JP2006245073A - Organic thin film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin film solar cell having high energy conversion efficiency.
The present invention includes a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer and having a hole transport layer and an electron transport layer, and An organic thin film solar cell formed on a photoelectric conversion layer and having a second electrode layer which is an electrode facing the first electrode layer, wherein the hole transport layer is a polythiophene derivative or a polyphenylene vinylene derivative (PPV) The above problem is solved by providing an organic thin-film solar cell having at least one of the above, wherein the electron transport layer has at least one of a polyfluorene derivative or a fullerene derivative.
[Selection] Figure 1

Description

  The present invention relates to a heterojunction type organic thin-film solar cell using a pn junction with a set of electron accepting and electron donating functions.

  An organic thin film solar cell is a solar cell in which an organic thin film having an electron donating function and an electron accepting function is disposed between two different electrodes, and has a manufacturing process compared to an inorganic solar cell represented by silicon or the like. It has an advantage that it is easy and can be enlarged at low cost. However, since the energy conversion efficiency is low, it has been difficult to put it to practical use. Therefore, in the organic thin-film solar cell, increasing the energy conversion efficiency is the biggest issue.

  Recently, in order to improve the energy conversion efficiency of organic thin film solar cells, attempts have been made to make use of the characteristics of organic materials used in organic thin films, which are disclosed in Non-Patent Document 1 and Non-Patent Document 2. .

  Examples of the organic thin film solar cell as described above include an example of a bilayer type organic thin film solar cell in which the organic thin film is composed of an electron transport layer and a hole transport layer. In general, a bilayer organic thin film solar cell includes a transparent substrate, a transparent electrode formed on the transparent substrate, a hole transport layer and an electron acceptor that are formed on the transparent electrode and function as an electron donor. A photoelectric conversion layer having a functioning electron transport layer, and a counter electrode which is formed on the photoelectric conversion layer and is opposed to the transparent electrode. In this bilayer organic thin-film solar cell, a p-type organic semiconductor is used for the hole transport layer that functions as an electron donor, and an n-type organic semiconductor is used for the electron transport layer that functions as an electron acceptor. A pn junction is formed at the interface of the layers and contributes to photoelectric conversion.

  As an example of such a bilayer type organic thin film solar cell, Non-Patent Document 1 discloses an organic thin film using a perylene derivative (PTCBI) which is a p-type organic semiconductor and copper phthalocyanine (CuPc) which is an n-type organic semiconductor. Solar cells are mentioned.

  Further, as a method for expanding the pn junction portion in order to improve energy conversion efficiency, there is a method in which a p-type organic semiconductor and an n-type organic semiconductor are not simply stacked but mixed. By mixing the p-type organic semiconductor and the n-type organic semiconductor, a pn junction at the molecular level is widely formed in the film, so that the volume that can contribute to photoelectric conversion increases.

  As an example of such a mixed organic thin film solar cell, Non-Patent Document 1 uses a polyphenylene vinylene-based p-type conjugated polymer (MEH-PPV) and a fullerene derivative (PCBM) which is an n-type organic semiconductor. Organic thin film solar cells are mentioned. In addition, a p-type conjugated polymer poly-3-alkylthiephene derivative (P3RT) is used, or a polyphenylene vinylene-based p-type conjugated polymer (MEH-PPV) is introduced with a n-type Examples include a system using a converted polyphenylene vinylene derivative (CN-PPV) or carbon nanotube (CNT) as an n-type organic semiconductor.

  As the p-type organic semiconductor and the n-type organic semiconductor, as described above, conjugated polymers represented by conductive polymers are widely used. However, since many organic materials such as conductive polymers exhibit p-type semiconductor properties, few n-type semiconductor properties with good characteristics are known. Conjugated polymers have the advantage of a relatively high hole transport capability, but the light absorption coefficient is not so large, and they are not incident on the long wavelength side of the visible light region. Since light cannot be used effectively, there is a drawback that the energy conversion efficiency does not increase. Furthermore, in the organic thin-film solar cell as described above, due to the lack of charge transport ability of the commonly used photoelectric conversion layer forming material, a voltage is obtained, but a sufficient current cannot be obtained, resulting in energy conversion. There is also a problem that efficiency is lowered.

  From the above, in order to improve the energy conversion efficiency, development of an organic material having good semiconductor properties and a high light absorption coefficient is required.

MATERIAL STAGE vol.2, No.9 2002 p.37-42 Junichi Nakamura et al. "Organic thin-film solar cells-utilization of donor-acceptor interaction" Applied Physics Vol.71 No.4 (2002) p.425-428 Akinori Kuno "Current Status and Prospects of Organic Solar Cells"

  The present invention has been made in view of the above problems, and has as its main object to provide an organic thin film solar cell with high energy conversion efficiency.

  In order to achieve the above object, the present inventors examined materials having a high charge transporting ability as a material for forming a photoelectric conversion layer, a novel combination thereof, and further studied a layer structure of an organic thin film solar cell. Thus, it has been found that high energy conversion efficiency can be obtained due to the effect that light absorption is relatively good and current can be increased.

That is, the present invention includes a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer and having a hole transport layer and an electron transport layer, and the photoelectric conversion. An organic thin film solar cell having a second electrode layer formed on a layer and facing the first electrode layer,
The hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV),
The electron transport layer provides at least one of a polyfluorene derivative or a fullerene derivative, and provides an organic thin film solar cell.

  In the present invention, the hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene (PPV) derivative, and the electron transport layer has a polyfluorene derivative and / or a fullerene derivative. By combining a plurality of materials having excellent properties, it is possible to obtain an organic thin film solar cell having excellent charge extraction properties and high energy conversion efficiency. Further, since the polyfluorene derivative has a high light absorption coefficient, when the electron transport layer has a polyfluorene derivative, the photovoltaic power is increased, and the energy conversion efficiency can be improved.

The present invention also includes a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, which is an electron-hole transport layer, and the photoelectric conversion layer. An organic thin film solar cell formed and having a second electrode layer that is an electrode facing the first electrode layer,
The electron-hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV), and has at least one of a polyfluorene derivative or a fullerene derivative, I will provide a.

  According to the present invention, the electron-hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene (PPV) derivative, and has a polyfluorene derivative and / or a fullerene derivative, such packing and charge transport. By combining a plurality of materials having excellent properties, it is possible to obtain an organic thin film solar cell having excellent charge extraction properties and high energy conversion efficiency. In addition, since the polyfluorene derivative has a high light absorption coefficient, when the electron-hole transport layer has a polyfluorene derivative, the photovoltaic power increases and the energy conversion efficiency can be further improved.

Furthermore, the present invention provides a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, which is an electron-hole transport layer, and the photoelectric conversion layer. An organic thin film solar cell formed and having a second electrode layer that is an electrode facing the first electrode layer,
The electron-hole transport layer provides an organic thin-film solar cell having a polyfluorene derivative and a fullerene derivative.

  According to the present invention, since the polyfluorene derivative and fullerene derivative contained in the electron-hole transport layer are materials excellent in packing and charge transportability, the organic thin film solar cell is excellent in charge extraction property and high in energy conversion efficiency. It can be.

  In the present invention, the polythiophene derivative preferably has any of an alkyl group, a thienyl group, or a phenyl group as a side chain. This is because by introducing the side chain as described above, the solubility in an organic solvent is increased and the handleability is improved.

  Furthermore, in this invention, it is preferable that the said polyphenylene vinylene derivative (PPV) has an alkoxy group as a side chain. This is because by introducing an alkoxy group, the solubility in an organic solvent is increased, and the handleability is improved.

  In the present invention, the polyfluorene derivative preferably has an alkyl group as a side chain. This is because by introducing an alkyl group, the solubility in an organic solvent is increased, and the handleability is improved.

  Furthermore, in the present invention, the fullerene derivative is preferably a higher-order fullerene, a surface-modified fullerene having a surface-modifying group, or a fullerene-bonded polymer.

