JP2011034813A - Photoelectric element - Google Patents

Abstract

Provided is an optoelectric device having an electron transport layer having excellent electron transport characteristics and a sufficiently wide interface, and having excellent conversion efficiency.
The present invention relates to an optoelectric device formed between a pair of electrodes and having an electron transport layer in contact with one electrode and a hole transport layer in contact with the other electrode. The electron transport layer is formed by including an organic compound having a redox part that can be repeatedly redox, and an electrolyte solution that stabilizes the reduction state of the redox part. In addition, the redox potential of the electron transport layer is inclined from noble to base toward the electrode side in contact with the electron transport layer.
[Selection] Figure 1

Description

  The present invention relates to a photoelectric element that converts light into electricity or electricity into light.

  In recent years, photoelectric elements have been used for photoelectric conversion elements such as photovoltaic cells and solar cells, light emitting elements such as organic EL, optical display elements such as electrochromic display elements and electronic paper, and sensor elements that sense temperature and light. It is used.

  In the electron transport layer used in these photoelectric devices, high electron transport properties are required, and electrons are generated by external energy, and the area of the interface where electrons are injected from the outside acts. Size is important. Conventionally, metals, organic semiconductors, inorganic semiconductors, conductive polymers, conductive carbon, and the like have been used for such electron transport layers.

  For example, in photoelectric conversion elements, organic materials that use electrons as carriers, such as fullerene, perylene derivatives, polyphenylene vinylene derivatives, and pentacene, are used in the electron transport layer for transporting electrons, which improves conversion efficiency due to the ability to transport electrons. (See Non-Patent Document 1 for fullerene, Non-Patent Document 2 for perylene derivatives, Non-Patent Document 3 for polyphenylene vinylene derivatives, and Non-Patent Document 4 for pentacene).

  There is also a report of forming a thin film on a substrate of a structure in which an electron donating molecule (donor) and an electron accepting molecule (acceptor) are chemically bonded as a molecular element solar cell (see Non-Patent Document 5).

P.Peumans, Appl. Phys. Lett., 79, 2001, p. 126 C.W.Tang, Appl. Phys. Lett., 48, 1986, p. 183 S.E.Shaheen, Appl. Phys. Lett., 78, 2001, 841 J.H.Schon, Nature (London), 403, 2000, 408 Chemical Industry July 2001, 41, “Prospects for Molecular Solar Cells” by Hiroshi Imabori and Shunichi Fukuzumi

  However, the electron transport layer reported in each of the above-mentioned non-patent documents does not have both sufficient electron transport properties and sufficient interface area to act as an electron transport layer. At present, an electron transport layer for transporting electrons having transport characteristics and a sufficiently wide interface is desired.

  For example, in the case of an organic electron transport layer using fullerene or the like, charge recombination of electrons is likely to occur and the effective diffusion distance is not sufficient, so that it is difficult to further improve the conversion efficiency. This effective diffusion distance is the distance from the end of charge separation to the arrival of the electrode. The larger the effective diffusion distance, the higher the conversion efficiency of the device. In addition, in the case of an inorganic electron transport layer such as titanium oxide, the conversion efficiency is reduced because the interface area for charge separation is not sufficient and the electron conduction potential affecting the open circuit voltage is uniquely determined by the constituent elements. Is not enough.

  The present invention has been made in view of the above points, and an object thereof is to provide a photoelectric device having an excellent electron transport property and an electron transport layer having a sufficiently wide interface, and having excellent conversion efficiency. is there.

  The photoelectric device according to claim 1 of the present invention is formed between a pair of electrodes, each having an electron transport layer in contact with one electrode and a hole transport layer in contact with the other electrode. An optoelectric device, wherein the electron transport layer includes an organic compound having a redox part capable of repeated redox, and an electrolyte solution that stabilizes the reduction state of the redox part, and includes electron transport. The layer is characterized in that the redox potential is inclined from noble to base toward the electrode side in contact with the electron transport layer.

  Thus, in the present invention, the electron transport layer is formed by including an organic compound having a redox part capable of repeated redox, and the organic compound is an electrolyte solution that stabilizes the reduced state of the redox part. As a result, the electron transport layer is formed as a gel layer, and the structure can be subdivided at the molecular level, the reaction interface can be enlarged, and electrons are transported efficiently and at a high reaction rate. It is something that can be done.

  Here, in the present invention, redox (redox reaction) means that an ion, atom or compound exchanges electrons, and the redox part stably exchanges electrons by a redox reaction (redox reaction). It refers to the part that can be done.

  The gel layer refers to a layer formed in a state where an organic compound having a redox portion is swollen by an electrolyte solution. That is, in the gel state, the organic compound has a three-dimensional network structure, and the state where the liquid fills the network space is called a gel layer.

  Thus, by forming an electron transport layer as an organic compound having a redox portion as a gel layer swollen with an electrolyte solution, the redox portion is held in the vicinity of the electrode, or the adjacent redox portion has electrons between them. The organic compound can be held so that the distance is sufficiently close to being exchangeable. In addition, the redox part can be present in the electron transport layer at a high density, thereby realizing a very fast self-electron exchange reaction rate constant and enhancing the electron transport ability. . Furthermore, by forming the electron transport layer as a gel layer of an organic compound, it becomes easy to impart adhesiveness to the electron transport layer or to impart flexibility and light transmission to the electron transport layer. is there.

  In addition, as described above, since the redox part is present in the molecule of the organic compound forming the gel layer, the redox part is placed in the gel layer in a state where electron transport by repeated redox reaction is performed more effectively. This makes it easier to hold. That is, since the oxidation-reduction part is chemically bonded to the organic compound forming the gel layer, the oxidation-reduction part can be held by the gel layer so that the oxidation-reduction part remains at a position where electrons are easily transported. The positional relationship of the redox part in the organic compound may be, for example, a structure in which the redox part is arranged as a side chain with respect to the skeleton of the organic compound forming the gel layer. The reducing units may be alternately or partially continuously arranged and connected.

  The redox part can transport electrons not by diffusion but by an electron exchange reaction between the redox parts. This electron exchange reaction is a reaction in which electrons are exchanged between the redox parts by oxidizing the redox part in the reduced state, which is in close proximity to the redox part in the oxidized state, thereby apparently in the layer of the electron transport layer. In this way, electrons are transported. Although the function is similar to that of an ion conductive material in which ions are conducted by diffusion, the electron transport mechanism in the electron transport layer of the present invention is not the diffusion of the redox part but the exchange of electrons with the adjacent redox part. The point of transportation is different. Also in the electron transport layer of the present invention, in order to pass electrons to the adjacent redox part, the redox parts need to be close to each other to enable electron transfer, but the redox part is held by the gel layer. Therefore, the distance of movement is expected to be several angstroms. In particular, when the redox moiety is present in the molecule of the organic compound forming the gel layer as in the present invention, the reaction for electron exchange with the adjacent redox moiety is a reaction called a self-electron exchange reaction.

  Japanese Patent Application Laid-Open No. 07-288142 discloses a photoelectric conversion element including a solid ionic conductor in which a redox system is contained in a polymer compound. It is a transport material, not an electron transport material.

  In the electron transport layer of the photoelectric element of the present invention, the redox part is held in the gel layer as described above, so that light is converted into electricity or electricity is converted into light without impairing electron transport properties. Therefore, the reaction field, that is, the reaction interface can be increased, and a photoelectric element with high conversion efficiency can be obtained.

