JP5381619B2 - Organic photoelectric conversion element, solar cell using the same, and optical sensor array - Google Patents

Description

  The present invention relates to an organic photoelectric conversion element, a solar cell, and an optical sensor array. More specifically, the present invention relates to a bulk heterojunction type organic photoelectric conversion element, a solar cell using the organic photoelectric conversion element, and an optical array sensor.

  Bulk heterojunction type organic solar cells (organic photoelectric conversion elements) are characterized by efficient charge separation before quenching excitons formed by light absorption. However, the generated carriers are organic donor materials or organic acceptor materials. Since each phase-separates and moves in the domain structure connected to the electrode by diffusion, the bipolar carriers are recombined on the electrode, causing a loss factor in energy conversion efficiency.

  In order to deal with such problems, attempts have been made to increase the carrier separation ability of holes and electrons by using a structure having a charge transport layer between the power generation layer and the electrode. For example, a method of forming a conjugated polymer layer having a band gap of 1.8 eV or more between the photoelectric conversion layer and the electrode (for example, see Patent Document 1), or a method of forming a heat conversion type benzoporphyrin layer (for example, Patent Document) 2), a method of forming a metal oxide layer by applying a metal alkoxide solution and hydrolyzing it in the air (see, for example, Patent Documents 3 and 4).

  The problem of the above-described conventional configuration will be described with reference to FIG. FIG. 1A shows a conventional element configuration, and FIG. 1B shows its energy diagram. The photoelectric conversion element 10 in FIG. 1 is a bulk heterojunction type power generation in which a hole transport layer 102 is stacked on a first electrode 101 (positive electrode) and a p-type semiconductor material 103a and an n-type semiconductor material 103b are mixed. A structure in which the layer 103, the electron transport layer 104, and the second electrode 105 (cathode) are stacked is generally used.

  Here, the power generation layer 103 has a domain structure in which 103a and 103b are phase-separated, and each domain is actually in contact with both sides, so that the backflow of electrons and holes is suppressed. Attempts have been made to increase the separation between electrons and holes by providing the hole transport layer 102 or the electron transport layer 104. In the conventional technology described above, the LUMO (conduction band / CB) level of the hole transport layer 102 is controlled to prevent electrons from flowing back from the power generation layer. In addition, the HOMO (valence band / VB) level of the electron transport layer 104 is controlled to prevent holes from flowing backward from the power generation layer.

  However, in fact, in such a configuration, since the hole transport layer 102 and the electron transport layer 104 have various internal defect levels (106 or 107 in FIG. 1b), the reverse carrier passes through this process. Is transported to the electrode and recombined, resulting in power generation loss.

  Therefore, there is a need for a technique that increases the number of carriers recovered by an electrode and efficiently develops photoelectric conversion characteristics by efficiently separating electrons and holes from the above-described problems.

  However, in any of the above-described solutions, the separation power of carriers (holes and electrons) generated by light absorption in the power generation layer is not sufficient, and recombination of free carriers on the electrode can be sufficiently suppressed. As a result, the photoelectric conversion characteristics could not be improved, and further, sufficient performance was not obtained in terms of element durability during light irradiation.

  For this purpose, a conductive polymer such as PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrenesulfonic acid) and a polyanion polymer layer were introduced as a buffer layer on the ITO side. In such a case, there is a problem that the acid in the layer diffuses to the cathode layer and promotes deterioration due to oxidation of the element (see, for example, Non-Patent Document 1).

WO2004 / 017422 pamphlet JP 2008-135622 A WO2007 / 011741 pamphlet JP 2007-273939 A

Proceedings of the Society of Polymer Science, vol. 158, No. 2, pages 5654-5655, 2009

  An object of the present invention is to provide an organic photoelectric conversion element having high photoelectric conversion efficiency and durability, a solar cell using the same, and an optical sensor array.

  The above object of the present invention can be achieved by the following configuration.

  1. An organic photoelectric conversion element having a structure in which at least a hole transport layer and a power generation layer are sequentially laminated between an anode and a cathode, wherein the hole transport layer comprises a π-conjugated conductive polymer and a poly anion. And the power generation layer is a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, and further includes the hole transport layer and the power generation layer. An organic photoelectric conversion element comprising a compound having an amino group represented by the following general formula (1) in between.

(In the formula, R ₁ represents a hydrogen atom or an alkyl group, and R ₂ represents a hydrogen atom or a hydrocarbon group.)
2. 2. The organic photoelectric conversion device as described in 1 above, wherein the π-conjugated conductive polymer has a repeating unit represented by the following general formula (2).

(In the formula, A ₁ represents an alkylene group having 1 to 4 carbon atoms which may have a substituent, and Q represents an oxygen atom or a sulfur atom)
3. The π-conjugated conductive polymer having a partial structure represented by the general formula (2) is a polymer or copolymer of poly (3,4-ethylenedioxy) thiophene, 2. The organic photoelectric conversion element according to 2.

  4). 4. The organic photoelectric conversion device according to any one of 1 to 3, wherein the poly anion is represented by the following general formula (3).

(In the formula, R ₃ represents a hydrogen atom or a methyl group, and A ₂ is a simple bond, a substituted or unsubstituted C ₁ -C ₃₀ alkyl group; a substituted or unsubstituted C ₁ -C ₃₀ heteroalkyl. group; an alkoxy group substituted or unsubstituted _C 1 _{-C 30;} substituted or unsubstituted _C 1 _{-C 30} heteroalkoxy group; an aryl group substituted or unsubstituted _C 6 _{-C 30;} a substituted or unsubstituted A C ₆ -C ₃₀ arylalkyl group; a substituted or unsubstituted C ₆ -C ₃₀ aryloxy group; a substituted or unsubstituted C ₂ -C ₃₀ heteroaryl group; a substituted or unsubstituted C ₂ -C ₃₀ heteroarylalkyl group; a substituted or unsubstituted _C 2 _{-C 30} heteroaryloxy group, substituted or cycloalkyl group unsubstituted _C 5 _{-C 20,} substituted or unsubstituted _C 2 ~ C ₃₀ heterocycloalkyl group; substituted or unsubstituted C ₁ -C ₃₀ alkyl ester group; substituted or unsubstituted C ₁ -C ₃₀ heteroalkyl ester group; substituted or unsubstituted C ₆ -C ₃₀ aryl ester group; and it is selected from the group consisting of heteroaryl ester group of C ₂ -C ₃₀ substituted or unsubstituted, B represents a group containing an ionic group or an ionic group, this time, the ionic group An anion and a cation, wherein the anion is selected from SO ₃ ⁻ , COO ⁻ , and the cation is Na ⁺ , K ⁺ , Li ⁺ , Mg ⁺² , Zn ⁺² , and Al _+, metal ion or ^H is selected from ^{_{+3 NH 3 +, CH 3 (}} -CH 2 -) n O + (n is an integer of 1 to 50) Izu organic ion selected from It is how.)
5. 5. The organic photoelectric conversion element as described in 4 above, wherein the poly anion has a sulfonic acid group.

  6). 6. The organic photoelectric conversion element as described in 5 above, wherein the poly anion is polystyrene sulfonic acid.

  7). The layer containing the compound having an amino group represented by the general formula (1) is formed with a film thickness of 0.5 to 10 nm, according to any one of the above 1 to 6, Organic photoelectric conversion element.

  8). 8. The organic photoelectric conversion device as described in any one of 1 to 7 above, wherein the compound having an amino group represented by the general formula (1) is a thiophene oligomer.