  Moreover, in this invention, it is preferable that the total light transmittance of the said 1st electrode layer is 90% or more, and sheet resistance is 20 ohms / square or less. When the total light transmittance is within the above range, light can be efficiently absorbed, and when the sheet resistance is within the above range, the generated photocharge can be sufficiently transmitted to an external circuit. Because.

  Furthermore, in the present invention, it is preferable that a hole extraction layer is formed between the first electrode layer and the photoelectric conversion layer. This is because the efficiency of extracting holes from the photoelectric conversion layer to the first electrode layer is increased, so that the energy conversion efficiency can be improved.

  Moreover, in this invention, it is preferable that the electron extraction layer is formed between the said photoelectric converting layer and the said 2nd electrode layer. This is because the efficiency of extracting electrons from the photoelectric conversion layer to the second electrode layer can be increased, so that the energy conversion efficiency can be improved.

  In the present invention, a polythiophene derivative and / or a polyphenylene vinylene (PPV) derivative is used as a material having a hole transport function, and a polyfluorene derivative and / or fullerene derivative is used as a material having an electron transport function. In addition, by combining a plurality of materials excellent in charge transportability, it is possible to obtain a more efficient organic thin-film solar cell with excellent charge extraction performance.

  Hereinafter, the organic thin film solar cell of the present invention will be described in detail.

A. First, the organic thin film solar cell of the present invention will be described.

  The organic thin film solar cell of the present invention is a heterojunction type organic thin film solar cell using a pn junction with a set of electron accepting and electron donating functions, and is divided into two modes according to the configuration of the photoelectric conversion layer. be able to. That is, the photoelectric conversion layer has a hole transport layer that functions as an electron donor and an electron transport layer that functions as an electron acceptor, and an electron hole transport layer that functions as both an electron donor and an electron acceptor It can be divided into the aspect which consists of. In the present invention, the bi-layer type organic thin film solar having a structure in which the electron transport layer having an electron-accepting function and the hole transport layer having an electron-donating function are separately laminated, respectively, in the above two embodiments. A bulk heterojunction organic thin-film solar cell using a battery and an electron-hole transport layer in which electron-donating and electron-accepting functions are mixed in one layer is assumed.

  In the present invention, the photoelectric conversion layer means a member that contributes to charge separation of the organic thin film solar cell and has a function of transporting the generated electrons and holes toward electrodes in opposite directions.

  Hereinafter, the bilayer type organic thin film solar cell and the bulk heterojunction type organic thin film solar cell will be described separately.

1. Bilayer type organic thin film solar cell The organic thin film solar cell of this aspect is formed on a substrate, a first electrode layer formed on the substrate, and a hole transport layer and an electron transport layer formed on the first electrode layer. An organic thin film solar cell having a photoelectric conversion layer having a second electrode layer formed on the photoelectric conversion layer and facing the first electrode layer, wherein the hole transport layer comprises polythiophene It has at least one of a derivative or a polyphenylene vinylene derivative (PPV), and the electron transport layer has at least one of a polyfluorene derivative or a fullerene derivative.

  The bilayer type organic thin film solar cell of this aspect is demonstrated using drawing. FIG. 1 is a schematic cross-sectional view showing an example of the bilayer organic thin film solar cell of this embodiment. As shown in FIG. 1, the bilayer organic thin film solar cell of this embodiment is formed on a substrate 1, a first electrode layer 2 formed on the substrate 1, and a first electrode layer 2. A photoelectric conversion layer 3 having a hole transport layer 4 and an electron transport layer 5, and a second electrode layer 7 formed on the photoelectric conversion layer 3 and facing the first electrode layer 2. .

  In this embodiment, the hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene derivative, and the electron transport layer has a polyfluorene derivative and / or a fullerene derivative. By combining these, an organic thin film solar cell with high energy conversion efficiency can be obtained.

Moreover, the bilayer type organic thin film solar cell of this aspect forms the electron transport layer 5 which has an electron-accepting function, and the positive hole transport layer 4 which has an electron-donating function separately as the photoelectric converting layer 3, respectively. The photocurrent is separated by using a pn junction formed at the interface to obtain a photocurrent.
Hereinafter, each structure of such a bilayer type organic thin film solar cell will be described.

(1) Substrate First, a substrate used for the bilayer organic thin film solar cell of this embodiment will be described. In this embodiment, the substrate is not particularly limited, whether it is transparent or opaque. For example, when the substrate side is a light receiving surface, it is a transparent substrate. Is preferred. The transparent substrate is not particularly limited, and for example, a non-flexible transparent rigid material such as quartz glass, Pyrex (registered trademark), synthetic quartz plate, or a transparent resin film, an optical resin plate, etc. The transparent flexible material which has flexibility can be mentioned.

  In this aspect, among the above, the substrate is preferably a flexible material such as a transparent resin film. Transparent resin films are excellent in processability, and are useful in the realization of organic thin-film solar cells that reduce manufacturing costs, reduce weight, and are difficult to break, and expand the applicability to various applications such as application to curved surfaces. is there.

(2) 1st electrode layer Next, the 1st electrode layer used for the bilayer type organic thin-film solar cell of this aspect is demonstrated. In this aspect, the first electrode layer is formed on the substrate.

The material for forming the first electrode layer is not particularly limited as long as it has conductivity. However, considering the irradiation direction of light, the work function of the material for forming the second electrode layer described later, and the like. It is preferable to select appropriately. For example, when the material for forming the second electrode layer is a material having a low work function, the material for forming the first electrode layer is preferably a material having a high work function. Examples of the material having a high work function include Au, Ag, Co, Ni, Pt, C, ITO, SnO ₂ , fluorine-doped SnO ₂ , and ZnO. Further, when the substrate of the bilayer type organic thin film solar cell is used as the light receiving surface, the first electrode layer is preferably a transparent electrode, and in this case, one generally used as a transparent electrode is used. Can do. Specifically, In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, and the like can be given.

  In this embodiment, the total light transmittance of the first electrode layer is 85% or more, preferably 90% or more, and particularly preferably 92% or more. When the substrate of the bilayer organic thin film solar cell of this aspect is a light receiving surface, the first electrode layer can sufficiently transmit light because the total light transmittance of the first electrode layer is in the above range. This is because light can be efficiently absorbed by the photoelectric conversion layer.

  In addition, the said total light transmittance is the value measured in the visible light area | region using the Suga Test Co., Ltd. total light transmittance apparatus (COLOUR S & M COMPUTER MODEL SM-C: model number).

  In this embodiment, the sheet resistance of the first electrode layer is preferably 20Ω / □ or less, more preferably 10Ω / □ or less, and particularly preferably 5Ω / □ or less. This is because when the sheet resistance is larger than the above range, the generated photocharge may not be sufficiently transmitted to the external circuit.

  The sheet resistance is measured based on JIS R1637 (low-efficiency test method for fine ceramic thin film: 4-probe method) using a surface resistance meter (Loresta MCP: 4-terminal probe) manufactured by Mitsubishi Chemical Corporation. It is the value.

  The first electrode layer may be a single layer, or may be laminated using materials having different work functions. As the film thickness of the first electrode layer, in the case of the first electrode layer made of a single layer, the film thickness thereof is in the range of 0.1 to 500 nm in the case of being made of a plurality of layers. Especially, it is preferable that it exists in the range of 1 nm-300 nm. When the film thickness is smaller than the above range, the sheet resistance of the first electrode layer becomes too large, and the generated photocharge may not be sufficiently transmitted to the external circuit. This is because there is a possibility that the total light transmittance is lowered and the energy conversion efficiency is lowered.

  The first electrode layer may be formed on the entire surface of the substrate or may be formed in a pattern.