  Here, the reaction interface is an interface between the electron transport layer and the hole transport material or the electrolyte solution. For example, in photoelectric conversion elements, the charge generated by light absorption is separated at the reaction interface, so the wider the reaction interface, the higher the conversion efficiency, but in the past the area of the reaction interface could not be sufficiently increased In contrast, since the electron transport layer of the present invention is formed as a gel layer containing an electrolyte solution, the organic compound having a redox portion as described above, and therefore, the electrolyte solution penetrating into the redox portion and the electron transport layer Thus, the reaction interface becomes larger and the conversion efficiency can be increased. The following two points can be considered as the reason why the reaction interface becomes large. The first is that the conventional electron transport material made of an inorganic semiconductor or the like is an inorganic substance, so even if it is made fine particles, it is difficult to fall below the nanometer scale. If the redox moiety is in a state that can be oxidized and reduced to transport electrons, the structure can be subdivided at the molecular level, and the interface area necessary for charge separation can be increased. In particular, when the electron transport layer is formed of a polymer organic compound, it is theoretically possible to form an interface on an angstrom scale. Second, there is a possibility that a special interface state that promotes charge separation is formed at the interface between the redox part of the organic compound constituting the electron transport layer and the hole transport layer or the electrolyte solution. It is possible that there is.

  In addition, since the electron transport layer is formed of an organic compound having a redox portion, it can be easily designed and synthesized according to electrical properties such as potential and structural properties such as molecular size. Furthermore, gelation and solubility control can be performed. In addition, since the electron transport layer is formed of an organic compound, high-temperature firing is not required, as in the case of forming an electron transport material layer of an inorganic material such as an inorganic semiconductor, which is advantageous in terms of the manufacturing process. In addition, flexibility can be imparted to the electron transport layer. Furthermore, unlike inorganic materials and precious metal materials, organic compounds have no problems of resource depletion, low toxicity, and heat energy can be recovered by incineration at the time of disposal. Can be mentioned.

  Furthermore, in the present invention, as described above, the organic compound that forms the electron transport layer contains the electrolyte solution, so that the reduction state of the redox portion existing in the organic compound can be stabilized, and thus more stable. Thus, electrons can be transported. That is, compared with inorganic compounds such as metal semiconductors and metal oxide semiconductors generally used as electron transport materials, organic compounds are difficult to use as materials for electron transport layers because of their unstable reduction state. However, by adopting a structure containing an electrolyte solution, the ionic state formed by the redox reaction of the redox part is compensated by the counter ion in the electrolyte solution, that is, for example, the redox part in a cationic state Is stabilized by the reverse charge of the anion in the electrolyte solution, and the reduction state can be stabilized by the action of the solvation of the solvent and the dipole moment. As a result, the redox part is stabilized. It can be made.

  Here, the degree of swelling is a physical index that affects the size of the reaction interface of the gel layer. The degree of swelling referred to here is represented by the following formula.

Swelling degree (%) = (weight of gel) / (weight of dried gel) × 100
The dried gel refers to a dried gel. The drying of the gel refers to the removal of the solution contained in the gel, particularly the removal of the solvent. Examples of the method for drying the gel include heating, removal of the solution or solvent in a vacuum environment, removal of the solution or solvent contained in the gel with another solvent, and the like.

  In the present invention, the degree of swelling of the gel layer is preferably 110 to 3000%, and more preferably 150 to 500%. If it is less than 110%, the electrolyte component in the gel is small, and thus there is a risk that the oxidation-reduction site will not be sufficiently stabilized. If it exceeds 3000%, the oxidation-reduction site in the gel is small. As a result, the electron transport capability may be lowered, and in any case, the characteristics of the photoelectric element will be lowered.

  In the present invention, the electron transport layer has a redox potential inclined from noble to base toward the electrode side in contact with the electron transport layer, so that the flow of electrons in the electron transport layer is caused by the gradient of the redox potential. Thus, the electron transport property from the electron transport layer to the electrode in contact with the electron transport layer is improved, and the conversion efficiency can be further increased.

  In the invention of claim 2, the electron transport layer is formed by combining two or more organic compounds selected from an imide derivative, a quinone derivative, a viologen derivative, and a phenoxyl derivative. This is characterized in that the oxidation-reduction potential is inclined from noble to base.

  Imide derivatives, quinone derivatives, viologen derivatives, and phenoxyl derivatives each exchange electrons at high speed within the molecule, and can be used to form an electron transport layer with high electron transport capability. It is. An electron transport layer in which the redox potential is inclined from noble to base can be formed by combining the organic compounds having different redox potentials to form the electron transport layer.

  The invention of claim 3 is characterized in that a sensitizing dye is provided in contact with at least one of the electron transport layer and the hole transport layer.

  As described above, the electron transport layer of the present invention has excellent electron transport properties and a sufficiently wide interface, and the efficiency of transferring electrons from the sensitizing dye to the organic compound of the electron transport layer is further improved, and the conversion efficiency is improved. It can be further enhanced.

  According to the present invention, the electron transport layer is formed of an organic compound having a redox part capable of repeated redox, and the organic compound includes an electrolyte solution that stabilizes the reduced state of the redox part. In this case, the reaction interface can be enlarged, electrons can be transported efficiently and at a high reaction rate, and the electron transport layer has a gradient of redox potential, thereby allowing electrons to be transported. Electron transportability from the transport layer to the electrode in contact with the electron transport layer is improved, and a photoelectric element having excellent light-electricity conversion efficiency can be obtained.

It is the schematic which shows the layer structure in an example of embodiment of this invention.

  Embodiments of the present invention will be described below.

  FIG. 1 shows an example of the layer structure of a photoelectric element according to the present invention, which is formed by sandwiching an electron transport layer 3 and a hole transport layer 4 between a pair of electrodes 1 and 2. The electron transport layer 3 is in contact with one electrode 1 and the hole transport layer 4 is in contact with the other electrode 2, and the electron transport layer 3 and the hole transport layer 4 are in contact with each other. In FIG. 1, 6 and 7 are base materials provided with the electrodes 1 and 2 described above.

  The one electrode 1 is a member that is electrically connected to the electron transport layer 3 and is used to take out electrons from the electron transport layer 3 or to inject electrons into the electron transport layer 3. It is also a member for physically holding the electron transport layer 3. Here, the outside means a power circuit, a secondary battery, a capacitor, or the like that is electrically connected to the device.

  The electrode 1 may be formed of a single metal film, or the electrode 1 is formed on the base material 6 by laminating a conductive material on the insulating base material 6 such as glass or film. It may be. Preferred examples of the conductive material include metals such as platinum, gold, silver, copper, aluminum, rhodium, and indium; carbon; indium-tin composite oxide, antimony-doped tin oxide, and fluorine-doped tin oxide. Examples include conductive metal oxides; composites of these metals and oxides; materials obtained by coating these metals and compounds with silicon oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, and the like. . The lower the surface resistance of the electrode 1, the better. The preferable surface resistance is 200Ω / □ or less, more preferably 50Ω / □ or less. The lower limit of the surface resistance is not particularly limited, but is usually 0.1Ω / □.

  When the electrode 1 is formed on the base material 6, when the photoelectric element needs to pass light through the base material 6 of the electrode 1, such as a power generation element, a light emitting element, a photosensor, etc., the base material 6 It is desirable that has a high light transmittance. The preferable light transmittance is 50% or more at a wavelength of 500 nanometers, and more preferably 80% or more. Moreover, it is preferable that the thickness of the electrode 1 exists in the range of 0.1-10 micrometers. Within this range, it is possible to form the electrode with a uniform thickness, suppress a decrease in light transmittance, and allow sufficient light to enter the electron transport layer 3 through the electrode 1.

  In forming the electrode 1 by providing a transparent conductive oxide layer on the base material 6, for example, a vacuum process such as sputtering or vapor deposition on the translucent base material 6 made of glass or resin. A transparent conductive oxide layer made of indium oxide, tin oxide, zinc oxide, or the like is formed by a method of forming the electrode 1 by using a wet method such as spin coating, spraying, or screen printing. There is a method of forming the electrode 1.

