JP4872281B2 - Photoelectric conversion material and organic thin film solar cell - Google Patents

Description

  The present invention relates to an organic thin-film solar cell having a photoelectric conversion layer containing a copolymer.

  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 a manufacturing process compared to an inorganic solar cell typified by silicon or the like. Is easy, and has the advantage that the area can be increased at low cost. However, since the photoelectric conversion efficiency is low, it is difficult to put it to practical use, and in the organic thin film solar cell, increasing the photoelectric conversion efficiency is the biggest issue.

  As a general organic thin film solar cell, for example, a transparent substrate, a transparent electrode layer, a photoelectric conversion layer functioning as an electron donor and an electron acceptor, and a metal electrode layer are sequentially laminated. A conductive polymer material is used for the photoelectric conversion layer, and further development of the conductive polymer material has been attempted for higher efficiency.

For example, polythiophene, which is one type of conductive polymer material, has high conductivity and excellent charge transport properties. However, polythiophene is oxidatively doped with ambient oxygen and increases conductivity, which is not considered stable when exposed to air. As described above, many of the conductive polymer materials have one of the characteristics such as light absorption characteristics, charge separation characteristics, charge transport characteristics, oxidation resistance characteristics, and water resistance characteristics required when applied to organic thin film solar cells. In some cases, it is an obstacle to higher efficiency.
In addition, the prior art document regarding this invention has not been discovered.

  The present invention has been made in view of the above problems, and has as its main object to provide a highly efficient organic thin-film solar cell.

  In order to achieve the above-mentioned object, the present invention is a copolymer comprising at least a monomer unit having conductivity, comprising a conductive polymer material having a Stokes shift of 0.2 eV or more. Provided is a photoelectric conversion material.

  When the Stokes shift is relatively large, it is assumed that the thermally stable structure between the ground state and the excited state is relatively different, and is sufficient for structural changes when the ground state changes to the excited state or from the excited state to the ground state. It is thought that the collision frequency between the electron donor and the electron acceptor is increased. Therefore, in the present invention, by setting the Stokes shift within the above range, it is assumed that charge separation is promoted and power generation efficiency is improved.

  Moreover, in this invention, it is preferable that the said monomer unit contains one selected from the group which consists of a thiophen ring, a fluorene ring, a phenylene vinylene group, and a phenylene ethynylene group. This is because the thiophene ring is excellent in charge transport property, the fluorene ring is excellent in oxidation resistance and water resistance, the phenylene vinylene group is excellent in charge separation property and charge transport property, and the phenylene ethynylene group is excellent in oxidation resistance.

  The present invention also provides a photoelectric conversion material comprising a fluorene-thiophene copolymer. Since the fluorene-thiophene copolymer has high oxidation resistance and water resistance even when exposed to air, quality deterioration is prevented and it can be made particularly chemically stable.

  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 and containing the above-described photoelectric conversion material, and the photoelectric conversion layer. There is provided an organic thin film solar cell including the formed second electrode layer.

  Since the organic thin film solar cell of the present invention uses a photoelectric conversion layer containing the above-described photoelectric conversion material, it is excellent in light absorption characteristics, charge separation characteristics, charge transport characteristics, oxidation resistance characteristics, water resistance characteristics, etc. Thereby, photoelectric conversion efficiency can be improved.

  In the said invention, it is preferable that the said photoelectric converting layer is a coating film. That is, the photoelectric conversion layer is preferably formed by a coating method. This is because the coating method can form a film by a simple method and does not require a vacuum facility as in the vapor deposition method, so that the manufacturing cost can be reduced.

  In the present invention, by using a photoelectric conversion material having a Stokes shift within a predetermined range, there is an effect that charge separation is promoted and power generation efficiency is improved.

Hereinafter, the photoelectric conversion material and the organic thin film solar cell of the present invention will be described in detail.
A. Photoelectric Conversion Material The photoelectric conversion material of the present invention can be divided into two embodiments. A first embodiment of the photoelectric conversion material of the present invention is a copolymer including at least a monomer unit having conductivity, and is characterized by comprising a conductive polymer material having a Stokes shift within a predetermined range. To do. Moreover, the second embodiment of the photoelectric conversion material of the present invention is characterized by comprising a fluorene-thiophene copolymer. In the following, each embodiment will be described separately.

1. First Embodiment A first embodiment of the photoelectric conversion material of the present invention is a copolymer including at least a monomer unit having conductivity, and is a conductive polymer material having a Stokes shift of 0.2 eV or more. It is characterized by.

  Here, the conductive polymer is a so-called π-conjugated polymer, and is composed of a π-conjugated system in which double bonds or triple bonds containing carbon-carbon or heteroatoms are alternately linked to single bonds, and has semiconducting properties. Is shown. In the conductive polymer material, π conjugation is developed in the polymer main chain, so that charge transport in the main chain direction is basically advantageous. In addition, the conductive polymer material can be easily formed by a coating method by using a coating solution in which the conductive polymer material is dissolved or dispersed in a solvent. There is an advantage that it can be manufactured at low cost without requiring expensive equipment.

Moreover, luminescence usually appears on the lower energy side than light absorption. This is because in the excited state, electrons emit light after losing a part of their energy due to interaction with surrounding atoms. This is called Stokes' law. Also, the difference between photon energies where light absorption and emission are observed is called Stokes shift.
In the case of organic molecules, when π electrons are excited to π antibonding orbitals by light absorption, the C—C bond length and the like change. The energy difference between the π antibonding orbital and the πbonding orbital at the bond length should be smaller than that of the original bond length (see FIG. 1).
The vertical axis in FIG. 1 represents the energy E of the whole molecule, and the horizontal axis represents the coordinate coordinate Q symbolizing the bond length and the like. When one electron is excited to π ^* , the stable bond length changes, so that the bottoms of the two parabolas shown by the solid lines are shifted. Since the masses of electrons and atoms are more than 1000 times different, it can be considered that the atoms are stationary during the optical transition process (Frank Condon's principle). As apparent from FIG. 1, the energy of light absorption indicated by the solid line arrow on the left side is different from the energy of light emission indicated by the solid line arrow on the right side. This is the Stokes shift, and the amount of shift varies depending on the magnitude of interaction between π electrons and molecular deformation.

  A large Stokes shift means that the thermally stable structure of the ground state and the excited state are significantly different. For this reason, it is assumed that the structure has a sufficiently long lifetime for the structural change when the ground state changes to the excited state or when the excited state changes to the ground state, and the collision frequency between the electron donor and the electron acceptor is considered to increase. Thereby, it is considered that charge separation is promoted and power generation efficiency is improved.

The Stokes shift of the conductive polymer material in the present invention is 0.2 eV or more, preferably 0.3 eV or more, and particularly preferably 0.7 eV or more. If the Stokes shift is in the above range, it is considered that charge separation is promoted as described above, and the power generation efficiency can be improved. The larger the Stokes shift, the better, but the upper limit is usually about 1.5 eV.
The Stokes shift measures the absorption wavelength and emission wavelength of the conductive polymer material, converts the wavelength to energy by the following formula, calculates the absorption energy and emission energy, and calculates the difference between the absorption energy and emission energy. It is a value obtained by obtaining.
Conversion formula: E (keV) = 1.24 / λ (nm)
(E: energy, λ: wavelength)

The monomer unit contained in the copolymer in the present invention is not particularly limited as long as it contains a cyclic structure having conductivity and a π-conjugated system. Any of the rings may be included, for example, it may include any of a single ring or a polycycle, and further, for example, may include any of a benzene ring or a condensed ring.
As carbon number of the said monomer unit, it is about 4-60 normally. The carbon number does not include the carbon number of the substituent.

  As such a monomer unit, for example, those containing any of a thiophene ring, a fluorene ring, a phenylene vinylene group, or a phenylene ethynylene group are preferably used. This is because the thiophene ring is excellent in charge transport property, the fluorene ring is excellent in oxidation resistance and water resistance, the phenylene vinylene group is excellent in charge separation property and charge transport property, and the phenylene ethynylene group is excellent in oxidation resistance.

The monomer unit is, for example, an alkyl group, an alkoxy group, an alkylthio group, an alkylsilyl group, an alkylamino group, an aryl group, an aryloxy group, an arylsilyl group, an arylamino group, an arylalkyl group, an arylalkoxy group, It may have a substituent such as an arylalkylsilyl group, an arylalkylamino group, an arylalkenyl group, an arylalkynyl group, a phenylethenyl group, an alkylphenylethenyl group, an alkoxyphenylethenyl group. Among these substituents, an alkyl group, an alkoxy group, an alkylamino group, an aryl group, an aryloxy group, an arylalkyl group, and an arylalkylamino group are preferable, an alkyl group, an alkoxy group, and an aryl group are more preferable, an alkyl group, Alkoxy groups are most preferred.
Specific examples of the monomer unit include those represented by the following formula.

