substituent. An aromatic group that may be used.
As an alkyl group, a C1-C10 alkyl group is preferable, a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, or an isobutyl group is more preferable, and a methyl group or an ethyl group is still more preferable.

As an alkoxy group, a C1-C10 alkoxy group is preferable, a C1-C6 alkoxy group is more preferable, and a methoxy group or an ethoxy group is especially preferable.
As an aromatic group, a C6-C20 aromatic hydrocarbon group or a C2-C20 aromatic heterocyclic group is preferable, a phenyl group, a thienyl group, a furyl group, or a pyridyl group is more preferable, a phenyl group or More preferred is a thienyl group.

  The substituent that the alkyl group, alkoxy group and aromatic group may have is preferably a halogen atom or a silyl group. As the halogen atom, a fluorine atom is preferable. The silyl group is preferably a diarylalkylsilyl group, a dialkylarylsilyl group, a triarylsilyl group or a trialkylsilyl group, more preferably a dialkylarylsilyl group, and even more preferably a dimethylarylsilyl group.

R ^{2 to} R ⁴ in the general formula (n1) each independently represent a substituent, which has a hydrogen atom, an optionally substituted alkyl group having 1 to 14 carbon atoms or a substituent. It is also a good aromatic group.
As an alkyl group, a C1-C10 alkyl group is preferable and a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, or n-hexyl group is preferable. The substituent that the alkyl group may have is preferably a halogen atom. As the halogen atom, a fluorine atom is preferable. The alkyl group substituted with a fluorine atom is preferably a perfluorooctyl group, a perfluorohexyl group or a perfluorobutyl group.

  The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group or a pyridyl group, and a phenyl group or a thienyl group. Groups are more preferred. Examples of the substituent that the aromatic group may have include a fluorine atom, an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, an alkoxy group having 1 to 14 carbon atoms, or 3 carbon atoms. Is preferably a fluorine atom or an alkoxy group having 1 to 14 carbon atoms, more preferably a methoxy group, an n-butoxy group or a 2-ethylhexyloxy group. When the aromatic group has a substituent, the number is not limited, but is preferably 1 or more and 3 or less, and more preferably 1. When the aromatic group has a plurality of substituents, the types of the substituents may be different, but are preferably the same.

R ^{5 to} R ⁶ in the general formula (n2) each independently have a hydrogen atom, an alkoxycarbonyl group, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. It is also a good aromatic group.
The alkoxy group in the alkoxycarbonyl group is preferably an alkoxy group having 1 to 12 carbon atoms or a fluorinated alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, a methoxy group, an ethoxy group, n -Propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group are more preferable, methoxy group, An ethoxy group, isopropoxy group, n-butoxy group, isobutoxy group or n-hexoxy group is particularly preferred.

  As the alkyl group, a linear alkyl group having 1 to 8 carbon atoms is preferable, and an n-propyl group is more preferable. The substituent that the alkyl group may have is not particularly limited, but is preferably an alkoxycarbonyl group. The alkoxy group of the alkoxycarbonyl group is preferably an alkoxy group having 1 to 14 carbon atoms or a fluorinated alkoxy group, more preferably a hydrocarbon group having 1 to 14 carbon atoms, a methoxy group, an ethoxy group, an n-propoxy group, an iso group. Propoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group are more preferable, and methoxy group or n-butoxy group is more preferable. Particularly preferred.

  As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms is preferable, and a phenyl group, a biphenyl group, a thienyl group, a furyl group, or a pyridyl group is preferable. A group or a thienyl group is more preferred. The substituent that the aromatic group may have is preferably an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, or an alkoxy group having 1 to 14 carbon atoms, 14 alkoxy groups are more preferable, and a methoxy group or 2-ethylhexyloxy group is particularly preferable. When it has a substituent, the number is not limited, but it is preferably 1 or more and 3 or less, more preferably 1. The types of substituents may be different or the same, preferably the same.

As the structure of the general formula (n2), preferably, R ⁵ and R ⁶ are both alkoxycarbonyl groups, R ⁵ and R ⁶ are both aromatic groups, or R ⁵ is an aromatic group and R ⁶ is 3- (alkoxycarbonyl) propyl group.
The n-type semiconductor compound used in the present invention may be a single compound or a mixture of multiple compounds.

  Examples of the specific structure of the fullerene compound obtained by condensing a fullerene with a 4-membered ring or more include the following.

The fullerene compound of the present invention can be used in combination with a low-molecular organic semiconductor compound described later to produce a photoelectric conversion element and an organic solar cell that are superior in durability compared to conventional ones. This is preferable in that a high open-circuit voltage can be applied to the battery.
[Film formation method of fullerene compound]
The fullerene compound film forming method of the present invention includes a vapor deposition method, a coating method, and the like. In view of process performance, a fullerene compound that can be formed by a coating method is more preferable. For this reason, it is preferable that the fullerene compound itself can be applied in a liquid state or that the fullerene compound is highly soluble in some solvent and can be applied as a solution.

The coating solvent for the fullerene compound of the present invention is not particularly limited as long as the solubility of the fullerene compound is high, but a nonpolar organic solvent is preferable, and a non-halogen solvent is more preferable from the viewpoint of environmental burden. Examples of the non-halogen solvent include non-halogen aromatic hydrocarbons. Of these, toluene, xylene, cyclohexylbenzene and the like are preferable.
[Thermal stability]
The glass transition temperature of the fullerene compound of the present invention may or may not be observed, but preferably the glass transition temperature is not observed or is 180 ° C. or higher. Since the compound does not change between an amorphous state and a crystalline state in the temperature range in the film forming process, there is an advantage that the functional stability as an n-type semiconductor is not impaired and the photoelectric conversion element efficiency is not lowered. When the glass transition temperature is observed, it is more preferably 200 ° C. or higher, further preferably 250 ° C. or higher, and particularly preferably 280 ° C. or higher. On the other hand, the upper limit is not particularly limited, but is usually 400 ° C. or lower, preferably 350 ° C. or lower.

  What is necessary is just to measure a glass transition temperature by a well-known method, for example, DSC method is mentioned. The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. The glass transition temperature of the amorphous solid state of the organic material is a temperature at which molecular motion starts from the glass state, and can be measured by DSC as the temperature at which the specific heat changes. In order to determine the glass transition temperature more clearly, it is desirable to measure after quenching a sample once heated to a temperature higher than the glass point transfer.

  The value of the lowest unoccupied molecular orbital (LUMO) of the fullerene compound of the present invention is not particularly limited. 3.80 eV or more. In order to efficiently move electrons from the electron donor layer (p-type semiconductor layer) to the electron acceptor layer (n-type semiconductor layer), the minimum vacancy of the materials used for each electron donor layer and electron acceptor layer is required. The relative relationship of the orbit (LUMO) is important. Specifically, the LUMO of the material of the electron donor layer is higher than the LUMO of the material of the electron acceptor layer by a predetermined energy, in other words, the electron affinity of the electron acceptor is higher than the electron affinity of the electron donor. It is preferable that the energy is larger by a predetermined energy. Since the open circuit voltage (Voc) is determined by the difference between the highest occupied orbit (HOMO) of the electron donor layer material and the LUMO of the electron acceptor layer material, increasing the LUMO of the electron acceptor increases the Voc. Tend. On the other hand, the value of LUMO is usually −1.0 eV or less, preferably −2.0 eV or less, more preferably −3.0 eV or less, and further preferably −3.3 eV or less. Lowering the LUMO of the electron acceptor tends to cause electron migration and increase the short-circuit current (Jsc).

  As a method for calculating the LUMO value of the fullerene compound, there are a theoretically calculated method and a method of actually measuring. The theoretically calculated values include semi-empirical molecular orbital methods and non-empirical molecular orbital methods, and the actual measurement methods include ultraviolet-visible absorption spectrum measurement method and cyclic voltammogram measurement method. It is done. Among them, the cyclic voltammogram measurement method is preferable.

[Production method of fullerene compound]
Although there is no restriction | limiting in particular as a manufacturing method of the fullerene compound of this invention, For example, as a synthesis method of the fullerene represented by general formula (II), Angew. Chem. Int. Ed. Engl. 1993, 32, 78-80, Tetrahedron Lett. 1997, 38, 285-288, International Publication No. 2008/018931 and International Publication No. 2009/086212 can be implemented. Of these, the Diels-Alder reaction method is preferred.

  The production method of fullerene formed by the Diels-Alder reaction is specifically a production method by a reaction represented by the following reaction formula, and a substituent is covalently bonded by a [4 + 2] cycloaddition reaction to fullerene. Depends on the reaction to form. Two covalent bonds are generated for each substituent to be added, and two carbon atoms on the fullerene formed by the covalent bonds are adjacent to each other. P in the reaction formula represents the number of substituents added, and p is usually an integer of 1 or more, more preferably an integer of 2 or more, and usually 10 or less, more preferably an integer of 6 or less. E in the formula represents a substituent to the additional group, and is the same as the substituent which may have the substituent described above.

As a method for synthesizing fullerene having an addition group represented by (n1), International Publication No. 2008/059771 and J. Org. Am. Chem. Soc. , 2008, 130 (46), 15429-15436.
As a method for synthesizing a fullerene having an addition group represented by (n2), J. et al. Chem. Soc. Perkin Trans. 1, 1997 1595, Thin Solid
Films 489 (2005) 251-256, Adv. Funct. Mater. 2005, 15, 1979-1987 and J. Org. Org. Chem. It can be carried out according to known documents described in 1995, 60, 532-538.

<P-type semiconductor compound>
In the present invention, a low molecular organic semiconductor compound is used as the p-type semiconductor compound.
The combined use of the fullerene compound of the present invention and a low-molecular organic semiconductor compound makes it possible to produce a photoelectric conversion element and an organic solar battery that are superior in durability compared to the prior art, and is high in the photoelectric conversion element and the organic solar battery. It is preferable at the point which can provide an open end voltage.

The molecular weight of the low-molecular organic semiconductor compound is not particularly limited both at the upper limit and the lower limit, but is usually 5000 or less, preferably 2000 or less, and is usually 100 or more, preferably 200 or more.
Further, the low molecular organic semiconductor compound preferably has crystallinity. Since the p-type semiconductor compound having crystallinity has a strong intermolecular interaction, it is expected that holes generated at the interface between the p-type semiconductor and the n-type semiconductor in the active layer can be efficiently transported to the positive electrode. It is.

The crystallinity in the present invention is a property of a compound that takes a three-dimensional periodic array in which orientation is aligned by intermolecular interaction or the like.
Examples of the method for measuring crystallinity include X-ray diffraction (XRD) or field effect mobility measurement. In particular, in the field effect mobility measurement, a crystalline compound having a hole mobility of 1.0 × 10 ⁽⁻⁵⁾ cm ² / (Vs) or more is preferable, and 1.0 × 10 ⁽⁻⁴⁾ cm ² / ( Vs) or more is more preferable. On the other hand, a crystalline compound having a hole mobility of usually 1.0 × 10 ⁽⁴⁾ cm ² / (Vs) or less is preferable, and a crystallinity of 1.0 × 10 ⁽³⁾ cm ² / (Vs) or less. A compound is more preferable, and a crystalline compound of 1.0 × 10 ⁽²⁾ cm ² / (Vs) or less is still more preferable.

The low-molecular organic semiconductor compound is not particularly limited as long as it satisfies the above performance. Specifically, the low-molecular organic semiconductor compound has four condensed aromatic hydrocarbons such as naphthacene, pentacene or pyrene; and four thiophene rings such as α-sexithiophene. Oligothiophenes containing above: those containing at least one of thiophene ring, benzene ring, fluorene ring, naphthalene ring, anthracene ring, thiazole ring, thiadiazole ring and benzothiazole ring, and a total of four or more linked; phthalocyanine compound And a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin and a macrocycle compound thereof such as a metal complex thereof. Preferably, they are a phthalocyanine compound and its metal complex, or a porphyrin compound and its metal complex.
The above low-molecular organic semiconductor compounds, particularly phthalocyanine compounds and porphyrin compounds are preferred because of their excellent thermal stability. That is, by combining with the fullerene having excellent thermal stability of the present invention, a photoelectric conversion element having excellent durability under high temperature conditions can be obtained.

  Examples of the porphyrin compound and its metal complex (Q in the figure are CH), the phthalocyanine compound and its metal complex (Q in the figure are N) used as the p-type semiconductor compound include compounds having the following structures: It is done.

Here, M represents a metal or two hydrogen atoms. As the metal, in addition to a divalent metal such as Cu, Zn, Pb, Mg, Co or Ni, a trivalent or higher metal having an axial ligand. Examples thereof include TiO, VO, SnCl ₂ , AlCl, InCl, and Si.
Y ^{1 to} Y ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 24 carbon atoms. The alkyl group having 1 to 24 carbon atoms is a saturated or unsaturated chain hydrocarbon group having 1 to 24 carbon atoms or a saturated or unsaturated cyclic hydrocarbon group having 3 to 24 carbon atoms. Of these, a saturated or unsaturated chain hydrocarbon group having 1 to 12 carbon atoms or a saturated or unsaturated cyclic hydrocarbon group having 3 to 12 carbon atoms is preferable.

  Among the phthalocyanine compounds and metal complexes thereof, 29H, 31H-phthalocyanine, copper phthalocyanine complex, zinc phthalocyanine complex, titanium phthalocyanine oxide complex, magnesium phthalocyanine complex, lead phthalocyanine complex or copper 4,4 ′, 4 ″, 4 '' '-Tetraaza-29H, 31H-phthalocyanine complex, more preferably 29H, 31H-phthalocyanine or copper phthalocyanine complex. In addition, the above kind of compound or a mixture of plural kinds of compounds may be used.

  Among the porphyrin compounds and metal complexes thereof, 5,10,15,20-tetraphenyl-21H, 23H-porphine, 5,10,15,20-tetraphenyl-21H, 23H-porphine cobalt (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II), 5,10,15,20- Tetraphenyl-21H, 23H-porphine nickel (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl)- 21H, 23H-porphine, 29H, 31H-tetrabenzo [b, g, l, q] porphine, 2 H, 31H-tetrabenzo [b, g, l, q] porphine cobalt (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine copper (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine zinc (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine nickel (II) or 29H, 31H-tetrabenzo [b, g, l, q] porphine vanadium (IV) oxide And preferably 5,10,15,20-tetraphenyl-21H, 23H-porphine or 29H, 31H-tetrabenzo [b, g, l, q] porphine. In addition, the above kind of compound or a mixture of plural kinds of compounds may be used.