  In the photoelectric device according to the present invention, the electron transport layer 3 is formed of an organic compound having a redox portion, and the organic compound is formed as a gel layer 5 swollen including an electrolyte solution. is there. That is, the electron transport layer 3 is formed as a gel layer 5 of an organic compound having a redox portion.

  Here, a redox part capable of being repeatedly redoxed is formed in a part of the molecule of the organic compound, and another part has a part (gel part) that swells and contains an electrolyte solution to form a gel. The oxidation-reduction part is chemically bonded to the gel part, and the positional relationship between the oxidation-reduction part and the gel part in the molecule is not particularly limited. For example, the skeleton such as the main chain of the molecule is present at the gel part. When formed, the redox moiety is bonded to the main chain as a side chain. Moreover, the structure which the molecular skeleton which forms a gel part and the molecular skeleton which forms a redox part couple | bonded alternately may be sufficient. Thus, when the redox part and the gel part are present in the same molecule of the organic compound, the gel layer 5 forming the electron transport layer 3 holds the redox part so as to remain at a position where electrons are easily transported. It is something that can be done.

  The organic compound having a redox moiety and a gel part may be a low molecular weight substance or a high molecular weight substance. In the case of a low molecular weight substance, an organic compound that forms a so-called low molecular gel through hydrogen bonding or the like can be used. In the case of a polymer, an organic compound having a number average molecular weight of 1000 or more is preferable because the gel function can be spontaneously expressed. The upper limit of the molecular weight of the organic compound in the case of a polymer is not particularly limited, but is preferably 1,000,000 or less. The gel state of the gel layer 5 is preferably, for example, konjac or an external shape such as an ion exchange membrane, but is not particularly limited.

  In the present invention, the redox moiety refers to a site that reversibly becomes an oxidant and a reductant in a redox reaction, and the redox part is a redox-based constituent material in which the oxidant and reductant have the same charge. It is preferable that

  An organic compound having a redox moiety and a gel site in one molecule as described above can be represented by the following general formula.

(X _i ) _nj : Y _k
(X _i ) _n and (X _i ) _{nj represent} a gel site, and X _i represents a monomer of a compound that forms the gel site, and can be formed of a polymer skeleton. The polymerization degree n of the monomer is preferably in the range of n = 1 to 100,000. Y represents a redox moiety bonded to X. J and k are each an arbitrary integer representing the number of (X _i ) _n and Y contained in one molecule, and both are preferably in the range of 1 to 100,000. The redox moiety Y may be bonded to any part of the polymer skeleton that forms the gel parts (X _i ) _n and (X _i ) _nj . The redox moiety Y may contain different types of materials. In this case, a material having a close redox potential is preferable from the viewpoint of the electron exchange reaction.

As an organic compound having such a redox moiety and gel sites (X _i ) _n and (X _i ) _nj in one molecule, a polymer having a quinone derivative skeleton in which quinones are chemically bonded, an imide derivative containing an imide Examples thereof include a polymer having a skeleton, a polymer having a phenoxyl derivative skeleton containing phenoxyl, and a polymer having a viologen derivative skeleton containing viologen. In these organic compounds, the polymer skeleton is a gel site, and the quinone derivative skeleton, the imide derivative skeleton, the phenoxyl derivative skeleton, and the viologen derivative skeleton are redox portions.

  Here, among the above organic compounds, examples of the polymer having a quinone derivative skeleton in which quinones are chemically bonded include those having a chemical structure of [Chemical Formula 1] to [Chemical Formula 4]. In [Chemical Formula 1] to [Chemical Formula 4], R represents methylene, ethylene, propane-1,3-dienyl, ethylidene, propane-2,2-diyl, alkanediyl, benzylidene, propylene, vinylidene, propene-1,3- Saturated or unsaturated hydrocarbons such as diyl, but-1-ene-1,4-diyl; cyclic hydrocarbons such as cyclohexanediyl, cyclohexenediyl, cyclohexadienediyl, phenylene, naphthalene, biphenylene; oxalyl, malonyl, succinyl, Glutanyl, adipoyl, alkanedioil, sebacoyl, fumaroyl, maleoyl, phthaloyl, isophthaloyl, terephthaloyl and other keto, divalent acyl groups; oxy, oxymethylenoxy, oxycarbonyl and other ethers, esters; Groups containing sulfur such as sulfonyl; groups containing nitrogen such as imino, nitrilo, hydrazo, azo, azino, diazoamino, urylene, amide; groups containing silicon such as silanediyl, disilane-1,2-diyl; A substituted group or a complex group is shown.

  [Chemical Formula 1] is an example in which anthraquinone is chemically bonded to the polymer main chain. [Chemical Formula 2] is an example in which anthraquinone is incorporated as a repeating unit in the polymer main chain. [Chemical Formula 3] is an example in which anthraquinone is a cross-linking unit. Furthermore, [Chemical Formula 4] shows an example of anthraquinone having a proton donating group that forms an intramolecular hydrogen bond with an oxygen atom.

  The above quinone polymer is capable of high-speed redox reaction that is not limited by proton transfer, and there is no electronic interaction between quinone groups, which are redox sites (redox sites), and chemical stability that can withstand long-term use. Have sex. Moreover, since this quinone polymer does not elute in the electrolyte solution, it is useful in that the electron transport layer 3 can be formed by being held on the surface of the electrode 1.

Moreover, the polyimide shown in [Chemical Formula 5] and [Chemical Formula 6] can be used as the polymer in which the redox moiety Y has an imide derivative skeleton containing imide. Here, in [Chemical Formula 5] and [Chemical Formula 6], R _{1 to} R ₃ are an aliphatic group such as an aromatic group such as a phenylene group, an alkylene group, and an alkyl ether. Can be obtained. The polyimide polymer skeleton may be cross-linked at R _{1 to} R ₃ , and may not have a cross-linked structure unless it swells in the solvent used and does not elute. In the case of cross-linking, the portion corresponds to the gel sites (X _i ) _n and (X _i ) _nj . Moreover, when introduce | transducing a crosslinked structure, the imide group may contain in the bridge | crosslinking unit. As the imide group, phthalimide, pyromellitic imide, and the like are preferable as long as they exhibit electrochemically reversible redox characteristics.

Examples of the polymer having a phenoxyl derivative skeleton containing phenoxyl include a galbi compound as shown in [Chemical Formula 7]. In this galbi compound, the galvinoxyl group (see [Chemical Formula 8]) corresponds to the redox moiety Y, and the polymer skeleton corresponds to the gel sites (X _i ) _n and (X _i ) _nj .

Examples of the polymer having a viologen derivative skeleton containing viologen include viologen compounds as shown in [Chemical Formula 9] and [Chemical Formula 10]. In this viologen compound, [Chemical Formula 11] corresponds to the redox moiety Y, and the polymer skeleton corresponds to the gel sites (X _i ) _n and (X _i ) _nj .

  Note that m and n shown in the above [Chemical Formula 1] to [Chemical Formula 7], [Chemical Formula 9] and [Chemical Formula 10] indicate the degree of polymerization of the monomer, and are preferably in the range of 1 to 100,000.

  The organic compound having the redox part and the polymer skeleton is one in which the polymer skeleton contains an electrolyte solution between the skeletons and swells to form the gel layer 5. Thus, the electrolyte is formed on the electron transport layer 3. By including the solution, the ionic state formed by the redox reaction of the redox part is compensated by the counter ion in the electrolyte solution, and the redox part can be stabilized.