Here, R ¹ is a hydrogen atom or a linear alkyl group, preferably a hydrogen atom or — (CH ₂ ) ₅ CH ₃ . R ² is a linear alkyl group, and preferably — (CH ₂ ) ₅ CH ₃ . R ³ is an alkyl group, preferably —CH ₂ CH (C ₂ H ₅ ) (CH ₂ ) ₂ CH ₃ , — (CH ₂ ) ₂ CH (CH ₃ ) (CH ₂ ) ₃ CH (CH ₃ ) _2, or _{- (CH 2)} 17 _{CH 3.} R ⁴ is an alkyl group, preferably —CH ₂ CH (C ₂ H ₅ ) (CH ₂ ) ₂ CH ₃ , — (CH ₂ ) ₂ CH (CH ₃ ) (CH ₂ ) ₃ CH (CH ₃ ) ₂ or —CH ₃ . R ⁵ is a linear alkyl group, preferably — (CH ₂ ) ₇ CH ₃ .

The copolymer in the present invention preferably has a weight average molecular weight of about 1,000 to 3,000,000. If the weight average molecular weight is less than the above range, the film may not be formed. If the weight average molecular weight exceeds the above range, the viscosity of the photoelectric conversion material becomes high and it becomes difficult to form a uniform film.
The weight average molecular weight can be measured by gel permeation chromatography (GPC). The measurement conditions are shown below.
Measurement column: Shodex HF-2002 Styrene-divinylbenzene copolymer detector: Differential refractive index detector (RI) Shimadzu RID-6A
Ultraviolet absorption detector Measurement wavelength 254nm SPD-10A manufactured by Shimadzu Corporation
Measurement conditions: mobile phase chloroform
Flow rate 3ml / min
Injection method 2ml injection by syringe

  In addition, if the polymerization active group remains as it is, the terminal group of the copolymer may be protected with a stable group because the performance when the organic thin film solar cell is formed may be deteriorated. Those having a conjugated bond continuous with a cyclic structure having π conjugation of the main chain are preferred, and examples thereof include a structure bonded to an aryl group or a heterocyclic ring via a carbon-carbon bond.

  The copolymer may be any of a random, block or graft copolymer. Further, it may be a copolymer having an intermediate structure thereof, for example, a random copolymer having a block property. From the viewpoint of obtaining a conductive polymer material having a high quantum yield, a random copolymer having a block property and a block or graft copolymer are preferable to a complete random copolymer. Further, the copolymer may be a dendrimer when the main chain is branched and there are three or more terminal portions.

The copolymer in the present invention may contain monomer units other than the above-mentioned monomer units having conductivity, as long as charge separation characteristics, charge transport characteristics and the like are not impaired.
In addition, the monomer units may be linked with non-conjugated units, or the monomer units may contain non-conjugated moieties. As the linking group of the monomer unit, —O—, —S—, —N (—R) —, —B (—R) —, —Si (—R) ₂ —, —C (—R) are used. _2- , -C (= O)-, -C (= O) -O-, -O-C (= O)-, -N (-R) -C (= O)-, -C (= O ) -N (-R)-, -C≡C- and the like. Here, R represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, and a heterocyclic ring having 4 to 60 carbon atoms.

  Examples of such a copolymer include a fluorene-thiophene copolymer, a thiophene-phenylene vinylene copolymer, a phenylene ethynylene-thiophene copolymer, a fluorene-phenylene vinylene copolymer, and a phenylene ethynylene-fluorene copolymer. And phenylene ethynylene-phenylene vinylene copolymer. Specific examples include a copolymer represented by the following formula.

Here, R ¹ is a hydrogen atom or a linear alkyl group, preferably a hydrogen atom or — (CH ₂ ) ₅ CH ₃ . R ² is a linear alkyl group, and preferably — (CH ₂ ) ₅ CH ₃ . R ³ is an alkyl group, preferably —CH ₂ CH (C ₂ H ₅ ) (CH ₂ ) ₂ CH ₃ , — (CH ₂ ) ₂ CH (CH ₃ ) (CH ₂ ) ₃ CH (CH ₃ ) _2, or _{- (CH 2)} 17 _{CH 3.} R ⁴ is an alkyl group, preferably —CH ₂ CH (C ₂ H ₅ ) (CH ₂ ) ₂ CH ₃ , — (CH ₂ ) ₂ CH (CH ₃ ) (CH ₂ ) ₃ CH (CH ₃ ) ₂ or —CH ₃ . R ⁵ is a linear alkyl group, preferably — (CH ₂ ) ₇ CH ₃ .

  More specifically, a copolymer represented by the following formula is exemplified.

  Among them, fluorene-thiophene copolymer, thiophene-phenylene vinylene copolymer, phenylene ethynylene-thiophene copolymer, fluorene-phenylene vinylene copolymer, phenylene ethynylene-fluorene copolymer, and phenylene ethynylene-phenylene vinylene. Since the copolymer has an appropriate energy level difference with respect to many electron-accepting organic semiconductor materials, the copolymer can be suitably used as an electron-donating conductive polymer material.

  Moreover, when the photoelectric converting layer in an organic thin-film solar cell is formed using the photoelectric converting material of this invention, it is preferable that the electrical conductivity of a photoelectric converting layer is favorable. This is because if the electrical conductivity is good, the charge transporting property required for the organic thin film solar cell can be obtained.

  Examples of the good solvent for the photoelectric conversion material of the present invention include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, mesitylene, tetralin, decalin, and n-butylbenzene. Although the photoelectric conversion material of this invention is based also on the structure and weight average molecular weight of a copolymer, it can be normally dissolved in these solvent 0.1weight% or more.

  Moreover, when using the photoelectric conversion material of this invention for the photoelectric converting layer of an organic thin-film solar cell, since it utilizes electricity, what has a light absorption characteristic, a charge-separation characteristic, and a charge transport property in a solid state is used suitably. . In this case, since the purity of the copolymer affects these properties, it is preferable to polymerize after purifying the monomer before polymerization by distillation, sublimation purification, recrystallization, or the like. It is preferable to perform a purification treatment such as purification and fractionation by chromatography.

Examples of the method for synthesizing the copolymer in the present invention include a method of polymerizing from a monomer by a Suzuki coupling reaction, a method of polymerizing by a Grignard reaction, a method of polymerizing by a Ni (0) catalyst, and a polymerization by an oxidizing agent such as FeCl _3. Examples thereof include a method, an electrochemical oxidative polymerization method, and a method of decomposing an intermediate polymer having an appropriate leaving group. Among these, the method of polymerizing by Suzuki coupling reaction, the method of polymerizing by Grignard reaction, and the method of polymerizing by Ni (0) catalyst are preferable because the reaction control is easy, and the method of polymerizing by Ni (0) catalyst is preferable. Most preferred.
For example, phenylene ethynylene-phenylene vinylene copolymer (Poly [1,4-phenyleneethynylene-1,4- (2,5-dioctadodecyloxyphenylene) -1,4-phenyleneethene-1,2-diyl-1,4- (2, For the synthesis method of 5-dioctadodecyloxyphenylene) ethene-1,2-diyl]), refer to the methods described in Macromolecules, 35, 3825 (2002) and Micromol. Chem. Phys., 202, 2712 (2001). be able to.

2. Second Embodiment A second embodiment of the photoelectric conversion material of the present invention is characterized by comprising a fluorene-thiophene copolymer.
Although thiophene is excellent in charge transportability, it is inferior in oxidation resistance and water resistance, while fluorene is excellent in oxidation resistance and water resistance, but charge transportability is not as high as thiophene, but by using a fluorene-thiophene copolymer, A photoelectric conversion material having excellent transportability, oxidation resistance, and water resistance can be obtained. As described above, the fluorene-thiophene copolymer has high oxidation resistance and water resistance even when exposed to air, so that quality deterioration is prevented and it is particularly chemically stable.

  The fluorene-thiophene copolymer in the present invention has a monomer unit containing a fluorene ring and a monomer unit containing a thiophene ring. The monomer unit containing a fluorene ring and the monomer unit containing a thiophene ring may have a substituent. The substituent is the same as that described in the first embodiment.

  Specific examples of the monomer unit containing a thiophene ring include groups represented by the following formulae.

Here, R ¹ is a hydrogen atom or a linear alkyl group, preferably a hydrogen atom or — (CH ₂ ) ₅ CH ₃ .

  Specific examples of the monomer unit containing a fluorene ring include groups represented by the following formulas.

Here, R ² is a linear alkyl group, preferably — (CH ₂ ) ₅ CH ₃ .