As a method for forming a low molecular organic semiconductor compound, there are a method of forming a film by vapor deposition and a method of forming a film by converting a low molecular organic semiconductor compound precursor into a low molecular organic semiconductor compound after coating. The latter is preferred because of the process advantage that coating can be formed.
[Low molecular organic semiconductor compound precursor]
A low molecular organic semiconductor compound precursor is a substance that changes its chemical structure and is converted into a low molecular organic semiconductor compound by applying an external stimulus such as heating or light irradiation. The low molecular weight organic semiconductor compound precursor according to the present invention is preferably excellent in film formability. In particular, in order to be able to apply the coating method, it is preferable that the precursor itself can be applied in a liquid state, or the precursor is highly soluble in some solvent and can be applied as a solution. For this reason, the solubility with respect to the solvent of a low molecular organic-semiconductor compound precursor is usually 0.1 weight% or more, Preferably it is 0.5 weight% or more, More preferably, it is 1 weight% or more. On the other hand, the upper limit is not particularly limited, but is usually 50% by weight or less, preferably 40% by weight or less.

The type of the solvent is not particularly limited as long as it can uniformly dissolve or disperse the semiconductor precursor compound. For example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane or decane; toluene, xylene , Aromatic hydrocarbons such as cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; lower alcohols such as methanol, ethanol or propanol; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; ethyl acetate, butyl acetate or methyl lactate Esters such as: Chloroform, methylene chloride, dichloroethane, trichloroethane, trichloroethylene, and other halogen hydrocarbons; Ethyl ether, tetrahydrofuran, dioxane, and other ethers; Dimethyl Formamide or amides such as dimethylacetamide and the like. Of these, aromatic hydrocarbons such as toluene, xylene, cyclohexylbenzene, chlorobenzene, or orthodichlorobenzene; ketones such as acetone, methyl ethyl ketone, cyclopentanone, or cyclohexanone; chloroform, methylene chloride, dichloroethane, trichloroethane, or trichloroethylene Halogen hydrocarbons; ethers such as ethyl ether, tetrahydrofuran or dioxane. More preferably, non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene; non-halogen ketones such as cyclopentanone or cyclohexanone; non-halogen aliphatic ethers such as tetrahydrofuran or 1,4-dioxane is there. Particularly preferred are non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene. In addition, a solvent may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, it is preferable that the low molecular weight organic semiconductor compound precursor according to the present invention can be easily converted into a semiconductor compound. In the step of converting a low-molecular organic semiconductor compound precursor to a semiconductor compound, which will be described later, what kind of external stimulus is given to the semiconductor precursor is arbitrary, but usually heat treatment, light treatment, etc. are performed. Preferably, it is heat treatment. In this case, it is preferable that a part of the skeleton of the low molecular organic semiconductor compound precursor has a solvophilic group with respect to a predetermined solvent that can be eliminated by a reverse Diels-Alder reaction.

  Moreover, it is preferable that the low molecular organic-semiconductor compound precursor which concerns on this invention is converted into a semiconductor compound with a high yield through a conversion process. At this time, the yield of the semiconductor compound obtained by conversion from the low molecular organic semiconductor compound precursor is arbitrary as long as the performance of the organic photoelectric conversion element is not impaired, but the low molecular organic obtained from the precursor of the low molecular organic semiconductor compound The yield of the semiconductor compound is usually 90 mol% or more, preferably 95 mol% or more, more preferably 99 mol% or more.

  The low molecular organic semiconductor compound precursor according to the present invention is not particularly limited as long as it has the above-described characteristics, but specifically, compounds described in JP-A-2007-324587 can be used. Among these, a preferred example is a compound represented by the following formula (5).

In Formula (5), at least one of X ¹ and X ² represents a group that forms a π-conjugated divalent aromatic ring, and Z ¹ -Z ² is a group that can be removed by heat or light, The π-conjugated compound obtained by elimination of Z ¹ -Z ² represents a pigment molecule. X ¹ and X ² which are not a group that forms a π-conjugated divalent aromatic ring represent a substituted or unsubstituted ethenylene group.

In the compound represented by the formula (5), Z ¹ -Z ² is eliminated by heat or light as shown in the following chemical reaction formula to form a π-conjugated compound having high planarity. This produced π-conjugated compound is a semiconductor compound according to the present invention. In the present invention, the semiconductor compound preferably exhibits semiconductor characteristics.

  Examples of the compound represented by the formula (5) include the following. T-Bu represents a t-butyl group. M represents an atomic group in which a divalent metal atom or a trivalent or higher metal is bonded to another atom.

  Specific examples of the conversion of the low-molecular organic semiconductor compound precursor into a semiconductor compound include the following.

  The low molecular organic semiconductor compound precursor represented by the formula (5) may have a structure in which positional isomers exist, and in that case, may consist of a mixture of a plurality of positional isomers. A low-molecular organic semiconductor compound precursor composed of a plurality of positional isomers is preferable because it has a higher solubility in a solvent than a low-molecular organic semiconductor compound precursor composed of a single isomer component, so that coating film formation is easy. The reason why the solubility is improved when a mixture of multiple positional isomers is used is that the detailed mechanism is not clear, but the crystallinity of the compound itself is potentially retained, but the mixture of multiple isomers is mixed in the solution. Therefore, it is assumed that the three-dimensional regular intermolecular interaction becomes difficult. In the present invention, the solubility of the precursor mixture composed of a plurality of isomeric compounds in a non-halogen solvent is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more. Although there is no restriction | limiting in an upper limit, Usually, it is 50 weight% or less, More preferably, it is 40 weight% or less.

<P-i-n laminated structure>
As the layer structure of the active layer in the present invention, a p-type semiconductor compound and an n-type semiconductor compound are mixed as an intermediate layer of a thin film laminated type composed of a p-type semiconductor compound layer 103 and an n-type semiconductor compound layer 105 as shown in FIG. It is preferable to adopt a pin stack structure including the layer (i layer) 104 formed. The p-i-n stacked structure has an advantage that an active layer capable of generating a photocurrent can be formed thick.
Further, it is particularly preferable that the i layer 104 has a nanostructure in the p-i-n stacked structure because a route for transporting electrons and holes generated from the mixed junction layer can be formed and the photocurrent can be increased. For example, the nanostructure refers to a state in which a p-type semiconductor compound and an n-type semiconductor compound are in contact with each other by forming irregularities with a depth of about 1 nm to 500 nm.

As the n-type semiconductor compound used for the i layer, the fullerene compound according to the present invention may be used, or another n-type semiconductor compound may be used.
The manufacturing method of i layer is demonstrated. The i layer can be formed by mixing and applying a p-type semiconductor compound and an n-type semiconductor compound, but a nanostructure-forming compound may be used to control the nanostructure in a desired shape.

That is, first, a nanostructure may be formed using a p-type semiconductor compound and a nanostructure-forming compound, and then the nanostructure-forming compound and the n-type semiconductor compound may be replaced to form a film. As the compound for forming a nanostructure, an n-type semiconductor compound having solubility and other properties suitable for controlling the nanostructure can be used, and examples thereof include SIMEF2 described later.
According to this method, it is possible to preferably control the nanostructure while using a fullerene compound suitable for a photoelectric conversion element, and thus there is an advantage that an increase in photocurrent and an improvement in open-circuit voltage can be achieved independently. .

<Electrodes 101, 107>
The electrodes (101 and 107) according to the present invention have a function of collecting holes and electrons generated by light absorption. Therefore, the pair of electrodes includes an electrode 101 suitable for collecting holes (hereinafter also referred to as an anode) and an electrode 107 suitable for collecting electrons (hereinafter also referred to as a cathode). Is preferably used. Any one of the pair of electrodes may be translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. In addition, it is preferable that the transparent electrode has a solar ray transmittance of 70% or more in order to allow light to reach the active layer through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

The electrode 101 (anode) suitable for collecting holes is generally an electroconductive material having a work function higher than that of the cathode, and is an electrode having a function of smoothly extracting holes generated in the active layer 108. is there.
Examples of the material of the anode 101 include conductive metal oxidation such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, or zinc oxide. A metal such as gold, platinum, silver, chromium or cobalt, or an alloy thereof.

  Since these substances have a high work function, they are preferable, and further, a conductive polymer material represented by PEDOT / PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid can be laminated. When laminating such a conductive polymer, the work function of the conductive polymer material is high, so that it is suitable for cathodes such as Al and Mg, even if it is not a material with a high work function as described above. Metals can also be widely used.

PEDOT / PSS doped with polystyrene sulfonic acid in a polythiophene derivative, or a conductive polymer material doped with iodine or the like in polypyrrole or polyaniline can also be used as the anode material.
When the anode 101 is a transparent electrode, it is preferable to use a conductive metal oxide having translucency such as ITO, zinc oxide or tin oxide, and ITO is particularly preferable.

  The film thickness of the anode 101 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the film thickness of the anode 101 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the anode 101 is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. it can. When used for a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

The sheet resistance of the anode 101 is not particularly limited, but is usually 1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.
A method for forming the anode 101 includes a vacuum film formation method such as vapor deposition or sputtering, or a method of forming a film by applying an ink containing nanoparticles or a precursor.

The electrode 107 (cathode) suitable for collecting electrons is a conductive material generally having a higher work function than that of the anode, and is an electrode having a function of smoothly extracting electrons generated in the active layer 108. It is characterized by being adjacent to the electron extraction layer 106 of the present invention.
Examples of the material of the cathode 107 include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium, and magnesium, and alloys thereof; Examples include inorganic salts such as lithium and cesium fluoride; metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. These materials are preferred because they have a low work function. Similarly to the anode 101, a material having a high work function suitable for the anode 101 can also be used for the cathode 107 by using an n-type semiconductor such as titania having conductivity for the electron extraction layer 106. From the viewpoint of electrode protection, the anode 101 material is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium, or indium and an alloy using these metals.

  The film thickness of the cathode 107 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 500 nm or less, more preferably 1 μm or less. When used for a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance. When the film thickness of the cathode 107 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the cathode 107 is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. it can.

The sheet resistance of the cathode 107 is not particularly limited, but is usually 1000Ω / □ or less, preferably 500Ω / □ or less, and more preferably 100Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more.
As a method for forming the cathode 107, there are a vacuum film forming method such as vapor deposition or sputtering, or a method of forming a film by applying an ink containing nanoparticles or a precursor.

Further, the anode 101 or the cathode 107 may be laminated in two or more layers, and characteristics (electric characteristics, wetting characteristics, etc.) may be improved by surface treatment.
After laminating the anode 101 and the cathode 107, the photoelectric conversion element is usually 50 ° C. or higher, preferably 80 ° C. or higher, and usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. It is preferable to heat (this process may be referred to as an annealing process). It is preferable to set the temperature of the annealing treatment step to 50 ° C. or higher because an effect of improving the adhesion between the electron extraction layer 106 and the electrode 107 and / or the electron extraction layer 106 and the active layer 108 can be obtained. It is preferable that the temperature of the annealing process be 300 ° C. or lower because the possibility that the organic compound in the active layer is thermally decomposed is reduced.

In addition, about temperature operation, you may heat in steps within the said range.
The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The annealing treatment is preferably terminated when the open circuit voltage, the short circuit current, and the fill factor, which are parameters of the solar cell performance, reach a certain value. Further, it is preferable that the annealing is performed under normal pressure and in an inert gas atmosphere.

The annealing treatment step improves the adhesion between the electron extraction layer and the electrode and / or the electron extraction layer and the active layer, thereby improving the thermal stability and durability of the photoelectric conversion element. The effect of promoting self-organization is obtained.
As a method for heating, the photoelectric conversion element may be placed on a heat source such as a hot plate, or the photoelectric conversion element may be put in a heating atmosphere such as an oven. Moreover, it may be a batch type or a continuous type.

<Board>
The photoelectric conversion element according to the present invention usually has a substrate serving as a support. That is, an electrode, an active layer, and preferably a buffer layer described later are formed on the substrate. The material of the substrate (substrate material) is arbitrary as long as the effects of the present invention are not significantly impaired. Preferred examples of the substrate material include inorganic materials such as quartz, glass, sapphire and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine Resin film, polyolefin such as vinyl chloride and polyethylene; organic materials such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene and epoxy resin; paper materials such as paper and synthetic paper; stainless steel, Examples thereof include a composite material obtained by coating or laminating a surface of a metal such as titanium or aluminum to provide insulation. Examples of the glass include soda glass, blue plate glass, and non-alkali glass. About the material of glass, since there are few elution ions from glass, an alkali free glass is preferable.

  There is no restriction | limiting in the shape of a board | substrate, For example, shapes, such as a board, a film, or a sheet | seat, can be used. The thickness of the substrate is not particularly limited, but is usually 5 μm or more, preferably 20 μm or more, and is usually 20 mm or less, preferably 10 mm or less. By setting the thickness of the substrate within this range, it is preferable because the strength of the semiconductor device can be sufficiently maintained, the cost for the substrate is suppressed, and the weight does not increase. Moreover, when a board | substrate is glass, Preferably it is 0.01 mm or more, More preferably, 0.1 mm or more is good. On the other hand, it is preferably 1 cm or less, more preferably 0.5 cm or less. By setting the thickness of the glass substrate within this range, it is preferable because the mechanical strength can be sufficiently maintained, the possibility of cracking is reduced, and the weight of the substrate is not increased.

<Buffer layer (102, 106)>
The photoelectric conversion element of the present invention preferably further includes one or more buffer layers in addition to the pair of electrodes (101, 107) and the active layer 108 disposed therebetween. The buffer layer can be classified into a hole extraction layer and an electron extraction layer, and can be provided between the active layer 108 and the electrodes (101, 107), respectively.