  9. 9. The organic photoelectric conversion device according to 8, wherein the thiophene oligomer has a molecular weight of 400 or more.

  10. 10. The organic photoelectric conversion device according to 9, wherein the thiophene oligomer has a molecular weight of 600 or more.

  11. After the hole transport layer is formed and the hole transport layer is formed on the hole transport layer, the layer containing the compound having an amino group and the power generation layer are compounds having the amino group. 11. The organic photoelectric conversion element as described in any one of 1 to 10 above, which is formed by applying a solution containing the p-type semiconductor material and the n-type semiconductor material.

  12 It consists of the organic photoelectric conversion element of any one of said 1-11, The solar cell characterized by the above-mentioned.

  13. The organic photoelectric conversion element of any one of said 1-11 is arrange | positioned at array form, The optical sensor array characterized by the above-mentioned.

  According to the present invention, an organic photoelectric conversion element having high photoelectric conversion efficiency and durability, a solar cell using the organic photoelectric conversion element, and an optical sensor array can be provided.

It is the figure which showed the tomographic structure and energy diagram of the organic photoelectric conversion element (organic solar cell element) in a prior art. It is sectional drawing which shows an example of the solar cell which consists of a bulk heterojunction type organic photoelectric conversion element of this invention. It is a figure which shows the structure of an optical sensor array.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  As a result of intensive studies on the above problems, the present inventors have found that the hole transport layer is formed of a conductive polymer including a π-conjugated conductive polymer and a polyanion, and the power generation layer is a p-type semiconductor. In the organic photoelectric conversion element which is a bulk heterojunction layer in which a material and an n-type semiconductor material are mixed, a compound having an amino group represented by the general formula (1) is included between the hole transport layer and the cathode. Thus, it has been found that high photoelectric conversion efficiency and durability can be expressed.

  Hereinafter, details of each component according to the present invention will be sequentially described.

[Compound having a partial structure represented by general formula (1) to general formula (3)]
First, the compound which has an amino group represented by General formula (1) in this invention is demonstrated.

In the general formula (1), in the formula, R ₁ represents a hydrogen atom or an alkyl group, and R ₂ represents a hydrogen atom or a hydrocarbon group. Examples of the alkyl group include a methyl group, an ethyl group, and an iso-propyl group. Examples of the hydrocarbon group include an alkyl group (such as a methyl group, an ethyl group, and an iso-propyl group), a cycloalkyl group (a cyclopropyl group, A cyclohexyl group), an aryl group (phenyl group, etc.), and the like. As the compound represented by the general formula (1), known conjugated polymer compounds, aromatic oligomer compounds, condensed polycyclic aromatic compounds and the like are preferably used.

  As the conjugated polymer, for example, a polythiophene such as poly-3-hexylthiophene (P3HT) and an oligomer thereof, or a technical group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Polythiophene, Nature Material, (2006) vol. 5, p328, polythiophene-thienothiophene copolymer, polythiophene-diketopyrrolopyrrole copolymer described in WO08 / 000664, Adv. Mater. , 2007, p4160, a polythiophene-thiazolothiazole copolymer, Nature Mat. vol. 6 (2007), p497 described in PCPDTBT, etc., polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, Examples thereof include polymer materials such as σ-conjugated polymers such as polysilane and polygermane.

  In addition, oligomeric materials instead of polymer materials include thiophene hexamer α-sexual thiophene α, ω-dihexyl-α-sexual thiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

  Examples of aromatic oligomer compounds include thiophene oligomers, pyrrole oligomers, polyaniline, polyphenylene and oligomers thereof, phenylene vinylene oligomers, and thienylene vinylenes. In the present invention, the oligomer represents a compound having a molecular weight of 3000 or less.

  As the condensed polycyclic aromatic compound, for example, anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, sarkham anthracene, bisanthene, zestrene, heptazelene, Compounds such as pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF)- Examples include perchloric acid complexes, and derivatives and precursors thereof.

  As the compound having an amino group represented by the general formula (1), a thiophene oligomer is preferably used, more preferably a thiophene oligomer having a molecular weight of 400 or more, and further preferably a thiophene oligomer having a molecular weight of 600 or more. Is used.

  Hereinafter, although the example of the compound which has the partial structure represented by General formula (1) based on this invention is given, this invention is not limited to these.

  In addition, these compounds are disclosed in Japanese Patent Application Publication Nos. 2004-137502, 2005-294588, 2006-117672, 2007-59558, J. Pat. Heterocyclic Chem. , 33, 173-178, 1996, etc., can be synthesized by a known method.

  Next, the conductive polymer in the present invention will be described.

  The conductive polymer in the present invention includes a π-conjugated conductive polymer and a polyanion, a main chain having a cationic π-conjugated conductive polymer, and a polyanion as a counter anion. Has a body structure.

  Next, the π-conjugated conductive polymer in the present invention will be described.

  The π-conjugated conductive polymer of the present invention represents a polymer substance that has metallic or semiconducting conductivity and whose main chain is a π-conjugated skeleton. In the present invention, “conductive” refers to a state in which electricity flows, and the sheet resistance measured by a method in accordance with JIS K 7194 “Resistivity Test Method by Conductive Plastic Four-Probe Method” is 10 ×. It means lower than 8Ω / □. Examples of the π-conjugated conductive polymer include aromatic hydrocarbon polymers and heterocyclic compound polymers. Specifically, polymers of thiophene and its derivatives (eg, poly-3-alkylthiophene, polyethylenedioxythiophene), polymers of pyrrole and its derivatives (eg, polypyrrole), polymers of aniline and its derivatives (eg, polyaniline) ), Polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, polyacetylene and its derivatives, polyphenylene and its derivatives, polyfluorene and its derivatives, polyisothionaphthene and its derivatives. Of these, polythiophenes, polypyrroles, and polyanilines are preferable, and polyanilines and polythiophenes are more preferable.

  These π-conjugated conductive polymers can obtain sufficient conductivity and compatibility with the binder resin even if they are not substituted, but in order to further improve conductivity and compatibility, an alkyl group, It is preferable to introduce a functional group such as a carboxyl group, a sulfo group, an alkoxy group, or a hydroxy group into the organic polymer.

  Specific examples of the organic polymer include polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), poly (3-butyl Pyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3 -Carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly (3-methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxypyrrole) , Poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-methyl-4-he Siloxypyrrole), poly (thiophene), poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), poly (3-hexylthiophene), Poly (3-heptylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), poly (3-octadecylthiophene), poly (3-bromothiophene), poly ( 3-chlorothiophene), poly (3-iodothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), Poly (3-hydroxythiophene), poly (3-methoxythiophene), poly (3-ethoxy Thiophene), poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3-heptyloxythiophene), poly (3-octyloxythiophene), poly (3-decyloxythiophene), poly (3 -Dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3-methyl-4-methoxythiophene), poly (3,4-ethylenedioxythiophene), poly (3-methyl-4-ethoxythiophene) , Poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene), polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), Examples include poly (2-aniline sulfonic acid), poly (3-aniline sulfonic acid), and the like.

  Among these, in particular, an organic polymer that repeatedly includes the structural unit represented by the general formula (2) is preferable, and an embodiment in which the conductive compound according to the present invention repeatedly includes the structural unit represented by the general formula (2). This is a preferred embodiment.