  The electrolyte solution only needs to contain an electrolyte and a solvent. Examples of the electrolyte include a supporting salt and a redox constituent material composed of an oxidant and a reductant, and either one or both of them may be used. Examples of the supporting salt (supporting electrolyte) include tetrabutylammonium perchlorate, tetraethylammonium hexafluorophosphate, ammonium salts such as imidazolium salt and pyridinium salt, alkali metals such as lithium perchlorate and potassium tetrafluoroborate. Examples include salt. The redox system constituent material means a substance that exists reversibly in the form of an oxidized form and a reduced form in a redox reaction. Examples of such a redox system constituent substance include chlorine compound-chlorine. , Iodine compound-iodine, bromine compound-bromine, thallium ion (III) -thallium ion (I), mercury ion (II) -mercury ion (I), ruthenium ion (III) -ruthenium ion (II), copper ion ( II) -copper ion (I), iron ion (III) -iron ion (II), nickel ion (II) -nickel ion (III), vanadium ion (III) -vanadium ion (II), manganate ion-peroxide Examples thereof include, but are not limited to, manganate ions. In this case, it functions differently from the redox part in the electron transport layer 3.

  Moreover, as a solvent which comprises electrolyte solution, what contains at least one of water, an organic solvent, and an ionic liquid can be mentioned.

  By using water or an organic solvent as the solvent of the electrolyte solution, the reduction state of the redox part of the organic compound can be stabilized, and electrons can be transported more stably. As the solvent, any of an aqueous solvent and an organic solvent can be used, but an organic solvent excellent in ion conductivity is preferable in order to further stabilize the redox moiety. Examples of such organic solvents include carbonate compounds such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate, ester compounds such as methyl acetate, methyl propionate, and γ-butyrolactone, diethyl ether, 1,2, and the like. -Ether compounds such as dimethoxyethane, 1,3-dioxosilane, tetrahydrofuran, 2-methyl-tetrahydrofuran, heterocyclic compounds such as 3-methyl-2-oxazodilinone, 2-methylpyrrolidone, acetonitrile, methoxyacetonitrile, propionitrile, etc. Examples thereof include aprotic polar compounds such as nitrile compounds, sulfolane, dimethyl sulfoxide, and dimethylformamide. These solvents can be used alone or in combination of two or more. In particular, when the photoelectric element is formed as a photoelectric conversion element, from the viewpoint of improving the solar cell output characteristics, the solvent is a carbonate compound such as ethylene carbonate or propylene carbonate, γ-butyrolactone, 3-methyl-2. A heterocyclic compound such as oxazozirinone and 2-methylpyrrolidone, and a nitrile compound such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and valeric nitrile are preferable.

  In addition, by using an ionic liquid as a solvent for the electrolyte solution, it is possible to obtain a stabilizing action of the redox moiety, and the ionic liquid is not volatile and has high flame retardancy, so it has excellent stability. It is. As the ionic liquid, known ionic liquids in general can be used. For example, imidazolium-based such as 1-ethyl-3-methylimidazolium tetracyanoborate, pyridine-based, alicyclic amine-based, aliphatic amine-based, Azonium amine-based ionic liquid, European Patent No. 718288 specification, International Publication WO95 / 18456 pamphlet, Electrochemical Vol. 65, No. 11 923 (1997), J. Electrochem. Soc. 143, 10 No., 3099 (1996), Inorg. Chem. 35, 1168 (1996).

  Further, the electrolyte solution may have a structure that is held in a polymer matrix. Examples of the polyvinylidene fluoride polymer compound used as the polymer matrix include a homopolymer of vinylidene fluoride, or a copolymer of vinylidene fluoride and another polymerizable monomer, preferably a radical polymerizable monomer. . Specific examples of other polymerizable monomers copolymerized with vinylidene fluoride include hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, ethylene, propylene, acrylonitrile, vinylidene chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, Styrene and the like can be exemplified.

  The electron transport layer 3 can be formed by providing the above-described organic compound gel layer 5 having a redox portion on the surface of the electrode 1. In the present invention, the electron transport layer 3 refers to a layer in which electrons behave as a dopant. For example, a layer having a redox portion whose redox potential is nobler than +100 mV with respect to a silver / silver chloride reference electrode. Say.

  The thickness of the electron transport layer 3 is preferably in the range of 10 nm to 10 mm, particularly preferably 100 nm to 100 μm, from the viewpoint of maintaining good electron transport properties. If it is the thickness of this range, the electron transport characteristic of the electron carrying layer 3 and the area of an interface can be made compatible on a higher level.

  In providing the electron transport layer 3 on the surface of the electrode 1, for example, a method of depositing an organic compound on the surface of the electrode 1 by a vacuum process such as sputtering or vapor deposition can be employed. A wet forming method in which a solution containing bismuth is applied is preferable because it is a simpler and lower cost manufacturing method. In particular, when the electron transport layer 3 is formed of a so-called high molecular organic compound having a number average molecular weight of 1000 or more, a wet forming method is preferable from the viewpoint of moldability. Examples of the wet process include a spin coating method, a drop cast method obtained by dripping and drying droplets, and a printing method such as screen printing and gravure printing.

  In the present invention, the electron transport layer 3 is such that the redox potential is inclined from noble to base toward the electrode 1 side with which the electron transport layer 3 is in contact, that is, the redox potential on the side close to the electrode 1 is It is formed so as to be higher than the redox potential on the far side. Thus, when the oxidation-reduction potential is inclined from noble to base electrode toward the electrode 1 side with which the electron transport layer 3 is in contact, the gradient of the oxidation-reduction potential in the electron transport layer 3 causes the electron transport layer 3 to enter the electron transport layer 3. The flow of electrons to the electrode 1 side can be made, the transportability of electrons from the electron transport layer 3 to the electrode 1 can be improved, and the conversion efficiency can be increased.

  As a method of forming the electron transport layer 3 with the redox potential gradient as described above, for example, a plurality of organic compounds having different redox potentials are used, and the layers of the organic compounds are stacked to form the electron transport layer 3. In this case, the organic compounds are combined so that the redox potential of the organic compound forming the layer closer to the electrode 1 is higher than the redox potential of the organic compound forming the layer far from the electrode 1. There is. For example, in the example of FIG. 1, two layers 3a and 3b are stacked to form the electron transport layer 3, and the redox potential of the organic compound forming the layer 3a on the side close to the electrode 1 is base, The kind of the organic compound forming the layers 3a and 3b is selected so as to be nobler than the redox potential of the organic compound forming the layer 3b far from 1. Needless to say, the electron transport layer 3 may be formed by stacking three or more layers. In this case, the layers closer to the electrode 1 are set so that the redox potential becomes lower in order.

  As described above, when an imide derivative, a quinone derivative, a viologen derivative, or a phenoxyl derivative is used as the organic compound that forms the electron transport layer 3, the electrode 1 in contact with the electron transport layer 3 by combining two or more of these organic compounds. The electron transport layer 3 can be formed such that the redox potential is inclined from noble to base toward the side.

A sensitizing dye can be provided in contact with at least one of the electron transport layer 3 and the hole transport layer 4. As the sensitizing dye, known materials can be used. For example, 9-phenylxanthene dye, coumarin dye, acridine dye, triphenylmethane dye, tetraphenylmethane dye, quinone dye Azo dyes, indigo dyes, cyanine dyes, merocyanine dyes, xanthene dyes, and the like. Or RuL ₂ (H ₂ O) ₂ type ruthenium-cis-diaqua-bipyridyl complex (where L represents 4,4′-dicarboxyl-2,2′-bipyridine), or ruthenium-tris Transition metal complexes of the type such as (RuL ₃ ), ruthenium-bis (RuL ₂ ), osnium-tris (OsL ₃ ), osnium-bis (OsL ₂ ), or zinc-tetra (4-carboxyphenyl) porphyrin, iron- Examples include hexacyanide complexes and phthalocyanines. For example, a dye as described in the DSSC chapter of “FPD / DSSC / Optical memory and functional dye and the latest technology and material development” (NTS Inc.) can be applied. Among these, dyes having associative properties are preferable from the viewpoint of promoting charge separation during photoelectric conversion. As a dye having an effect by forming an aggregate, for example, a dye represented by the structural formula of [Chemical Formula 12] is preferable.