<Electron extraction layer 106>
The material of the electron extraction layer is not particularly limited as long as it can improve the efficiency of extracting electrons from the active layer 108 containing the p semiconductor compound and the n semiconductor compound to the electrode (cathode 107). . Specifically, an inorganic compound or an organic compound is mentioned.

As the material of the inorganic compound, an alkali metal salt such as Li, Na, K, or Cs; an n-type oxide semiconductor such as titanium oxide (TiOx) or zinc oxide (ZnO) is desirable.
As the alkali metal salt, a fluoride salt such as LiF, NaF, KF or CsF is desirable. Although the operation mechanism of such a material is unknown, it is conceivable to reduce the work function of the cathode in combination with an electron extraction electrode (cathode) such as Al and increase the voltage applied to the inside of the solar cell element.

Specific examples of organic compound materials include bathocuproin (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato) aluminum (Alq3), boron compounds, oxadiazole compounds, benzimidazole compounds, and naphthalenetetracarboxylic acids. Examples include acid anhydrides (NTCDA), perylene tetracarboxylic acid anhydrides (PTCDA), and phosphine compounds having a double bond with a Group 16 element such as a phosphine oxide compound or a phosphine sulfide compound. Among them, a phosphine compound having a double bond with a group 16 element substituted with an aryl group, such as a phosphine oxide compound substituted with an aryl group or a phosphine sulfide compound substituted with an aryl group,
More preferably, a triarylphosphine oxide compound, a triarylphosphine sulfide compound, an aromatic hydrocarbon compound having two or more diarylphosphine oxide units, an aromatic hydrocarbon compound or diarylphosphine oxide unit having two or more diarylphosphine sulfide units Is an aromatic hydrocarbon compound having two or more. The aryl group may be substituted with an alkyl group substituted with a fluorine atom such as a fluorine atom or a perfluoroalkyl group. In addition to the above materials, alkali metal or alkaline earth metal may be doped.

  The group 16 element substituted with an aryl group and the phosphine compound having a double bond are represented by the following general formula (6).

In the formula, R ⁸ and R ⁹ each independently represents an aromatic group which may have a substituent, and n represents an integer of 1 or more. R ¹⁰ is an aromatic group. U is a Group 16 element.
In the formula, R ⁸ and R ⁹ are each independently an aromatic group which may have a substituent. Preferably, at least one of R ⁸ and R ⁹ is a condensed polycyclic aromatic group which may have a substituent.

  Aromatic groups include phenyl, naphthyl, phenanthryl, biphenylenyl, triphenylene, anthryl, pyrenyl, fluorenyl, azulenyl, acenaphthenyl, fluoranthenyl, naphthacenyl, perylenyl, pentacenyl or Aromatic hydrocarbon group such as triphenylenyl group; pyridyl group, thienyl group, furyl group, pyrrole group, oxazole group, thiazole group, oxadiazole group, thiadiazole group, pyrazyl group, pyrimidyl group, pyrazoyl group, imidazoyl group, benzothienyl group Group, dibenzofuryl group, dibenzothienyl group, phenylcarbazoyl, phenoxathienyl group, xanthenyl group, benzofuranyl group, thianthenyl group, indolizinyl group, phenoxazinyl group, phenothiazinyl group, acridin Group, phenanthridinyl group, quinolyl group, isoquinolyl group, an aromatic heterocyclic group such as indolyl, or quinoxalinyl group. Preferably, an aromatic hydrocarbon group such as phenyl group, naphthyl group, phenanthryl group, triphenylene group, anthryl group, pyrenyl group, fluorenyl group, acenaphthenyl group, fluoranthenyl group, perylenyl group or triphenylenyl group; pyridyl group, pyrazyl group , Pyramidyl group, pyrazoyl group, quinolyl group, isoquinolyl group, imidazoyl group, acridinyl group, phenanthridinyl group, quinoxalinyl group, dibenzofuryl group, dibenzothienyl group, phenylcarbazoyl, xanthenyl group or phenoxazinyl group It is a cyclic group.

The ring forming the condensed polycyclic aromatic group preferably has a cyclic alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a substituent. An aromatic heterocyclic group that may be used.
Specific examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. A specific example of the aromatic hydrocarbon group is a phenyl group. Specific examples of the aromatic heterocyclic group include pyridyl group, thienyl group, furyl group, pyrrole group, oxazole group, thiazole group, oxadiazole group, thiadiazole group, pyrazyl group, pyrimidyl group, pyrazoyl group or imidazolyl group. Can be mentioned. The aromatic heterocyclic group is preferably a pyridyl group or a thienyl group.

  The substituent that the cyclic alkyl group, aromatic hydrocarbon group and aromatic heterocyclic group may have is not particularly limited, but includes a halogen atom, a hydroxyl group, a cyano group, an amino group, a carboxyl group, a carbonyl group, Acetyl group, sulfonyl group, silyl group, boryl group, nitrile group, alkyl group, fluorinated alkyl group, alkenyl group, alkynyl group, alkoxy group, aromatic hydrocarbon group or aromatic heterocyclic group are preferred.

  The condensed polycyclic aromatic group is a group in which the ring is condensed. Preferably, a condensed polycyclic hydrocarbon group such as a phenanthryl group, an anthryl group, a pyrenyl group, a fluoranthenyl group, a naphthacenyl group, a perylenyl group, a pentacenyl group, or a triphenylenyl group; a phenoxazinyl group, a phenothiazinyl group, an acridinyl group, or a phenant Examples thereof include condensed polycyclic heterocyclic groups such as lysinyl groups.

U is a Group 16 element. Among these, an oxygen atom or a sulfur atom is preferable.
Preferable specific examples of the phosphine oxide compound substituted with an aryl group or the phosphine sulfide compound substituted with an aryl group of the present invention include those exemplified below. However, as long as the gist of the present invention is not exceeded, it is not limited to these.

  Examples other than the phosphine oxide compound substituted with the aryl group and the phosphine sulfide compound substituted with the aryl group include the following.

The glass transition temperature of the organic compound used in the electron extraction layer according to the present invention is not particularly limited, but is preferably 50 ° C. or higher, more preferably 80 ° C. or higher. The upper limit is not particularly limited, but it is a compound whose glass transition temperature by DSC method is not observed below 300 ° C.
The glass transition temperature according to the present invention is defined as the point at which the specific heat of an organic compound in an amorphous state is changed to a temperature at which local molecular motion is initiated by thermal energy. When the temperature further increases, the solid structure changes and crystallization occurs (the temperature at this time is defined as the crystallization temperature (Tc)). When the temperature rises further, it generally melts at the melting point (Tm) and changes to a liquid state. However, the molecules may be decomposed or sublimated at a high temperature, and their phase transition may not be observed. What is necessary is just to measure a glass transition temperature by a well-known method, for example, the above-mentioned DSC method is mentioned.

  When the glass transition temperature of the organic compound used in the electron extraction layer is 50 ° C. or higher, the structure of the compound changes with respect to external stress such as applied electric field, flowing current, stress due to bending or temperature change. This is preferable in terms of durability. Furthermore, since there is a tendency that the crystallization of the thin film of the organic compound does not proceed easily, the stability of the organic extraction layer is improved by making the organic compound difficult to change between the amorphous state and the crystalline state in the operating temperature range. Therefore, it is preferable in terms of durability. Among the compounds used in the electron extraction layer of the present invention, there are compounds in which the glass transition temperature by DSC method is not observed below 300 ° C., which is preferable because it has high thermal stability. .

  The thickness of the electron extraction layer 106 is not particularly limited, but is usually 0.01 nm or more. On the other hand, it is usually 40 nm or less, preferably 20 nm or less. When the film thickness of the electron extraction layer 106 is 0.01 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer 106 is 40 nm or less, electrons are easily extracted, and photoelectric conversion is performed. Efficiency is improved.

<Hole extraction layer 102>
The material of the hole extraction layer 102 is not particularly limited as long as the hole extraction efficiency from the active layer 108 including the p-type semiconductor compound and the n-type semiconductor compound to the electrode 101 (anode) can be improved. Specific examples include conductive organic compounds such as polythiophene, polypyrrole, polyacetylene, and triphenylenediamine. A thin film of metal such as Au, In, Ag, or Pd can also be used. Furthermore, a thin film of metal or the like may be formed alone or in combination with the above organic material.

The thickness of the hole extraction layer 102 is not particularly limited, but is usually 2 nm or more. On the other hand, it is usually 40 nm or less, preferably 20 nm or less. When the film thickness of the hole extraction layer 102 is 2 nm or more, it functions as a buffer material. When the film thickness of the hole extraction layer 102 is 40 nm or less, holes are easily extracted, Conversion efficiency is improved.
[Solar cell module]
It is preferable that the photoelectric conversion element of this invention is used as a thin film solar cell as a solar cell element.

  FIG. 2 is a cross-sectional view schematically showing the configuration of a thin film solar cell as one embodiment of the present invention. As shown in FIG. 2, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 in this order, and further a sealing material 11 that seals the edges of the weatherproof protective film 1 and the back sheet 10. I have. And light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 is formed, and the solar cell element 6 generates power. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[Weather-resistant protective film 1]
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes.
Some components of the solar cell element 6 are deteriorated by temperature change, humidity change, natural light, and / or erosion caused by wind and rain. Therefore, by covering the solar cell element 6 with the weather-resistant protective film 1, the solar cell element 6 and the like are protected from weather changes and the like, and the power generation capacity is kept high.

Since the weather resistant protective film 1 is located on the outermost layer of the thin film solar cell 14, the surface covering material of the thin film solar cell 14 such as weather resistance, heat resistance, transparency, water repellency, stain resistance and / or mechanical strength is provided. It is preferable to have a property suitable for the above and to maintain it for a long period of time in outdoor exposure.
Moreover, the weather-resistant protective film 1 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, more preferably 90% or more, and particularly preferably 95%.

  Furthermore, since the thin-film solar cell 14 is often heated by receiving light, it is preferable that the weather-resistant protective film 1 also has heat resistance. From this viewpoint, the melting point of the constituent material of the weather-resistant protective film 1 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower. Preferably it is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility that the weather resistant protective film 1 is melted and deteriorated when the thin film solar cell 14 is used.

  The material which comprises the weather-resistant protective film 1 is arbitrary as long as it can protect the solar cell element 6 from a weather change. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicone resins, and polycarbonate resins.

  Among them, fluorine resin is preferable, and specific examples thereof include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoride. Propylene copolymer (FEP), 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Can be mentioned.

In addition, the weather-resistant protective film 1 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the weather-resistant protective film 1 may be formed with the single layer film, the laminated | multilayer film provided with the film of 2 or more layers may be sufficient as it.
The thickness of the weather-resistant protective film 1 is not particularly specified, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

Moreover, you may perform surface treatments, such as a corona treatment and / or a plasma treatment, for the weather-resistant protective film 1 in order to improve adhesiveness with another film.
The weatherproof protective film 1 is preferably provided on the outer side as much as possible in the thin-film solar cell 14. This is because more of the constituent members of the thin-film solar cell 14 can be protected.

[UV cut film 2]
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays.
Some components of the thin film solar cell 14 are deteriorated by ultraviolet rays. Some of the gas barrier films 3, 9 and the like are deteriorated by ultraviolet rays depending on the type. there,
The ultraviolet cut film 2 is provided in the light receiving portion of the thin-film solar cell 14, and the ultraviolet cut film 2 covers the light receiving surface 6a of the solar cell element 6, so that the solar cell element 6 and, if necessary, the gas barrier films 3 and 9 are exposed to ultraviolet rays. The power generation capacity can be maintained at a high level.

The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is such that the transmittance of ultraviolet rays (for example, wavelength 300 nm) is preferably 50% or less, more preferably 30% or less, and particularly preferably. 10% or less.
Further, the ultraviolet cut film 2 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the ultraviolet cut film 2 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the ultraviolet cut film 2 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. If the melting point is too low, the ultraviolet cut film 2 may melt when the thin film solar cell 14 is used.

Moreover, the ultraviolet cut film 2 has a high softness | flexibility, its adhesiveness with an adjacent film is favorable, and what can cut water vapor | steam and oxygen is preferable.
The material which comprises the ultraviolet cut film 2 is arbitrary if the intensity | strength of an ultraviolet-ray can be weakened. Examples of the material include films formed by blending an ultraviolet absorber with an epoxy, acrylic, urethane, or ester resin. Further, a film in which a layer of an ultraviolet absorbent dispersed or dissolved in a resin (hereinafter referred to as “ultraviolet absorbing layer” as appropriate) is formed on a base film may be used.

  As the ultraviolet absorber, for example, salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones can be used. Of these, benzophenone and benzotriazole are preferable. Examples of this include various aromatic organic compounds such as benzophenone and benzotriazole. In addition, a ultraviolet absorber may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

As described above, a film in which an ultraviolet absorbing layer is formed on a base film can be used as the ultraviolet absorbing film. Such a film can be produced, for example, by applying a coating solution containing an ultraviolet absorber on a substrate film and drying it.
Although the material of a base film is not specifically limited, For example, polyester is mentioned at the point from which the balance of heat resistance and a softness | flexibility is obtained.

  Application | coating can be performed by arbitrary methods. Examples thereof include reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor method, impregnation / coating method and curtain coating method. In addition, these methods may be performed alone or in any combination of two or more.

  The solvent used for the coating solution is not particularly limited as long as it can uniformly dissolve or disperse the UV absorber. For example, a liquid resin can be used as a solvent, and examples thereof include various synthetic resins such as polyester, acrylic, polyamide, polyurethane, polyolefin, polycarbonate, or polystyrene. It is done. Further, for example, natural polymers such as gelatin and cellulose derivatives; water, alcohol mixed solutions such as water and ethanol, and the like can also be used as the solvent. Further, an organic solvent may be used as the solvent. If an organic solvent is used, it becomes possible to dissolve or disperse the pigment and the resin, and to improve the coatability. In addition, 1 type may be used for a solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

The coating solution may further contain a surfactant. Use of the surfactant improves the dispersibility of the ultraviolet absorbing dye in the resin. Thereby, in an ultraviolet absorption layer, generation | occurrence | production of the dent by the adhesion | attachment of the leakage of a micro bubble, a foreign material, etc. and / or a repellency in a drying process is suppressed.