(Structural unit represented by general formula (2))
In General Formula (2), A ₁ represents an alkylene group having 1 to 4 carbon atoms which may have a substituent, and Q represents an oxygen atom or a sulfur atom.

  The organic polymer containing the structural unit represented by the general formula (2) may repeatedly contain the same structural unit, or may contain two or more different structural units repeatedly.

  Among these, polyethylenedioxythiophene (Poly (3,4-ethylenediothiophene); PEDOT) is more preferable.

  The synthesis of the thiophene compound that is the structural unit represented by the general formula (2) can be performed, for example, as follows.

  In the general formula (2), 3,4-di-substituted thiophene, in which Q is an oxygen atom, comprises an alkali metal salt of 3,4-dihydroxythiophene-2,5-dicarboxylic acid ester and a suitable alkylene-vic-dihalide. And then free 3,4- (alkylene-vic-dioxy-) thiophene-2,5-dicarboxylic acid can be obtained by decarboxylation (see, for example, Tetrahedron, 1967, 23, 2437-2441 and J. Am. Am. Chem. Soc., 1945, 67, 2217-2218).

  Next, the poly anion in the present invention will be described.

  Examples of the polyanion in the present invention include polymeric carboxylic acids such as polyacrylic acid, polymethacrylic acid and polymaleic acid, and polymeric sulfonic acids such as polystyrene sulfonic acid and polyvinyl sulfonic acid. Further, polyanions such as these polymeric carboxylic acids and polymeric sulfonic acids are homopolymers polymerized from only one kind of anionic monomer selected from vinyl carboxylic acids or vinyl sulfonic acids. Or a copolymer comprising a plurality of types of anionic monomers, and further a copolymer of an anionic monomer and other non-anionic monomers copolymerizable with the monomer. There may be. Examples of other non-anionic monomers copolymerizable with anionic monomers include non-anionic acrylic acids and styrene. When the polyanion is a copolymer, it is sufficient that at least one kind of anionic monomer is contained as a copolymer component, and a plurality of kinds of anionic monomers, or a plurality of kinds of other copolymerization monomers are used. It can be used arbitrarily.

  Moreover, the polyanion which has a fluorine (F) in a compound may be sufficient. Specifically, Nafion (manufactured by Aldrich) containing a perfluorosulfo group, Flemion (manufactured by Asahi Glass Co., Ltd.) made of perfluoro vinyl ether containing a carboxylic acid group, and the like can be mentioned.

  In the present invention, the polyanion is preferably represented by the general formula (3).

In the general formula (3), R ₃ represents a hydrogen atom or a methyl group, A ₂ is merely a bond, a substituted or unsubstituted C _{1 to} C ₃₀ alkyl group; a substituted or unsubstituted C _{1 to} C ₃₀ heteroalkyl group; a substituted or unsubstituted _C 1 _{-C 30} alkoxy group of; substituted or unsubstituted _C 6 _{-C 30} aryl group; a substituted or unsubstituted _C 1 _{-C 30} heteroalkoxy groups, substituted or An unsubstituted C ₆ -C ₃₀ arylalkyl group; a substituted or unsubstituted C ₆ -C ₃₀ aryloxy group; a substituted or unsubstituted C ₂ -C ₃₀ heteroaryl group; a substituted or unsubstituted C ₂ cycloalkyl substituted or unsubstituted _C 5 _{-C 20;;} heteroaryloxy group _C 2 _{-C 30} substituted or unsubstituted; heteroarylalkyl group -C ₃₀ substituted or Heterocycloalkyl group of _C 2 _{-C 30} substituted; substituted or unsubstituted alkyl ester group substituted _C 1 _{-C 30,} substituted or hetero alkyl ester group unsubstituted _C 1 _{-C 30;} a substituted or unsubstituted C Selected from the group consisting of _{6 to} C ₃₀ aryl ester groups; and substituted or unsubstituted C _{2 to} C ₃₀ heteroaryl ester groups, and preferably represents a substituted or unsubstituted phenyl group or a simple bond.

B represents an ionic group or a group containing an ionic group, wherein the ionic group is a conjugate of an anion and a cation, and the anion is selected from SO ₃ ⁻ and COO ⁻ , Cations can be metal ions such as Na ⁺ , K ⁺ , Li ⁺ , Mg ⁺² , Zn ⁺² , and Al ⁺³ or H ⁺ , NH ₃ ⁺ , CH ₃ (—CH ₂ —) _n O ⁺ (n is Selected from organic ions such as 1 to 50). Preferred B is a _-SO 3 Na.

The polyanion represented by the general formula (3) is polystyrene sulfonic acid in which A ₂ is phenyl and R ₁ is a hydrogen atom, or A ₂ is a simple bond and polyvinyl sulfonic acid in which R ₁ is a hydrogen atom. Is preferred.

  The synthesis of the polyanion in the present invention can be carried out by bulk, solution, precipitation, suspension or (inverse) emulsion polymerization. A solution polymerization method is preferred for obtaining an appropriate molecular weight.

  As an initiator used for the synthesis | combination of the polyanion in this invention, a peroxide, hydroperoxides, a persulfate, an azo compound, a redox catalyst etc. can be used, for example. A persulfate such as potassium persulfate, sodium persulfate and ammonium persulfate, and an azo compound such as 2,2'-azobisbutyronitrile are preferably used.

  The polymerization solvent used for the synthesis of the polyanion in the present invention is not particularly limited as long as it is inert under the reaction conditions and can dissolve the monomer and the polymer to be formed, but water is preferred. Solution polymerization can be carried out at a total monomer concentration of 1 to 80% by weight, preferably 10 to 60% by weight.

  The polymerization temperature for carrying out the synthesis of the polyanion in the present invention varies depending on the initiator used, but is generally -10 to 250 ° C, preferably 0 to 200 ° C, more preferably 10 to 100 ° C. The starting materials may be introduced first into the solvent, introduced separately into the solvent or together. In some cases, the addition of the free radical initiator dissolved in a suitable solvent can be carried out before, simultaneously with or after the addition of the starting material. In order to avoid interference with the polymerization, the reaction is preferably carried out under reflux or in a protective gas atmosphere, preferably nitrogen gas or argon.

  Examples of the monomer used for the synthesis of the polyanion in the present invention include acrylic acid, methacrylic acid, maleic acid, styryl sulfonic acid, vinyl sulfonic acid and alkali metal salts and ammonium salts thereof. A copolymer may be synthesized using a plurality.

  The molecular weight of the polyanion in the present invention is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 2,000 to 500,000, and still more preferably in the range of 3000 to 100,000. If the molecular weight is less than 1000 or exceeds 2,000,000, it is not preferable because sufficient conductivity cannot be obtained.

  The molecular weight of the polyanion in the present invention can be measured by a conventional method such as gel permeation chromatography or osmotic pressure measurement.

  As the conductive polymer comprising the π-conjugated conductive polymer and the polyanion according to the present invention, a commercially available dispersion may be used. If not commercially available, a synthetic product may be used. As for the synthesis method of these conductive polymers, the case of having a cationic organic polymer having a 3,4-dialkoxythiophene structure, which is an organic polymer having a structural unit represented by the general formula (4), is taken as an example. I will explain.

  It is obtained by oxidative polymerization of 3,4-dialkoxythiophene in a solvent using an oxidizing agent typically used for oxidative polymerization of pyrrole in the presence of the polyanion in the present invention.

  Polythiophene is positively charged by oxidative polymerization, but it is difficult to determine its number and position clearly.