  The fluorene-thiophene copolymer in the present invention preferably has a weight average molecular weight of about 1,000 to 3,000,000. If the weight average molecular weight is less than the above range, the film may not be formed. If the weight average molecular weight exceeds the above range, the viscosity of the photoelectric conversion material becomes high and it becomes difficult to form a uniform film. In addition, about the measuring method of the said weight average molecular weight, it is the same as that of what was described in the said 1st embodiment.

  In addition, the terminal group of the fluorene-thiophene copolymer is protected with a stable group, because if the polymerization active group is left as it is, there is a possibility that the performance when the organic thin film solar cell is formed may be lowered. Also good.

  The fluorene-thiophene copolymer may be any of a random, block or graft copolymer. Further, it may be a copolymer having an intermediate structure thereof, for example, a random copolymer having a block property. From the viewpoint of obtaining a conductive polymer material having a high quantum yield, a random copolymer having a block property and a block or graft copolymer are preferable to a complete random copolymer. Further, the fluorene-thiophene copolymer may be a dendrimer when the main chain is branched and there are three or more terminal portions.

The fluorene-thiophene copolymer in the present invention contains a monomer unit other than a monomer unit containing a fluorene ring and a monomer unit containing a thiophene ring within a range not impairing charge separation characteristics, charge transport characteristics, and the like. You may go out.
In addition, these monomer units may be linked with non-conjugated units, or the monomer units may contain non-conjugated parts. The linking group of the monomer unit is the same as that described in the first embodiment.

  Specific examples of such a fluorene-thiophene copolymer include those represented by the following formula.

Here, R ¹ is a hydrogen atom or a linear alkyl group, preferably a hydrogen atom or — (CH ₂ ) ₅ CH ₃ . R ² is a linear alkyl group, and preferably — (CH ₂ ) ₅ CH ₃ .

  More specifically, what is shown by a following formula is mentioned.

  Moreover, when the photoelectric converting layer in an organic thin-film solar cell is formed using the photoelectric converting material of this invention, it is preferable that the electrical conductivity of a photoelectric converting layer is favorable. This is because if the electrical conductivity is good, the charge transporting property required for the organic thin film solar cell can be obtained.

  Examples of the good solvent for the photoelectric conversion material of the present invention include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, mesitylene, tetralin, decalin, and n-butylbenzene. Although the photoelectric conversion material of this invention is based also on the structure and weight average molecular weight of a fluorene-thiophene copolymer, it can be normally dissolved in these solvent 0.1weight% or more.

  Moreover, when using the photoelectric conversion material of this invention for the photoelectric converting layer of an organic thin-film solar cell, since it utilizes electricity, what has a light absorption characteristic, a charge-separation characteristic, and a charge transport property in a solid state is used suitably. . In this case, since the purity of the fluorene-thiophene copolymer affects these properties, it is preferable to polymerize after purifying the monomer before polymerization by a method such as distillation, sublimation purification, and recrystallization. It is preferable to carry out purification treatment such as reprecipitation purification and fractionation by chromatography.

Examples of the method for synthesizing a fluorene-thiophene copolymer in the present invention include a method of polymerizing from a monomer by a Suzuki coupling reaction, a method of polymerizing by a Grignard reaction, a method of polymerizing by a Ni (0) catalyst, and an oxidizing agent such as FeCl ₃ Examples thereof include a method of polymerizing by oxidization, a method of electrochemically oxidative polymerization, a method of decomposing an intermediate polymer having an appropriate leaving group, and the like. Among these, the method of polymerizing by Suzuki coupling reaction, the method of polymerizing by Grignard reaction, and the method of polymerizing by Ni (0) catalyst are preferable because the reaction control is easy, and the method of polymerizing by Ni (0) catalyst is preferable. Most preferred.

B. Next, the organic thin film solar cell of the present invention will be described.
The organic thin film solar cell of 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 containing the above-described photoelectric conversion material, and the photoelectric And a second electrode layer formed on the conversion layer.

  Since the organic thin film solar cell of the present invention uses a photoelectric conversion layer containing the above-described photoelectric conversion material, it is excellent in light absorption characteristics, charge separation characteristics, charge transport characteristics, oxidation resistance characteristics, water resistance characteristics, etc. Thereby, photoelectric conversion efficiency can be improved.

The organic thin-film solar cell of this invention is demonstrated referring drawings.
FIG. 2 is a schematic cross-sectional view showing an example of the organic thin film solar cell of the present invention. In the example shown in FIG. 2, the organic thin film solar cell 10 is obtained by sequentially laminating a first electrode layer 2, a photoelectric conversion layer 3, and a second electrode layer 4 on a substrate 1.
Hereinafter, each structure of such an organic thin film solar cell is demonstrated.

1. Photoelectric Conversion Layer The photoelectric conversion layer used in the present invention contains the above-described photoelectric conversion material. Here, the “photoelectric conversion layer” is a layer having both an electron-accepting function and an electron-donating function, contributing to charge separation of the organic thin film solar cell, and generating generated electrons and holes in opposite directions, respectively. A member having a function of transporting toward an electrode. Charge separation occurs using a pn junction formed in the photoelectric conversion layer.

  The photoelectric conversion layer has both an electron donating property and an electron accepting property. However, since the properties of the above-described photoelectric conversion material vary depending on the structure of the copolymer, the photoelectric conversion layer has a photoelectric conversion property depending on the properties of the photoelectric conversion material. The constituent material of the conversion layer is appropriately selected. For example, when the photoelectric conversion material has an electron donating property, the photoelectric conversion layer contains an electron donating photoelectric conversion material and an electron accepting organic semiconductor material. For example, when the photoelectric conversion material has an electron accepting property, the photoelectric conversion layer contains an electron accepting photoelectric conversion material and an electron donating organic semiconductor material. Further, for example, when the photoelectric conversion material has both an electron donating property and an electron accepting property, the photoelectric conversion layer contains an electron donating property and an electron accepting photoelectric conversion material.

As the photoelectric conversion material having an electron donating property, among those described in the above section “A. Photoelectric conversion material”, a fluorene-thiophene copolymer, a thiophene-phenylene vinylene copolymer, a phenylene ethynylene-thiophene copolymer, A fluorene-phenylene vinylene copolymer, a phenylene ethynylene-fluorene copolymer, a phenylene ethynylene-phenylene vinylene copolymer, or the like is preferably used. This is because the energy level difference is appropriate for many electron-accepting organic semiconductor materials.
Specific examples of the fluorene-thiophene copolymer include (Poly [(9,9-dihexylfluorenyl-2,7-diyl) -co- (bithiophene)] and the like.

The electron-accepting organic semiconductor material used when the photoelectric conversion material has an electron donating property is not particularly limited as long as it has a function as an electron acceptor, but can be formed by a coating method. In particular, an electron-donating conductive polymer material is preferable. In the conductive polymer material, π conjugation is developed in the polymer main chain, so that charge transport in the main chain direction is basically advantageous. In addition, the conductive polymer material can be easily formed by a coating method by using a coating solution in which the conductive polymer material is dissolved or dispersed in a solvent. There is an advantage that it can be manufactured at low cost without requiring expensive equipment.
Examples of the electron-accepting conductive polymer material include polyphenylene vinylene, polyfluorene, and derivatives thereof, and copolymers thereof, or carbon nanotubes, fullerene derivatives, CN group or CF ₃ group-containing polymers, and their it can be mentioned -CF ₃ substituted polymer. Specific examples of the polyphenylene vinylene derivative include CN-PPV (Poly [2-Methoxy-5- (2′-ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene]), MEH-CN-PPV (Poly [2 -Methoxy-5- (2′-ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene]) and the like.

  In addition, the photoelectric conversion material having electron acceptability can be appropriately selected from those described in the section “A. Photoelectric conversion material” according to the electron-donating organic semiconductor material to be used.

The electron-donating organic semiconductor material used when the photoelectric conversion material has an electron accepting property is not particularly limited as long as it has a function as an electron donor, but can be formed by a coating method. In particular, an electron-donating conductive polymer material is preferable. This is because the conductive polymer material has the advantages as described above.
Examples of the electron-donating conductive polymer material include polyphenylene, polyphenylene vinylene, polysilane, polythiophene, polycarbazole, polyvinyl carbazole, porphyrin, polyacetylene, polypyrrole, polyaniline, polyfluorene, polyvinyl pyrene, polyvinyl anthracene, and derivatives thereof. And copolymers thereof, phthalocyanine-containing polymers, carbazole-containing polymers, organometallic polymers, and the like.