In the above structural formula, X ₁ and X ₂ are each independently an alkyl group, an alkenyl group, an aralkyl group, an aryl group, or an organic group having at least one heterocyclic ring, and each may have a substituent. . It is known that a dye such as the above [Chemical Formula 12] is associative. In this case, the electrons and holes present in the electron transport material and the hole transport material can dramatically reduce the recombination point, and thus the conversion efficiency of the photoelectric conversion element can be improved. is there.

  When a sensitizing dye is provided in the electron transport layer 3, the sensitizing dye may be present on the surface of the gel layer 5, or the sensitizing dye may be present in the gel layer 5. In particular, it is preferable that a sensitizing dye is present in the gel layer 5 forming the electron transport layer 3. Here, “the sensitizing dye is present in the gel layer 5” means that the sensitizing dye is present not only in the surface layer of the gel layer 5 but also in the inside thereof. Thereby, the state in which the amount of the sensitizing dye present in the gel layer 5 is at or above a certain value can be continuously maintained, and the output improvement effect of the photoelectric element is brought about.

  In the present invention, the sensitizing dye may be in a state where it is present in the gel layer 5. In the “state where the sensitizing dye is present in the gel layer 5”, the “sensitizing dye is present in the gel layer 5”. And the state in which the sensitizing dye is physically and chemically interacted with the organic compound constituting the gel layer 5. State ". The sensitizing dye is preferably present throughout the gel layer 5.

  In particular, it is preferable that the sensitizing dye is fixed in the gel layer 5 by physical or chemical interaction with the organic compound constituting the gel layer 5.

  Here, “the state in which the sensitizing dye is present in the gel layer 5 by physical interaction with the organic compound constituting the gel layer 5” means, for example, sensitization as the organic compound constituting the gel layer 5. This is achieved by using an organic compound having a structure that prevents movement of the dye molecule. The structure that prevents the movement of the molecules of the sensitizing dye includes a structure in which the organic compound exhibits steric hindrance due to various molecular chains such as an alkyl chain, or a void size that exists between the molecular chains of the organic compound. For example, a structure that is small enough to suppress the movement of. It is also effective to bring a factor that causes physical interaction to the pigment side. Specifically, it is also effective to increase the molecular size of the dye by, for example, a structure in which the dye exhibits steric hindrance due to various molecular chains such as an alkyl chain, or by cross-linking the dyes.

  In addition, “the state in which the sensitizing dye is present in the gel layer by chemical interaction with the organic compound constituting the gel layer 5” includes, for example, covalent bond, coordination bond, ionic bond, hydrogen bond, van der This is achieved by a method in which a sensitizing dye is held in the gel layer 5 by an interaction such as a Waals bond, a hydrophobic interaction, a hydrophilic interaction, or a force based on an electrostatic interaction. In particular, when the sensitizing dye is fixed in the gel layer 5 by a chemical interaction between the sensitizing dye and the organic compound constituting the gel layer 5, the distance between the sensitizing dye and the organic compound is made closer and the efficiency is improved. It will be possible to create a good electronic transfer.

  In the case where the sensitizing dye is fixed in the gel layer 5 by chemical interaction between the organic compound and the sensitizing dye, a functional group is appropriately provided in the organic compound and the sensitizing dye, and the functional group is interposed therebetween. It is preferable to fix the sensitizing dye to the organic compound by a chemical reaction or the like. Examples of such functional groups include hydroxyl groups, carboxyl groups, phosphate groups, sulfo groups, nitro groups, alkyl groups, carbonate groups, aldehyde groups, thiol groups, and the like. In addition, examples of the reaction format of the chemical reaction via the functional group include a condensation reaction, an addition reaction, and a ring-opening reaction.

  In addition, when the sensitizing dye and the organic compound constituting the gel layer 5 are chemically bonded, a functional group in the sensitizing dye is introduced in the vicinity of a site where the electron density is increased in a state where the sensitizing dye is photoexcited, Moreover, it is preferable that the functional group in the organic compound in the gel layer 5 is introduced in the vicinity of a site involved in electron transport in the organic compound. In this case, the efficiency of electron transfer from the sensitizing dye to the organic compound and the efficiency of electron transport in the organic compound can be improved. In particular, the sensitizing dye and the organic compound constituting the gel layer 5 are bonded by a bonding group having a high electron transporting property that connects the electron cloud of the sensitizing dye and the electron cloud of the organic compound. Enables efficient electron transfer from dye-sensitive organic compounds. Specifically, an example in which an ester bond having a π electron system or the like is used as a chemical bond that links a π electron cloud of a sensitizing dye and a π electron cloud of an organic compound.

  In addition, when the organic compound is in a monomer state, the organic compound is polymerized, the organic compound is polymerized, and then the organic compound is gelled, the organic compound is in a monomer state. Any of these may be used after gelation. As an example of a specific method, a method of immersing the electron transport layer 3 formed of an organic compound in a bath containing a sensitizing dye, a coating solution containing an organic compound and a sensitizing dye is applied to the electrode 1 Examples of the method include forming the electron transport layer 3 by forming a film, and a plurality of methods may be combined.

  Although content of the sensitizing dye in the gel layer 5 which forms the electron carrying layer 3 is set suitably, the range of 0.1-1000 mass parts with respect to 100 mass parts of organic compounds of the gel layer 5 is preferable. When the content of the sensitizing dye is 0.1 parts by mass or more with respect to 100 parts by mass of the organic compound, the amount of the sensitizing dye per unit film thickness of the gel layer 5 is sufficiently increased, The light absorption capability can be improved and a high current value can be obtained. Moreover, if content of a sensitizing dye is 1000 mass parts or less with respect to 100 mass parts of organic compounds, it will suppress that an excessive amount of sensitizing dye interposes between organic compounds, and the electron transfer in an organic compound will be carried out. High conductivity can be secured by suppressing inhibition by the sensitizing dye.

  The hole transport material for forming the hole transport layer 4 includes an electrolyte solution in which an electrolyte such as a redox couple is dissolved in a solvent, a solid electrolyte such as a molten salt, a p-type semiconductor such as copper iodide, triphenyl, and the like. Examples thereof include amine derivatives such as amines, and conductive polymers such as polyacetylene, polyaniline, and polythiophene.

  When the hole transport layer 4 is formed of an electrolyte solution, the hole transport layer 4 can also be formed of an electrolyte solution that constitutes the gel layer 5. In this case, the electrolyte solution constituting the gel layer 5 constitutes a part of the hole transport layer 4.

  The hole transport layer 4 can contain a stable radical compound. In this case, holes generated by charge separation can be efficiently transported to the counter electrode by a very fast electron transfer reaction of a stable radical compound, thereby improving the photoelectric conversion efficiency of the photoelectric element. .

  The stable radical compound is not particularly limited as long as it is a chemical species having an unpaired electron, that is, a compound having a radical, but a radical compound having nitroxide (NO.) In the molecule is preferable. The molecular weight (number average molecular weight) of the stable radical compound is preferably 1000 or more. In this case, since the stable radical compound is solid or close to a solid at room temperature, volatilization hardly occurs and the stability of the device is improved. Can do.