  The synthesis of a conductive polymer comprising a π-conjugated conductive polymer and a polyanion according to the present invention includes a compound which is a structural unit forming a cationic organic polymer with the polyanion in the present invention. In the solvent to be stirred at a predetermined polymerization temperature until the polymerization reaction is completed.

  The mass ratio of the cationic organic polymer to the polyanion in the present invention is not particularly limited as long as the polyanion is rich, but the π-conjugated conductive polymer is preferably 50 or less, more preferably Preferably it is 25 or less, More preferably, it is 10 or less.

  The polymerization time can be between a few minutes and 30 hours depending on the size of the batch, the polymerization temperature and the oxidizing agent. The polymerization time is generally between 30 minutes and 24 hours.

Suitable oxidizing agents are for example described in J. Am. Soc. 85, 454 (1963). Any oxidant suitable for oxidative polymerization of pyrrole. For practical reasons, inexpensive and easy to handle oxidants such as iron (III) salts such as FeCl ₃ , Fe (ClO ₄ ) ₃ , organic acids and iron (III) salts of inorganic acids containing organic residues (eg Fe ₂ (SO ₄ ) ₃ ), or H ₂ O ₂ , K ₂ Cr ₂ O ₇ , alkali persulfate (eg potassium persulfate, sodium persulfate) or ammonium, alkali perborate, potassium permanganate and copper It is preferred to use a salt such as copper tetrafluoroborate. In addition, air and oxygen in the presence of catalytic amounts of metal ions such as iron, cobalt, nickel, molybdenum and vanadium ions can be used as oxidants at any time. The use of persulfates and iron (III) salts of inorganic acids containing organic acids and organic residues has great application advantages because they are not corrosive. Examples of iron (III) salts of inorganic acids containing organic residues are the iron (III) salts of C1-20 alkanol sulfate hemiether, such as the Fe (III) salt of lauryl sulfate. Examples of iron (III) salts of organic acids include: C1-20 alkyl sulfonic acids such as methane or dodecane sulfonic acid; aliphatic C1-20 carboxylic acids such as 2-ethylhexyl carboxylic acid; aliphatic perfluorocarboxylic acids Acids such as trifluoroacetic acid and perfluorooctanoic acid; aliphatic dicarboxylic acids such as oxalic acid and especially aromatic, optionally C1-20-alkyl substituted sulfonic acids such as benzesenesulfonic acid, p-toluenesulfonic acid and It is also possible to use a Fe (III) salt of dodecylbenzenesulfonic acid or a mixture of the above-mentioned Fe (III) salts of organic acids.

  In the oxidative polymerization reaction, for example, the structural unit represented by the general formula (3), which is a preferable structure of the polyanion in the present invention, is 0.25 to 10, preferably 0, per 1 mol of the corresponding thiophene. It is preferable to add in an amount in which 8 to 8 anionic groups are present.

  Theoretically, 2.25 equivalents of oxidizing agent per mole of thiophene are required for the oxidative polymerization of the corresponding thiophene [see, for example, J. Org. Polym. Sci. Part A, Polymer Chemistry, Vol. 26, page 1287 (1988)]. In practice, however, the oxidizing agent is used in some excess, for example in an excess of 0.1 to 2 equivalents per mole of thiophene.

  Organic solvents used for the polymerization are inert under reaction conditions, such as aliphatic alcohols such as methanol, ethanol and propanol; aliphatic ketones such as acetone, methyl ethyl ketone; aliphatic carboxylic acid esters such as ethyl acetate and butyl acetate. Aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane, heptane and cyclohexane; chlorinated hydrocarbons such as dichloromethane and dichloroethane; aliphatic nitriles such as acetonitrile; aliphatic sulfoxides and sulfones such as dimethyl sulfoxide and Sulfolane; aliphatic carboxamides such as methylacetamide and dimethylformamide; aliphatic and aromatic ethers such as diethyl ether and anisole It is. Furthermore, water or a mixture of water and the above organic solvent can also be used as the solvent. Preferably it is water.

  As the amount of the solvent used for the oxidative polymerization, from the viewpoint of dispersibility of the synthesized conductive polymer, the conductive polymer according to the present invention is 0.1 to 80% by mass, preferably 0.5 to 50% by mass. The amount of solvent having a solids content of

  In oxidative polymerization, although it changes with the oxidizing agent to be used and reaction time required, it is generally carried out at -10 to 250 ° C, preferably 0 to 200 ° C, more preferably 10 to 100 ° C.

  The starting materials may be introduced first into the solvent, introduced separately into the solvent or together. In some cases, the addition of the oxidizing agent dissolved in a suitable solvent can be carried out before, simultaneously with or after the addition of the starting materials. In order to avoid interference with the polymerization, the reaction is preferably carried out under reflux or in a protective gas atmosphere, preferably nitrogen gas or argon.

  The conductive polymer according to the present invention may have a structural unit having an anionic group in addition to the structural unit represented by the general formula (1), but 50% (mol) or more of the total anionic group is general. The structural unit represented by the formula (1) is preferable, and 90% or more is particularly preferably the structural unit represented by the general formula (1).

[Organic photoelectric conversion element and solar cell]
FIG. 2 is a cross-sectional view showing an example of a solar cell composed of the bulk heterojunction organic photoelectric conversion element of the present invention. In FIG. 2, a bulk heterojunction type organic photoelectric conversion element 20 includes an anode 202, a hole transport layer 203, an amine compound-containing layer 207, a bulk heterojunction power generation layer 204, and electron transport on one surface of a substrate 201. A layer 205 and a cathode 206 are sequentially stacked.

  The substrate 201 is a member that holds an anode 202, a hole transport layer 203, an amine compound-containing layer 207, a bulk heterojunction power generation layer 204, an electron transport layer 205, and a cathode 206, which are sequentially stacked. In the present embodiment, since light that is photoelectrically converted enters from the substrate 201 side, the substrate 201 can transmit the light that is photoelectrically converted, that is, with respect to the wavelength of the light to be photoelectrically converted. It is a transparent member. As the substrate 201, for example, a glass substrate or a resin substrate is used. The substrate 201 is not essential. For example, the bulk heterojunction type organic photoelectric conversion element 20 may be configured by forming the anode 202 and the cathode 206 on both surfaces of the photoelectric conversion unit 204.

  The photoelectric conversion unit 204 is a layer that converts light energy into electrical energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

  In FIG. 2, light incident from the anode 202 through the substrate 201 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the power generation layer 204, and electrons move from the electron donor to the electron acceptor. A pair of holes and electrons (charge separation state) is formed. The generated electric charge is caused by an internal electric field, for example, when the work functions of the anode 202 and the cathode 206 are different, the potential difference between the anode 202 and the cathode 206 causes electrons to pass between the electron acceptors, and the holes serve as electron donors. The photocurrent is detected by passing through different electrodes to different electrodes. For example, when the work function of the anode 202 is greater than that of the cathode 206, electrons are transported to the anode 202 and holes are transported to the cathode 206. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, by applying a potential between the anode 202 and the cathode 206, the transport direction of electrons and holes can be controlled.

  In addition, although not described in FIG. 2, you may have other layers, such as a smoothing layer.