Furthermore, as a photoelectric conversion material having an electron donating property and an electron accepting property, an electron accepting photoelectric conversion material doped with an electron donating compound, an electron donating photoelectric conversion material doped with an electron accepting compound, etc. Can be used.
As the electron-donating compound to be doped, for example, a Lewis base such as an alkali metal such as Li, K, Ca, or Cs or an alkaline earth metal can be used. The Lewis base acts as an electron donor.
As the electron-accepting compound to be doped, for example, a Lewis acid such as FeCl ₃ (III), AlCl ₃ , AlBr ₃ , AsF ₆ or a halogen compound can be used. In addition, Lewis acid acts as an electron acceptor.

  In order to generate charges efficiently, it is preferable that the electron-donating material and the electron-accepting material are uniformly dispersed in the photoelectric conversion layer. At this time, the mixing ratio of the electron-donating material and the electron-accepting material is appropriately adjusted to an optimal mixing ratio depending on the type of material used.

  The film thickness of the photoelectric conversion layer is not particularly limited as long as it is a film thickness generally employed in a bulk heterojunction organic thin film solar cell, but specifically within a range of 0.2 nm to 3000 nm. It can be set, and is preferably in the range of 1 nm to 600 nm. If the film thickness of the photoelectric conversion layer is larger than the above range, the volume resistance in the photoelectric conversion layer may be increased, and if the film thickness of the photoelectric conversion layer is smaller than the above range, a short circuit may occur between the electrodes. Because there is.

  In the present invention, a plurality of photoelectric conversion layers may be laminated. In organic thin-film solar cells in which a plurality of photoelectric conversion layers are directly laminated, photoelectric conversion materials and organic semiconductor materials having different absorption wavelength regions can be used for each photoelectric conversion layer. The absorption wavelength region can be expanded. In addition, in the case where a photoelectric conversion material or an organic semiconductor material having the same absorption wavelength region is used for each photoelectric conversion layer, a plurality of photoelectric conversion layers are formed as compared with an organic thin-film solar cell having only one photoelectric conversion layer. Since the organic thin film solar cell having a thickness increases, it is considered that the absorbance can be increased as the thickness increases. Therefore, by directly laminating a plurality of photoelectric conversion layers, it is possible to produce an organic thin film solar cell that can generate power over a wide wavelength range and can realize high photoelectric conversion efficiency.

Here, FIG. 3 shows an example of an organic thin film solar cell. In the organic thin-film solar cell S having a configuration in which the photoelectric conversion layer 22 is sandwiched between the two electrode layers 21 and 23, the current J is generated by irradiating the light energy L in the photoelectric conversion layer 22, and the electromotive force of V Is obtained (FIG. 3A). When two organic thin film solar cells S are connected in series and irradiated with 2 L of light energy, the light energy equivalent to each of the two organic thin film solar cells S (= 2L / 2 = L) Can be obtained, a double electromotive force (= 2V) can be obtained (FIG. 3B). That is, if any of the plurality of organic thin-film solar cells connected in series can absorb light, the electromotive force increases accordingly.
In the present invention, for example, by directly laminating the photoelectric conversion layers 22a and 22b, it is expected that, in a pseudo manner, an electromotive force of 2 V can be obtained in the same level as when two organic thin-film solar cells are connected in series. (FIG. 3C). Therefore, the photoelectric conversion efficiency can be increased, and more ideally, a plurality of organic thin film solar cells can be used as a single organic thin film solar cell, instead of being connected in series.
Thus, in the present invention, effective use of light can be realized by stacking a plurality of photoelectric conversion layers.

  In the case where a plurality of photoelectric conversion layers are stacked, the number of stacked photoelectric conversion layers may be two or more, preferably about 2 to 5 layers, more preferably 2 layers or 3 layers. It is. This is because if the number of stacked layers is too large, the transmittance decreases and the light utilization efficiency decreases.

Moreover, what is necessary is just to select the absorption wavelength area | region of a photoelectric conversion material or an organic-semiconductor material suitably in order to implement | achieve effective utilization of light. Since the photoelectric conversion layer contains an electron-donating material and an electron-accepting material, any one of the electron-donating material and the electron-accepting material only needs to have a predetermined absorption maximum wavelength. . At this time, when the electron donating material has a predetermined absorption maximum wavelength, the electron accepting material may form a pn junction with the electron donating material to cause charge separation. There is no particular limitation. Similarly, if the electron-accepting material has a predetermined absorption maximum wavelength, the electron-donating material may form a pn junction with the electron-accepting material to cause charge separation. There is no particular limitation.
When electron donating materials having different absorption wavelength regions are used for the photoelectric conversion layer, the maximum absorption wavelength of each electron donating material is 50 nm in order to absorb sunlight (white light) in a wide range. It is preferable that the difference is more than about.

  In this case, it is particularly preferable that three photoelectric conversion layers are laminated. For example, the first layer uses an electron-donating material with an absorption maximum wavelength in the red wavelength region, the second layer uses an electron-donating material with an absorption maximum wavelength in the green wavelength region, and the third layer has a blue color. This is because sunlight (white light) can be absorbed in a wider range by using an electron-donating material having an absorption maximum wavelength in the wavelength region.

  The method for forming the photoelectric conversion layer used in the present invention is not particularly limited as long as it can be uniformly formed in a predetermined film thickness, but a coating method is preferably used. That is, the photoelectric conversion layer is preferably a coating film. In the present invention, the “coating film” refers to a film formed by a coating method, for example, a film formed by coating using a coating solution.

In the case of forming a photoelectric conversion layer by a coating method, a photoelectric conversion material is prepared by dispersing a photoelectric conversion material in a solvent and applying the photoelectric conversion layer forming coating liquid. A layer can be formed.
The solvent used in the coating liquid for forming a photoelectric conversion layer is not particularly limited as long as the photoelectric conversion material can be dispersed.

  Examples of the coating method for the photoelectric conversion layer forming coating liquid include a die coating method, a spin coating method, a dip coating method, a roll coating method, a bead coating method, a spray coating method, a bar coating method, a gravure coating method, an inkjet method, Examples thereof include a screen printing method and an offset printing method. Among these, a spin coating method or a die coating method is preferably used. This is because these methods can accurately form the photoelectric conversion layer so as to have a predetermined film thickness.

  Moreover, when the photoelectric converting layer is laminated | stacked in multiple layers, it is preferable that the weight average molecular weight of the photoelectric converting material contained in the lower photoelectric converting layer is comparatively high. Thereby, for example, it is possible to suppress the constituent components of the lower photoelectric conversion layer from eluting into the solvent in the upper photoelectric conversion layer forming coating liquid, and used for the upper photoelectric conversion layer forming coating liquid. This is because the solvent is not limited. Therefore, a large number of photoelectric conversion layers can be stacked by adopting such a method.

The weight average molecular weight of the photoelectric conversion material is preferably 100,000 or more, more preferably 300,000 or more, most preferably 500,000 or more, and preferably 5 million or less, more preferably 3 million. It is as follows. This is because if the weight average molecular weight of the photoelectric conversion material is too small, the photoelectric conversion material may be dissolved in the solvent in the upper photoelectric conversion layer forming coating solution. On the contrary, if the weight average molecular weight of the photoelectric conversion material is too large, the viscosity of the coating liquid for forming the lower photoelectric conversion layer is increased, and it may be difficult to form a uniform coating film.
The weight average molecular weight is a value measured by gel permeation chromatography (GPC). The measurement conditions are shown below.
Measurement column: Shodex HF-2002 Styrene-divinylbenzene copolymer detector: Differential refractive index detector (RI) Shimadzu RID-6A
Ultraviolet absorption detector Measurement wavelength 254nm SPD-10A manufactured by Shimadzu Corporation
Measurement conditions: mobile phase chloroform
Flow rate 3ml / min
Injection method 2ml injection by syringe

  The lower photoelectric conversion layer may contain a polymer material having a predetermined weight average molecular weight in addition to the photoelectric conversion material. The polymer material is not particularly limited as long as it does not dissolve in the solvent in the upper photoelectric conversion layer forming coating solution, and the type of the solvent used in the upper photoelectric conversion layer forming coating solution Is appropriately selected. Specifically, an electron donating organic semiconductor material, an electron accepting organic semiconductor material, an insulating resin material, or the like can be given.

The insulating resin material is not particularly limited as long as it improves the solvent resistance of the lower photoelectric conversion layer and increases the film strength. For example, a thermoplastic resin material, a thermosetting resin material, and ionizing radiation. Examples thereof include curable resin materials.
Specific examples of the thermoplastic resin material include polypropylene, polyethylene, polystyrene, polyvinyl acetate, polyamide, polyvinyl chloride, polyurethane, polyethylene terephthalate, polyvinylidene chloride, and polyacrylonitrile.
Specific examples of the thermosetting resin material include phenol resin, melamine resin, urea resin, urethane resin, and epoxy resin.
Examples of the ionizing radiation curable resin material include an ultraviolet curable resin material and an electron beam curable resin material. Specific examples of the ultraviolet curable resin material include urethane acrylate, epoxy acrylate, ester acrylate, acrylate, epoxy, vinyl ether, oxetane, and the like. Specific examples of the electron beam curable resin material include unsaturated polyester, unsaturated acrylic, polyepoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, polyene, and polythiol.