  Furthermore, the shape of the first electrode layer may be a flat shape, or may be an uneven shape such as a texture structure, a pyramid structure, a wave structure, a comb structure, or a nano pillow structure. For example, when the shape of the first electrode layer is uneven, incident light is scattered by the uneven shape of the first electrode layer, so that the photoelectric conversion layer described later can take in much light. Thereby, since light can be used effectively, energy conversion efficiency can be improved.

  As the method for forming the first electrode layer, a generally used method can be used. Specifically, a PVD method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a dry method such as a CVD method. Examples thereof include a coating method and a wet coating method in which a coating solution containing ITO fine particles is applied. The patterning method for forming the first electrode layer in a pattern is not particularly limited as long as it can accurately form the first electrode layer in a desired pattern. Lithographic methods and the like can be mentioned.

(3) Photoelectric conversion layer Next, the photoelectric conversion layer used for the bilayer type organic thin film solar cell of this aspect is demonstrated. The photoelectric conversion layer in the bilayer type organic thin film solar cell of this embodiment is formed on the first electrode layer and is composed of a hole transport layer and an electron transport layer.

In this embodiment, the hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene derivative, and the electron transport layer has a polyfluorene derivative and / or a fullerene derivative. By combining these, an organic thin film solar cell with high energy conversion efficiency can be obtained.
Hereinafter, description will be made by dividing into a hole transport layer and an electron transport layer constituting such a photoelectric conversion layer.

(Hole transport layer)
In this embodiment, the hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV).

  Examples of the polythiophene derivative used in this embodiment include polythiophene, polythiophene derivatives, and a mixture of polythiophene and polythiophene derivatives.

  Examples of the polythiophene derivative include a compound having a thiophene skeleton represented by the following general formula (1).

  In this embodiment, in the general formula (1), all of the carbon atoms in the thiophene skeleton may be substituted with any group, and these substituents may be bonded to each other to form a ring. . Further, the n thiophene skeleton units contained in one molecule may be the same or different including the substituent.

  Moreover, in the said polythiophene derivative, it does not specifically limit as a polymerization degree at the time of making the above structural units mainly, and an average molecular weight.

  In this embodiment, the polythiophene derivative preferably has a substituent. Polythiophene itself is poorly soluble in organic solvents, but by introducing a substituent as described later, the solubility in organic solvents is increased, so that a hole transport layer can be formed by a wet coating method described later. Because. Such substituents are not particularly limited as long as they do not impair the required properties of polythiophene. For example, halogen atoms such as fluorine atoms and chlorine atoms; alkyl groups such as methyl groups and ethyl groups; alkenyl groups such as vinyl groups; A cyano group; an alkoxy group such as a methoxy group and an ethoxy group; an aromatic hydrocarbon group such as a phenyl group and a naphthyl group; and an aromatic heterocyclic group such as a thienyl group and a pyridyl group. Moreover, in this aspect, among the above, a polythiophene derivative having any of an alkyl group, a thienyl group, or a phenyl group as a side chain is more preferable.

  In addition, a polythiophene derivative having an alkyl group (R) as a side chain represented by the following chemical formula is preferable.

  Examples of the polyphenylene vinylene derivative used in this embodiment include polyphenylene vinylene, polyphenylene vinylene derivatives, and mixtures of polyphenylene vinylene and polyphenylene vinylene derivatives.

  Moreover, as a polyphenylene vinylene derivative, the compound which has a phenylene vinylene skeleton as represented by following General formula (2) is mentioned.

  In this embodiment, in the above general formula (2), any carbon atom in the phenylene vinylene skeleton may be substituted with any group, and these substituents may be bonded to each other to form a ring. Good. Further, the n phenylene vinylene skeleton units contained in one molecule may be the same or different including the substituent.

  Moreover, in the said polyphenylene vinylene derivative, it does not specifically limit as a polymerization degree at the time of making the above structural units mainly, and an average molecular weight.

  In this embodiment, it is preferable that the polyphenylene vinylene derivative has a substituent. This is because by introducing a substituent as described later, the solubility in an organic solvent is increased, so that a hole transport layer can be formed by a wet coating method described later. In addition, the charge transport ability is improved by the introduction of the substituent. Such a substituent is not particularly limited as long as it does not hinder the required characteristics of polyphenylene vinylene. For example, a halogen atom such as a fluorine atom or a chlorine atom; an alkyl group such as a methyl group or an ethyl group; an alkenyl group such as a vinyl group; Cyano group; alkoxy group such as methoxy group and ethoxy group; aromatic hydrocarbon group such as phenyl group and naphthyl group; aromatic heterocyclic group such as thienyl group and pyridyl group; Moreover, in this aspect, among the above, a polyphenylene vinylene derivative having an alkoxy group as a side chain is preferable.

  In this embodiment, examples of the material for forming the hole transport layer include (i) polythiophene derivatives, (ii) polyphenylene vinylene derivatives, (iii) polythiophene derivatives, and polyphenylene vinylene derivatives.

  When the hole transport layer has both a polythiophene derivative and a polyphenylene vinylene derivative (PPV), the mixing ratio depends on the type of the polythiophene derivative and the polyphenylene vinylene derivative and the combination with the first electrode layer and the second electrode layer. Therefore, it is preferable to adjust the mixing ratio appropriately. Specifically, it is desirable that the polythiophene derivative: polyphenylene vinylene derivative = 100: 1 to 1: 100 by weight ratio.

(Electron transport layer)
Next, the electron transport layer used in this embodiment will be described. In this embodiment, the electron transport layer has at least one of a polyfluorene derivative or a fullerene derivative.

  First, polyfluorene will be described. Polyfluorene is attracting attention as a material that emits blue light while having excellent film formability and a long conjugated system. Derivatives in which an alkyl group or the like is introduced as a side chain into this polyfluorene are highly soluble in organic solvents, and therefore are being applied as organic electroluminescent devices.

  Examples of the polyfluorene derivative used in this embodiment include polyfluorene, a polyfluorene derivative, and a mixture of polyfluorene and a polyfluorene derivative.

  Examples of the polyfluorene derivative include compounds having a fluorene skeleton as represented by the following general formula (3).

  In this aspect, in the above general formula (3), any carbon atom in the fluorene skeleton may be substituted with any group, and these substituents may be bonded to each other to form a ring. . Further, the n fluorene skeleton units contained in one molecule may be the same or different including the substituent.

  Moreover, in the said polyfluorene derivative, it does not specifically limit as a polymerization degree at the time of making the above structural units mainly, and an average molecular weight.

  In this embodiment, it is preferable that the polyfluorene derivative has a substituent. This is because by introducing a substituent as described later, the solubility in an organic solvent is increased, so that an electron transport layer can be formed by a wet coating method described later. Such a substituent is not particularly limited as long as the required properties of polyfluorene are not impaired. For example, a halogen atom such as a fluorine atom or a chlorine atom; an alkyl group such as a methyl group or an ethyl group; an alkenyl group such as a vinyl group; Cyano group; alkoxy group such as methoxy group and ethoxy group; aromatic hydrocarbon group such as phenyl group and naphthyl group; aromatic heterocyclic group such as thienyl group and pyridyl group; Moreover, in this aspect, among the above, a polyfluorene derivative having an alkyl group as a side chain is preferable.

Meanwhile, the fullerene is a spherical carbon molecules represented by C _60, known as a soccer ball-like molecule, since it was discovered by Kroto and Smalley in 1985, new to exert a peculiar features derived from its unique structure It is expected to be able to create new materials. For example, since _C60 is very easy to receive electrons and can exist stably as an anion radical, it has attracted attention as a functional material such as a photoelectric conversion element. Such in order to use as the material is formed of a thin film is essential, C ₆₀ because very easy to associate to form a uniform thin film is difficult. In order to reduce the thickness of fullerenes, a technique that has been mainly performed conventionally is to chemically modify fullerenes with substituents that are excellent in thin film formation properties or substituents that are bonded to a substrate. For example, C ₆₀ having a modified thiol sites, etc. As can be combined with gold substrates. Further, it is generally known that an electron-accepting substance is combined with a substance that can easily give an electron and can exist as a cation radical, so that the photoelectric conversion ability is generally improved. In the case of fullerene, a compound having an electron-donating moiety the is also a method of bonding via a covalent bond to the fullerene such as C _60.