  In FIG. 2, the hole transport layer 203 is composed of a π-conjugated conductive polymer and a polyanion, and a layer 207 containing an amine compound is inserted between the power generation layer 204. As a result of intensive studies, the present inventors have been able to realize a photoelectric conversion element having high photoelectric conversion efficiency and durability by including an amine compound between the hole transport layer and the power generation layer. The cause of this is not clear, but it is likely that the amine compound neutralizes the acid portion of the hole transport layer 203 and prevents the acid from diffusing into the power generation layer 204, thereby improving the durability of the device. Moreover, since recombination on an electrode can be prevented, it is thought that the photoelectric conversion efficiency is improved. Furthermore, it is good also as a tandem-type structure which laminated | stacked such a photoelectric conversion element for the purpose of the improvement of sunlight utilization factor (photoelectric conversion efficiency).

  Below, the material which comprises these layers is described.

(Hole transport layer)
The organic photoelectric conversion element 20 of the present invention has a hole transport layer 202 between the power generation layer and the anode. This makes it possible to extract charges generated in the bulk heterojunction layer more efficiently.

  The hole transport layer 202 of the present invention is formed of a conductive polymer including a π-conjugated conductive polymer and a polyanion.

  The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method. Forming the coating film in the lower layer before forming the bulk heterojunction layer is preferable because it has the effect of leveling the coating surface and reduces the influence of leakage and the like.

(Layer containing amine compound)
The photoelectric conversion element 20 of the present invention preferably has a layer containing an amine compound represented by the general formula (1) between the power generation layer and the hole transport layer. The amine compound represented by the general formula (1) is preferably a thiophene compound, more preferably a molecular weight of 400 or more, and still more preferably a molecular weight of 700 or more.

  As a means for forming this layer, either a vacuum vapor deposition method or a solution coating method may be used, but a solution coating method is preferable. For example, after forming a hole transport layer, an amine compound is deposited on the hole transport layer side in a self-organized manner by applying a solution in which the amino group-containing compound, p-type material and n-type material are mixed. A laminated structure may be formed by such a method.

(P-type semiconductor material)
In the present invention, as the p-type semiconductor material, a known p-type semiconductor material (such as a condensed polycyclic aromatic low-molecular compound or a conjugated polymer) can be used.

  Examples of the condensed polycyclic aromatic low-molecular compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, circumanthracene, bisanthene, zesulene, Compounds such as heptazeslen, pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF ) -Perchloric acid complexes, and derivatives and precursors thereof.

  Examples of the derivative having the above-mentioned condensed polycycle include WO 03/16599 pamphlet, WO 03/28125 pamphlet, US Pat. No. 6,690,029, JP 2004-107216 A. A pentacene derivative having a substituent described in JP-A-2003-136964, a pentacene precursor described in US Patent Application Publication No. 2003/136964, and the like; Amer. Chem. Soc. , Vol. 127, no. 14, 4986, J.A. Amer. Chem. Soc. , Vol. 123, p9482; Amer. Chem. Soc. , Vol. 130 (2008), no. Examples include acene compounds substituted with a trialkylsilylethynyl group described in 9,2706, and porphyrin compounds described in JP-A-2008-16834.

  As the conjugated polymer, for example, a polythiophene such as poly-3-hexylthiophene (P3HT) and an oligomer thereof, or a technical group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Polythiophene, Nature Material, (2006) vol. 5, p328, polythiophene-thienothiophene copolymer, polythiophene-diketopyrrolopyrrole copolymer described in WO08 / 000664, Adv. Mater. , 2007, p4160, a polythiophene-thiazolothiazole copolymer, Nature Mat. vol. 6 (2007), p497 described in PCPDTBT, etc., polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, Examples thereof include polymer materials such as σ-conjugated polymers such as polysilane and polygermane.

  In addition, oligomeric materials instead of polymer materials include thiophene hexamer α-sexual thiophene α, ω-dihexyl-α-sexual thiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

(N-type semiconductor material)
The n-type semiconductor material used for the bulk heterojunction layer of the present invention is not particularly limited. Perfluorophthalocyanine), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide and other aromatic carboxylic acid anhydrides and imidized compounds thereof as a skeleton Etc.

  However, fullerene derivatives that can perform charge separation with various p-type semiconductor materials at high speed (˜50 fs) and efficiently are preferable. Fullerene derivatives include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotubes, multi-walled nanotubes, single-walled nanotubes, nanohorns (conical), and the like. Partially by hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, cycloalkyl group, silyl group, ether group, thioether group, amino group, silyl group, etc. Examples thereof include substituted fullerene derivatives.

  Among them, [6,6] -phenyl C61-butyric acid methyl ester (abbreviation PCBM), [6,6] -phenyl C61-butyric acid-nbutyl ester (PCBnB), [6,6] -phenyl C61-buty Rick acid-isobutyl ester (PCBiB), [6,6] -phenyl C61-butyric acid-n hexyl ester (PCBH), Adv. Mater. , Vol. 20 (2008), p2116, etc., aminated fullerenes such as JP-A 2006-199674, metallocene fullerenes such as JP-A 2008-130889, and cyclics such as US Pat. No. 7,329,709. It is preferable to use a fullerene derivative having a substituent and having improved solubility, such as fullerene having an ether group.

(Method for forming power generation layer)
Examples of a method for forming a power generation layer in which a P-type semiconductor material and an n-type semiconductor material are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. The coating method is also excellent in production speed.

  After coating, it is preferable to perform heating in order to cause removal of residual solvent, moisture and gas, and improvement of mobility and absorption longwave due to crystallization of the semiconductor material. When annealing is performed at a predetermined temperature during the manufacturing process, a part of the particles is microscopically aggregated or crystallized, and the bulk heterojunction layer can have an appropriate phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved and high efficiency can be obtained.

  The power generation layer 14 may be composed of a single layer in which a P-type semiconductor material and an n-type semiconductor material are uniformly mixed. However, the power generation layer 14 may be a plurality of layers in which the mixing ratio of the P-type semiconductor material and the n-type semiconductor material is changed. It may be configured. In this case, it can be formed by using a material that can be insolubilized after coating as described above.

(Electron transport layer / hole blocking layer)
Since the organic photoelectric conversion element 10 of the present invention can take out charges generated in the bulk heterojunction layer more efficiently by forming the electron transport layer 18 between the bulk heterojunction layer and the cathode. It is preferable to have this layer.

  As the electron transport layer 18, octaazaporphyrin and a p-type semiconductor perfluoro (perfluoropentacene, perfluorophthalocyanine, etc.) can be used. Similarly, a HOMO of a p-type semiconductor material used for a bulk heterojunction layer. The electron transport layer having a HOMO level deeper than the level is given a hole blocking function having a rectifying effect so that holes generated in the bulk heterojunction layer do not flow to the cathode side. More preferably, a material deeper than the HOMO level of the n-type semiconductor is used as the electron transport layer. Moreover, it is preferable to use a compound with high electron mobility from the characteristic of transporting electrons.

  Such an electron transport layer is also called a hole blocking layer, and it is preferable to use an electron transport layer having such a function. Examples of such materials include phenanthrene compounds such as bathocuproine, n-type semiconductor materials such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide, and titanium oxide. N-type inorganic oxides such as zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride, and cesium fluoride can be used. A layer made of a single n-type semiconductor material used for the bulk heterojunction layer can also be used.

  The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method.

(Other layers)
For the purpose of improving energy conversion efficiency and improving the lifetime of the element, a structure having various intermediate layers in the element may be employed. Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, and a wavelength conversion layer.