The insulating resin material preferably has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more. Moreover, it is preferable that a weight average molecular weight is 3 million or less, More preferably, it is 1 million or less. This is because if the weight average molecular weight of the insulating resin material is too small, the insulating resin material may be dissolved in the solvent in the upper photoelectric conversion layer forming coating solution. On the contrary, if the weight average molecular weight of the insulating resin material is too large, the viscosity of the lower layer photoelectric conversion layer forming coating solution increases, and it may be difficult to form a uniform coating film.
The method for measuring the weight average molecular weight is the same as that described above.

  As a method of increasing the molecular weight so that the above-described photoelectric conversion material or polymer material has a predetermined weight average molecular weight, a generally used method can be employed, for example, an oxidation polymerization method, an electrolytic polymerization method, or the like. , Vapor deposition polymerization method, chemical polymerization method, energy irradiation polymerization method and the like. The method for increasing the molecular weight is appropriately selected depending on the type of the photoelectric conversion material or the polymer material. For example, for a method of increasing the molecular weight of polyphenylene vinylene (MDMO-PPV; poly (2-methoxy-5- (3 ′, 7′-dimethyloctyloxy) -1--4-phenylene vinylene), see Thin Solid Films, 363, The method described in 98-101 (2002) can be referred to.

  Furthermore, when laminating a plurality of photoelectric conversion layers, a method using a difference in solubility in a solvent may be partially used together with the above method. For example, when three layers of photoelectric conversion layers are stacked, when a second photoelectric conversion layer is formed on the first photoelectric conversion layer, a method using a difference in solubility in a solvent is applied, and the second layer When the third photoelectric conversion layer is formed on the photoelectric conversion layer, the above method can be applied.

2. First electrode layer The material for forming the first electrode layer used in the present invention is not particularly limited as long as it has conductivity, but the irradiation direction of light and the work function of the material for forming the second electrode layer described later. It is preferable to select appropriately considering the above.
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 side is the light receiving surface, the first electrode layer is preferably a transparent electrode. In this case, what is generally used as a transparent electrode can be used. Specifically, In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, and the like can be given.

In the present invention, the total light transmittance of the first electrode layer is preferably 85% or more, more preferably 90% or more, and particularly preferably 92% or more. When the substrate side 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, and light is efficiently transmitted by the photoelectric conversion layer. It is because it can absorb.
The total light transmittance is a value measured using an SM color computer (model number: SM-C) manufactured by Suga Test Instruments Co., Ltd. in the visible light region.

In the present invention, 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 if the sheet resistance is larger than the above range, the generated charge 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, when it is a single layer, the film thickness is within a range of 0.1 to 500 nm, particularly within a range of 1 nm to 300 nm when it is composed of a plurality of layers. Preferably there is. If the film thickness is smaller than the above range, the sheet resistance of the first electrode layer may become too large, and the generated charge may not be sufficiently transmitted to the external circuit. On the other hand, if the film thickness is larger than the above range, This is because the total light transmittance is lowered and the photoelectric conversion efficiency may be lowered.

The first electrode layer may be formed on the entire surface of the substrate or may be formed in a pattern.
As a method for forming the first electrode layer, a general electrode forming method can be used, and examples thereof include a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method.

3. Second electrode layer The second electrode layer used in the present invention is an electrode facing the first electrode layer. The material for forming the second electrode layer is not particularly limited as long as it has conductivity, but may be appropriately selected in consideration of the light irradiation direction, the work function of the material for forming the first electrode layer, and the like. preferable.
For example, when the substrate side 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 the case where 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. Specific examples of the material having a low work function include Li, In, Al, Ca, Mg, Sm, Tb, Yb, Zr, and LiF.

The second electrode layer may be a single layer or may be laminated using materials having different work functions.
When the second electrode layer is a single layer, the film thickness is in the range of 0.1 nm to 500 nm, particularly 1 nm to 500 nm. It is preferable to be within the range of 300 nm. If the film thickness is smaller than the above range, the sheet resistance of the second electrode layer may become too large, and the generated charge may not be sufficiently transmitted to the external circuit. On the other hand, if the film thickness is larger than the above range, This is because the total light transmittance is lowered and the photoelectric 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 the second electrode layer, a general electrode forming method can be used, for example, a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method.

4). Substrate The substrate used in the present invention 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 the present invention, 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.

5. Organic Semiconductor Layer In the present invention, an organic semiconductor layer may be formed between at least one of the photoelectric conversion layer and the first electrode layer and between the photoelectric conversion layer and the second electrode layer. When a plurality of photoelectric conversion layers are stacked, an organic semiconductor layer may be formed between the photoelectric conversion layers. Examples of the organic semiconductor layer used in the present invention include an electron hole transporting layer having electron accepting property and electron donating property, an electron transporting layer having electron accepting property, and a hole transporting layer having electron donating property. Hereinafter, the electron hole transport layer, the electron transport layer, and the hole transport layer will be described.

(I) Electron hole transport layer The electron hole transport layer used in the present invention contains an electron donating organic semiconductor material and an electron accepting organic semiconductor material. The electron hole transport layer is a layer having both electron accepting and electron donating functions, and charge separation occurs by using a pn junction formed in the electron hole transport layer.

Note that the electron-donating organic semiconductor material and the electron-accepting organic semiconductor material are the same as those described in the section of the photoelectric conversion layer, and thus description thereof is omitted here.
In the present invention, an electron-accepting organic semiconductor material doped with an electron-donating compound, an electron-donating organic semiconductor material doped with an electron-accepting compound, or the like can also be used. Among these, a conductive polymer material doped with an electron donating compound or an electron accepting compound is preferably used. Conductive polymer materials are basically advantageous in charge transport in the direction of the main chain because of the development of π conjugation in the polymer main chain, and are doped with electron-donating compounds and electron-accepting compounds. This is because electric charges are generated in the π-conjugated main chain, and the electrical conductivity can be greatly increased.
Examples of the electron-accepting conductive polymer material doped with the electron-donating compound include the above-described electron-accepting conductive polymer material. Examples of the electron-donating conductive polymer material doped with the electron-accepting compound include the above-described electron-donating conductive polymer material. Note that the electron-donating compound and the electron-accepting compound to be doped are the same as those described in the section of the photoelectric conversion layer, and thus description thereof is omitted here.

  In order to generate charges efficiently, it is preferable that the electron-donating organic semiconductor material and the electron-accepting organic semiconductor material are uniformly dispersed in the electron-hole transport layer. At this time, the mixing ratio of the electron-donating organic semiconductor material and the electron-accepting organic semiconductor material is appropriately adjusted to an optimal mixing ratio depending on the type of the organic semiconductor material to be used.

  The film thickness of the electron-hole transport layer is not particularly limited as long as it is a film thickness generally employed in bulk heterojunction organic thin-film solar cells, but specifically ranges from 0.2 nm to 3000 nm. Within the range of 1 nm to 600 nm. If the thickness of the electron-hole transport layer is larger than the above range, the volume resistance in the electron-hole transport layer may be increased. This is because it may not be absorbed.

(Ii) Electron transport layer The electron transport layer used in the present invention contains an electron-accepting organic semiconductor material. Note that the electron-accepting organic semiconductor material is the same as that described in the section of the photoelectric conversion layer, and thus description thereof is omitted here.

  Although the film thickness of an electron carrying layer is not specifically limited, Specifically, it can set in the range of 0.1 nm-1500 nm, Preferably it exists in the range of 1 nm-300 nm. If the thickness of the electron transport layer is larger than the above range, the volume resistance in the electron transport layer may be increased. If the thickness of the electron transport layer is smaller than the above range, light may not be sufficiently absorbed. It is.

(Iii) Hole transport layer The hole transport layer used in the present invention contains an electron-donating organic semiconductor material. Note that the electron-donating organic semiconductor material is the same as that described in the section of the photoelectric conversion layer, and thus the description thereof is omitted here.

  Although the film thickness of a positive hole transport layer is not specifically limited, Specifically, it can set in the range of 0.1 nm-1500 nm, Preferably it exists in the range of 1 nm-300 nm. If the thickness of the hole transport layer is thicker than the above range, the volume resistance in the hole transport layer may increase, and if the thickness of the hole transport layer is thinner than the above range, light cannot be absorbed sufficiently Because there is.