  Examples of the fullerene derivative used in this embodiment include fullerene, a fullerene derivative, and a mixture of fullerene and a fullerene derivative.

  In this embodiment, the fullerene derivative is not particularly limited as long as it is a compound having a fullerene skeleton. In addition, any carbon atom in the fullerene skeleton may be surface-modified with an arbitrary group, and the surface-modifying groups may be bonded to each other to form a ring. Further, the fullerene skeleton units contained in one molecule may be the same or different including the surface modifying group.

  In the fullerene derivative, the degree of polymerization and the average molecular weight when the above-described structural units are mainly used are not particularly limited.

  Examples of such fullerene derivatives include higher-order fullerenes, surface-modified fullerenes having a surface-modifying group, bucky onions, and fullerene-bonded polymers. Among these, in this embodiment, higher-order fullerenes, surface-modified fullerenes, or fullerene-bonded polymers are preferable.

Specific examples of the higher order fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C _{84, and the} like. In the present invention, higher-order fullerenes mean higher-order fullerenes and derivatives of higher-order fullerenes.

Examples of the surface modifying group in the surface modified fullerene having the surface modifying group include a hydrogen atom; a hydroxyl group; a halogen atom such as a fluorine atom and a chlorine atom; an alkyl group such as a methyl group and an ethyl group; and an alkenyl such as a vinyl group. A cyano group; an alkoxy group such as a methoxy group or an ethoxy group; an aromatic hydrocarbon group such as a phenyl group or a naphthyl group; an aromatic heterocyclic group such as a thienyl group or a pyridyl group; Specific examples include hydrogenated fullerenes such as C ₆₀ H ₃₆ and C ₇₀ H ₃₆ , oxide fullerenes such as C ₆₀ and C ₇₀ , fullerene metal complexes, and the like. In the present invention, the surface-modified fullerenes mean surface-modified fullerenes and surface-modified fullerene derivatives.

  Furthermore, examples of the fullerene-bonded polymers include those having a conductive polymer as a main skeleton and fullerenes as side chains thereof. Examples of the conductive polymer include cyclic compounds having liquid crystallinity, and those containing a porphyrin ring. Examples of fullerenes include the above-described higher-order fullerenes and surface-modified fullerenes. In the present invention, fullerene bonded polymers mean fullerene bonded polymers and derivatives of fullerene bonded polymers.

  In this embodiment, the combination of materials forming the electron transport layer includes (i) a polyfluorene derivative, (ii) a fullerene derivative, (iii) a polyfluorene derivative and a fullerene derivative.

  When the electron transport layer has both a polyfluorene derivative and a fullerene derivative, the mixing ratio varies depending on the type of the polyfluorene derivative and the fullerene derivative and the combination with the first electrode layer and the second electrode layer. It is preferable to adjust appropriately to the optimum mixing ratio. Specifically, it is desirable that the weight ratio is within the range of polyfluorene derivative: fullerene derivative = 5: 1 to 1:10.

(Hole transport layer and electron transport layer)
In this embodiment, as described above, the hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene derivative, and the electron transport layer has a polyfluorene derivative and / or a fullerene derivative. By combining materials having excellent properties, an organic thin film solar cell with high energy conversion efficiency can be obtained.

  As a combination of the material for forming the hole transport layer and the electron transport layer used in the bilayer type organic thin film solar cell of this embodiment, the combination of the materials for forming the hole transport layer and the electron transport layer described above may be used. Can be mentioned. (I) hole transport layer: polythiophene derivative, electron transport layer: polyfluorene derivative, (ii) hole transport layer: polythiophene derivative, electron transport layer: fullerene derivative, (iii) hole transport layer: polythiophene derivative, Electron transport layer: polyfluorene derivative and fullerene derivative, (iv) hole transport layer: polyphenylene vinylene derivative, electron transport layer: polyfluorene derivative, (v) hole transport layer: polyphenylene vinylene derivative, electron transport layer: fullerene derivative, (Vi) hole transport layer: polyphenylene vinylene derivative, electron transport layer: polyfluorene derivative and fullerene derivative, (vii) hole transport layer: polythiophene derivative and polyphenylene vinylene derivative, electron transport layer: polyfluorene derivative, (viii) positive Pore transport layer: polythiophene derivative and poly Examples include rephenylene vinylene derivatives, electron transport layers: fullerene derivatives, (ix) hole transport layers: polythiophene derivatives and polyphenylene vinylene derivatives, electron transport layers: polyfluorene derivatives and fullerene derivatives.

  In this embodiment, among the above combinations, the electron transport layer preferably has a polyfluorene derivative. This is because the polyfluorene derivative has a high light absorption coefficient, so that incident light can be used effectively and the photovoltaic power increases, so that the energy conversion efficiency can be improved.

  In this embodiment, a preferable combination of materials used for the hole transport layer and the electron transport layer is, among the above combinations, the hole transport layer has at least a polythiophene derivative, and the electron transport layer has at least a polyfluorene derivative. The combination which has is mentioned.

  In the bilayer type organic thin film solar cell of this embodiment, the photoelectric conversion layer may be composed of one hole transport layer 4 and one electron transport layer 5 as shown in FIG. 1, and as shown in FIG. There may be a case where each of the hole transport layer 4 and the electron transport layer 5 has a plurality of layers.

  In addition, the thicknesses of the electron transport layer and the hole transport layer are not particularly limited, but specifically, each thickness is in the range of 0.1 nm to 1500 nm, and in particular, in the range of 5 nm to 300 nm. Is preferred. This is because when the film thickness of the electron transport layer and the hole transport layer is thicker than the above range, the film resistance in the electron transport layer and the hole transport layer may be increased. On the other hand, when the film thicknesses of the electron transport layer and the hole transport layer are thinner than the above range, a short circuit may occur between the first electrode layer and the second electrode layer.

  The method for forming the electron transport layer or the hole transport layer is not particularly limited as long as it can be uniformly formed in a predetermined film thickness. For example, there is a wet coating method in which a material for forming an electron transport layer or a hole transport layer is dissolved or dispersed in a solvent and applied.

  Specific examples of such wet coating methods include die coating methods, spin coating methods, dip coating methods, roll coating methods, bead coating methods, spray coating methods, and ink jet methods. Among these, a spin coating method or a die coating method is preferable. This is because these methods can form the photoelectric conversion layer with high accuracy so that the film thickness is in the above range.

(4) 2nd electrode layer Next, the 2nd electrode layer used for the bilayer type organic thin film solar cell of this aspect is demonstrated. The 2nd electrode layer in the bilayer type organic thin film solar cell of this aspect is an electrode which is formed on the said photoelectric converting layer, and opposes the said 1st electrode layer.

  The material for forming the second electrode layer is not particularly limited as long as it has conductivity, but considering the irradiation direction of light, the work function of the material for forming the first electrode layer, and the like. It is preferable to select appropriately. For example, when the substrate is a light receiving surface, the first electrode layer is a transparent electrode. In such a case, the second electrode layer may not be transparent. In addition, when the first electrode layer is formed using a material having a high work function, the second electrode layer is preferably formed using a material having a low work function. , Li, In, Al, Ca, Mg, Sm, Tb, Yb, Zr, LiF, and the like. In addition, the second electrode layer may be a single layer or may be laminated using materials having different work functions.

  The film thickness of the second electrode layer is in the range of 0.1 nm to 500 nm when the second electrode layer is composed of a single layer, and in the case where the second electrode layer is composed of a plurality of layers, the total film thickness of each layer is combined. Among these, it is preferable to be in the range of 1 nm to 300 nm. When the film thickness is smaller than the above range, the sheet resistance of the second electrode layer becomes too large, and the generated photocharge may not be sufficiently transmitted to the external circuit. This is because the light transmittance is lowered and the light conversion efficiency may be lowered.