〔electrode〕
The organic photoelectric conversion element of the present invention has at least an anode and a cathode. Further, when a tandem configuration is adopted, the tandem configuration can be achieved by using an intermediate electrode. In the present invention, an electrode through which holes mainly flow is called an anode, and an electrode through which electrons mainly flow is called a cathode.

  Further, because of the function of whether or not there is a light-transmitting property, a light-transmitting electrode may be called a transparent electrode, and a non-light-transmitting electrode may be called a counter electrode. Usually, the anode is a translucent transparent electrode, and the cathode is a non-translucent counter electrode.

(anode)
The anode of the present invention is preferably an electrode that transmits light of 380 to 800 nm. As the material, for example, transparent conductive metal oxides such as indium tin oxide (ITO), SnO ₂ and ZnO, metal thin films such as gold, silver and platinum, metal nanowires and carbon nanotubes can be used.

  Also, a conductive material selected from the group consisting of polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene, and polynaphthalene. A functional polymer can also be used. Further, a plurality of these conductive compounds can be combined to form an anode.

(cathode)
The cathode may be a single layer of a conductive material, but in addition to a conductive material, a resin that holds these may be used in combination. As a conductive material for the cathode, a material having a work function (4 eV or less) metal, alloy, electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the viewpoint of electron extraction performance and durability against oxidation, etc., a mixture of these metals and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, magnesium / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

  If a metal material is used as the conductive material of the cathode, the light coming to the cathode side is reflected and reflected to the first electrode side, and this light can be reused and absorbed again by the photoelectric conversion layer, further improving the photoelectric conversion efficiency. It is preferable.

  Further, the cathode 206 may be a metal (eg, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), carbon nanoparticle, nanowire, or nanostructure. A dispersion is preferable because a transparent and highly conductive cathode can be formed by a coating method.

  When the cathode side is made light transmissive, for example, a conductive material suitable for the cathode, such as aluminum and aluminum alloy, silver and silver compound, is formed with a thin film thickness of about 1 to 20 nm, and By providing a film of the conductive light-transmitting material mentioned in the description, a light-transmitting cathode can be obtained.

(substrate)
When light that is photoelectrically converted enters from the substrate side, the substrate is preferably a member that can transmit the light that is photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of light weight and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things. For example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, polyolefin resins such as cyclic olefin resin Film, vinyl resin film such as polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, A polyamide resin film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more at ~800nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

  The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesiveness of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  Further, for the purpose of suppressing the permeation of oxygen and water vapor, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred. Good.

(Optical function layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of more efficient reception of sunlight. As the optical functional layer, for example, a light condensing layer such as an antireflection film or a microlens array, a light diffusion layer that can scatter the light reflected by the cathode and enter the power generation layer again may be provided. .

  Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1.57. It is more preferable to set it to ˜1.63 because the interface reflection between the film substrate and the easy adhesion layer can be reduced and the transmittance can be improved. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

  As the condensing layer, for example, it is processed so as to provide a structure on the microlens array on the sunlight receiving side of the support substrate, or the amount of light received from a specific direction is increased by combining with a so-called condensing sheet. Conversely, the incident angle dependency of sunlight can be reduced.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  Examples of the light scattering layer include various antiglare layers, layers in which nanoparticles or nanowires such as metals or various inorganic oxides are dispersed in a colorless and transparent polymer, and the like.

(Patterning)
The method and process for patterning the electrode, the power generation layer, the hole transport layer, the electron transport layer, and the like according to the present invention are not particularly limited, and known methods can be appropriately applied.

  If it is a soluble material such as a bulk heterojunction layer or a transport layer, only unnecessary portions may be wiped after the entire surface of die coating, dip coating, etc., or direct patterning at the time of coating using a method such as an ink jet method or screen printing. May be.

  In the case of an insoluble material such as an electrode material, the electrode can be patterned by a known method such as mask vapor deposition during vacuum deposition or etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

(Sealing)
Moreover, since the produced organic photoelectric conversion element is not deteriorated by oxygen, moisture, or the like in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescence element by a known method. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and an organic photoelectric conversion element are pasted with an adhesive. Method, spin coating of organic polymer material (polyvinyl alcohol, etc.) with high gas barrier property, inorganic thin film (silicon oxide, aluminum oxide, etc.) or organic film (parylene etc.) with high gas barrier property are deposited under vacuum Examples thereof include a method and a method of laminating these in a composite manner.

[Optical sensor array]
Next, an optical sensor array to which the bulk heterojunction type organic photoelectric conversion element described above is applied will be described in detail. The optical sensor array is produced by arranging the photoelectric conversion elements in a fine pixel form by utilizing the fact that the bulk heterojunction type organic photoelectric conversion elements generate a current upon receiving light, and projected onto the optical sensor array. A sensor having an effect of converting an image into an electrical signal.

  FIG. 3 is a diagram showing the configuration of the photosensor array. 3A is a top view, and FIG. 3B is a cross-sectional view taken along line A-A ′ of FIG.

  In FIG. 3, an optical sensor array 20 is paired with an anode 22 as a lower electrode, a photoelectric conversion unit 24 for converting light energy into electric energy, and an anode 22 on a substrate 21 as a holding member. The cathode 23 is sequentially laminated. The photoelectric conversion unit 24 includes a photoelectric conversion layer 24c having a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed, a layer 24b containing the amine compound of the present invention, holes It consists of three layers of transport layer 24a. In the example shown in FIG. 3, six bulk heterojunction type organic photoelectric conversion elements are formed.

  The substrate 21, the anode 22, the photoelectric conversion layer 24b, and the cathode 23 have the same configuration and role as the anode 202, the photoelectric conversion unit 204, and the cathode 206 in the bulk heterojunction photoelectric conversion element 20 described above.

  For example, glass is used for the substrate 21, ITO is used for the anode 22, and aluminum is used for the cathode 23, for example. For example, the poly-3-hexylthiophene (P3HT) is used as the p-type semiconductor material of the photoelectric conversion layer 24c, and the AM-5 is used as the layer 24b containing the amine compound. For example, the PCBM is used as the type semiconductor material. The hole transport layer 24a is made of PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrene sulfonic acid) conductive polymer (trade name BaytronP, manufactured by Stark Vitec). Such an optical sensor array 20 was manufactured as follows.

  An ITO film was formed on the glass substrate by sputtering and processed into a predetermined pattern shape by photolithography. The thickness of the glass substrate was 0.7 mm, the thickness of the ITO film was 200 nm, and the measurement area (light receiving area) of the ITO film after photolithography was 0.5 mm × 0.5 mm. Next, a PEDOT-PSS film was formed on the glass substrate 21 by spin coating (conditions: rotational speed = 1000 rpm, filter diameter = 1.2 μm). Thereafter, the substrate was heated in an oven at 140 ° C. for 10 minutes and dried. The thickness of the PEDOT-PSS film after drying was 30 nm.

  Next, 5 nm of an amine compound AM-5 film was formed on the PEDOT-PSS film by a vapor deposition method. On top of that, a 1: 4 mixed film of P3HT and PCBM was formed by a spin coating method (conditions: rotational speed = 3300 rpm, filter diameter = 0.8 μm). In this spin coating, P3HT and PCBM were mixed with a chlorobenzene solvent at a ratio of 1: 4, and a mixture obtained by stirring (5 minutes) was used. After forming the mixed film of P3HT and PCBM, annealing was performed by heating in an oven at 180 ° C. for 30 minutes in a nitrogen gas atmosphere. The thickness of the mixed film of P3HT and PCBM after the annealing treatment was 70 nm.