As the surfactant, a known surfactant (cationic surfactant, anionic surfactant or nonionic surfactant) can be used. Among these, a silicon-based surfactant or a fluorine-based surfactant is preferable. In addition, 1 type may be used for surfactant and it may use 2 or more types together by arbitrary combinations and a ratio.

In addition, the drying after apply | coating a coating liquid to a base film can employ | adopt well-known drying methods, such as hot air drying and drying by an infrared heater, for example. Among these, hot air drying with a high drying speed is preferable.
Examples of specific products of the ultraviolet cut film 2 include cut ace (MKV Plastic Co., Ltd.).

In addition, the ultraviolet cut film 2 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Further, the ultraviolet cut film 2 may be formed of a single layer film, but may be a laminated film including two or more layers.
The thickness of the ultraviolet cut film 2 is not particularly defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase the absorption of ultraviolet rays, and decreasing the thickness tends to increase the transmittance of visible light.

Although the ultraviolet cut film 2 should just be provided in the position which covers at least one part of the light-receiving surface 6a of the solar cell element 6, Preferably it is provided in the position which covers all the light-receiving surfaces 6a of the solar cell element 6. FIG.
However, the ultraviolet cut film 2 may be provided at a position other than the position covering the light receiving surface 6 a of the solar cell element 6.
[Gas barrier film 3]
The gas barrier film 3 is a film that prevents permeation of water and oxygen.

The solar cell element 6 tends to be vulnerable to moisture and oxygen. In particular, transparent electrodes such as ZnO: Al, compound semiconductor solar cell elements, and organic solar cell elements may be deteriorated by moisture and oxygen. Therefore, by covering the solar cell element 6 with the gas barrier film 3, the solar cell element 6 can be protected from water and oxygen, and the power generation capacity can be kept high.
The degree of moisture resistance required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the water vapor permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ g / m ² / day or less. Is preferably 1 × 10 ⁻² g / m ² / day or less, more preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ^2. / Day or less is particularly preferable, 1 × 10 ⁻⁵ g / m ² / day or less is particularly preferable, and 1 × 10 ⁻⁶ g / m ² / day or less is particularly preferable.

Moreover, when the solar cell element 6 is an organic solar cell element, it is preferable that the water vapor permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ g / m ² / day or less. It is more preferably 1 × 10 ⁻² g / m ² / day or less, further preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ² / day. Among them, the following is particularly preferable, and it is particularly preferably 1 × 10 ⁻⁵ g / m ² / day or less, and particularly preferably 1 × 10 ⁻⁶ g / m ² / day or less. The more water vapor has to pass through, the lower the degradation caused by the reaction of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 with moisture, thus increasing the power generation efficiency and extending the life.

The degree of oxygen permeability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. For example, when the solar cell element 6 is an organic solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. The deterioration due to oxidation of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 is suppressed as the oxygen does not permeate.

  Conventionally, it has been difficult to mount the gas barrier film 3 having such a high moisture-proof and oxygen-blocking capability, so that a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element is realized. Although it was difficult to carry out, implementation of the thin film solar cell 14 which utilized the outstanding properties, such as a compound semiconductor type solar cell element and an organic solar cell element, becomes easy by applying such a gas barrier film 3.

  Further, the gas barrier film 3 is preferably one that transmits visible light from the viewpoint of not preventing the light absorption of the solar cell element 6. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the gas barrier film 3 also has heat resistance. From this viewpoint, the melting point of the constituent material of the gas barrier film 3 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. It is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility that the gas barrier film 3 is melted and deteriorated when the thin film solar cell 14 is used.

The specific configuration of the gas barrier film 3 is arbitrary as long as the solar cell element 6 can be protected from water. However, since the manufacturing cost increases as the amount of water vapor or oxygen that can permeate the gas barrier film 3 increases, it is preferable to use an appropriate film considering these points comprehensively.
Hereinafter, the configuration of the gas barrier film 3 will be described with examples.

The following two examples are preferable as the configuration of the gas barrier film 3.
The first example is a film in which an inorganic barrier layer is disposed on a plastic film substrate. In this case, the inorganic barrier layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the number of inorganic barrier layers formed on both surfaces may be the same or different.

The second example is a film in which a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is formed on a plastic film substrate. At this time, a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is regarded as one unit, and this unit layer is composed of one unit (one inorganic barrier layer and one polymer layer are combined into one unit). (Meaning of unit) may be formed, but two or more units may be formed. For example, 2 to 5 units may be laminated.

  The unit layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the numbers of inorganic barrier layers and polymer layers formed on both surfaces may be the same or different. In addition, when forming a unit layer on a plastic film substrate, an inorganic barrier layer may be formed and then a polymer layer may be formed thereon, or after forming a polymer layer and forming an inorganic barrier layer. Also good.

(Plastic film substrate)
The plastic film substrate used for the gas barrier film 3 is not particularly limited as long as it is a film capable of holding the above-described inorganic barrier layer and polymer layer, and can be appropriately selected from the purpose of use of the gas barrier film 3 and the like.
Examples of the material for the plastic film substrate include polyester resin, polyarylate resin, polyethersulfone resin, fluorene ring-modified polycarbonate resin, alicyclic modified polycarbonate resin, and acryloyl compound. It is also preferable to use a condensation polymer containing spirobiindane or spirobichroman. Among the polyester resins, biaxially stretched polyethylene terephthalate (PET) or biaxially stretched polyethylene naphthalate (PEN) is excellent in thermal dimensional stability, and is preferably used as a plastic film substrate.

In addition, 1 type may be used for the material of a plastic film base material, and 2 or more types may be used together by arbitrary combinations and a ratio.
The thickness of the plastic film substrate is not particularly defined, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

  The plastic film substrate is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  An anchor coat agent layer (anchor coat layer) may be formed on the plastic film substrate in order to improve adhesion to the inorganic barrier layer. Usually, the anchor coat layer is formed by applying an anchor coat agent. Examples of the anchor coating agent include polyester resins, urethane resins, acrylic resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate-containing resins, and copolymers thereof. Among them, at least one resin selected from polyester resins, urethane resins and acrylic resins, and at least one resin selected from oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins and isocyanate group-containing resins. What combined the above resin is preferable. In addition, an anchor coat agent may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The thickness of the anchor coat layer is usually 0.005 μm or more, preferably 0.01 μm or more, and usually 5 μm or less, preferably 1 μm or less. If the thickness is less than or equal to the upper limit of this range, the slipperiness is good, and there is almost no peeling from the plastic film substrate due to the internal stress of the anchor coat layer itself. Moreover, if it is the thickness more than the lower limit of this range, a uniform thickness can be maintained and it is preferable.

In addition, in order to improve the applicability and adhesion of the anchor coating agent to the plastic film substrate, the plastic film substrate may be subjected to a surface treatment such as normal chemical treatment or discharge treatment before application of the anchor coating agent. Good.
(Inorganic barrier layer)
The inorganic barrier layer is usually a layer formed of a metal oxide, nitride or oxynitride. In addition, the metal oxide, nitride, and oxynitride which form an inorganic barrier layer may be 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Examples of the metal oxide include oxides such as Si, Al, Mg, In, Ni, Sn, Zn, Ti, Cu, Ce, and Ta. Among these, in order to achieve both high barrier properties and high transparency, it is preferable to include aluminum oxide or silicon oxide, and it is particularly preferable to include silicon oxide from the viewpoint of moisture permeability and light transmittance.
The ratio of each metal atom to oxygen atom is also arbitrary, but in order to improve the transparency of the inorganic barrier layer and prevent coloring, the oxygen atom ratio should be extremely small from the stoichiometric ratio of the oxide. Is desirable. On the other hand, in order to improve the denseness of the inorganic barrier layer and increase the barrier property, it is desirable to reduce oxygen atoms. From this viewpoint, for example, when SiO _x is used as the metal oxide, the value of x is particularly preferably 1.5 to 1.8. For example, when AlO _x is used as the metal oxide, the value of x is particularly preferably 1.0 to 1.4.

  When the inorganic barrier layer is composed of two or more kinds of metal oxides, it is desirable that the metal oxide includes aluminum oxide and silicon oxide. Among them, when the inorganic barrier layer is made of aluminum oxide and silicon oxide, the ratio of aluminum and silicon in the inorganic barrier layer can be arbitrarily set, but the ratio of Si / Al is usually 1/9 or more, preferably 2/8 or more, and usually 9/1 or less, preferably 2/8 or less.

When the thickness of the inorganic barrier layer is increased, the barrier property tends to be increased. However, it is desirable to reduce the thickness in order to prevent cracking and prevent cracking when bent. Therefore, the appropriate thickness of the inorganic barrier layer is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 200 nm or less.
Although there is no restriction | limiting in the film-forming method of an inorganic barrier layer, Generally, it can carry out by sputtering method, a vacuum evaporation method, an ion plating method, plasma CVD method etc. For example, the sputtering method can be formed by a reactive sputtering method using plasma using one or more metal targets and oxygen gas as raw materials.

(Polymer layer)
Any polymer can be used for the polymer layer, and for example, a film that can be formed in a vacuum chamber can be used. In addition, the polymer which comprises a polymer layer may use 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
A wide variety of compounds can be used as the compound that gives the polymer, and examples include the following (i) to (vii). In addition, 1 type may be used for a monomer and it may use 2 or more types together by arbitrary combinations and a ratio.

(I) Examples include siloxanes such as hexamethyldisiloxane. An example of a method for forming a polymer layer in the case of using hexamethyldisiloxane is to introduce hexamethyldisiloxane as a vapor into a parallel plate type plasma apparatus using an RF electrode, to cause a polymerization reaction in the plasma, The polymer layer can be formed as a polysiloxane thin film by being deposited on a plastic film substrate.

  (Ii) Examples include paraxylylene such as diparaxylylene. As an example of a method for forming a polymer layer in the case of using diparaxylylene, first, the vapor of diparaxylylene is heated at 650 ° C. to 700 ° C. in a high vacuum to generate thermal radicals. And the polymer layer can be formed by guiding the radical monomer vapor into the chamber and adsorbing it on the plastic film substrate, and at the same time proceeding radical polymerization reaction to deposit polyparaxylylene.

(Iii) For example, a monomer capable of alternately repeating addition polymerization of two kinds of monomers can be mentioned. The polymer thus obtained is a polyaddition polymer. Examples of the polyaddition polymer include polyurethane (diisocyanate / glycol), polyurea (diisocyanate / diamine), polythiourea (dithioisocyanate / diamine), polythioether urethane (bisethyleneurethane / dithiol), polyimine ( Bisepoxy / primary amine), polypeptide amide (bisazolactone / diamine) or polyamide (diolefin / diamide).

(Iv) For example, an acrylate monomer can be mentioned. The acrylate monomer includes monofunctional, bifunctional or polyfunctional acrylate monomers, and any of them may be used. However, in order to obtain an appropriate evaporation rate, degree of cure and / or cure rate, it is preferable to use a combination of two or more of the above acrylate monomers.
Examples of monofunctional acrylate monomers include aliphatic acrylate monomers, alicyclic acrylate monomers, ether acrylate monomers, cyclic ether acrylate monomers, aromatic acrylate monomers, hydroxyl group-containing acrylate monomers, or carboxy group-containing acrylate monomers. There are, but any can be used.

  (V) Monomers capable of obtaining a photocationically cured polymer, such as epoxy and oxetane, are exemplified. As an epoxy-type monomer, an alicyclic epoxy-type monomer, a bifunctional monomer, or a polyfunctional oligomer etc. are mentioned, for example. Examples of the oxetane-based monomer include monofunctional oxetane, bifunctional oxetane, and oxetane having a silsesquioxane structure.

(Vi) An example is vinyl acetate. When vinyl acetate is used as a monomer, polyvinyl alcohol is obtained by saponifying the polymer, and this polyvinyl alcohol can be used as a polymer.
(Vii) For example, acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, maleic acid,
Examples thereof include unsaturated carboxylic acids such as itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride or itaconic anhydride. These constitute a copolymer with ethylene, and the copolymer can be used as a polymer. Furthermore, a mixture thereof, a mixture obtained by mixing glycidyl ether compounds, and a mixture with an epoxy compound can also be used as the polymer.

There is no restriction | limiting in the polymerization method of a monomer when superposing | polymerizing the said monomer and producing | generating a polymer. However, the polymerization is usually carried out after a composition containing a monomer is applied or vapor deposited to form a film. As an example of the polymerization method, when a thermal polymerization initiator is used, the polymerization is started by contact heating with a heater or the like, or radiation heating such as infrared rays or microwaves. Moreover, when a photoinitiator is used, an active energy ray is irradiated and polymerization is started. Various light sources can be used when irradiating active energy rays, such as mercury arc lamps, xenon arc lamps, fluorescent lamps, carbon arc lamps, tungsten-halogen radiation lamps, or irradiation light from sunlight. Can do. Further, electron beam irradiation or atmospheric pressure plasma treatment can also be performed.

Examples of the method for forming the polymer layer include a coating method and a vacuum film forming method.
When the polymer layer is formed by a coating method, for example, methods such as roll coating, gravure coating, knife coating, dip coating, curtain flow coating, spray coating, and bar coating can be used. Moreover, you may make it apply | coat the coating liquid for polymer layer formation in mist form. In this case, the average particle diameter of the droplets may be adjusted to an appropriate range. For example, in the case of forming a coating liquid containing a polymerizable monomer in the form of a mist on a plastic film substrate, the droplets The average particle size of is usually 5 μm or less, preferably 1 μm or less.

On the other hand, when forming a polymer layer by a vacuum film-forming method, film-forming methods, such as vapor deposition and plasma CVD, are mentioned, for example.
The thickness of the polymer layer is not particularly limited, but is usually 10 nm or more, and is usually 5000 nm or less, preferably 2000 nm or less, more preferably 1000 nm or less. By increasing the thickness of the polymer layer, the uniformity of the thickness can be easily obtained, and structural defects of the inorganic barrier layer can be efficiently filled with the polymer layer, and the barrier property tends to be improved. In addition, by reducing the thickness of the polymer layer, the barrier property can be improved because the polymer layer itself is less likely to crack due to an external force such as bending.