  Further, the second electrode layer may be formed on the entire surface of the photoelectric conversion layer or may be formed in a pattern.

  As a method for forming such a second electrode layer, a generally used method can be used, for example, a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, or a dry coating method such as a CVD method. And a wet coating method in which a metal paste containing a metal colloid such as Ag is used.

  The patterning method for forming the second electrode layer in a pattern is not particularly limited as long as the second electrode layer can be accurately formed in a desired pattern. Lithographic methods and the like can be mentioned.

(5) Others (Hole extraction layer)
In the bilayer type organic thin film solar cell of this aspect, for example, as shown in FIG. 4, a hole extraction layer 8 may be formed between the first electrode layer 2 and the photoelectric conversion layer 3.

  In this embodiment, the hole extraction layer is a layer provided so that holes can be easily extracted from the photoelectric conversion layer to the first electrode layer. Thereby, since the hole extraction efficiency from the photoelectric conversion layer to the first electrode layer is increased, the energy conversion efficiency can be improved.

  The material used for such a hole extraction layer is not particularly limited as long as the material can stabilize the extraction of holes from the photoelectric conversion layer to the first electrode layer. Specifically, conductive organic compounds such as doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, triphenyldiamine (TPD), or electron donation such as tetrathiofulvalene, tetramethylphenylenediamine, etc. An organic material that forms a charge transfer complex composed of an organic compound and an electron-accepting compound such as tetracyanoquinodimethane and tetracyanoethylene. Also, a thin film of metal such as Au, In, Ag, Pd, etc. can be used. Furthermore, a thin film of metal or the like may be formed alone or in combination with the above organic material.

  In this aspect, among the above, polyethylenedioxythiophene (PEDOT), triphenyldiamine (TPD) and the like are particularly preferable.

  The thickness of the hole extraction layer is preferably in the range of 10 to 200 nm when the organic material is used, and in the range of 0.1 to 5 nm in the case of the metal thin film. It is preferable.

(Electronic extraction layer)
In the bilayer type organic thin film solar cell of this embodiment, for example, as shown in FIG. 4, an electron extraction layer 9 may be formed between the photoelectric conversion layer 3 and the second electrode layer 7.

  In this embodiment, the electron extraction layer is a layer provided so that electrons can be easily extracted from the photoelectric conversion layer to the second electrode layer. Thereby, since the electron extraction efficiency from the photoelectric conversion layer to the second electrode layer is increased, the energy conversion efficiency can be improved.

  A material used for such an electron extraction layer is not particularly limited as long as it is a material that stabilizes extraction of electrons from the photoelectric conversion layer to the second electrode layer. Specifically, conductive organic compounds such as doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, triphenyldiamine (TPD), or electron donation such as tetrathiofulvalene, tetramethylphenylenediamine, etc. An organic material that forms a charge transfer complex composed of an organic compound and an electron-accepting compound such as tetracyanoquinodimethane and tetracyanoethylene. Moreover, the metal dope layer with an alkali metal or alkaline-earth metal is mentioned. Suitable materials include BCP (bathocuproin) or Bphen (bassophenantrone) and metal doped layers such as Li, Cs, Ba, Sr.

(Protective sheet)
In this embodiment, for example, as shown in FIG. 4, a protective sheet 10 may be formed on the second electrode layer 7. In this embodiment, the protective sheet is a layer provided to protect the organic thin film solar cell of the present invention from the outside world.

  Materials used for such protective sheets include metal plates or metal foils such as aluminum, fluorine resin sheets, cyclic polyolefin resin sheets, polycarbonate resin sheets, poly (meth) acrylic resin sheets, polyamide resin sheets. , A polyester resin sheet, or a composite sheet obtained by laminating and laminating a weather resistant film and a barrier film.

  The thickness of the protective sheet is preferably in the range of 20 μm to 500 μm, more preferably in the range of 50 μm to 200 μm.

  Further, the protective sheet may have a barrier property as described in the column of a barrier layer described later.

  Furthermore, the design properties can be imparted to the protective sheet by coloring or the like. At this time, it may be colored by kneading the pigment into the protective sheet or the like, for example, by laminating a colored layer such as a blue hard coat layer.

(Filler layer)
In this aspect, a filler layer may be formed between the second electrode layer and the protective sheet. In this embodiment, the filler layer is a layer provided to seal the organic thin film solar cell by bonding the back surface side of the organic thin film solar cell, that is, the second electrode layer and the protective sheet.

  As such a filler layer, what is generally used as a filler layer of a solar cell should just be mentioned, for example, ethylene-vinyl acetate copolymer resin is mentioned.

  Moreover, it is preferable that the thickness of the said filler layer exists in the range of 50 micrometers-2000 micrometers, and it is more preferable that it exists in the range of 200 micrometers-800 micrometers. This is because when the thickness is less than the above range, the strength is reduced, and conversely, when the thickness is greater than the above range, cracks and the like are likely to occur.

(Barrier layer)
In this embodiment, a barrier layer may be formed on the surface of the substrate or the surface of the protective sheet. Moreover, when the said board | substrate or the said protective sheet consists of multiple layers, you may provide a barrier layer between each layer. The barrier layer used in this embodiment is a transparent layer, and is a layer provided to prevent the entry of oxygen and water vapor from the outside and protect the organic thin film solar cell of the present invention.

The barrier layer used in this embodiment has an oxygen permeability of 5 cc / m ² · day or less, and preferably 10 ⁻¹ cc / m ² · day or less. The water vapor transmission rate is 1 g / m ² · day or less, and preferably 10 ⁻¹ g / m ² · day or less.

  Here, the oxygen permeability is measured under the conditions of 23 ° C. and 90% Rh using an oxygen gas permeability measuring device (manufactured by MOCON, OX-TRAN 2/20). The water vapor transmission rate was measured using a water vapor transmission rate measuring device (manufactured by MOCON, PERMATRAN-W 3/31) under conditions of 37.8 ° C. and 100% Rh.

  Such a barrier layer is not particularly limited as long as it has the above-described barrier properties, but it is preferable to have a vapor deposition layer formed by a vapor deposition method because of its high barrier properties. .

  The vapor deposition layer is not particularly limited as long as it is a layer formed by a vapor deposition method, and may be a CVD method or a PVD method. When the vapor deposition layer is formed by a CVD method such as a plasma CVD method, it is possible to form a dense and high barrier layer, but in this aspect, from the viewpoint of manufacturing efficiency and cost The PVD method is preferred. Examples of the PVD method used in this embodiment include a vacuum vapor deposition method, a sputtering method, and an ion plating method. Among these, the vacuum vapor deposition method is preferable from the standpoint of barrier properties. Specific examples of the vacuum deposition method used in this embodiment include a vacuum deposition method using an electron beam (EB) heating method, a vacuum deposition method using a high frequency dielectric heating method, and the like.

Further, the material for the vapor deposition layer is preferably a metal or an inorganic oxide, Ti, Al, Mg, Zr, silicon oxide, aluminum oxide, silicon oxynitride, aluminum oxynitride, magnesium oxide, zinc oxide, indium oxide, oxide Tin, yttrium oxide, B ₂ O ₃ , CaO and the like can be mentioned, and among these, silicon oxide is preferable. This is because the layer made of silicon oxide has high barrier properties and transparency.

  In addition, the thickness of the vapor deposition layer in this embodiment is appropriately selected depending on the type and configuration of the material used, and is appropriately selected, but is preferably within a range of 5 nm to 1000 nm, and more preferably 10 nm to 500 nm. This is because if the thickness of the vapor deposition layer is thinner than the above range, it may be difficult to obtain a uniform layer and the barrier property may not be obtained. In addition, when the thickness of the vapor deposition layer is larger than the above range, the barrier property may be significantly impaired after the film formation due to a crack in the vapor deposition layer due to external factors such as pulling. In addition, it takes time to form and the productivity is also lowered.