  Then, using a metal mask having a predetermined pattern opening, 5 nm of lithium fluoride is deposited as an electron transport layer on the mixed film of P3HT and PCBM, and then an aluminum layer as a cathode is formed by a deposition method (thickness). = 10 nm). Thereafter, 1 μm of PVA (polyvinyl alcohol) was formed by spin coating and baked at 150 ° C. to prepare a passivation layer (not shown). The optical sensor array 20 was produced as described above.

  When this photosensor array 20 was irradiated with light having a predetermined pattern, it was confirmed that the photocurrent was detected only from the cells that were exposed to light and functioned as a photosensor.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
[Production of organic photoelectric conversion element]
(Preparation of organic photoelectric conversion element SC-101)
The transparent electrode patterned on the glass substrate was cleaned in the order of ultrasonic cleaning with surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally UV ozone cleaning. .

  On this transparent substrate, Baytron P4083 (manufactured by Starck Vitec), which is a conductive polymer, was spin-coated with a film thickness of 30 nm to form a PEDOT-PSS layer, and then heated and dried at 140 ° C. in the atmosphere for 10 minutes.

After fixing this board | substrate to the board | substrate holder of a commercially available vacuum evaporation system, the resistance heating boat made from a tantalum, each compound AM-1 of this invention was put, and after attaching to a vacuum evaporation system (1st vacuum chamber), a vacuum chamber was set to 4 After reducing the pressure to × 10 ⁻⁴ Pa, the heating boat containing the compound AM-1 was energized and heated to a thickness of 5 nm on the transparent support substrate at a deposition rate of 0.1 to 0.2 nm / second. It vapor-deposited so that it might become.

  After this, the substrate was brought into the glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere.

  A solution is prepared by dissolving 1.5% by mass of Plexcore OS2100 Plexcore OS2100 as a p-type semiconductor material and 1.5% by mass of Frontier Carbon E100 (PCBM) as an n-type semiconductor material in chlorobenzene. While being filtered through a 45 μm filter, spin coating was performed at 500 rpm for 60 seconds, then at 2200 rpm for 1 second, and left at room temperature for 30 minutes.

  Next, a solution in which Ti-isopropoxide is dissolved in ethanol to a concentration of 25 mmol / l is prepared, and after the take-out electrode portion is masked and spin-coated at 2000 rpm, it is taken out into the atmosphere and left for 60 minutes to leave Ti- By hydrolyzing isopropoxide, a 10 nm thick TiOx layer was formed, and a 10 nm thick hole blocking layer was formed.

Next, the substrate on which the series of organic layers was formed was placed in a vacuum deposition apparatus without being exposed to the atmosphere. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less, and then 100 nm of Al was deposited. Finally, heating was performed at 120 ° C. for 30 minutes to obtain a comparative organic photoelectric conversion element SC-101. The vapor deposition rate was 2 nm / second, and the size was 2 mm square.

  The obtained organic photoelectric conversion element SC-101 was sealed with an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere. .

(Production of organic photoelectric conversion elements SC-102 to SC-105)
In the production of the organic photoelectric conversion element SC-101, the organic photoelectric conversion elements SC-102 to SC-105 of the present invention were prepared in the same manner except that the compound AM-1 was changed to the compound of the present invention described in Table 1 below. did.

(Production of Comparative Organic Photoelectric Conversion Device SC-106)
In the production of the organic photoelectric conversion element SC-101, a comparative organic photoelectric conversion element SC-106 was produced in the same manner except that the film of the compound AM-1 was not formed.

[Evaluation of organic photoelectric conversion elements]
About the obtained organic photoelectric conversion elements SC-101 to SC-106, the following conversion efficiency, durability, and bending resistance were evaluated.

(Energy conversion efficiency)
Photoelectric conversion elements prepared above, was irradiated with light having an intensity of 100 mW / cm ² solar simulator (AM1.5G filter), a superposed mask in which the effective area 4.0 mm ² on the light receiving portion, the short circuit current density Jsc ( The four light-receiving portions formed on the same element were measured for mA / cm ² ), open-circuit voltage Voc (V), and fill factor (fill factor) FF, and the average value was obtained. The energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 1, and the relative values when the energy conversion efficiency of SC-101 was set to 100 are shown in Table 1.

Formula 1 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)
(Durability) (Relative reduction efficiency)
A solar simulator (AM1.5G) was irradiated at an irradiation intensity of 100 mW / cm ² , voltage-current characteristics were measured, and initial conversion efficiency was measured. Furthermore, assuming that the initial conversion efficiency at this time is 100, the conversion efficiency after 100 hours of irradiation with an irradiation intensity of 100 mW / cm ² with the resistance connected between the anode and the cathode is evaluated, and the relative reduction efficiency according to Equation 2 Was calculated.

Formula 2 Relative reduction efficiency (%) = (1−conversion efficiency after exposure / conversion efficiency before exposure) × 100
(Bending resistance retention rate)
About the organic photoelectric conversion element produced by the above method, a 1-inch φ plastic cylindrical rod is prepared, the front and back are set as one set, and the retention rate of energy conversion efficiency η before and after winding 50 sets is obtained according to Equation 2, It is shown in Table 4.

Formula 3 Retention ratio (%) = η after winding / η × 100 before winding
The evaluation results are shown in Table 1.

  Table 1 shows that the organic photoelectric conversion element of this invention has a high conversion efficiency. In addition, it was found that the relative reduction efficiency was low and the durability was improved, and the bending resistance was also improved.

Example 2
(Preparation of organic photoelectric conversion element 201)
Next, after providing the PEDOT-PSS layer in the same manner as in the organic photoelectric conversion element SC-101 of Example 1, the substrate was similarly brought into the glove box and operated in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere. A solution prepared by dissolving 0.1% by mass of compound AM-2 as an amine compound in ethyl acetate was prepared, spin-coated at 2000 rpm for 60 seconds while being filtered through a 0.45 μm filter, and heated at 50 ° C. for 5 minutes. Then, it was left at room temperature for 6 hours.

  Next, 0.5% by mass of P3HT (manufactured by Plextronics: regioregular poly-3-hexylthiophene) (Mw = 52000) as a p-type semiconductor material on chlorobenzene, and the above-mentioned Frontier Carbon Corporation as an n-type semiconductor material A solution in which 2.0% by mass of E100 (PCBM) was dissolved was prepared, spin-coated at 2000 rpm for 60 seconds while being filtered through a 0.45 μm filter, heated at 50 ° C. for 10 minutes, and then at room temperature for 12 hours. I left it alone.

Next, the substrate on which the series of organic layers was formed was placed in a vacuum deposition apparatus without being exposed to the atmosphere. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less, and then 0.6 nm of lithium fluoride and 100 nm of Al were deposited. Finally, heating was performed at 120 ° C. for 30 minutes to obtain an organic photoelectric conversion element SC-201. The vapor deposition rate was 2 nm / second, and the size was 2 mm square.

  The obtained organic photoelectric conversion element SC-201 was sealed with an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere. .

(Production of organic photoelectric conversion elements SC-202 to SC-206)
In the production of the organic photoelectric conversion element 21, the organic photoelectric conversion elements SC-202 to SC-206 of the present invention were similarly performed except that the compound of the present invention described in Table 2 below was used instead of the amine compound AM-2. Was made.