Particularly suitable gas barrier film 3 includes, for example, a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).
In addition, the gas barrier film 3 may be formed with 1 type of material, and may be formed with 2 or more types of materials. The gas barrier film 3 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the gas barrier film 3 is not particularly defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and is usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase gas barrier properties, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  As long as the gas barrier film 3 covers the solar cell element 6 and can be protected from moisture and oxygen, the formation position is not limited. However, the front surface of the solar cell element 6 (surface on the light receiving surface side, lower surface in FIG. 2) and It is preferable to cover the back surface (the surface opposite to the light receiving surface; the upper surface in FIG. 2). This is because the front and back surfaces of the thin film solar cell 14 are often formed in a larger area than the other surfaces. In this embodiment, the gas barrier film 3 covers the front surface of the solar cell element 6, and a gas barrier film 9 described later covers the back surface of the solar cell element 6. Then, the edges of the gas barrier films 3 and 9 are sealed with the sealing material 11, and the solar cell element 6 is placed in the space surrounded by the gas barrier films 3 and 9 and the sealing material 11. It can be protected from oxygen. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[Getter material film 4]
The getter material film 4 is a film that absorbs moisture and / or oxygen. Some components of the solar cell element 6 are deteriorated by moisture as described above, and some are deteriorated by oxygen. Therefore, by covering the solar cell element 6 with the getter material film 4, the solar cell element 6 and the like are protected from moisture and / or oxygen, and the power generation capacity is kept high.

  Here, unlike the gas barrier film 3 as described above, the getter material film 4 does not prevent moisture permeation but absorbs moisture. By using a film that absorbs moisture, when the solar cell element 6 is covered with the gas barrier film 3 or the like, the getter material film 4 absorbs moisture that slightly enters the space formed by the gas barrier films 3 and 9 and the sealing material 11. Can be captured and the influence of moisture on the solar cell element 6 can be eliminated.

The degree of water absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, preferably 0.5 mg / cm ² or more, more preferably 1 mg / cm ² or more. The higher this value, the higher the water absorption capacity, and the deterioration of the solar cell element 6 can be suppressed. Moreover, although there is no restriction | limiting in an upper limit, it is usually 10 mg / cm < ² > or less.
Further, when the solar cell element 6 is covered with the gas barrier films 3, 9, etc., because the getter material film 4 absorbs oxygen, it slightly enters the space formed by the gas barrier films 3, 9 and the sealing material 11. Oxygen is captured by the getter material film 4 and the influence of the oxygen on the solar cell element 6 can be eliminated.

  Furthermore, the getter material film 4 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the getter material film 4 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the getter material film 4 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. By increasing the melting point, it is possible to reduce the possibility that the getter material film 4 melts and deteriorates when the thin-film solar cell 14 is used.

  The material constituting the getter material film 4 is arbitrary as long as it can absorb moisture and / or oxygen. Examples of the material include alkali metal, alkaline earth metal or alkaline earth metal oxides; alkali metal or alkaline earth metal hydroxides; silica gel, zeolitic compounds, magnesium sulfate. And sulfates such as sodium sulfate and nickel sulfate; and organometallic compounds such as aluminum metal complexes and aluminum oxide octylates. Specifically, examples of the alkaline earth metal include Ca, Sr, and Ba. Examples of the alkaline earth metal oxide include CaO, SrO, and BaO. In addition, Zr-Al-BaO and aluminum metal complexes are also included. Specific product names include, for example, OleDry (Futaba Electronics).

Examples of the substance that absorbs oxygen include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, and iron oxide. In addition, Fe, Mn, Zn, and inorganic salts such as sulfates, chlorides, and nitrates of these metals are also included.
In addition, the getter material film 4 may be formed of one type of material or may be formed of two or more types of materials. The getter material film 4 may be formed of a single layer film, but may be a laminated film including two or more layers.

The thickness of the getter material film 4 is not particularly limited, but is usually 5 μm or more, preferably 10
It is not less than μm, more preferably not less than 15 μm, and is usually not more than 200 μm, preferably not more than 180 μm, more preferably not more than 150 μm. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.
If the getter material film 4 is in the space formed by the gas barrier films 3 and 9 and the sealing material 11, the formation position is not limited, but the front surface of the solar cell element 6 (surface on the light receiving surface side; lower in FIG. 2). Side surface) and the back surface (surface opposite to the light receiving surface; upper surface in FIG. 2) are preferably covered. This is because, in the thin film solar cell 14, the front and back surfaces are often formed in a larger area than the other surfaces, and therefore moisture and oxygen tend to enter through these surfaces. From this viewpoint, the getter material film 4 is preferably provided between the gas barrier film 3 and the solar cell element 6. In this embodiment, the getter material film 4 covers the front surface of the solar cell element 6, a getter material film 8 described later covers the back surface of the solar cell element 6, and the getter material films 4 and 8 are respectively the solar cell element 6 and the gas barrier film 3. , 9 are located between them. In addition, when using a highly waterproof sheet such as a sheet obtained by bonding a fluororesin film on both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

  The getter material film 4 can be formed by any method depending on the type of the water-absorbing agent or desiccant. For example, a method of attaching a film in which the water-absorbing agent or desiccant is dispersed with an adhesive, water-absorbing agent or desiccant The method of apply | coating this solution with a spin coat method, the inkjet method, or a dispenser method etc. can be used. Further, a film forming method such as a vacuum evaporation method or a sputtering method may be used.

  As a film for a water absorbing agent or a desiccant, for example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, or the like can be used. Among these, a film of polyethylene resin, fluorine resin, cyclic polyolefin resin or polycarbonate resin is preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[Sealing material 5]
The sealing material 5 is a film that reinforces the solar cell element 6. Since the solar cell element 6 is thin, the strength is usually weak, and thus the strength of the thin film solar cell tends to be weak. However, the strength can be maintained high by the sealing material 5.
Moreover, it is preferable that the sealing material 5 has high strength from the viewpoint of maintaining the strength of the thin-film solar cell 14.

The specific strength is related to the strength of the weatherproof protective film 1 other than the sealing material 5 and the strength of the back sheet 10 and is generally difficult to define, but the thin film solar cell 14 as a whole has good bending workability. However, it is desirable to have a strength that does not cause peeling of the bent portion.
In addition, the sealing material 5 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 5 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 5 is usually 1
It is 00 ° C or higher, preferably 120 ° C or higher, more preferably 130 ° C or higher, and is usually 350 ° C or lower, preferably 320 ° C or lower, more preferably 300 ° C or lower. By increasing the melting point, it is possible to reduce the possibility that the sealing material 5 melts and deteriorates when the thin film solar cell 14 is used.

  The thickness of the sealing material 5 is not particularly defined, but is usually 100 μm or more, preferably 150 μm or more, more preferably 200 μm or more, and usually 700 μm or less, preferably 600 μm or less, more preferably 500 μm or less. Increasing the thickness tends to increase the strength of the thin-film solar cell 14 as a whole, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  As a material which comprises the sealing material 5, what used the ethylene-vinyl acetate copolymer (EVA) resin composition for the film (EVA film) etc. can be used, for example. In order to improve weather resistance, the EVA film is usually blended with a crosslinking agent to form a crosslinked structure. As the crosslinking agent, an organic peroxide that generates radicals at 100 ° C. or higher is generally used. Examples of such organic peroxides include 2,5-dimethylhexane, 2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and 3- Di-t-butyl peroxide or the like can be used. The compounding amount of these organic peroxides is usually 5 parts by weight or less, preferably 3 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  This EVA resin composition may contain a silane coupling agent for the purpose of improving the adhesive strength. Examples of the silane coupling agent used for this purpose include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris- (β-methoxyethoxy) silane, γ-methacryloxypropyltri Examples thereof include methoxysilane and β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane. The compounding amount of these silane coupling agents is usually 5 parts by weight or less, preferably 2 parts by weight or less, and usually 0.1 parts by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a silane coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, in order to improve the gel fraction of the EVA resin and improve the durability, a crosslinking aid may be included in the EVA resin composition. Examples of the crosslinking aid provided for this purpose include monofunctional crosslinking aids such as trifunctional crosslinking aids such as triallyl isocyanurate or triallyl isocyanate. The amount of these crosslinking aids is usually 10 parts by weight or less, preferably 5 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking adjuvant, and 2 or more types may be used together by arbitrary combinations and a ratio.

Furthermore, for the purpose of improving the stability of the EVA resin, the EVA resin composition may contain, for example, hydroquinone, hydroquinone monomethyl ether, p-benzoquinone, or methylhydroquinone. These compounding quantities are normally 5 weight part or less with respect to 100 weight part of EVA resin.
However, since the EVA resin cross-linking process requires a relatively long time of about 1 to 2 hours, it may cause a reduction in the production rate and production efficiency of the thin-film solar cell 14. In addition, when used for a long time, the decomposition gas (acetic acid gas) of the EVA resin composition or the vinyl acetate group of the EVA resin itself may adversely affect the solar cell element 6 and reduce the power generation efficiency.
Therefore, as the sealing material 5, in addition to the EVA film, a copolymer film made of a propylene / ethylene / α-olefin copolymer can also be used. As this copolymer, the thermoplastic resin composition with which the following component 1 and the component 2 were mix | blended is mentioned, for example.

Component 1: The propylene polymer is usually 0 part by weight or more, preferably 10 parts by weight or more, and usually 70 parts by weight or less, preferably 50 parts by weight or less.
Component 2: The soft propylene copolymer is 30 parts by weight or more, preferably 50 parts by weight or more, and is usually 100 parts by weight or less, preferably 90 parts by weight or less.
The total amount of component 1 and component 2 is 100 parts by weight. As described above, when component 1 and component 2 are in the preferred ranges, the moldability of the encapsulant 5 into a sheet is good, and the resulting encapsulant 5 has good heat resistance, transparency, and flexibility. Therefore, it is suitable for the thin film solar cell 14.

The thermoplastic resin composition in which the above components 1 and 2 are blended has a melt flow rate (ASTM D 1238, 230 degrees, load 2.16 kg), usually 0.0001 g / 10 min or more. It is 1000 g / 10 min or less, preferably 900 g / 10 min or less, more preferably 800 g / 10 min or less.
The melting point of the thermoplastic resin composition containing component 1 and component 2 is usually 100 ° C. or higher, preferably 110 ° C. or higher. Moreover, it is 140 degrees C or less normally, Preferably it is 135 degrees C or less.

Density of The thermoplastic resin composition components 1 and 2 is blended is preferably from 0.98 g / cm ³ or less, more preferably 0.95 g / cm ³ or less, more preferably 0.94 g / cm ³ or less .
In this sealing material 5, it is possible to mix | blend a coupling agent with the said component 1 and component 2 as an adhesion promoter with respect to a plastics. As the coupling agent, silane, titanate, and chromium coupling agents are preferably used, and a silane coupling agent (silane coupling agent) is particularly preferably used.

  Known silane coupling agents can be used and are not particularly limited. For example, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), γ-glycidoxypropyl-tri Examples include piltrimethoxysilane or γ-aminopropyltriethoxysilane. In addition, 1 type may be used for a coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

Further, these usually contain 0.1 parts by weight or more of the silane coupling agent, and usually 5 parts by weight or less, preferably 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). It is desirable to contain 3 parts by weight or less.
The coupling agent may be grafted to the thermoplastic resin composition using an organic peroxide. In this case, it is desirable to contain 0.1 to 5 parts by weight of the coupling agent with respect to 100 parts by weight of the thermoplastic resin composition (total amount of component 1 and component 2). Even when a silane-grafted thermoplastic resin composition is used, the same or better adhesiveness as that of the silane coupling agent blend can be obtained with respect to glass or plastic.

When the organic peroxide is used, the organic peroxide is usually 0.001 part by weight or more, preferably 0.01 part by weight with respect to 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). The amount is usually 5 parts by weight or less, preferably 3 parts by weight or less.
Further, a copolymer made of an ethylene / α-olefin copolymer can be used as the sealing material 5. As this copolymer, a laminate film having a hot tack property of 5 to 25 ° C., which is formed by laminating a resin composition for a sealing material comprising the following components A and B and a substrate, is exemplified.

Component A: ethylene resin.
Component B: a copolymer of ethylene and an α-olefin having the following properties (a) to (d).
(A) Density is 0.86-0.935 g / cm ³ .
(B) Melt flow rate (MFR) is 1 to 50 g / 10 min.

(C) There is one peak in the elution curve obtained by temperature rising elution fractionation (TREF), and the peak temperature is 100 ° C. or lower.
(D) The integrated elution amount by temperature rising elution fractionation (TREF) is 90% or more at 90 ° C.
The blending ratio (component A / component B) of component A and component B is usually 50/50 or more, preferably 55/45 or more, more preferably 60/40 or more, and usually 99 / 1 or less, preferably 90/10 or less, more preferably 85/15 or less. Increasing the amount of component B tends to increase transparency and heat sealability, and decreasing the amount of component B tends to increase the workability of the film.

  The melt flow rate (MFR) of the resin composition for a sealing material produced by blending component A and component B is usually 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and usually 50 g / 10 minutes. Hereinafter, it is preferably 40 g / 10 min or less. In addition, the measurement and evaluation of MFR can be implemented by the method based on JISK7210 (190 degreeC, 2.16kg load).

The melting point of the encapsulant resin composition is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower. By increasing the melting point, the possibility of melting and deterioration during use of the thin-film solar cell 14 can be reduced.
The density of the resin composition for a sealing material is preferably 0.80 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, and preferably 0.98 g / cm ³ or less, 0.95 g / cm ^3. The following is more preferable, and 0.94 g / cm ³ or less is more preferable. The measurement and evaluation of density can be performed by a method based on JIS K7112.