(Layer structure)
In this embodiment, there is no particular limitation as long as a photoelectric conversion layer is disposed between the first electrode layer and the second electrode layer. For example, as described above, the photoelectric conversion layer may be provided not only as a single layer but also as a plurality of layers. When a plurality of photoelectric conversion layers are formed, a separate electrode layer is provided between the photoelectric conversion layers. It may be provided. Specifically, as shown in FIG. 5, the second electrode layer 7 is separately formed between the two photoelectric conversion layers 3.

2. Bulk heterojunction type organic thin film solar cell Next, the bulk heterojunction type organic thin film solar cell of this aspect is demonstrated. The bulk heterojunction organic thin film solar cell of this embodiment can be divided into two embodiments depending on the combination of materials used for the photoelectric conversion layer which is an electron-hole transport layer. Hereinafter, each aspect will be described.

(1) 1st aspect The 1st aspect of the bulk heterojunction type organic thin film solar cell of this aspect is formed on a substrate, a first electrode layer formed on the substrate, and the first electrode layer. An organic thin-film solar cell having a photoelectric conversion layer that is an electron-hole transport layer and a second electrode layer that is formed on the photoelectric conversion layer and is opposed to the first electrode layer, The electron-hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV), and has at least one of a polyfluorene derivative or a fullerene derivative.

  The bulk heterojunction type organic thin film solar cell of this aspect is demonstrated using drawing. FIG. 2 is a schematic cross-sectional view showing an example of the bulk heterojunction organic thin film solar cell of this embodiment. As shown in FIG. 2, the bulk heterojunction organic thin film solar cell of this embodiment is formed on the substrate 1, the first electrode layer 2 formed on the substrate 1, and the first electrode layer 2. The photoelectric conversion layer 3 that is the electron-hole transport layer 6 and the second electrode layer 7 that is formed on the photoelectric conversion layer 3 and that faces the first electrode layer 2 are provided.

  This embodiment is characterized in that the electron-hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene derivative and has a polyfluorene derivative and / or a fullerene derivative. By combining materials excellent in charge transportability, an organic thin film solar cell with high energy conversion efficiency can be obtained.

  Moreover, the bulk heterojunction type organic thin-film solar cell of this aspect is the electron hole transport layer 6 having both functions of the electron accepting property and the electron donating property as the photoelectric conversion layer 3, and in the electron hole transport layer. This is a solar cell that uses the pn junction formed to generate photocharge separation and obtain a photocurrent.

  In the present invention, although not particularly limited, the organic thin film solar cell is preferably a bulk heterojunction organic thin film solar cell as compared with the bilayer organic thin film solar cell. This is because the pn junction is widely formed in the electron-hole transport layer, so that the volume that can contribute to photoelectric conversion increases.

  Hereinafter, each structure of such a bulk heterojunction organic thin film solar cell will be described. In addition, regarding the substrate, the first electrode layer, the second electrode layer, the hole extraction layer, the electron extraction layer, and other layers used in the bulk heterojunction organic thin film solar cell of this embodiment, the above-mentioned “1. Since it is the same as that described in “Layer Type Organic Thin Film Solar Cell”, the description here is omitted.

(Photoelectric conversion layer)
The photoelectric conversion layer in the bulk heterojunction organic thin film solar cell of this embodiment is formed on the first electrode layer and is an electron hole transport layer having both electron accepting and electron donating functions. .

  In this embodiment, the electron-hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV), and has at least one of a polyfluorene derivative or a fullerene derivative.

  According to this aspect, the electron-hole transport layer has a polythiophene derivative and / or a polyphenylene vinylene derivative, and also has a polyfluorene derivative and / or a fullerene derivative, and such a material having excellent charge transportability. By combining these, an organic thin film solar cell with high energy conversion efficiency can be obtained.

  In this embodiment, the combination of materials for forming the electron-hole transport layer includes a combination of an electron-donating polythiophene derivative and a polyphenylenevinylene derivative, and an electron-accepting polyfluorene derivative and a fullerene derivative. It is done. (I) polythiophene derivative / polyfluorene derivative, (ii) polythiophene derivative / fullerene derivative, (iii) polythiophene derivative / polyfluorene derivative and fullerene derivative, (iv) polyphenylene vinylene derivative / polyfluorene derivative, (v) polyphenylene vinylene Derivatives / fullerene derivatives, (vi) polyphenylene vinylene derivatives / polyfluorene derivatives and fullerene derivatives, (vii) polythiophene derivatives and polyphenylene vinylene derivatives / polyfluorene derivatives, (viii) polythiophene derivatives and polyphenylene vinylene derivatives / fullerene derivatives, (ix) polythiophenes Derivatives and polyphenylene vinylene derivatives / polyfluorene derivatives and fullerene derivatives.

  In this embodiment, among the above combinations, the electron-hole transport layer preferably has a polyfluorene derivative. This is because the polyfluorene derivative has a high light absorption coefficient, so that incident light can be used effectively and the photovoltaic power is increased, so that the energy conversion efficiency can be further improved.

  In this embodiment, a preferable combination of materials used for the electron-hole transport layer includes at least a fullerene derivative as a material having an electron transport function among the above combinations, and at least as a material having a hole transport function. A combination having a polythiophene derivative.

  The polythiophene derivative, the polyphenylene vinylene derivative, the polyfluorene derivative, and the fullerene derivative are the same as those described in “1. Bilayer type organic thin film solar cell” described above, and thus description thereof is omitted here.

  The mixing ratio of the polythiophene derivative, polyphenylene vinylene derivative (PPV), polyfluorene derivative, and fullerene derivative in the electron hole transport layer varies depending on the type of each material and the combination of the first electrode layer and the second electrode layer. Therefore, it is preferable to adjust the mixing ratio appropriately depending on the material used.

  For example, among the preferred combinations of materials used for the electron hole transport layer described above, when the electron hole transport layer has a polythiophene derivative, a polyfluorene derivative, or a fullerene derivative, the mixing ratio of these may be a polythiophene derivative: polyfluorene. Derivative: Fullerene derivative = X: Y: Z (weight ratio) When X = 1, it is preferable that Y = 1 to 4, Z = 0.5 to 5 and Y = 2 to 3 , Z = 1 to 2 is more preferable.

  The film thickness of such an electron hole transport layer is not particularly limited as long as it is a film thickness generally employed in a bulk heterojunction type, and specifically, within a range of 0.2 nm to 3000 nm, Especially, it is preferable that it exists in the range of 10 nm-600 nm. When the film thickness is thicker than the above range, the film resistance in the electron-hole transport layer may be increased. On the other hand, when the film thickness is thinner than the above range, the first electrode layer and the second electrode layer This is because a short circuit may occur.

  In addition, the method for forming the electron hole transport layer is not particularly limited as long as it can be uniformly formed in a predetermined film thickness. For example, the electron hole transport layer can be formed by a wet coating method in which the above-described material for forming the electron hole transport layer is dissolved or dispersed in a solvent and applied.

  Specific examples of such a wet coating method include a die coating method, a spin coating method, a dip coating method, a roll coating method, a bead coating method, and a spray coating method. Among these, a spin coating method or a die coating method is preferable. This is because these methods can form the photoelectric conversion layer with a film thickness within the above range with high accuracy.

  Moreover, the number of layers of the electron hole transport layer may be one layer or a plurality of layers.

(2) Second Aspect A second aspect of the bulk heterojunction organic thin film solar cell of this aspect is formed on a substrate, a first electrode layer formed on the substrate, and on the first electrode layer. An organic thin-film solar cell having a photoelectric conversion layer that is an electron-hole transport layer and a second electrode layer that is formed on the photoelectric conversion layer and is opposed to the first electrode layer, The electron-hole transport layer has a polyfluorene derivative and a fullerene derivative.

