Charge transport composition for perovskite photoelectric conversion element

Abstract

Provided is a charge transport composition for a perovskite photoelectric conversion element, which comprises a charge transport substance made of a conductive polymer, an organosilane compound, and a solvent.

Description

Technical Field

[0001] The present invention relates to a charge transport composition for a perovskite photoelectric conversion element.

Background Art

[0002] An electronic device, particularly an organic photoelectric conversion device, is a device that converts light energy into electrical energy using an organic semiconductor, and examples thereof include an organic solar cell. An organic solar cell is a solar cell element that uses an organic substance for an active layer or a charge transport material, and a dye-sensitized solar cell developed by M. Grätzel and an organic thin-film solar cell developed by C.W. Tang are well known (Non-Patent Documents 1 and 2). Both have features different from those of the current mainstream inorganic solar cells, such as being lightweight and thin-film, being flexible, and being capable of roll-to-roll production, and thus new market formation is expected.

[0003] On the other hand, in recent years, research results have been reported that a solar cell using a metal halide as a compound having a perovskite crystal structure (hereinafter referred to as "perovskite semiconductor compound") can achieve a relatively high photoelectric conversion efficiency, and it has attracted attention. For example, Patent Document 1 describes a photoelectric conversion element and a solar cell including an active layer containing a perovskite semiconductor compound.

[0004] However, in a photoelectric conversion element using a perovskite semiconductor compound for an active layer, the stability of the element may decrease depending on the conditions of other layers combined with the active layer, and further improvement is desired.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and can be suitably used as a hole collection layer of a perovskite photoelectric conversion element, and provides a charge transport composition capable of providing a perovskite photoelectric conversion element having high conversion efficiency (PCE) and excellent stability. The purpose is to do.

Means for Solving the Problems

[0008] As a result of intensive studies to achieve the above object, the present inventors used a composition containing a charge transport substance made of a conductive polymer, an organosilane compound, and a solvent as a hole collection layer of a perovskite photoelectric conversion element. As a result, it was found that a perovskite photoelectric conversion element having high PCE and excellent stability can be obtained, and the present invention was completed.

[0009] That is, the present invention is 1. A charge transport composition for a perovskite photoelectric conversion element, comprising a charge transport substance made of a conductive polymer, an organosilane compound, and a solvent, 2. The charge transport composition for a perovskite photoelectric conversion element according to 1, wherein the conductive polymer is a p-type conjugated homopolymer, 3. The charge transport composition for a perovskite photoelectric conversion element according to 1 or 2, wherein the conductive polymer is a polythiophene derivative, 4. The charge transport composition for a perovskite photoelectric conversion element according to any one of 1 to 3, wherein the conductive polymer is a polythiophene derivative containing a repeating unit represented by the formula (1),

Chemical formula

Effect of the Invention

[0010] The charge transport composition for a perovskite photoelectric conversion element of the present invention can be suitably employed for forming the hole collection layer of a perovskite photoelectric conversion element, and when a thin film obtained using the composition is used as the hole collection layer, a perovskite photoelectric conversion element having high PCE and excellent stability can be obtained.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in more detail. The charge transport composition for a perovskite photoelectric conversion element of the present invention contains a charge transport substance composed of a conductive polymer, an organosilane compound, and a solvent.

[0012] In the present invention, as the conductive polymer, from the viewpoint of exhibiting high PCE in the fabricated photoelectric conversion element, a p-type conjugated homopolymer is preferable, a polythiophene derivative is more preferable, and a polythiophene derivative containing a repeating unit represented by the following formula (1) is even more preferable.