  This stable radical compound will be further described. A stable radical compound is a compound that generates a radical compound in at least one of an electrochemical oxidation reaction and an electrochemical reduction reaction. Although the kind of radical compound is not specifically limited, It is preferable that it is a stable radical compound. In particular, an organic compound containing any one or both of the following [Chemical 13] and [Chemical 14] is preferable.

In the above chemical formula, the substituent R ₁ is a substituted or unsubstituted C2-C30 alkylene group, a C2-C30 alkenylene group or a C4-C30 arylene group, and X is an oxy radical group, a nitroxyl radical group, It is a sulfur radical group, a hydrazyl radical group, a carbon radical group or a boron radical group, and n ¹ is an integer of 2 or more.

In the above chemical formula, substituents R ² and R ³ are independent of each other, and are substituted or unsubstituted C ² -C 30 alkylene group, C 2 -C 30 alkenylene group or C 4 -C 30 arylene group, Y is nitroxyl It is a radical group, a sulfur radical group, a hydrazyl radical group or a carbon radical group, and n ² is an integer of 2 or more.

  Examples of radical compounds represented by [Chemical Formula 13] and Formula [Chemical Formula 14] include oxy radical compounds, nitroxyl radical compounds, carbon radical compounds, nitrogen radical compounds, boron radical compounds, and sulfur radical compounds. .

  Specific examples of the oxy radical compound include aryloxy radical compounds represented by the following [Chemical Formula 15] to [Chemical Formula 16] and semiquinone radical compounds represented by [Chemical Formula 17].

In the chemical formulas represented by [Chemical Formula 15] to [Chemical Formula 17], the substituents R ^{4 to} R ⁷ are each independently a hydrogen atom, a substituted or unsubstituted aliphatic or aromatic C1-C30 hydrocarbon group, A halogen group, a hydroxyl group, a nitro group, a nitroso group, a cyano group, an alkoxy group, an aryloxy group or an acyl group; In the chemical formula of [Chemical Formula 17], n ³ is an integer of 2 or more.

  Specific examples of the nitroxyl radical compound include a radical compound having a piperidinoxy ring represented by the following [Chemical Formula 18], a radical compound having a pyrrolidinoxy ring represented by [Chemical Formula 19], and [Chemical Formula 20]. Examples thereof include a radical compound having a pyrrolinoquin ring and a radical compound having a nitronyl nitroxide structure represented by [Chemical Formula 21].

In the chemical formulas represented by [Chemical Formula 18] to [Chemical Formula 20], R ^{8 to} R ¹⁰ and R ^{A to} R ^L are each independently a hydrogen atom, substituted or unsubstituted aliphatic or aromatic C1 to C30. It is a hydrocarbon group, halogen group, hydroxyl group, nitro group, nitroso group, cyano group, alkoxy group, aryloxy group or acyl group. In the chemical formula represented by [Chemical Formula 21], n4 is an integer of 2 or more.

  Specific examples of the nitroxyl radical compound include a radical compound having a trivalent hydrazyl group represented by the following [Chemical Formula 22], a radical compound having a trivalent ferdazyl group represented by [Chemical Formula 23], and And a radical compound having an aminotriazine structure represented by [Chemical Formula 24].

In the chemical formulas of [Chemical Formula 22] to [Chemical Formula 24], R ^{11 to} R ¹⁹ are each independently a hydrogen atom, a substituted or unsubstituted aliphatic or aromatic C1-C30 hydrocarbon group, halogen group, hydroxyl group. Group, nitro group, nitroso group, cyano group, alkoxy group, aryloxy group or acyl group.

  The organic polymer compound of any one of the above [Chemical Formula 13] to [Chemical Formula 24] has excellent stability, and as a result, it can be stably used as a photoelectric conversion element or an energy storage element. An optoelectric device having excellent response speed can be easily obtained.

  Among the organic compounds described above as the stable radical, it is more preferable to select and use an organic compound that is in a solid state at room temperature. By using a radical compound in a solid state at room temperature, the contact between the radical compound and the semiconductor can be kept stable, and side reactions with other chemical substances, transformation and deterioration due to melting and diffusion can be suppressed. As a result, a photoelectric device having excellent stability can be obtained.

  The electrode material for forming the electrode 2 in contact with the hole transport layer 4 that is a counter electrode with respect to the electrode 1 in contact with the electron transport layer 3 described above depends on the element to be produced. For example, platinum, gold, silver, Metals such as copper, aluminum, rhodium, and indium, or carbon materials such as graphite, carbon nanotube, and carbon carrying platinum, or indium-tin composite oxide, tin oxide doped with antimony, tin oxide doped with fluorine, etc. Examples thereof include conductive metal oxides, and conductive polymers such as polyethylene dioxythiophene, polypyrrole, and polyaniline.

  For the production of the photoelectric element, for example, the electron transport layer 3 (3a, 3b) is fixed on the electrode 1 by laminating an organic compound on the electrode 1 provided on the substrate 6 by a wet method or the like. It can be formed by stacking the hole transport layer 4 and the electrode 2 serving as a counter electrode on the electron transport layer 3. In the case of forming the hole transport layer 4 with an electrolyte solution, for example, in a state where the space between the electron transport layer 3 and the counter electrode 2 is sealed with a sealing material, the hole transport layer 4 is interposed between the electron transport layer 3 and the counter electrode 2. The hole transport layer 4 can be formed by filling the gap with the electrolyte solution. At this time, a part of the electrolyte solution penetrates into the electron transport layer 3 and the organic compound constituting the electron transport layer 3 swells to form the gel layer 5.

  The photoelectric element configured as described above can function as a photoelectric conversion element. In this photoelectric conversion element, when light is irradiated through the electrode 1 from the base 6 side, the sensitizing dye absorbs light and is excited, and the generated excited electrons flow into the electron transport layer 3, 1 is taken out through 1 and holes in the sensitizing dye are taken out from the hole transport layer 4 through the counter electrode 2.

  In addition to producing the photoelectric conversion element as described above by using the photoelectric element formed by sandwiching an electron transport layer and a hole transport layer between a pair of electrodes of the present invention, a light emitting element such as an organic EL An optoelectric element or the like can be manufactured as an optical display element such as an electrochromic display element or electronic paper, a sensor element that senses temperature, light, or the like.

  Next, the present invention will be specifically described with reference to examples.

Example 1
The above-described Galvi compound of [Chemical Formula 7] was synthesized by the reaction procedure shown in [Chemical Formula 25].

(Synthesis of galbi monomer)
4-Bromo-2,6-di-tert-butylphenol (135.8 g; 0.476 mol) and acetonitrile (270 ml) were placed in a reaction vessel, and N, O-bis (trimethylsilyl) acetamide was further added under an inert atmosphere. (BSA) (106.3 g; 129.6 ml) was added, and the mixture was stirred at 70 ° C. overnight and reacted until crystals were completely precipitated. Then, the precipitated white crystals are filtered, vacuum-dried, recrystallized with ethanol, and purified to obtain (4-bromo-2,6-di-tert-) represented by the symbol “1” in [Chemical Formula 25]. White plate crystals of butylphenoxy) trimethylsilane (150.0 g; 0.420 mol) were obtained.