  In this embodiment, the electron-hole transport layer has a polyfluorene derivative and a fullerene derivative, the fullerene derivative functions as electron transport, and the polyfluorene derivative functions as hole transport. This fullerene derivative has excellent electron transport properties, and the polyfluorene derivative has a high light absorption coefficient, so that incident light can be used effectively and the photovoltaic power is increased, resulting in higher energy conversion efficiency. High organic thin film solar cell.

  The polyfluorene derivative and the fullerene derivative are the same as those described in “1. Bilayer type organic thin film solar cell” described above, and thus the description thereof is omitted here.

  The mixing ratio of the polyfluorene derivative and the fullerene derivative in the electron-hole transport layer varies depending on the combination of the first electrode layer and the second electrode layer. For example, polyfluorene derivative: fullerene derivative = A: B (weight ratio) ), When A = 1, B = 0.01 to 100 is preferable, and B = 0.1 to 10 is more preferable.

  In addition, about the other point of the photoelectric converting layer which is an electron hole transport layer, it is the same as that of what was described in the said 1st aspect, Moreover, a board | substrate, a 1st electrode layer, a 2nd electrode layer, a hole extraction The layers, the electron extraction layer, and other layers are the same as those described in “1. Bi-layer type organic thin film solar cell” described above, and thus the description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[Example 1]
(Formation of first electrode layer)
A barrier layer made of SiO ₂ is formed on the surface of the super-barrier film substrate, and an ITO film (film thickness: 150 nm, sheet resistance: 15Ω / □), which is a transparent electrode, is formed on the barrier layer by the IP method and patterned. did. Next, the substrate with ITO film was washed with acetone and washed with IPA to form a patterned first electrode layer.

(Formation of hole extraction layer)
On the first electrode layer, PEDOT: PSS (poly (3,4) -ethylenedioxythiophene / polystyrene sulfonate aqueous dispersion) (Bayer, product name: BaytronP) was spin-coated and heated at 150 ° C. for 30 minutes. It was made to dry and the 40-nm-thick hole extraction layer was formed.

(Formation of photoelectric conversion layer)
As a hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)) was dissolved in a chloroform solvent so as to have a concentration of 0.1% by weight. A coating solution was prepared by filtering with a 2 μm filter paper. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form a hole transport layer having a thickness of 30 nm.

  Next, as an electron transport layer, a polyfluorene derivative was dissolved in a xylene solvent so as to have a concentration of 0.3% by weight, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried at 110 ° C. for 10 minutes to form an electron transport layer having a thickness of 30 nm.

  Further, the substrate on which the hole transport layer and the electron transport layer were formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
A second electrode layer is formed by depositing Ca on the electron transport layer to a thickness of 10 nm by a vapor deposition method, and further depositing Al on the electron transport layer to a thickness of 50 nm by a vapor deposition method. Formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 2]
(Formation of first electrode layer)
A barrier layer made of SiO ₂ is formed on the surface of the super-barrier film substrate, and an ITO film (film thickness: 150 nm, sheet resistance: 15Ω / □) as a transparent electrode is formed on the barrier layer to have a texture structure by sputtering. A film was formed and patterned. Next, the substrate with ITO film was washed with acetone and washed with IPA to form a first electrode layer.

(Formation of hole extraction layer)
In the same manner as in Example 1, a hole extraction layer was formed on the first electrode layer.

(Formation of photoelectric conversion layer)
As an electron hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)), a polyfluorene derivative, and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyl) Rick Acid Methyl Ester) is dissolved in a chloroform solvent so that the weight ratio is 1: 1: 1 and the concentration is 0.1% by weight, and this solution is filtered with a 0.2 μm filter paper and coated. A working solution was prepared. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form an electron-hole transport layer having a thickness of 50 nm.

  Furthermore, the substrate on which the electron hole transport layer was formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
In the same manner as in Example 1, a second electrode layer was formed on the electron hole transport layer.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Example 3]
(Formation of first electrode layer)
A barrier layer made of SiO ₂ is formed on the surface of the glass substrate in order to prevent alkali diffusion from the glass substrate, and the SnO ₂ film that is a transparent electrode is formed on the barrier layer as a transparent texture. A film having an uneven structure, a film thickness of 900 nm, and a sheet resistance of 10Ω / □ was formed by a CVD method and patterned. Next, the SnO ₂ film-coated substrate was washed with acetone and washed with IPA to form a patterned first electrode layer.

(Formation of hole extraction layer)
In the same manner as in Example 1, a hole extraction layer was formed on the first electrode layer.

(Formation of photoelectric conversion layer)
As an electron hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)), a polyfluorene derivative, and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyl) Rick Acid Methyl Ester) is dissolved in a chloroform solvent so that the weight ratio is 1: 2: 2 and the concentration is 0.5% by weight, and this solution is filtered with a filter paper of φ0.2 μm. A working solution was prepared. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form an electron-hole transport layer having a thickness of 120 nm.

  Furthermore, the substrate on which the electron hole transport layer was formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
On the electron-hole transport layer, LiF was deposited to a thickness of 1 nm by a vapor deposition method, and further Al was deposited to a thickness of 50 nm by a vapor deposition method. An electrode layer was formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Example 4]
(Formation of first electrode layer)
In the same manner as in Example 2, a first electrode layer was formed on the super-barrier film substrate.

(Formation of hole extraction layer)
On the first electrode layer, Au was deposited to a thickness of 0.5 nm by a vapor deposition method, and further, PEDOT: PSS (poly (3,4) -ethylenedioxythiophene / polystyrene sulfone) was formed thereon. (Nate aqueous dispersion) (product name: BaytronP, manufactured by Bayer) was spin-coated and dried at 150 ° C. for 30 minutes to form a hole extraction layer having a thickness of 40 nm.

(Formation of photoelectric conversion layer)
As an electron-hole transport layer, a polyphenvinylene derivative, a polyfluorene derivative, and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) in a chloroform solvent in a weight ratio of 1: The solution was dissolved so as to have a ratio of 2: 4 and a concentration of 0.5% by weight, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form an electron-hole transport layer having a thickness of 120 nm.

  Furthermore, the substrate on which the electron hole transport layer was formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
In the same manner as in Example 3, a second electrode layer was formed on the electron hole transport layer.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Example 5]
(Formation of first electrode layer)
In the same manner as in Example 2, a first electrode layer was formed on the super-barrier film substrate.

(Formation of hole extraction layer)
In the same manner as in Example 4, a hole extraction layer was formed on the first electrode layer.

(Formation of photoelectric conversion layer)
As the electron-hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)), a polyphenivinylene derivative, a polyfluorene derivative, and a fullerene derivative (PCBM: [6, 6 ] -Phenyl-C61 butyric acid methyl ester) is dissolved in chloroform solvent so that the weight ratio is 1: 1: 1: 2 and the concentration is 0.5% by weight. A coating solution was prepared by filtering with a filter paper. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form an electron-hole transport layer having a thickness of 120 nm.

  Furthermore, the substrate on which the electron hole transport layer was formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
On the electron-hole transport layer, In was deposited to a thickness of 0.5 nm by an evaporation method, and further Al was deposited to a thickness of 50 nm by an evaporation method, A second electrode layer was formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Example 6]
(Formation of first electrode layer)
A first electrode layer was formed in the same manner as in Example 2 except that a glass substrate was used.

(Formation of photoelectric conversion layer)
As a hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)) was dissolved in a chloroform solvent so as to have a concentration of 0.1% by weight. A coating solution was prepared by filtering with a 2 μm filter paper. This coating solution was spin-coated on the first electrode layer and dried at 110 ° C. for 10 minutes to form a 30 nm-thick hole transport layer.

  Next, as an electron transport layer, a polyfluorene derivative and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) in a chloroform solvent have a weight ratio of 1: 4 and a concentration of 0. The solution was dissolved to 5 wt%, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried at 110 ° C. for 10 minutes to form an electron transport layer having a thickness of 30 nm.