Further, in the encapsulant 5 using the ethylene / α-olefin copolymer, a coupling agent can be used as in the case of using the propylene / ethylene / α-olefin copolymer.
Since the sealing material 5 described above does not generate a decomposition gas derived from the material, there is no adverse effect on the solar cell element 6, and good heat resistance, mechanical strength, flexibility (solar cell sealing property) and transparency. Have sex. In addition, since a material cross-linking step is not required, the manufacturing time of the sheet solar cell 100 and the thin film solar cell 100 can be greatly reduced, and the thin film solar cell 14 after use can be easily recycled.

In addition, the sealing material 5 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the sealing material 5 may be formed with the single layer film, the laminated | multilayer film provided with the film of 2 or more layers may be sufficient as it.
The thickness of the sealing material 5 is usually 2 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 500 μm or less, preferably 300 μm or less, more preferably 100 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility and light transmittance.

Although there is no restriction | limiting in the position which provides the sealing material 5, Usually, it provides so that the solar cell element 6 may be inserted | pinched. This is for reliably protecting the solar cell element 6. In this embodiment, the sealing material 5 and the sealing material 7 are provided on the front surface and the back surface of the solar cell element 6, respectively.
[Solar cell element 6]
The solar cell element 6 is the same as the above-described photoelectric conversion element.

・ Connection between solar cell elements
Although only one solar cell element 6 may be provided for each thin film solar cell 14, usually two or more solar cell elements 6 are provided. The specific number of solar cell elements 6 may be set arbitrarily. When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are often arranged in an array.

When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are usually electrically connected to each other, and electricity generated from the connected group of solar cell elements 6 is taken out from a terminal (not shown). At this time, the solar cell elements are usually connected in series in order to increase the voltage.
Thus, when connecting the solar cell elements 6, it is preferable that the distance between the solar cell elements 6 is small, and the clearance between the solar cell element 6 and the solar cell element 6 is preferably narrow. This is because the light receiving area of the solar cell element 6 is widened to increase the amount of received light, and the amount of power generated by the thin film solar cell 14 is increased.

[Encapsulant 7]
The sealing material 7 is a film similar to the sealing material 5 described above, and the same material as the sealing material 7 can be used in the same manner except that the arrangement position is different.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[Getter material film 8]
The getter material film 8 is the same film as the getter material film 4 described above, and the same material as the getter material film 4 can be used as necessary, except for the arrangement position.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. It is also possible to use a film containing more water or oxygen absorbent than the getter material film 4. As such an absorbent, CaO, BaO, Zr-Al-BaO, etc. are mentioned as a moisture absorbent, and activated carbon, molecular sieve, etc. are mentioned as an oxygen absorbent.

[Gas barrier film 9]
The gas barrier film 9 is the same film as the gas barrier film 3 described above, and the same material as the gas barrier film 9 can be used as necessary except that the arrangement position is different.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[Backsheet 10]
The back sheet 10 is the same film as the weather-resistant protective film 1 described above, and the same material as the weather-resistant protective film 1 can be used in the same manner except that the arrangement position is different. In addition, if the back sheet 10 is difficult to permeate water and oxygen, the back sheet 10 can also function as a gas barrier layer.

Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. For this reason, it is particularly preferable to use the following (i) to (iv) as the backsheet 10.
(I) As the back sheet 10, it is possible to use various resin films or sheets having excellent strength and weather resistance, heat resistance, water resistance and / or light resistance. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, various polyamide resins such as nylon, polyimide resin, polyamideimide resin, polyaryl phthalate resin , Silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin or other resin It can be used. Among these resin sheets, it is preferable to use a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin sheet. In addition, these may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Ii) As the back sheet 10, a metal thin film can also be used. For example, corrosion-resistant aluminum metal foil, stainless steel thin film, and the like can be mentioned. In addition, the said metal may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
(Iii) As the back sheet 10, for example, a highly waterproof sheet in which a fluorine resin film is bonded to both surfaces of an aluminum foil may be used. Examples of the fluorine resin include ethylene monofluoride (trade name: Tedlar, manufactured by DuPont), polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE), and a vinylidene fluoride resin. (PVDF) or vinyl fluoride resin (PVF). In addition, 1 type may be used for fluororesin and it may use 2 or more types together by arbitrary combinations and a ratio.

  (Iv) As the back sheet 10, for example, an inorganic oxide vapor-deposited film is provided on one side or both sides of the base film, and the base film provided with the inorganic oxide vapor-deposited film has heat resistance on both sides. What laminated | stacked the property polypropylene-type resin film may be used. Usually, when a polypropylene resin film is laminated on the base film, the lamination is performed by laminating with a laminating adhesive. By providing an inorganic oxide vapor-deposited film, it can be used as a back sheet 10 having excellent moisture resistance that prevents intrusion of moisture and / or oxygen.

・ Base film
Basically, as the base film, various resin films having excellent close adhesion with an inorganic oxide vapor deposition film, etc., excellent strength, weather resistance, heat resistance, water resistance, and light resistance are used. Can be used. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, various polyamide resins such as nylon, polyimide resin, polyamideimide resin, polyaryl phthalate resin , Silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, acetal resins, cellulose resins, and other resins. It is possible to use the beam. Among these, it is preferable to use a film of a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin.

Among the various resin films as described above, for example, a fluororesin film such as polytetrafluoroethylene (PTFE), vinylidene fluoride resin (PVDF), or vinyl fluoride resin (PVF) is used. It is more preferable. Further, among these fluororesin films, in particular, a fluororesin film made of polyvinyl fluoride resin (PVF) or a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE) is particularly preferable from the viewpoint of strength and the like. preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Of the various resin films as described above, it is more preferable to use a film of a cyclic polyolefin resin such as cyclopentadiene and a derivative thereof or cyclohexadiene and a derivative thereof.
The film thickness of the base film is usually 12 μm or more, preferably 20 μm or more, and is usually 300 μm or less, preferably 200 μm or less.

・ Deposited film of inorganic oxide
As the inorganic oxide vapor-deposited film, basically any thin film on which a metal oxide is vapor-deposited can be used. For example, a deposited film of an oxide of silicon (Si) or aluminum (Al) can be used. At this time, for example, SiO _x (x = 1.0 to 2.0) can be used as silicon oxide, and for example, AlO _x (x = 0.5 to 1.5) can be used as aluminum oxide. .

In addition, the kind of metal and inorganic oxide to be used may be 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The film thickness of the inorganic oxide vapor deposition film is usually 50 mm or more, preferably 100 mm or more, and is usually 4000 mm or less, preferably 1000 mm or less.
As a method for forming the deposited film, a chemical vapor deposition method (chemical vapor deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or a photochemical vapor deposition method can be used. As a specific example, on one surface of the base film, a monomer gas for vapor deposition such as an organosilicon compound is used as a raw material, an inert gas such as argon gas or helium gas is used as a carrier gas, and oxygen is supplied. An oxygen oxide vapor or the like can be used as a gas, and a vapor deposition film of an inorganic oxide such as silicon oxide can be formed using a low temperature plasma chemical vapor deposition method using a low temperature plasma generator or the like.

-Polypropylene-type resin film As a polypropylene-type resin, the homopolymer of propylene or the copolymer of propylene and another monomer (for example, alpha-olefin etc.) can be used, for example. Moreover, an isotactic polymer can also be used as a polypropylene resin.
The melting point of the polypropylene resin is usually 164 ° C or higher, and is usually 170 ° C or lower. The specific gravity of the polypropylene resin is usually 0.90 or more, and usually 0.91 or less. The molecular weight of the polypropylene resin is usually 100,000 or more, and usually 200,000 or less.

Polypropylene resins are largely controlled by their crystallinity, but high isotactic polymers have excellent tensile strength and impact strength, good heat resistance and bending fatigue strength, and workability. Is very good.
·adhesive
When a polypropylene resin film is laminated on the base film, a laminating adhesive is usually used. Thereby, a base film and a polypropylene resin film are laminated | stacked via the adhesive bond layer for lamination.

Examples of the adhesive constituting the adhesive layer for laminating include, for example, a polyvinyl acetate adhesive, a polyacrylate adhesive, a cyanoacrylate adhesive, an ethylene copolymer adhesive, a cellulose adhesive, and a polyester adhesive. Adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives, phenol resin adhesives, epoxy adhesives, polyurethane adhesives, reactive (meth) acrylic adhesives, silicone adhesives, etc. Is mentioned. In addition, 1 type may be used for an adhesive agent and it may use 2 or more types together by arbitrary combinations and a ratio.

The composition system of the adhesive may be any composition form such as an aqueous type, a solution type, an emulsion type, or a dispersion type. Further, the property may be any of film / sheet, powder, solid and the like. Furthermore, the bonding mechanism may be any form such as a chemical reaction type, a solvent volatilization type, a hot melt type, or a hot pressure type.
The adhesive can be applied by, for example, a coating method such as a roll coating method, a gravure roll coating method, a kiss coating method, or the like, or a printing method. The coating amount is usually preferably 0.1 g / m ² or more in a dry state, and usually 10 g / m ² or less.

[Sealant 11]
The sealing material 11 includes the weatherproof protective film 1, the ultraviolet cut film 2, the gas barrier film 3, the getter material film 4, the sealing material 5, the sealing material 7, the getter material film 8, the gas barrier film 9, and the back sheet 10. It is a member that seals the edge so that moisture and oxygen do not enter the space covered with these films.

The degree of moisture capacity required for the sealing member 11 is preferably water vapor transmission rate per day unit area (1 m ²⁾ is not more than ^{0.1g / m 2 / day, 0.05g} / m 2 / More preferably, it is not more than day. Conventionally, since it has been difficult to mount the sealing material 11 having such a high moisture-proof capability, it is possible to realize a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element. Although it was difficult, the implementation of the thin-film solar cell 14 utilizing the excellent properties of the compound semiconductor solar cell element and the organic solar cell element is facilitated by applying such a sealing material 11.

Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 11 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 11 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower.
If the melting point is too low, the sealing material 11 may melt when the thin film solar cell 14 is used.

Examples of the material constituting the sealing material 11 include polymers such as a fluorine resin, a silicone resin, and an acrylic resin.
In addition, the sealing material 11 may be formed with 1 type of material, and may be formed with 2 or more types of materials.

The sealing material 11 is provided at a position where at least the edges of the gas barrier films 3 and 9 can be sealed. Thereby, the space surrounded by at least the gas barrier films 3 and 9 and the sealing material 11 can be sealed, and moisture and oxygen can be prevented from entering the space.
Although there is no restriction | limiting in the method of forming this sealing material 11, For example, it can form by inject | pouring material between the weather-resistant protective film 1 and the back sheet | seat 10. FIG. Specific examples of the forming method include the following methods.

That is, for example, while the curing of the sealing material 5 proceeds, the semi-cured thin-film solar cell 14 is taken out from the laminating apparatus, and is the outer peripheral portion of the solar cell element 6, which is the weatherproof protective sheet 1 and the back sheet 10. A liquid polymer may be injected into a portion between the two and the polymer may be cured together with the sealing material 5. Further, after the sealing material 5 has been cured, it may be taken out from the laminating apparatus and cured alone. The temperature range for crosslinking and curing the polymer is usually 130 ° C. or higher, preferably 140 ° C. or higher, and is usually 180 ° C. or lower, preferably 170 ° C. or lower.

[Dimensions]
The thin film solar cell 14 of the present embodiment is usually a thin film member. Thus, by forming the thin film solar cell 14 as a film-like member, the thin film solar cell 14 can be easily installed in a building material, an automobile, an interior, or the like. The thin-film solar cell 14 is light and difficult to break, and thus a highly safe solar cell can be obtained and can be applied to a curved surface, so that it can be used for more applications. Since it is thin and light, it is preferable in terms of distribution such as transportation and storage. Furthermore, since it is in the form of a film, it can be manufactured in a roll-to-roll manner, and the cost can be greatly reduced.

Although there is no restriction | limiting in the specific dimension of the thin film solar cell 14, The thickness is 300 micrometers or more normally, Preferably it is 500 micrometers or more, More preferably, it is 700 micrometers or more, Moreover, it is 3000 micrometers or less normally, Preferably it is 2000 micrometers or less, More preferably. It is 1500 micrometers or less.
[Production method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14 of this embodiment, For example, between the weather-resistant protective film 1 and the back sheet | seat 10, the 1 or 2 or more solar cell element 6 was connected in series or in parallel. The product can be manufactured by laminating with a general vacuum laminating apparatus together with the ultraviolet cut film 2, the gas barrier films 3, 9, the getter material films 4, 8, and the sealing materials 5, 7. At this time, the heating temperature is usually 130 ° C. or higher, preferably 140 ° C. or higher, and is usually 180 ° C. or lower, preferably 170 ° C. or lower. The heating time is usually 10 minutes or longer, preferably 20 minutes or longer, usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure is usually 0.001 MPa or more, preferably 0.01 MPa or more, and usually 0.2 MPa or less, preferably 0.1 MPa or less. By setting the pressure within this range, sealing can be reliably performed, and the sealing materials 5 and 7 from the end can be prevented from protruding or reduced in film thickness due to over-pressurization, thereby ensuring dimensional stability.

[Usage]
There is no restriction | limiting in the use of the thin film solar cell 14 mentioned above, It is arbitrary. For example, as schematically shown in FIG. 3, a solar cell module 13 in which a thin film solar cell 14 is provided on a certain base material 12 is prepared and used at a place of use. As a specific example, when a building material plate is used as the base material 12, a thin film solar cell 14 is provided on the surface of the plate material to produce a solar cell panel as the solar cell module 13, and this solar cell panel is attached to the outer wall of the building. It can be installed and used.

  The substrate 12 is a support member that supports the solar cell element 6. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine. Organic materials such as resin film, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene; paper materials such as paper or synthetic paper; metals such as stainless steel, titanium or aluminum For example, a composite material such as a material whose surface is coated or laminated in order to impart insulating properties can be used. In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength.

Examples of fields to which the thin film solar cell of the present invention is applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, solar cells for spacecraft. It is suitable for use in batteries, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like. Specific examples include the following.
1. Architectural use
1.1 Solar cell as house roofing material
When a roof plate or the like is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell unit, and this solar cell panel is installed on the roof of the house. That's fine. Moreover, a roof tile can also be used directly as a base material. The solar cell of the present invention is suitable because it can be brought into close contact with the roof tiles by taking advantage of its flexibility.