[0013]

Chemical formula

[0014] In formula (1), R 1 and R 2are, independently of each other, a hydrogen atom, an alkyl group having 1 to 40 carbon atoms, a fluoroalkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a fluoroalkoxy group having 1 to 40 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, -O-[Z-O] p -R e or a sulfonic acid group, or R 1 and R 2 are -O-Y-O- formed by bonding, Y is an alkylene group having 1 to 40 carbon atoms which may contain an ether bond and may be substituted with a sulfonic acid group, Z is an alkylene group having 1 to 40 carbon atoms which may be substituted with a halogen atom, p is an integer of 1 or more, and R e is a hydrogen atom, an alkyl group having 1 to 40 carbon atoms, a fluoroalkyl group having 1 to 40 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0015] Examples of the alkyl group having 1 to 40 carbon atoms include linear, branched, and cyclic ones. Specific examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosanyl group, behenyl group, triacontyl group, and tetracontyl group. Among them, an alkyl group having 1 to 18 carbon atoms is preferred, and an alkyl group having 1 to 8 carbon atoms is more preferred.

[0016] Examples of fluoroalkyl groups having 1 to 40 carbon atoms include groups in which at least one hydrogen atom in the alkyl group having 1 to 40 carbon atoms is substituted with a fluorine atom, and are not particularly limited. For example, fluoromethyl group, difluoromethyl group, trifluoromethyl group, perfluoromethyl group, 1-fluoroethyl group, 2-fluoroethyl group, 1,2-difluoroethyl group, 1,1-difluoroethyl group, 2,2-difluoroethyl group, 1,1,2-trifluoroethyl group, 1,2,2-trifluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, 1,2,2,2-tetrafluoroethyl group, perfluoroethyl group, 1-fluoropropyl group, 2-fluoropropyl group, 3-fluoropropyl group, 1,1-difluoropropyl group, 1,2-difluoropropyl group, 1,3-difluoropropyl group, 2,2-difluoropropyl group, 2,3-difluoropropyl group, 3,3-difluoropropyl group, 1,1,2-trifluoropropyl group, 1,1,3-trifluoropropyl group, 1,2,3-trifluoropropyl group, 1,3,3-trifluoropropyl group, 2,2,3-trifluoropropyl group, 2,3,3-trifluoropropyl group, 3,3,3-trifluoropropyl group, 1,1,2,2-tetrafluoropropyl group, 1,1,2,3-tetrafluoropropyl group, 1,2,2,3-tetrafluoropropyl group, 1,3,3,3-tetrafluoropropyl group, 2,2,3,3-tetrafluoropropyl group, 2,3,3,3-tetrafluoropropyl group, 1,1,2,2,3-pentafluoropropyl group, 1,2,2,3,3-pentafluoropropyl group, 1,1,3,3,3-pentafluoropropyl group, 1,2,3,3,3-pentafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, perfluorooctyl group, and the like.

[0017] As the alkoxy group having 1 to 40 carbon atoms, the alkyl group therein may be linear, branched or cyclic. For example, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, c-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t-butoxy group, n-pentoxy group, n-hexoxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n-octadecyloxy group, n-nonadecyloxy group, and n-eicosanyloxy group, etc. may be mentioned.

[0018] The fluoroalkoxy groups having 1 to 40 carbon atoms are not particularly limited as long as they are alkoxy groups in which at least one hydrogen atom on the carbon atom is substituted with a fluorine atom. For example, fluoromethoxy group, difluoromethoxy group, trifluoromethoxy group, 1-fluoroethoxy group, 2-fluoroethoxy group, 1,2-difluoroethoxy group, 1,1-difluoroethoxy group, 2,2-difluoroethoxy group, 1,1,2-trifluoroethoxy group, 1,2,2-trifluoroethoxy group, 2,2,2-trifluoroethoxy group, 1,1,2,2-tetrafluoroethoxy group, 1,2,2,2-tetrafluoroethoxy group, 1,1,2,2,2-pentafluoroethoxy group, 1-fluoropropoxy group, 2-fluoropropoxy group, 3-fluoropropoxy group, 1,1-difluoropropoxy group, 1,2-difluoropropoxy group, 1,3-difluoropropoxy group, 2,2-difluoropropoxy group, 2,3-difluoropropoxy group, 3,3-difluoropropoxy group, 1,1,2-trifluoropropoxy group, 1,1,3-trifluoropropoxy group, 1,2,3-trifluoropropoxy group, 1,3,3-trifluoropropoxy group, 2,2,3-trifluoropropoxy group, 2,3,3-trifluoropropoxy group, 3,3,3-trifluoropropoxy group, 1,1,2,2-tetrafluoropropoxy group, 1,1,2,3-tetrafluoropropoxy group, 1,2,2,3-tetrafluoropropoxy group, 1,3,3,3-tetrafluoropropoxy group, 2,2,3,3-tetrafluoropropoxy group, 2,3,3,3-tetrafluoropropoxy group, 1,1,2,2,3-pentafluoropropoxy group, 1,2,2,3,3-pentafluoropropoxy group, 1,1,3,3,3-pentafluoropropoxy group, 1,2,3,3,3-pentafluoropropoxy group, 2,2,3,3,3-pentafluoropropoxy group, and heptafluoropropoxy group, etc. can be mentioned.