(Iv) Others In the present invention, for example, as shown in FIG. 4, a hole transport layer 11 is formed between the photoelectric conversion layer 3 and the first electrode layer 2, and the photoelectric conversion layer 3 and the second electrode layer 4. The electron transport layer 12 may be formed between the two. In the organic thin film solar cell 10, electrons and holes generated inside the photoelectric conversion layer 3 move in the opposite directions toward the first electrode layer 2 or the second electrode layer 4. In this case, since the hole transport layer 11 and the electron transport layer 12 are provided between the photoelectric conversion layer 3 and the first electrode layer 2 and the second electrode layer 4, respectively, the photoelectric conversion layer 3 and the first electrode layer The resistance barrier at the interface between the second electrode layer 4 and the second electrode layer 4 can be reduced, and holes and electrons can be taken out efficiently.

  Moreover, in this invention, as shown, for example in FIG. 5, the positive hole transport layer 11 may be formed between the photoelectric converting layer 3a and the photoelectric converting layer 3b. In the organic thin film solar cell 10, electrons and holes generated inside the photoelectric conversion layers 3 a and 3 b move in the opposite directions toward the first electrode layer 2 or the second electrode layer 4, respectively. In this case, since the hole transport layer 11 is provided between the photoelectric conversion layer 3a and the photoelectric conversion layer 3b, the resistance barrier at the interface between the photoelectric conversion layer 3a and the photoelectric conversion layer 3b can be reduced. For example, when the first electrode layer 2 is used as an anode, holes can easily move from the photoelectric conversion layer 3b to the photoelectric conversion layer 3a, so that the hole extraction efficiency can be improved.

  Furthermore, in this invention, as shown, for example in FIG. 6, the electron carrying layer 12 may be formed between the photoelectric converting layer 3a and the photoelectric converting layer 3b. In the organic thin film solar cell 10, electrons and holes generated inside the photoelectric conversion layers 3 a and 3 b move in the opposite directions toward the first electrode layer 2 or the second electrode layer 4, respectively. In this case, since the electron transport layer 12 is provided between the photoelectric conversion layer 3a and the photoelectric conversion layer 3b, the resistance barrier at the interface between the photoelectric conversion layer 3a and the photoelectric conversion layer 3b can be reduced. When the second electrode layer 4 is a cathode, electrons are likely to move from the photoelectric conversion layer 3a to the photoelectric conversion layer 3b, so that the electron extraction efficiency can be improved.

  Thus, when the hole transport layer or the electron transport layer is formed adjacent to the photoelectric conversion layer, the resistance barrier at the interface between the layers becomes loose, and the extraction of charges can be promoted. In addition, since it is possible to facilitate the extraction of charges, there is an advantage that it is not necessary to separately provide a conventional charge extraction layer.

In the present invention, for example, as shown in FIG. 7, an electron-hole transport layer 13 may be formed between the photoelectric conversion layer 3 and the first electrode layer 2. For example, as shown in FIG. 8, a hole transport layer 11 and an electron transport layer 12 may be formed between the photoelectric conversion layer 3 and the first electrode layer 2. In the electron hole transport layer, a pn junction is formed inside the layer and charge separation occurs. When the hole transport layer and the electron transport layer are directly laminated, a pn junction is formed at the interface between the hole transport layer and the electron transport layer, and charge separation occurs. Thus, in the organic thin film solar cell in which a plurality of layers in which charge separation occurs is laminated, light can be used effectively as in the case where the plurality of photoelectric conversion layers are laminated. In this case, when the material used for each layer has a different absorption wavelength region, the absorption wavelength region can be expanded, and the material used for each layer has the same absorption wavelength region. In some cases, the absorbance can be increased.
Note that other points in the case of effectively using light are the same as those described in the section of the photoelectric conversion layer, and thus description thereof is omitted here.

  The method for forming the organic semiconductor layer used in the present invention is not particularly limited as long as it can be uniformly formed to a predetermined film thickness, but a coating method is preferably used. That is, the organic semiconductor layer is preferably a coating film.

  In the present invention, since the photoelectric conversion layer and the organic semiconductor layer are laminated, it is preferable that the material contained in the lower layer has a relatively high weight average molecular weight. Thereby, for example, it is possible to suppress the lower layer constituents from eluting into the solvent in the upper layer forming coating liquid, and there is an advantage that the solvent used in the upper layer forming coating liquid is not limited. Because. Therefore, many layers can be laminated by adopting such a method.

The weight average molecular weight of the material contained in the lower layer is preferably 100,000 or more, more preferably 300,000 or more, most preferably 500,000 or more, and preferably 5 million or less, more preferably 3 million or less. This is because if the weight average molecular weight of the material contained in the lower layer is too small, the material contained in the lower layer may be dissolved in the solvent in the upper layer forming coating solution. On the contrary, if the weight average molecular weight of the material contained in the lower layer is too large, the viscosity of the lower layer forming coating solution increases, and it may be difficult to form a uniform coating film.
The method for measuring the weight average molecular weight is the same as that described above.

  The lower layer may contain an insulating resin material. This is because the solvent resistance of the lower layer can be improved and the film strength can be increased. Note that the insulating resin material is the same as that described in the section of the photoelectric conversion layer, and a description thereof is omitted here.

  Furthermore, when a plurality of photoelectric conversion layers and organic semiconductor layers are laminated, a method using a difference in solubility in a solvent may be partially used together with the above method.

When an organic semiconductor layer is formed by a coating method, an organic semiconductor material is dispersed in a solvent to prepare an organic semiconductor layer forming coating solution, and the organic semiconductor layer forming coating solution is applied to apply the organic semiconductor layer. A layer can be formed.
The solvent used in the organic semiconductor layer forming coating solution is not particularly limited as long as the organic semiconductor material can be dispersed.
Examples of the coating method of the organic semiconductor layer forming coating liquid include a die coating method, a spin coating method, a dip coating method, a roll coating method, a bead coating method, a spray coating method, a bar coating method, a gravure coating method, an inkjet method, Examples thereof include a screen printing method and an offset printing method. Among these, a spin coating method or a die coating method is preferably used. This is because these methods can form the organic semiconductor layer with high accuracy so as to have a predetermined film thickness.

6). Hole extraction layer In the present invention, a hole extraction layer may be formed between the photoelectric conversion layer or the organic semiconductor layer and the anode. When the first electrode layer is an anode, a hole extraction layer is formed between the photoelectric conversion layer or organic semiconductor layer and the first electrode layer, and when the second electrode layer is an anode, the photoelectric conversion layer Alternatively, a hole extraction layer is formed between the organic semiconductor layer and the second electrode layer.

  The hole extraction layer is a layer provided so that holes can be easily extracted from the photoelectric conversion layer or the organic semiconductor layer to the anode. Thereby, since the hole extraction efficiency from the photoelectric conversion layer or the organic semiconductor layer to the anode is increased, the photoelectric conversion efficiency can be improved.

The material used for such a hole extraction layer is not particularly limited as long as it is a material that stabilizes extraction of holes from the photoelectric conversion layer or the organic semiconductor layer to the anode. Specifically, doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, conductive organic compounds such as 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.
Among these, polyethylenedioxythiophene (PEDOT) and triphenyldiamine (TPD) are particularly preferably used.

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

7). Electron Extraction Layer In the present invention, an electron extraction layer may be formed between the photoelectric conversion layer or organic semiconductor layer and the cathode. When the second electrode layer is a cathode, an electron extraction layer is formed between the photoelectric conversion layer or organic semiconductor layer and the second electrode layer, and when the first electrode layer is a cathode, the photoelectric conversion layer or An electron extraction layer is formed between the organic semiconductor layer and the first electrode layer.

  The electron extraction layer is a layer provided so that electrons can be easily extracted from the photoelectric conversion layer or the organic semiconductor layer to the cathode. As a result, the efficiency of extracting electrons from the photoelectric conversion layer or the organic semiconductor layer to the cathode can be increased, so that the photoelectric conversion efficiency can be improved.

  The 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 or the organic semiconductor layer to the cathode. Specifically, doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, conductive organic compounds such as 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 bathocuproin (BCP) or bathophenantrone (Bphen) and metal doped layers such as Li, Cs, Ba, Sr.

8). Other constituent members The organic thin-film solar cell of the present invention may have constituent members to be described later as needed in addition to the constituent members described above. For example, the organic thin film solar cell of the present invention includes a protective sheet, a filler layer, a barrier layer, a protective hard coat layer, a strength support layer, an antifouling layer, a high light reflection layer, a light containment layer, an ultraviolet / infrared shielding layer, a sealing You may have functional layers, such as a material layer. In addition, an adhesive layer may be formed between the functional layers depending on the layer configuration.