1.2 Rooftop
It can also be installed on the roof of a building. A solar cell unit in which a thin film solar cell is provided on a base material can be prepared and installed on the roof of a building. At this time, it is desirable to use a waterproof sheet together with the base material to have a waterproof action. Furthermore, taking advantage of the property that the thin film solar cell of the present invention has flexibility, it can be brought into close contact with a roof that is not flat, for example, a folded roof. In this case, it is desirable to use a waterproof sheet in combination.

1.3 Top light
The thin-film solar cell of the present invention can also be used as an exterior at the entrance or a blow-off portion. Curves are often used for entrances and the like that have undergone some design processing, and in such a case, the flexibility of the thin film solar cell of the present invention is utilized. In addition, there is a case of see-through in an entrance or the like. In such a case, the green color of the organic solar cell is suitable because a design aesthetic can be obtained in an era when environmental measures are regarded as important.

1.4 Wall
When a building material plate is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell unit, and this solar cell panel may be installed on the outer wall of a building and used. . It can also be installed on curtain walls. In addition, it can be attached to a spandrel or a vertical.

In this case, although there is no restriction | limiting in the shape of a base material, Usually, a board | plate material is used. Moreover, what is necessary is just to set the material of a base material, a dimension, etc. arbitrarily according to the use environment. As an example of such a substrate, Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like can be mentioned.
1.5 windows
It can also be used for see-through windows. The green color of the organic solar cell is preferable because a design aesthetic can be obtained in an era when environmental measures are important.

1.6 Other
It can also be used for eaves, louvers, handrails, etc. Even in such a case, the flexibility of the thin film solar cell of the present invention is suitable for these applications.
2. Interior
The thin film solar cell of the present invention can also be attached to a blind slat. Since the thin-film solar cell of the present invention is lightweight and rich in flexibility, such a use is possible. Further, the contents window can be used by utilizing the characteristic that the organic solar cell element is see-through.

3. Vegetable factory
Although the number of plant factories that use illumination light such as fluorescent lamps is increasing, the current situation is that it is difficult to reduce the cultivation cost due to the electricity bill for lighting and the replacement cost of the light source. Then, the thin film solar cell of this invention can be installed in a vegetable factory, and the illumination system combined with LED or the fluorescent lamp can be produced.

At this time, it is preferable to use an illumination system that combines an LED having a longer life than a fluorescent lamp and the solar cell of the present invention, because the cost required for illumination can be reduced by about 30% compared to the current situation.
Moreover, the solar cell of this invention can also be used for the roof and side wall of the reefer container (reefer container) which conveys vegetables etc. at fixed temperature.

4). Road materials and civil engineering
The thin film solar cell of the present invention can be used for an outer wall of a parking lot, a sound insulation wall of an expressway, an outer wall of a water purification plant, and the like.
5. Automobile
The thin film solar cell of the present invention can be used on the surface of an automobile bonnet, roof, trunk lid, door, front fender, rear fender, pillar, bumper, rearview mirror or the like. The roof includes the roof of the truck bed. The obtained electric power can be supplied to any of a traveling motor, a motor driving battery, an electrical component, and an electrical component battery. By providing the power generation status in the solar cell panel and the control means for selecting according to the power usage status in the motor for driving, the battery for driving the motor, the electrical equipment, and the battery for electrical equipment, the obtained power is Can be used properly and efficiently
In the above case, the shape of the substrate 12 is not limited, but a plate material is usually used. Moreover, what is necessary is just to set the material of the base material 12, a dimension, etc. arbitrarily according to the use environment.

  Examples of such a substrate 12 include Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like.

EXAMPLES Hereinafter, although the Example of this invention is shown and this invention is demonstrated more concretely, this invention is not limited to a following example, unless it deviates from the summary.
[Synthesis Example 1]
Preparation of Dimethylylcyclopyrrole Derivatives Ethyl-4,7-dihydro-8,8-dimethyl-4,7-ethano-2Hisindole-1-carboxylate 5.00 g (20 g) in a 500 mL four-necked flask equipped with a condenser under a nitrogen atmosphere. .4 mmol) and 6.25 g (150 mmol) of sodium hydroxide previously ground in a mortar were dissolved in 150 mL of ethylene glycol, and the solvent was degassed and replaced with nitrogen. The reaction vessel was shielded from light, stirred at 170 ° C. for 60 minutes, and cooled to room temperature. The reaction solution was poured into 300 mL ice water, extracted with chloroform, and dried by adding anhydrous sodium sulfate. After filtering the powder, the filtrate was concentrated under reduced pressure. The obtained oil was purified by sublimation to obtain 2.54 g (14.7 mmol, 72%) of a dimethylethylcyclopyrrole derivative.

It was confirmed by 1H NMR that the obtained compound was a dimethylcyclopropyl derivative. The results of 1H NMR are shown below.
1H NMR (400 MHz, CDCl3) δ 7.46 (brs, 1H), 6.54 (m, 1H), 6.48 (m, 1H), 6.47 (m, 1H), 6.41 (m, 1H), 3.70 (m, 1H), 3.22 (d, 1H, J.5.9 Hz), 1.41 (dd, 1H, J.11.5, 2.7 Hz), 1.24 ( dd, 1H, J.11.5, 2.7 Hz), 1.04 (s, 3H), and 0.72 (s, 3H).

[Synthesis Example 2]
Production of Bicycloporphyrin Compound Isomeric Mixture (CP-1) 3.81 g (22 mmol) of the Dimethylcyclopropyl derivative synthesized in Example 1 was dissolved in 400 mL of chloroform (containing amylene), and 850 mg of paraformaldehyde was added thereto under a nitrogen atmosphere. Then, 200 mg of p-toluenesulfonic acid monohydrate was added and stirred at room temperature for 5 hours. Subsequently, 2.17 g of p-chloranil was added and further stirred for 5 hours. The reaction solution was poured into water, the organic layer was separated, washed with saturated sodium bicarbonate solution, water and brine, and dried over anhydrous sodium sulfate. After filtration of the powder, the filtrate was concentrated under reduced pressure, and the residue was first purified by alumina column chromatography using chloroform as the solvent, and then purified by silica gel chromatography with ethyl acetate / chloroform to form the desired regioisomer. As a result, 2.44 g (3.30 mmol, 60%) of a mixture of bicycloporphyrin compounds was obtained (hereinafter referred to as CP-1).

It was confirmed by 1H NMR, LC analysis, and MS analysis that the obtained compound was an isomer mixture of the target bicycloporphyrin compound. Various analysis results are shown below. The LC analysis results are shown in Table 1. By mass spectrometry (FAB-MS method), m / z: 736 [M ⁺ ] corresponding to the mass of the target product was detected.
1H NMR (400 MHz, CDCl3) δ 10.26-10.33 (m, 4H), 7.11-7.26 (m, 8H), 5.63 (m, 4H), 5.12-5.16 (M, 4H), 2.06-2.11 (m, 4H), 1.75-1.88 (m, 4H), 1.55-1.56 (m, 12H), 0.59-0 .80 (m, 12H), and -4.63 (brs, 2H).

[Synthesis Example 3]
Tetrakis (bicyclo [2.2.2] octadiene) porphyr
Production of in (CP-2) Synthesis was performed based on the description of [0060] to [0066] of JP-A-2003-304014. The resulting compound is referred to as compound CP-2. The LC analysis results are shown in Table 1. By mass spectrometry (FAB-MS method), m / z: 623 [M ⁺ +1] consistent with the mass of the target product was detected.
1H NMR (400 MHz, CDCl3) δ 10.40 (m, 4H), 7.20 (m, 8H), 5.81 (m, 8H), 2.24 (m, 8H), and -4.80 (brs) , 2H).

LC analysis results

[Synthesis Example 4]
Synthesis example of POPy2

In a nitrogen atmosphere, 1-bromopyrene (Tokyo Kasei: 14 g, 50 mmol) was dissolved in dehydrated THF (Kanto Chemical: 200 mL), cooled to −78 ° C., and then n-BuLi (Kanto Chemical: 33 mL, 1.6 M) was slowly added. The solution was added dropwise and stirred for 30 minutes while maintaining -78 ° C. Subsequently, dichlorophenylphosphine (Tokyo Kasei: 4.3 g, 9.0 mmol) was added dropwise, and after sufficient stirring, the mixture was warmed to room temperature and stirred for 1.5 hours. 30 mL of methanol (Pure Chemical) was added to the resulting reaction solution, and the resulting crude product was filtered and recrystallized using benzene to obtain 10.7 g of the desired product. The compound obtained here was dissolved in 350 mL of THF (Pure Chemical), 300 mL of CH ₂ Cl ₂ (Kanto Chemical), 100 mL of acetone (Kanto Chemical), hydrogen peroxide (Wako Pure Chemicals: 10 mL of 30% solution) was added, Stir at room temperature for 30 minutes. The reaction solution was added with 30 mL of water, concentrated to 600 mL, and then filtered to obtain 7.5 g of the desired product (POPy ₂ ).

[Synthesis Example 5]
Synthesis of C ₆₀ (QM) ₂ (fullerene compound A)

Under a nitrogen atmosphere, fullerene C ₆₀ (500 mg, 0.694 mmol), tetra-n-butylammonium iodide (TBAI; 1.28 g, 3.47 mmol, 5 equivalents), and toluene (230 mL) were placed in a 500 mL three-necked eggplant flask. . After degassing under reduced pressure, α, α′-dibromo-o-xylene (916 mg, 3.47 mmol, 5 equivalents) was added and heated to reflux. After 10 hours, the temperature was returned to room temperature, applied to a silica gel filtration column (toluene), and concentrated. After subjecting to silica gel column chromatography (carbon disulfide: hexane = 1: 2), GPC purification (chloroform) was performed to obtain the desired product in a yield of 47% (304 mg, 0.328 mmol). By mass spectrometry (APCI method, negative), m / z: 928 [M ⁻ ] corresponding to the mass of the target product was detected. The glass transition temperature was not observed below 250 ° C. in the DSC method.

[Synthesis Example 6]
Synthesis of C ₆₀ (Ind) ₂ (fullerene compound B)

The synthesis of C ₆₀ (Ind) ₂ was performed with reference to a patent document (International Publication No. 2008/018931), and obtained as an isomer mixture. It refine | purified by performing GPC refinement | purification (chloroform), m / z: 952 [M < ^- >] corresponding to the mass of a target object was detected by mass spectrometry (APCI method, negative). The glass transition temperature was not observed below 200 ° C. in the DSC method.

[Synthesis Example 7]
Synthesis of C60 (PCBM) (QM) (fullerene compound C)

PCBM (1- (3-methoxycarbonyl) propyl-1-phenyl (6,6) -C ₆₀ , E100H manufactured by Frontier Carbon Co., 1.0 g, 1.098 mmol), iodine in a 500 mL three-necked eggplant flask under a nitrogen atmosphere Tetra n-butylammonium bromide (TBAI; 2.03 g, 5.49 mmol, 5 equivalents) and toluene (200 mL) were added. After degassing under reduced pressure, α, α′-dibromo-o-xylene (1.45 g, 5.49 mmol, 5 equivalents) was added and heated to reflux. After 9 hours, the temperature was returned to room temperature, applied to a silica gel filtration column (toluene), and concentrated. After subjecting to silica gel column chromatography (toluene), GPC purification (chloroform) was performed to obtain the target product (C60 (PCBM) (QM)) with a yield of 49% (545 mg, 0.537 mmol). By mass spectrometry (APCI method, negative), m / z: 1014 [M ⁻ ] corresponding to the mass of the target product was detected. The glass transition temperature was not observed below 200 ° C. in the DSC method.

[Synthesis Example 8]
Synthesis of C60 (PCBM) (Ind) (fullerene compound D)

PCBM (1- (3-methoxycarbonyl) propyl-1-phenyl (6,6) -C ₆₀ , E100H manufactured by Frontier Carbon Corporation, 300 mg, 0.329 mmol), indene (0 .46 mL, 3.95 mmol) and o-dichlorobenzene (50 mL) were added, and after degassing under reduced pressure, the mixture was heated to reflux for 21 hours. After concentrating the solvent, GPC purification (chloroform) was performed to obtain a yield of 43% (145 mg, 0
. 141 mmol) to obtain the desired product (C60 (PCBM) (Ind)). By mass spectrometry (APCI method, positive), m / z: 1026 [M ⁺ ] corresponding to the mass of the target product was detected. The glass transition temperature was not observed below 200 ° C. in the DSC method.

[Synthesis Example 9]
Synthesis of SIMEF (fullerene compound E)

The fullerene compound E was synthesized by the method described in the patent document (International Publication No. 2009/008323).
[Synthesis Example 10]
Synthesis of SIMEF2 (fullerene compound F)

The synthesis of fullerene compound F was performed as follows.
[Intermediate 1]
Chloromethyl (2-methoxyphenyl) dimethylsilane, (o-An) Me ₂ SiCH ₂ Cl

In a 500-mL three-necked eggplant flask, a 1.0 M THF solution (100 mL, 0.1 mol) of 2-methoxyphenylmagnesium bromide was placed in a nitrogen atmosphere and stirred at room temperature. Chloromethyldimethylchlorosilane (11.25 mL, 0.085 mol) was slowly added dropwise thereto. After stirring at room temperature for 1 hour, the mixture was stirred at 40 ° C. for 3 hours. It returned to room temperature and water was added slowly. The mixture was extracted with ethyl acetate, washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The obtained liquid was distilled under reduced pressure to give the target product (chloromethyl (2-methoxyphenyl) dimethylsilane, (o-An) Me ₂ SiCH ₂ Cl) as a colorless liquid in a yield of 52% (11.2 g, 0 0522 mol).