(Production of Comparative Organic Photoelectric Conversion Device SC-207)
In the production of the organic photoelectric conversion element SC-201, a comparative organic photoelectric conversion element SC-207 was produced in the same manner except that the amine compound layer was not formed.

[Evaluation of organic photoelectric conversion elements]
About the obtained organic photoelectric conversion element, it carried out similarly to Example 1, and evaluated the relative value of energy conversion efficiency, relative fall efficiency (durability), and bending tolerance retention.

  The evaluation results are shown in Table 2.

  Table 2 also shows that the organic photoelectric conversion element of the present invention has a high conversion efficiency. Further, it was found that the relative reduction efficiency was low and the durability was high, and the bending resistance was also improved.

Example 3
(Preparation of organic photoelectric conversion element SC-301)
When producing the organic photoelectric conversion element SC-202 of Example 2, the PEDOT-PSS layer was provided in the same manner as the organic photoelectric conversion element 1 of Example 1 without forming the layer of the amine compound AM-5. Thereafter, 0.1% by mass of AM-5 as an amine compound in chlorobenzene, 0.5% by mass of P3HT (manufactured by Plextronics: regioregular poly-3-hexylthiophene) (Mw = 52000) as a p-type semiconductor material, Prepare a solution prepared by dissolving 2.0% by mass of the above-mentioned Frontier Carbon E100 (PCBM) as an n-type semiconductor material, spin-coat at 2000 rpm for 60 seconds while filtering through a 0.45 μm filter, and at 50 ° C. After heating for 10 minutes, it was left at room temperature for 12 hours. Thereafter, as in SC-202, lithium fluoride and a cathode were formed and then sealed to prepare an organic photoelectric conversion element SC-301.

[Evaluation of organic photoelectric conversion elements]
For the obtained organic photoelectric conversion element, the relative value of energy conversion efficiency, the relative reduction efficiency (durability), and the bending resistance retention rate were evaluated in the same manner as in Example 2, and the results are shown in Table 3.

  From Table 3, when the energy conversion efficiency of SC-201 is 100, the relative value of the energy conversion efficiency of SC-301 is 101, the relative reduction efficiency is 20%, and the bending resistance retention is 85%. Compared to As described above, even when the power generation layer is formed by mixing the amine compound, the n-type material, and the p-type material, the photoelectric conversion characteristics, durability, and bending resistance are effective. Although this is not certain, it is considered that the amine compound is probably localized on the PEDOT layer side due to van der Waals interaction. If the laminated structure is formed by such a method, it leads to simplification of the film forming process.

10 Photoelectric conversion element 101 First electrode (positive electrode)
102 hole transport layer 103 bulk heterojunction type power generation layer (photoelectric conversion layer)
104 Electron transport layer 105 Second electrode (cathode)
20 Photosensor Array 21 Substrate 22 Anode 23 Cathode 24 Photoelectric Conversion Unit 24a Buffer Layer 24b Layer Containing Amine Compound 24c Photoelectric Conversion Layer 200 Photoelectric Conversion Element 201 Substrate 202 Anode 203 Hole Transport Layer 204 Power Generation Layer of Bulk Heterojunction Layer 205 Electron Transport layer 206 Cathode 207 Layer containing amine compound

Claims (13)

An organic photoelectric conversion element having a structure in which at least a hole transport layer and a power generation layer are sequentially laminated between an anode and a cathode, wherein the hole transport layer comprises a π-conjugated conductive polymer and a poly anion. And the power generation layer is a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, and further includes the hole transport layer and the power generation layer. An organic photoelectric conversion element comprising a compound having an amino group represented by the following general formula (1) in between.

(In the formula, R ₁ represents a hydrogen atom or an alkyl group, and R ₂ represents a hydrogen atom or a hydrocarbon group.) The organic photoelectric conversion device according to claim 1, wherein the π-conjugated conductive polymer has a repeating unit represented by the following general formula (2).

(In the formula, A ₁ represents an alkylene group having 1 to 4 carbon atoms which may have a substituent, and Q represents an oxygen atom or a sulfur atom)   The π-conjugated conductive polymer having a partial structure represented by the general formula (2) is a polymer or copolymer of poly (3,4-ethylenedioxy) thiophene, Item 3. An organic photoelectric conversion device according to Item 2. The organic photoelectric conversion element according to any one of claims 1 to 3, wherein the poly anion is represented by the following general formula (3).

(In the formula, R ₃ represents a hydrogen atom or a methyl group, and A ₂ is a simple bond, a substituted or unsubstituted C ₁ -C ₃₀ alkyl group; a substituted or unsubstituted C ₁ -C ₃₀ heteroalkyl. group; an alkoxy group substituted or unsubstituted _C 1 _{-C 30;} substituted or unsubstituted _C 1 _{-C 30} heteroalkoxy group; an aryl group substituted or unsubstituted _C 6 _{-C 30;} a substituted or unsubstituted A C ₆ -C ₃₀ arylalkyl group; a substituted or unsubstituted C ₆ -C ₃₀ aryloxy group; a substituted or unsubstituted C ₂ -C ₃₀ heteroaryl group; a substituted or unsubstituted C ₂ -C ₃₀ heteroarylalkyl group; a substituted or unsubstituted _C 2 _{-C 30} heteroaryloxy group, substituted or cycloalkyl group unsubstituted _C 5 _{-C 20,} substituted or unsubstituted _C 2 ~ C ₃₀ heterocycloalkyl group; substituted or unsubstituted C ₁ -C ₃₀ alkyl ester group; substituted or unsubstituted C ₁ -C ₃₀ heteroalkyl ester group; substituted or unsubstituted C ₆ -C ₃₀ aryl ester group; and it is selected from the group consisting of heteroaryl ester group of C ₂ -C ₃₀ substituted or unsubstituted, B represents a group containing an ionic group or an ionic group, this time, the ionic group An anion and a cation, wherein the anion is selected from SO ₃ ⁻ , COO ⁻ , and the cation is Na ⁺ , K ⁺ , Li ⁺ , Mg ⁺² , Zn ⁺² , and Al _+, metal ion or ^H is selected from ^{_{+3 NH 3 +, CH 3 (}} -CH 2 -) n O + (n is an integer of 1 to 50) Izu organic ion selected from It is how.)   The organic photoelectric conversion element according to claim 4, wherein the poly anion has a sulfonic acid group.   6. The organic photoelectric conversion element according to claim 5, wherein the poly anion is polystyrene sulfonic acid.   The layer containing the compound having an amino group represented by the general formula (1) is formed with a film thickness of 0.5 to 10 nm. Organic photoelectric conversion element.   The organic photoelectric conversion device according to claim 1, wherein the compound having an amino group represented by the general formula (1) is a thiophene oligomer.   The organic photoelectric conversion element according to claim 8, wherein the thiophene oligomer has a molecular weight of 400 or more.   The organic photoelectric conversion device according to claim 9, wherein the thiophene oligomer has a molecular weight of 600 or more.   After the hole transport layer is formed and the hole transport layer is formed on the hole transport layer, the layer containing the compound having an amino group and the power generation layer are compounds having the amino group. The organic photoelectric conversion element according to claim 1, wherein the organic photoelectric conversion element is formed by applying a solution containing the p-type semiconductor material and the n-type semiconductor material.   It consists of an organic photoelectric conversion element of any one of Claims 1-11, The solar cell characterized by the above-mentioned.   The organic photoelectric conversion element of any one of Claims 1-11 is arrange | positioned at array form, The optical sensor array characterized by the above-mentioned.

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