(I) Protective sheet In this invention, the protective sheet may be formed on the 2nd electrode layer. A protective sheet is a layer provided in order to protect the organic thin-film solar cell of this invention from the external environment.

  Examples of the material used for the protective sheet include a metal plate or metal foil such as aluminum, a fluorine resin sheet, a cyclic polyolefin resin sheet, a polycarbonate resin sheet, a poly (meth) acrylic resin sheet, a polyamide resin sheet, and a polyester. And 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, and more preferably in the range of 50 μm to 200 μm.

  Further, the protective sheet may have a barrier property as described in the section of the 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.

(Ii) Filler layer In the present invention, a filler layer may be formed between the second electrode layer and the protective sheet. A filler layer is a layer provided in order to adhere the back surface side of an organic thin film solar cell, ie, a 2nd electrode layer, and the said protective sheet, and to seal an organic thin film solar cell.

  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.

(Iii) Barrier layer In the present invention, 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 the present invention 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 has an oxygen permeability of 5 cc / m ² / day / atm or less, preferably 0.1 cc / m ² / day / atm or less. On the other hand, the lower limit of the oxygen transmission rate is set to 5.0 × 10 ⁻³ cc / m ² / day / atm from the accuracy of the measuring apparatus. The oxygen permeability is a value measured under conditions of 23 ° C. and 90% Rh using an oxygen gas permeability measuring device (manufactured by MOCON, OX-TRAN 2/21).
Further, the water vapor permeability of the barrier layer is 5 g / m ² / day or less under the conditions of 37.8 ° C. and 100% Rh, and preferably 0.01 g / m ² / day or less. Furthermore, under the conditions of 40 ° C. and 90% Rh, the water vapor transmission rate is preferably 1 g / m ² / day or less, and the lower limit of the water vapor transmission rate is 5.0 × 10 ⁻³ g / ^d from the accuracy of the measuring apparatus. Let m ² / day. The water vapor transmission rate is a value measured using a water vapor transmission rate measurement device (manufactured by MOCON, PERMATRAN-W 3/33).

The material for forming the barrier layer is not particularly limited as long as the above-described barrier property can be obtained, and examples thereof include inorganic oxides, metals, and sol-gel materials. Specifically, as the inorganic oxide, silicon oxide (SiO _x ), aluminum oxide (Al _n O _m ), titanium oxide (TiO ₂ ), yttrium oxide, boron oxide (B ₂ O ₃ ), calcium oxide (CaO) ), Silicon oxynitride carbide (SiO _x N _y C _z ), etc., examples of the metal include Ti, Al, Mg, Zr, etc., and examples of the sol-gel material include siloxane-based sol-gel materials. These materials may be used alone or in combination of two or more.

The thickness of the barrier layer is appropriately selected depending on the type of material used and the like, but is preferably in the range of 10 nm to 1000 nm. If the film thickness is smaller than the above range, sufficient barrier properties may not be obtained. If the film thickness is larger than the above range, it takes a long time for film formation.
In addition, the barrier layer may be a single layer or a stack of a plurality of layers. In the case of laminating a plurality of layers, they may be directly laminated or bonded together.

  Examples of the method for forming the barrier layer include vapor deposition methods such as a PVD method and a CVD method such as a sputtering method and an ion plating method, a roll coating method, and a spin coating method. Moreover, you may combine these methods.

Furthermore, the barrier layer is not particularly limited as long as it has the above-described barrier property, but it is preferable to have a vapor deposition layer formed by a vapor deposition method because of its high barrier property.
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 the PVD method is preferable from the viewpoint of manufacturing efficiency and cost. . Examples of the PVD method 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. Examples of the vacuum deposition method 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.

In addition, 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, among which silicon oxide is preferable. This is because the layer made of silicon oxide has high barrier properties and transparency.

  The thickness of the vapor-deposited layer varies depending on the type and configuration of the material used and is appropriately selected, but is preferably in the range of 5 nm to 1000 nm, particularly 10 nm to 500 nm. This is because if the thickness of the deposited layer is thinner than the above range, it may be difficult to obtain a uniform layer, and the barrier property may not be obtained. Moreover, when the thickness of the vapor deposition layer is thicker than the above range, the barrier property may be remarkably impaired due to a crack in the vapor deposition layer due to an external factor such as pulling after film formation. . Moreover, it takes time to form and productivity is also lowered.

An anchor layer may be formed as a base layer for the barrier layer. This is because the barrier properties and weather resistance can be improved. Examples of the material for forming the anchor layer include an adhesive resin, an inorganic oxide, an organic oxide, and a metal.
Examples of the method for forming the anchor layer include PVD methods such as sputtering and ion plating, CVD, roll coating, and spin coating. Moreover, you may combine these methods. Of these, in-line coating during film formation is preferred. This is because it is excellent in mass productivity and can improve the adhesion of the anchor layer.

(Iv) Protective hard coat layer In the present invention, a protective hard coat layer may be formed on the outermost surface of the organic thin film solar cell. The protective hard coat layer has ultraviolet shielding properties and weather resistance, and protects the organic thin film solar cell from the external environment, and thus protects the photoelectric conversion layer, the organic semiconductor layer, etc., and the organic material contained in these layers It is a layer provided in order to prevent deterioration.

The material for forming the protective hard coat layer is not particularly limited as long as it has ultraviolet shielding properties and weather resistance. For example, acrylic resin, fluorine resin, silicon resin, melamine resin, polyester resin And polycarbonate resins. These resins may be used alone or in combination of two or more.
Moreover, you may add a light resistance additive to the said resin. Examples of the light-resistant additive include a light stabilizer (HALS) and an ultraviolet absorber (UVA).

  The thickness of the protective hard coat layer is preferably in the range of 0.5 μm to 20 μm. If the film thickness is thinner than the above range, the ultraviolet shielding property and weather resistance may be insufficient, and if the film thickness is thicker than the above range, the coating process becomes difficult and the mass productivity may be inferior. .

  Examples of the method for forming the protective hard coat layer include PVD methods such as sputtering and ion plating, CVD, roll coating, and spin coating. Moreover, you may combine these methods. Of these, the roll coating method is preferably used. This is because the roll coating method is excellent in mass productivity and can form a protective hard coat layer having excellent ultraviolet shielding and weather resistance.

Further, an anchor layer may be formed as a base layer of the protective hard coat layer. This is because the weather resistance can be increased.
Examples of the method for forming the anchor layer include PVD methods such as sputtering and ion plating, CVD, roll coating, and spin coating. Moreover, you may combine these methods. Of these, in-line coating during film formation is preferred. This is because it is excellent in mass productivity and can improve the adhesion of the anchor layer.

(V) Strength Support Layer In the present invention, a strength support layer may be formed inside the protective hard coat layer. The strength support layer may be formed at any position as long as it is inside the protective hard coat layer, but is preferably provided between the functional layers. Moreover, the function of the strength support layer may be imparted to the substrate itself.

The strength support layer is excellent in heat resistance, heat and humidity resistance, hydrolysis resistance, and transparency.
As heat resistance, when a heat resistance test is performed for 72 hours at a temperature of 100 ° C., it is preferable that the rate of decrease in power generation efficiency after the heat resistance test before the heat resistance test is within 10%. Furthermore, when the heat resistance test held at a temperature of 125 ° C. for 72 hours is performed, the rate of decrease in power generation efficiency after the heat resistance test with respect to before the heat resistance test is preferably within 10%. The heat resistance test shall comply with JIS C60068-2-2.
Moisture and heat resistance is determined when a moisture and heat resistance test is performed in which the organic thin-film solar cell is maintained for 96 hours or more in a constant temperature and humidity chamber environment adjusted to a temperature of 40 ° C. or higher and a humidity of 90% RH or higher in advance. It is preferable that the reduction rate of the power generation efficiency after the wet heat resistance test before the test is within 10%. Furthermore, when a moisture and heat resistance test for holding an organic thin film solar cell for 500 hours or more in a constant temperature and humidity chamber environment adjusted to a temperature of 80 ° C. or higher and a humidity of 80% RH or higher in advance is performed. The rate of decrease in power generation efficiency after the wet heat resistance test is preferably within 10%. In addition, according to JIS C60068-2-3, the moisture and heat resistance test shall be evaluated using an environmental testing machine “HIFLEX α series FX424P” manufactured by Enomoto Kasei Co., Ltd.
As the transparency, the total light transmittance is preferably 70% or more, more preferably 85% or more. The total light transmittance is a value measured in the visible light region using an SM color computer (model number: SM-C) manufactured by Suga Test Instruments Co., Ltd.
This is because the organic thin-film solar cell is required to have excellent heat resistance, moisture heat resistance, and permeability.