  Next, the above (4-bromo-2,6-di-tert-butylphenoxy) trimethylsilane (9.83 g; 0.0275 mol) is dissolved in tetrahydrofuran (200 ml) under an inert atmosphere in a reaction vessel. The solution was then cooled to −78 ° C. using dry ice / methanol. Furthermore, 1.58M n-butyllithium / hexane solution (15.8 ml; 0.025 mol) was added to the reaction vessel, and the mixture was lithiated by stirring at a temperature of 78 ° C. for 30 minutes. Next, a solution of methyl 4-bromobenzoate (1.08 g; 0.005 mol, Mw: 215.0, TCI) in tetrahydrofuran (75 ml) was added to this solution, followed by stirring at −78 ° C. to room temperature overnight. As a result, the solution changed from yellow to light yellow, and further to dark blue indicating the generation of anions. After the reaction, a saturated aqueous ammonium chloride solution was added to the solution in the reaction vessel until the solution was completely yellow, and this solution was subjected to liquid separation extraction with ether / water to obtain a yellow viscous liquid product.

  Next, this product, THF (10 ml), methanol (7.5 ml), and a stirrer are placed in a reaction vessel, and after dissolution, 10N-HCl (1-2 ml) is changed to a red-orange solution in the reaction vessel. The mixture was gradually added and stirred at room temperature for 30 minutes. Next, it is purified through operations of solvent removal, liquid separation extraction with ether / water, solvent removal, fractionation by column chromatography (hexane / chloroform = 1/1), and recrystallization by hexane. Orange crystals of (p-bromophenyl) hydrogalvinoxyl (2.86 g; 0.0049 mol) indicated by “2” were obtained.

  Next, the above (p-bromophenyl) hydrogalvinoxyl (2.50 g; 4.33 mmol) was dissolved in toluene (21.6 ml; 0.2 M) under an inert atmosphere in a reaction vessel. 2,6-di-tert-butyl-p-cresol (4.76 mg; 0.0216 mmol), tetrakis (triphenylphosphine) palladium (0) (0.150 g; 0.130 mmol), tri-n-butylvinyltin ( 1.65 g; 5.20 mmol, Mw: 317.1, TCI) was quickly added, and the mixture was heated and stirred at 100 ° C. for 17 hours.

  Then, the reaction product is separated and extracted with ether / water, and after removing the solvent, it is fractionated by flash column chromatography (hexane / chloroform = 1/3), and further purified by recrystallization from hexane. Orange microcrystals of p-hydrogalvinoxyl styrene (1.54 g; 2.93 mmol) indicated by the symbol “3” in [Chemical Formula 25] were obtained.

(Polymerization of galbi monomer)
After 1 g of galbi monomer (p-hydrogalvinoxyl styrene) obtained by the synthesis of the galbi monomer, 57.7 mg of tetraethylene glycol diacrylate, and 15.1 mg of azobisisobutyronitrile are dissolved in 2 ml of tetrahydrofuran The galbi monomer was polymerized by substituting with nitrogen and refluxed overnight to obtain a galbi polymer represented by [4] in [Chemical Formula 25].

(Formation of electron transport layer)
On the other hand, a conductive glass substrate having a thickness of 0.7 mm and a sheet resistance of 100Ω / □ was prepared as the substrate 6 on which the electrode 1 was provided. This conductive glass substrate is composed of a glass substrate and a coating film made of fluorine-doped SnO ₂ laminated on one side of the glass substrate. The glass substrate is a base material 6 and the coating film is an electrode. 1

  Then, the galbi polymer obtained by polymerization as described above was dissolved in chlorobenzene at a ratio of 2% by mass, and this galbi polymer solution was spin-coated on the electrode 1 of the conductive glass substrate at 2000 rpm, 60 ° C., A layer 3a having a thickness of 60 nm was formed by drying at 0.01 MPa for 1 hour.

  After forming the galbi polymer layer 3a in this manner, the galbi polymer constituting the layer 3a was anionized by immersing in a 0.1 M concentration of tetrabutylammonium aqueous solution for 15 minutes. After washing the galbipolymer layer 3a with water, the layer 3b in which polydecylviologen is electrostatically bound to the anionized galbipolymer is immersed in a 0.1M aqueous polydecylviologen solution (pH 10) for 15 minutes. Then, an electron transport layer 3 composed of a galbipolymer layer 3a and a polydecylviologen layer 3b was formed. When the redox potential of each layer 3a, 3b of the electron transport layer 3 was measured by the method described later, the redox potential of the layer 3a was 0V, the redox potential of the layer 3b was -0.4V, and the electron transport layer 3 The redox potential was inclined from noble to base toward the electrode 1 side.

  Next, the electron transport layer 3 thus formed was immersed in an acetonitrile solution containing a sensitizing dye (D131) represented by [Chemical Formula 26] at a concentration of 0.3 mM for 1 hour, and then washed with water. Thereby, a sensitizing dye was provided in the electron transport layer 3.

(Production of element)
A conductive glass substrate having the same configuration as that of the conductive glass substrate used in forming the electron transport layer 3 was prepared. Then, chloroplatinic acid is dissolved in isopropyl alcohol so as to have a concentration of 5 mM, and the obtained solution is spin-coated on the coating film of the conductive glass substrate, followed by baking at 400 ° C. for 30 minutes. Thus, the counter electrode 2 was formed.

  Next, the conductive glass substrate provided with the electron transport layer 3 and the conductive glass substrate provided with the counter electrode 2 are arranged so that the electron transport layer 3 and the counter electrode 2 face each other. A hot-melt adhesive (Bunel, manufactured by DuPont) having a width of 1 mm and a thickness of 50 μm was interposed at the outer edge between the two. Then, the two conductive glass substrates were pressed in the thickness direction while heating the hot melt adhesive, thereby joining the two conductive glass substrates through the hot melt adhesive. At this time, voids serving as electrolyte injection ports were formed in the hot-melt adhesive.

  Subsequently, the electrolytic solution was filled between the electron transport layer 3 and the counter electrode 2 from the above injection port. Next, after applying a UV curable resin to the injection port, the injection port was filled by irradiating UV light to cure the UV curable resin. As a result, the hole transport layer 4 made of the electrolytic solution is formed and the electrolytic solution is permeated into the electron transport layer 3 to swell the organic compound (galbi polymer) constituting the electron transport layer 3 to form the gel layer 5. did. As this electrolyte, 2,2,6,6-tetramethylpiperidine-1-oxyl is 1 M, sensitizing dye (D131) is 2 mM, LiTFSI is 0.5 M, and N-methylbenzimidazole is 1.6 M in concentration. Acetonitrile solution contained in As described above, a photoelectric element having a layer structure as shown in FIG. 1 was produced.

(Example 2)
(Synthesis of quinone polymer)
As the quinone polymer, poly (1-methacrylamideamithraquinone) of [Chemical Formula 4] described above was synthesized by the reaction shown in [Chemical Formula 27].

  First, 50 mg (0.172 mmol, 1 eq) of 1-methacrylamide anthraquinone, 25 μl (0.172 mmol, 1 eq) of divinylbenzene, 0.48 g of AIBN (azobisisobutyronitrile) in a 10 ml eggplant flask under an argon atmosphere (3 .43 μmol, 0.02 eq) was added and dissolved in 1.72 ml of THF, and oxygen dissolved in the solvent was removed by argon. And after deaeration, it was made to react at 70 degreeC for 48 hours. After completion of the reaction, a precipitate was produced with methanol and washed with Soxhlet with THF to obtain 37.3 mg of a polymer as a yellow solid.

(Formation of electron transport layer)
In the same manner as in Example 1, a galbipolymer layer 3a was formed on the electrode 1 of the conductive glass substrate. Next, a solution obtained by dissolving 10 mg of the above polymer in 0.1 g of N-methylpyrrolidone was spin-coated at 1000 rpm on the galbi polymer layer 3a to form a quinone polymer layer 3b having a thickness of 100 nm. An electron transport layer 3 composed of a galbi polymer layer 3a and a quinone polymer layer 3b was formed. When the redox potential of each layer 3a, 3b of the electron transport layer 3 was measured by the method described later, the redox potential of the layer 3a was 0V, the redox potential of the layer 3b was -0.8V, and the electron transport layer 3 The redox potential was inclined from noble to base toward the electrode 1 side.