  Further, the substrate on which the hole transport layer and the electron transport layer were formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
On the said electron carrying layer, Al was formed into a film by the vapor deposition method so that it might become a film thickness of 500 nm, and the 2nd electrode layer was formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 7]
(Formation of first electrode layer)
A barrier layer made of SiO ₂ is formed on the surface of the glass substrate in order to prevent alkali diffusion from the glass substrate, and the SnO ₂ film that is a transparent electrode is formed on the barrier layer as a transparent texture. A film having an uneven structure, a film thickness of 900 nm, and a sheet resistance of 10Ω / □ was formed by a CVD method and patterned. Next, the SnO ₂ film-coated substrate was washed with acetone and washed with IPA to form a patterned first electrode layer.

(Formation of hole extraction layer)
On the first electrode layer, Au was deposited to a thickness of 0.5 nm by an evaporation method to form a hole extraction layer.

(Formation of photoelectric conversion layer)
As a hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)) and a polyphenylene vinylene derivative are mixed in a chloroform solvent at a weight ratio of 1: 1 and a concentration of 0.1. The solution was dissolved to 3% by weight, and this solution was filtered with a filter paper of φ0.2 μm to prepare a coating solution. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form a hole transport layer having a thickness of 30 nm.

  Next, as an electron transport layer, a polyfluorene derivative was dissolved in a xylene solvent so as to have a concentration of 0.3% by weight, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried at 110 ° C. for 10 minutes to form an electron transport layer having a thickness of 30 nm.

  Further, the substrate on which the hole transport layer and the electron transport layer were formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
In the same manner as in Example 6, a second electrode layer was formed on the electron transport layer.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 8]
(Formation of first electrode layer)
In the same manner as in Example 2, a first electrode layer was formed on the super-barrier film substrate.

(Formation of hole extraction layer)
In the same manner as in Example 4, a hole extraction layer was formed on the first electrode layer.

(Formation of photoelectric conversion layer)
As a hole transport layer, a polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)) and a polyphenylene vinylene derivative are mixed in a chloroform solvent at a weight ratio of 1: 1 and a concentration of 0.1. The solution was dissolved to 3% by weight, and this solution was filtered with a filter paper of φ0.2 μm to prepare a coating solution. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form a hole transport layer having a thickness of 30 nm.

  Next, as an electron transport layer, a polyfluorene derivative and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) in a chloroform solvent have a weight ratio of 1: 2, and the concentration is The solution was dissolved so as to be 0.3% by weight, and this solution was filtered with a filter paper of φ0.2 μm to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried at 110 ° C. for 10 minutes to form an electron transport layer having a thickness of 30 nm.

  Further, the substrate on which the hole transport layer and the electron transport layer were formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
In the same manner as in Example 5, a second electrode layer was formed on the electron transport layer.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Comparative Example 1]
A barrier layer of SiO ₂ was formed on the glass substrate surface, and an ITO film (film thickness: 150 nm, sheet resistance: 15Ω / □) as a transparent electrode was formed on the barrier layer by the IP method and patterned. Next, the substrate with ITO film was washed with acetone and washed with IPA to form a patterned first electrode layer.

(Formation of hole extraction layer)
On the first electrode layer, PEDOT: PSS (poly (3,4) -ethylenedioxythiophene / polystyrene sulfonate aqueous dispersion) (Bayer, product name: BaytronP) was spin-coated and heated at 150 ° C. for 30 minutes. It was made to dry and the 40-nm-thick hole extraction layer was formed.

(Formation of photoelectric conversion layer)
As a hole transport layer, zinc [5,10,15,20 tetraphenylporphyrin] is dissolved in chloroform solvent so that the concentration becomes 0.1% by weight, and this solution is filtered with a filter paper of φ0.2 μm. Thus, a coating solution was prepared. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form a hole transport layer having a thickness of 30 nm.

  Next, as an electron transport layer, rhodamine B was dissolved in a chloroform solvent so as to have a concentration of 0.1% by weight, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried at 110 ° C. for 10 minutes to form an electron transport layer having a thickness of 30 nm.

  Further, the substrate on which the hole transport layer and the electron transport layer were formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
A second electrode layer is formed by depositing Ca on the electron transport layer to a thickness of 10 nm by a vapor deposition method, and further depositing Al on the electron transport layer to a thickness of 50 nm by a vapor deposition method. Formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Comparative Example 2]
(Formation of first electrode layer and hole extraction layer)
In the same manner as in Comparative Example 1, a first electrode layer and a hole extraction layer were formed on a glass substrate.

(Formation of photoelectric conversion layer)
As an electron-hole transport layer, zinc [5,10,15,20 tetraphenylporphyrin] and rhodamine B are mixed in a chloroform solvent so that the weight ratio is 1: 1 and the concentration is 0.1% by weight. The solution was dissolved, and this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole extraction layer and dried at 110 ° C. for 10 minutes to form an electron-hole transport layer having a thickness of 50 nm.

  Furthermore, the substrate on which the electron hole transport layer was formed was annealed at 150 ° C. for 30 minutes to improve the packing and orientation of the coating components.

(Formation of second electrode layer)
In the same manner as in Comparative Example 1, a second electrode layer was formed on the electron hole transport layer.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Evaluation]
Regarding the solar cell characteristics, AM1.5 and simulated sunlight (100 mW / cm ² ) were used as irradiation light sources, and current-voltage characteristics were evaluated by applying voltage with a source measure unit (HP4100, manufactured by HP). The evaluation results are shown in Table 1 below. The evaluation results showed the open circuit voltage Voc (V) and the energy conversion efficiency η (%).

It is a schematic sectional drawing which shows an example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... 1st electrode layer 3 ... Photoelectric conversion layer 4 ... Hole transport layer 5 ... Electron transport layer 6 ... Electron hole transport layer 7 ... 2nd electrode layer

Claims (10)

A substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, having a hole transport layer and an electron transport layer, and formed on the photoelectric conversion layer; An organic thin film solar cell having a second electrode layer that is an electrode facing the first electrode layer,
The hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV),
The organic thin film solar cell, wherein the electron transport layer has at least one of a polyfluorene derivative or a fullerene derivative. A substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer and being an electron-hole transport layer, formed on the photoelectric conversion layer, and the first An organic thin-film solar cell having a second electrode layer that is an electrode facing the electrode layer,
The electron-hole transport layer has at least one of a polythiophene derivative or a polyphenylene vinylene derivative (PPV), and has at least one of a polyfluorene derivative or a fullerene derivative. . A substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer and being an electron-hole transport layer, formed on the photoelectric conversion layer, and the first An organic thin-film solar cell having a second electrode layer that is an electrode facing the electrode layer,
The electron-hole transport layer has an organic thin-film solar cell having a polyfluorene derivative and a fullerene derivative.   The organic thin-film solar cell according to claim 1 or 2, wherein the polythiophene derivative has an alkyl group, a thienyl group, or a phenyl group as a side chain.   The organic thin-film solar cell according to claim 1, 2, or 4, wherein the polyphenylene vinylene derivative (PPV) has an alkoxy group as a side chain.   The organic thin-film solar cell according to any one of claims 1 to 5, wherein the polyfluorene derivative has an alkyl group as a side chain.   The organic thin film according to any one of claims 1 to 6, wherein the fullerene derivative is a higher-order fullerene, a surface-modified fullerene having a surface-modifying group, or a fullerene-bonded polymer. Solar cell.   The organic thin film according to any one of claims 1 to 7, wherein the first electrode layer has a total light transmittance of 90% or more and a sheet resistance of 20Ω / □ or less. Solar cell.   The organic thin-film solar cell according to any one of claims 1 to 8, wherein a hole extraction layer is formed between the first electrode layer and the photoelectric conversion layer. . The organic thin-film solar cell according to any one of claims 1 to 9, wherein an electron extraction layer is formed between the photoelectric conversion layer and the second electrode layer.

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