[Intermediate 2]
1- (Dimethylphenylsilylmethyl) -1,9-dihydro (C ₆₀ -I _h ) [5,6] fullerene, C ₆₀ (CH ₂ SiMe ₂ Ph) H

Under a nitrogen atmosphere, N, N-dimethylformamide (6.45 mL, 83.3 mmol), fullerene C ₆₀ (2.00 g, 2.78 mmol) and 1,2-dichlorobenzene solution (500 mL) were mixed and degassed. Then, the pressure was restored with nitrogen. To this was added a THF solution of Grignard reagent (PhMe ₂ SiCH ₂ MgCl, 9.80 mL, 0.850 M, 8.33 mmol) prepared from (chloromethyl) dimethylphenylsilane at 25 ° C. After stirring for 10 minutes, degassed saturated aqueous ammonium chloride solution (1.0 mL) was added and stirred. The obtained solution was concentrated, dissolved in toluene (200 mL), passed through a silica gel filtration column, and concentrated. Methanol (about 100 to 200 mL) was added and reprecipitated to obtain a brown solid. The resulting solid HPLC (Buckyprep column, eluent: toluene / 2-propanol = 7/3) minute by preparative, the desired product 1- (dimethylphenylsilyl methyl) 1,9-dihydro _{(C 60} - I _h ) [5,6] fullerene (C ₆₀ (CH ₂ SiMe ₂ Ph) H, 1.99 g, 2.28 mmol, 82% isolated yield, analytically pure) was obtained.

[Fullerene Compound F (C ₆₀ (CH ₂ SiMe ₂ Ph) [CH ₂ SiMe ₂ (o-An)])]

1- (Dimethylphenylsilylmethyl) -1,9-dihydro (C ₆₀ -I _h ) [5,6] fullerene (C ₆₀ (CH ₂ SiMe ₂ Ph) obtained in the production of intermediate 2 under a nitrogen atmosphere After degassing the benzonitrile solution of H, 1.02 g, 1.17 mmol), a THF solution of t-butoxy potassium (1.41 mL, 1.0 M, 1.41 mmol) was added at 25 ° C. After stirring for 10 minutes, chloromethyl (2-methoxyphenyl) dimethylsilane ((o-An) Me ₂ SiCH ₂ Cl, 5.03 g, 23.4 mmol) obtained in the preparation of Intermediate 1 and potassium iodide were combined. The mixture was further stirred at 110 ° C. for 17 hours. To the obtained solution, 1.0 mL of a saturated aqueous ammonium chloride solution was added and concentrated. Toluene (100 mL) was added to the obtained crude product, and after concentration by filtration, methanol (ca. 50 to 100 mL) was added to perform reprecipitation. The obtained crude product was subjected to silica gel column chromatography (eluent: CS ₂ / hexane = 1/1) purification, followed by HPLC preparative (Buckyprep).
column, elements: toluene / 2-propanol = 7/3) Purification was performed to obtain a target product (0.810 g, 0.772 mmol, 66% isolated yield).

[Synthesis Example 11]
Synthesis Method of Tetrabenzoporphyrin (BP) 2.75 g of the compound (CP-2) produced in Synthesis Example 3 was placed in an Erlenmeyer flask under a nitrogen atmosphere, and heated at 280 ° C. for 3 hours in the nitrogen atmosphere. After confirming that the color was completely changed, the container was returned to room temperature and transferred to a brown glass vial to obtain 2.05 g of BP (yield 90.9%).

[Example 1]
Application Conversion Type Organic Thin Film Solar Cell Using Fullerene Compound A (C ₆₀ (QM) ₂ ) Poly (3,4-ethylenedioxythiophene) poly (poly (3,4) as a hole extraction layer on a glass substrate on which an ITO electrode is patterned (Styrenesulfonic acid) aqueous dispersion (trade name “CLEVIOUS ^™ PVP AI4083” manufactured by H.C. Starck Co., Ltd.) was applied by spin coating, and then the substrate was subjected to heat treatment on the hot plate at 120 ° C. for 10 minutes in the atmosphere. gave. The film thickness was about 30 nm.

The substrate was first heat-treated at 180 ° C. for 3 minutes under a nitrogen atmosphere, and then the toluene solution containing 0.5 wt% of the coating conversion type bicycloporphyrin compound CP-1 produced in Synthesis Example 2 was filtered, and the substrate was filtered. It was applied by spin coating at 1500 rpm. The substrate was heat-treated at 180 ° C. for 20 minutes in a nitrogen atmosphere to form a p-type semiconductor tetranbenzoporphyrin (BP) layer having a thickness of about 25 nm on the hole extraction layer.

  A chloroform: chlorobenzene = 1: 1 (weight ratio) solution containing 0.75% by weight of the coating conversion type bicycloporphyrin compound CP-2 produced in Synthesis Example 3 and 1.75% by weight of the fullerene compound F was prepared and filtered. The filtrate obtained in a nitrogen atmosphere was spin-coated at 1500 rpm and heated at 180 ° C. for 20 minutes. As a result, a mixture layer containing about 100 nm of tetrabenzoporphyrin (BP) and the fullerene compound F produced in Synthesis Example 10 was formed on the p-type semiconductor layer.

Then, a solution prepared by dissolving the fullerene compound A prepared in Synthesis Example 5 in toluene 0.65 wt% to steel tone, filtered, and spin-coated at 3000rpm The obtained filtrate under a nitrogen atmosphere, 5 at 120 ° C. Heat treatment was performed for a minute. As a result, the fullerene compound F in the mixture layer was replaced by the fullerene compound A, and a fullerene compound A layer was formed on the tetrabenzoporphyrin (BP) layer.

Subsequently, POPy2 synthesized in Synthesis Example 4 was placed in a metal boat arranged in a vacuum vapor deposition apparatus, heated and evaporated to a film thickness of 6 nm, and a buffer layer was formed on the fullerene compound A layer.
Further, after an aluminum electrode having a thickness of 80 nm is provided on the buffer layer by vacuum deposition, the solar cell is placed on a hot plate at 180 ° C. for 10 minutes, on a hot plate at 210 ° C. for 10 minutes, and on a hot plate at 220 ° C. The photoelectric conversion element was produced by heating for 10 minutes with a 230 degreeC hotplate for 10 minutes.

A solar cell sealed using a glass plate as a sealing plate was irradiated with light of 100 mW / cm ² from the ITO electrode side with a solar simulator (AM1.5G), and a source meter (type 2400, manufactured by Keithley) The current-voltage characteristics between the ITO electrode and the aluminum electrode were measured. After that, light irradiation was continuously performed for a certain period of time with an indoor solar cell durability test apparatus ECL-350 manufactured by Eiko Seiki Co., Ltd. set at a substrate temperature of 85 ° C. When measuring the current-voltage characteristics, the current-voltage characteristics (durability test) were measured at room temperature once taken out from ECL-350. Table 2 shows the conversion efficiency (%) at each time and the conversion efficiency at each time when the initial value is 100% as durability (%).

[Example 2]
Coating Conversion Type Organic Thin Film Solar Cell Using Fullerene Compound B In Example 1, a solar cell was prepared in the same manner except that Compound B obtained in Synthesis Example 6 was used instead of Fullerene Compound A. A durability test was conducted. Table 2 shows the conversion efficiency (%) and durability (%) at each time.

[Example 3]
Coating Conversion Organic Thin Film Solar Cell Using Fullerene Compound C In Example 1, a solar cell was prepared in the same manner except that the fullerene compound C obtained in Synthesis Example 7 was used instead of the fullerene compound A. A durability test was conducted. Table 2 shows the conversion efficiency (%) and durability (%) at each time.

[Example 4]
Application Conversion Type Organic Thin Film Solar Cell Using Fullerene Compound D In Example 1, a solar cell was prepared in the same manner except that fullerene compound D obtained in Synthesis Example 8 was used instead of fullerene compound A. A durability test was conducted. Table 2 shows the conversion efficiency (%) and durability (%) at each time.

[Comparative Example 1]
Application Conversion Type Organic Thin Film Solar Cell Using Fullerene Compound C Poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) aqueous dispersion (as a hole extraction layer) on a glass substrate on which an ITO electrode is patterned ( The product name “CLEVIOUS ^™ PVP AI4083” manufactured by H.C. Starck Co., Ltd.) was applied by spin coating, and then the substrate was subjected to heat treatment on the hot plate at 120 ° C. for 10 minutes in the air. The film thickness was about 30 nm.

  A tetrabenzoporphyrin (BP) synthesized in Synthesis Example 11 is placed in a metal boat, vacuum-deposited on the substrate, and then the substrate is heat-treated at 180 ° C. for 20 minutes in a nitrogen atmosphere to thereby obtain a hole extraction layer. A p-type semiconductor layer having a thickness of about 25 nm was formed thereon.

  In a 1: 1 mixed solvent (weight) of chloroform / monochlorobenzene, 0.6% by weight of compound CP-2 obtained in Synthesis Example 3 and 1.4% by weight of fullerene compound E obtained in Synthesis Example 9 were dissolved. The filtrate was prepared, filtered, and the filtrate obtained under a nitrogen atmosphere was spin-coated at 1500 rpm and heated at 180 ° C. for 20 minutes. Thus, a mixture layer containing tetrabenzoporphyrin (BP) and fullerene compound E was formed on the p-type semiconductor layer.

Next, a solution in which 1.2% by weight of fullerene compound E was dissolved in toluene was prepared, filtered, and the filtrate obtained in a nitrogen atmosphere was spin-coated at 3000 rpm, and heat-treated at 120 ° C. for 5 minutes. Thus, a fullerene compound E layer was formed on the mixture layer.
Thereafter, aluminum having a thickness of 80 nm was formed by resistance heating vacuum deposition to produce a 5 mm square bulk heterojunction organic thin film solar cell. A solar cell sealed with a glass plate as a sealing plate is attached with a 4 mm square metal mask, irradiated with light of 100 mW / cm ^{2 with} a solar simulator (AM1.5G) from the ITO electrode side, and a source meter ( The current-voltage characteristics between the ITO electrode and the aluminum electrode were measured using a 2400 model manufactured by Keithley. After that, light irradiation was continuously performed for a certain period of time with an indoor solar cell durability test apparatus ECL-350 manufactured by Eiko Seiki Co., Ltd. set at a substrate temperature of 85 ° C. When measuring the current-voltage characteristics, the current-voltage characteristics (durability test) were measured at room temperature once taken out from ECL-350. Table 2 shows the conversion efficiency (%) at each time and the conversion efficiency at each time when the initial value is 100% as durability (%).

[Comparative Example 2]
Polymer type organic thin film solar cell Regioregular poly-3-hexylthiophene (P3HT, manufactured by Rieke Metals) having an electron-donating molecular structure and fullerene compound B obtained in Synthesis Example 6 at a weight ratio of 1: 0.8 And dissolved in o-dichlorobenzene at a concentration of 2.1% by weight. The obtained solution was stirred and mixed with a stirrer at 40 ° C. in a nitrogen atmosphere for 4 hours. The solution was filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter to prepare a photoelectric conversion layer coating solution.

A glass substrate on which an indium tin oxide (ITO) transparent conductive film with a thickness of 155 nm is deposited is cleaned in the order of ultrasonic cleaning with a surfactant, water with ultrapure water, and ultrasonic cleaning with ultrapure water, followed by nitrogen blowing. And dried by heating at 120 ° C. in the air for 5 minutes. Finally, ultraviolet ozone cleaning was performed.
On this transparent substrate, an aqueous dispersion of poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) filtered through a 0.45 μm polyvinylidene fluoride (PVDF) filter (manufactured by HC Starck Co., Ltd.) After spin-coating “CLEVIOUS ^™ PVP AI4083”), it was dried by heating at 120 ° C. in air for 10 minutes. Further, the substrate was heat-treated at 180 ° C. for 3 minutes in a nitrogen atmosphere. The film thickness was 60 nm.

The photoelectric conversion layer coating solution was applied by spin coating on a glass substrate under a nitrogen atmosphere, thereby forming an active layer having a thickness of 200 nm. Annealing treatment was performed at 150 ° C. for 10 minutes in a nitrogen atmosphere. Thereafter, aluminum having a thickness of 80 nm was formed by resistance heating vacuum deposition to produce a 5 mm square bulk heterojunction organic thin film solar cell.
Using a solar simulator with air mass (AM) 1.5 and irradiance of 100 mW / cm ² as the irradiation light source, a 4 mm square metal mask is used to measure the current-voltage characteristics of the produced solar cell with a source meter (Type 2400 manufactured by Keithley). It was attached and measured. The durability test was evaluated by continuously irradiating simulated sunlight for 22 hours with an indoor solar cell durability test apparatus ECL-350 manufactured by Eiko Seiki Co., Ltd. set at a substrate temperature of 85 ° C. Table 2 shows the conversion efficiency (%) at each time and the conversion efficiency at each time when the initial value is 100% as durability (%).

  As mentioned above, it turns out that the Example improved the photoelectric conversion efficiency and durability of the organic solar cell element compared with the comparative example.

100 Substrate 101 Anode (transparent electrode)
102 hole extraction layer 103 p-type semiconductor compound layer 104 mixed layer 105 of p-type semiconductor compound and n-type semiconductor compound n-type semiconductor compound layer 106 electron extraction layer 107 cathode (counter electrode)
108 Active layer 109 Photoelectric conversion element 1 Weather-resistant protective film
2 UV cut film
3, 9 Gas barrier film
4, 8 Getter material film
5, 7 Sealing material
6 Solar cell elements
10 Back sheet
11 Sealing material
12 Base material
13 Solar cell module
14 Thin film solar cells

Claims (6)

A photoelectric conversion element including at least an active layer and a pair of electrodes, wherein the active layer contains a fullerene compound obtained by condensing a fullerene with a ring having a 4-membered ring or more and a low molecular organic semiconductor compound,
The fullerene compound is the following fullerene compound A or the following fullerene compound B, A photoelectric conversion device.
The photoelectric conversion element according to claim 1 , wherein the low-molecular organic semiconductor compound has crystallinity. The photoelectric conversion device according to claim 1, wherein the low-molecular organic semiconductor compound is a phthalocyanine compound and a metal complex thereof, and a porphyrin compound and a metal complex thereof. Comprising said photoelectric conversion element further buffer layer, the photoelectric conversion device according to any one of claims 1-3. The solar cell characterized by including the photoelectric conversion element of any one of Claims 1-4 . A solar cell module comprising the solar cell according to claim 5 .