  Next, the electron transport layer 3 was immersed in an acetonitrile solution containing the sensitizing dye (D131) of [Chemical Formula 26] described above at a concentration of 0.3 mM for 1 hour, washed with water, and applied to the electron transport layer 3. A sensitizing dye was provided.

  In this way, the electron transport layer 3 was formed, and thereafter, in the same manner as in Example 1, a photoelectric device having a layer structure as shown in FIG.

(Example 3)
(Polyimide synthesis)
In an argon atmosphere, in a 30 ml eggplant flask, 310.20 mg (0.001 mol) of 4-4′-oxydiphthalic anhydride, 2 ml of NN-dimethylacetamide, 108.15 mg (0.001 mol) of 1.4-phenylenediamine. And allowed to react at room temperature for 18 hours. After completion of the reaction, 411.8 mg of the polymer shown in [Chemical Formula 28] was obtained as a white solid by precipitation in acetone and purification.

(Formation of electron transport layer)
In the same manner as in Example 1, a galbipolymer layer 3a was formed on the electrode 1 of the conductive glass substrate. Next, a solution in which 5.47 mg of the above polymer and 0.1 g of N-methylpyrrolidone were mixed was prepared, and this solution was formed on the surface of the galbi polymer layer 3a by spin coating at 1000 rpm to a thickness of 100 nm. This is heated stepwise at 150 ° C., 180 ° C., 200 ° C. and 220 ° C. for 20 minutes each and at 250 ° C. for 30 minutes, and imidized as shown in [Chemical Formula 29] to form a polyimide layer 3b. Thus, an electron transport layer 3 composed of a galbi polymer layer 3a and a polyimide layer 3b was formed. When the redox potential of each layer 3a, 3b of the electron transport layer 3 was measured by the method described later, the redox potential of the layer 3a was 0V, the redox potential of the layer 3b was -1.0V, and the electron transport layer 3 The redox potential was inclined from noble to base toward the electrode 1 side.

  Next, the electron transport layer 3 was immersed in an acetonitrile solution containing the sensitizing dye (D131) of [Chemical Formula 26] described above at a concentration of 0.3 mM for 1 hour, washed with water, and applied to the electron transport layer 3. A sensitizing dye was provided.

  In this way, the electron transport layer 3 was formed, and thereafter, in the same manner as in Example 1, a photoelectric device having a layer structure as shown in FIG.

(Comparative Example 1)
In Example 1, the galbi polymer layer 3a was formed on the electrode 1 of the conductive glass substrate (the layer 3b was not formed). The electron transport layer 3 formed of the galbipolymer layer 3a is immersed in an acetonitrile solution containing the sensitizing dye (D131) of [Chemical Formula 26] described above at a concentration of 0.3 mM for 1 hour, and then washed with water. The electron transport layer 3 was provided with a sensitizing dye. Thereafter, a photoelectric element was produced in the same manner as in Example 1.

  Measurement of redox potential of galbi polymer layer of Examples 1 to 3 and Comparative Example 1, polydecyl viologen layer of Example 1, quinone polymer layer of Example 2, polyimide layer of Example 3 The law is as follows:

(Measurement of redox potential of galbi polymer layer)
Spin coating was performed on a glass substrate with a transparent conductive film in the same manner as in Example 1 to form a galbi polymer layer having a thickness of 100 nm. Next, the electrode provided with the galbi polymer layer was immersed in the electrolytic solution, and the electrolytic solution was infiltrated into the voids in the galbi polymer layer. As an electrolytic solution, a 0.1 mol / l tetrabutylammonium perchlorate acetonitrile solution was used. A half cell was prepared using a platinum electrode as a counter electrode and an Ag / AgCl electrode as a reference electrode, and the potential was evaluated. As a result, the oxidation-reduction potential was 0V.

(Measurement of redox potential of polydecylviologen layer)
A glass substrate with a transparent conductive film was immersed in an aqueous solution of polydecyl viologen (pH 10) having a concentration of 0.1 M for 15 minutes to form a polydecyl viologen layer on the transparent conductive film. Next, the electrode provided with the polydecyl viologen layer was immersed in the electrolytic solution, and the electrolytic solution was infiltrated into the voids in the polydecyl viologen layer. As an electrolytic solution, a 0.1 mol / l tetrabutylammonium perchlorate acetonitrile solution was used. A half cell was prepared using a platinum electrode as a counter electrode and an Ag / AgCl electrode as a reference electrode, and the potential was evaluated. The redox potential of the polydecylviologen layer was -0.4V.

(Measurement of redox potential of quinone polymer layer)
A glass substrate with a transparent conductive film was spin-coated in the same manner as in Example 3 to produce a quinone polymer layer having a thickness of 100 nm. Next, the electrode provided with the quinone polymer layer was immersed in an electrolytic solution, and the electrolytic solution was infiltrated into voids in the quinone polymer layer. As an electrolytic solution, a 0.1 mol / l tetrabutylammonium perchlorate acetonitrile solution was used. A half cell was prepared using a platinum electrode as a counter electrode and an Ag / AgCl electrode as a reference electrode, and the potential was evaluated. The oxidation-reduction potential of the quinone polymer layer was -0.8V.
(Measurement method of redox potential of polyimide layer)
A polyimide layer was formed with a thickness of 100 nm by spin coating on a glass substrate with a transparent conductive film in the same manner as in Example 3. Next, the electrode provided with the polyimide layer was immersed in the electrolytic solution, and the electrolytic solution was infiltrated into the voids in the polyimide layer. As an electrolytic solution, a 0.1 mol / l tetrabutylammonium perchlorate acetonitrile solution was used. A half cell was prepared using a platinum electrode as a counter electrode and an Ag / AgCl electrode as a reference electrode, and the potential was evaluated. The redox potential of the polyimide layer was -1.0V.

With respect to the photoelectric elements obtained in each of the above examples and comparative examples, while irradiating 200 lux light onto a region having a 1 cm ² planar view area of the photoelectric conversion portion, a “Keithley 2400 source meter” (2400 manufactured by Caseley) was used. The open circuit voltage and the short circuit current value of each photoelectric element were measured by IV measurement using a general-purpose source meter). At this time, a fluorescent lamp (Rapid fluorescent lamp “FLR20S · W / M” manufactured by Panasonic Corporation) was used as a light source, and measurement was performed in an environment of 25 ° C. The results are shown in Table 1.

  As can be seen from Table 1, it is confirmed that each example has a higher open-circuit voltage value and short-circuit current value than those of the comparative example, and the conversion efficiency is improved.

1 electrode 2 electrode (counter electrode)
3 Electron transport layer 4 Hole transport layer 5 Gel layer

Claims (3)

  An optoelectric element formed between a pair of electrodes and having an electron transport layer in contact with one electrode and a hole transport layer in contact with the other electrode, wherein the electron transport layer is repeated It is formed including an organic compound having a redox part capable of redox and an electrolyte solution that stabilizes the reduced state of the redox part, and the electron transport layer is directed toward the electrode side in contact with the electron transport layer. A photoelectric element characterized in that the oxidation-reduction potential is inclined from noble to base.   The electron transport layer is formed by combining two or more organic compounds selected from an imide derivative, a quinone derivative, a viologen derivative, and a phenoxyl derivative, so that the redox potential is increased toward the electrode in contact with the electron transport layer. 2. The photoelectric element according to claim 1, wherein the photoelectric element is inclined from noble to base.   The photoelectric element according to claim 1, wherein a sensitizing dye is provided in contact with at least one of the electron transport layer and the hole transport layer.

Images