  Examples of the material for forming the strength support layer include silicone resins, acrylic resins, cyclic polyolefin resins, syndiotactic polystyrene (SPS) resins, polyamide (PA) resins, polyacetal (POM) resins, and modified polyphenylenes. Ether (mPPE) resin, polyphenylene sulfide (PPS) resin, fluorine resin (polytetrafluoroethylene (PTEE), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), fluorine Ethylene propylene (FEP)), polyether ether ketone (PEEK) resin, liquid crystal polymer (LCP), polyether nitrile (PEN) resin, polysulfone (PSF) resin, polyether sulfone (PES) resin, poly Relate (PAR) resin, polyamideimide (PAI) resin, polyimide (PI) resin, polyethylene terephthalate (PEN), polypropylene (PP), acrylonitrile / butadiene / styrene copolymer (ABS), biaxially oriented polystyrene ( OPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyester (PE), polyacrylonitrile (PAN) and the like. Also, weathering grades of these resins can be used. Further, these resins may be further reinforced by combining with glass fiber or the like.

  The thickness of the strength support layer is preferably in the range of 10 μm to 800 μm, and particularly preferably in the range of 100 μm to 400 μm. This is because if the film thickness is thinner than the above range, sufficient strength may not be obtained, and if the film thickness is thicker than the above range, processing in the manufacturing process may be difficult.

(Vi) Adhesive layer In the present invention, an adhesive layer may be formed between the respective layers according to the layer structure.
The adhesive layer is excellent in heat resistance and wet heat resistance.
As heat resistance, when a heat resistance test is performed for 72 hours at a temperature of 100 ° C., it is preferable that the rate of decrease in power generation efficiency after the heat resistance test before the heat resistance test is within 10%. Furthermore, when the heat resistance test held at a temperature of 125 ° C. for 72 hours is performed, the rate of decrease in power generation efficiency after the heat resistance test with respect to before the heat resistance test is preferably within 10%.
Moisture and heat resistance is determined when a moisture and heat resistance test is performed in which the organic thin-film solar cell is maintained for 96 hours or more in a constant temperature and humidity chamber environment adjusted to a temperature of 40 ° C. or higher and a humidity of 90% RH or higher in advance. It is preferable that the reduction rate of the power generation efficiency after the wet heat resistance test before the test is within 10%. Furthermore, when a moisture and heat resistance test for holding an organic thin film solar cell for 500 hours or more in a constant temperature and humidity chamber environment adjusted to a temperature of 80 ° C. or higher and a humidity of 80% RH or higher in advance is performed. The rate of decrease in power generation efficiency after the wet heat resistance test is preferably within 10%.
This is because the organic thin film solar cell is required to have excellent heat resistance and heat and humidity resistance. The heat resistance test and the moist heat resistance test are the same as those described above.

  Examples of the material for forming the adhesive layer include silicone resins, rubber resins, acrylic resins, polyester urethane resins, vinyl acetate resins, polyvinyl alcohol resins, phenol resins, melamine resins, hot melt resins, polyurethanes. Resin, polyolefin resin, epoxy resin, styrene butadiene resin and the like. Also, weathering grades of these resins can be used.

  The film thickness of the adhesive layer is preferably in the range of 1 μm to 200 μm, particularly in the range of 2 μm to 20 μm. This is because if the film thickness is thinner than the above range, the strength may be inferior, and if the film thickness is thicker than the above range, processing in the manufacturing process may be difficult.

  Examples of the method for forming the adhesive layer include a dry laminating method and a melt extrusion laminating method. Moreover, you may laminate | stack through an adhesive sheet. Preferably, a dry lamination method by roll coating is used. This is because this method is excellent in mass productivity and good adhesion can be obtained.

  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.
[Example 1]
(Formation of transparent electrode layer)
A SiO ₂ thin film is formed on the surface of a polyethylene naphthalate (PEN) film substrate (thickness: 125 μm) by the PVD method, and an ITO film (film thickness: 150 nm, sheet resistance: 20Ω / sheet) as a transparent electrode on the upper surface of the SiO ₂ thin film. □) reactive ion plating method using a pressure gradient plasma gun (power: 3.7 kW, oxygen partial pressure: 73%, film forming pressure: 0.3 Pa, film forming rate: 150 nm / min, substrate temperature: (20 ° C.) and then patterned by etching. Next, the substrate on which the ITO pattern was formed was cleaned using acetone, a substrate cleaning solution, and IPA.

(Formation of hole extraction layer)
A coating solution for forming a hole extraction layer (conductive polymer paste; aqueous dispersion of poly (3,4) -ethylenedioxythiophene) is applied by spin coating onto the substrate on which the ITO pattern is formed. And dried for 30 minutes at 150 ° C. to form a hole extraction layer (film thickness: 100 nm).

(Formation of photoelectric conversion layer)
A 0.3 wt% chloroform solution of fluorene-thiophene copolymer (Poly [(9,9-dihexylfluorenyl-2,7-diyl) -co- (bithiophene)]) and fullerene (PCBM; 1- (3-methoxycarbonyl) A 0.1 wt% chloroform solution of propyl-1-phenyl (6,6) -C ₆₀ ) was mixed at a weight ratio of 1: 1 to prepare a photoelectric conversion layer forming coating solution.
This photoelectric conversion layer forming coating solution was applied onto the hole extraction layer by a spin coating method and dried at 110 ° C. for 10 minutes to form a photoelectric conversion layer (film thickness: 100 nm).
The Stokes shift of the fluorene-thiophene copolymer (Poly [(9,9-dihexylfluorenyl-2,7-diyl) -co- (bithiophene)]) used is shown in Table 1 below.

(Formation of metal electrodes)
Next, a Ca thin film (film thickness: 100 nm) and an Al thin film (film thickness: 500 nm) were sequentially formed on the photoelectric conversion layer by a vapor deposition method to obtain a metal electrode.
Finally, sealing was performed from above the metal electrode with a sealing glass material to produce a bulk heterojunction type organic thin film solar cell.

[Example 2]
An organic thin film solar cell was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed as follows.

(Formation of photoelectric conversion layer (first layer))
As the thiophene-phenylene vinylene copolymer, one represented by the following formula was used. The Stokes shift of this thiophene-phenylene vinylene copolymer was 0.5 eV.

0.3 wt% chloroform solution of thiophene-phenylene vinylene copolymer and polyphenylene vinylene (MDMO-PPV; poly (2-methoxy-5- (3 ′, 7′-dimethyloctyloxy) -1--4-phenylene vinylene) A 0.3 wt% chloroform solution of (weight average molecular weight 1 million) and a 0.1 wt% chloroform solution of fullerene (PCBM; 1- (3-methoxycarbonyl) propyl-1-phenyl (6,6) -C ₆₀ ) Were mixed at a weight ratio of 3: 5: 2 to prepare a coating liquid for forming the first photoelectric conversion layer.
This photoelectric conversion layer forming coating solution was applied onto the hole extraction layer by a spin coating method and dried at 110 ° C. for 10 minutes to form a first photoelectric conversion layer (film thickness: 100 nm).

(Formation of photoelectric conversion layer (second layer))
As the phenylene ethynylene-thiophene copolymer, one represented by the following formula was used. The Stokes shift of this phenylene ethynylene-thiophene copolymer was 0.6 eV.

Phenyleneethynylene - and 0.3 wt% chloroform solution of thiophene copolymer, fullerene; 0.1 wt% chloroform solution of (PCBM 1- (3- methoxycarbonyl) propyl-1-phenyl (6,6) _{-C 60)} Were mixed at a weight ratio of 3: 1 to prepare a coating solution for forming a second photoelectric conversion layer.
This photoelectric conversion layer forming coating solution is applied onto the first photoelectric conversion layer by spin coating, and dried at 110 ° C. for 10 minutes to form a second photoelectric conversion layer (film thickness: 100 nm). did.

It is explanatory drawing of Stokes shift. It is a schematic sectional drawing which shows an example of the organic thin film solar cell of this invention. It is explanatory drawing for demonstrating an organic thin film solar cell. 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. 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 ... Substrate 2 ... 1st electrode layer 3, 3a, 3b ... Photoelectric conversion layer 4 ... 2nd electrode layer 10 ... Organic thin film solar cell 11 ... Hole transport layer 12 ... Electron transport layer 13 ... Electron hole transport layer

Claims (3)

A photoelectric conversion material comprising a conductive polymer material having a Stokes shift of 0.2 eV or more, which is a copolymer represented by any one of the following chemical formulas (1) to ( 2 ).

  A substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer containing the photoelectric conversion material according to claim 1 formed on the first electrode layer, and formed on the photoelectric conversion layer An organic thin-film solar cell.   The organic thin film solar cell according to claim 2, wherein the photoelectric conversion layer is a coating film.

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