[0019] As the alkylene group having 1 to 40 carbon atoms, any of linear, branched, and cyclic groups may be used. For example, methylene group, ethylene group, propylene group, trimethylene group, tetramethylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, nonadecylene group, eicosanylene group, etc. may be mentioned.

[0020] As the aryl group having 6 to 20 carbon atoms, for example, phenyl group, tolyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, and 9-phenanthryl group, etc. may be mentioned, and phenyl group, tolyl group, and naphthyl group are preferable.

[0021] As the aryloxy group having 6 to 20 carbon atoms, for example, phenoxy group, anthracenoxy group, naphthoxy group, phenanthrenoxy group, and fluorenoxy group, etc. may be mentioned.

[0022] Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom.

[0023] In the polythiophene derivative containing the repeating unit represented by the above formula (1), R 1 and R 2 are each independently a hydrogen atom, a fluoroalkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, -O[C(R a R b )-C(R c R d )-O] p -R e , -OR f , or a sulfonic acid group, or those in which R 1 and R 2 are bonded to form -O-Y-O-. R a to R drepresents, independently of each other, a hydrogen atom, an alkyl group having 1 to 40 carbon atoms, a fluoroalkyl group having 1 to 40 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R e is the same as described above. p is preferably 1, 2, or 3. R f is preferably an alkyl group having 1 to 40 carbon atoms, a fluoroalkyl group having 1 to 40 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0024] In the present invention, among these, R 1 and R 2 which form -O-Y-O- by bonding are more preferable.

[0025] As a preferable embodiment of the above polythiophene derivative, for example, an embodiment containing a repeating unit in which R 1 and R 2 form -O-Y-O- by bonding can be mentioned.

[0026] As still another preferable embodiment of the above polythiophene derivative, an embodiment containing a repeating unit in which R 1 and R 2 are groups represented by the following formula (Y1) can be mentioned.

[0027]

Chemical formula

[0028] As a preferable specific example of the above polythiophene derivative, for example, polythiophene containing a repeating unit represented by the following formula (1-1) can be mentioned.

[0029]

Chemical formula

[0030] Furthermore, the polythiophene derivative may be a homopolymer or a copolymer (including statistical, random, gradient, and block copolymers). As polymers containing monomer A and monomer B, block copolymers include, for example, A-B diblock copolymers, A-B-A triblock copolymers, and (AB) m - including multiblock copolymers. The polythiophene may contain repeating units derived from other types of monomers (e.g., thienothiophene, selenophene, pyrrole, furan, tellurophene, aniline, arylamine, and arylene (e.g., phenylene, phenylene vinylene, and fluorene, etc.)).

[0031] In the present invention, the content of the repeating unit represented by formula (1) in the polythiophene derivative is preferably more than 50% by mass, more preferably 80% by mass or more, still more preferably 90% by mass or more, further preferably 95% by mass or more, and most preferably 100% by mass, based on the total mass of the repeating units.

[0032] In the present invention, depending on the purity of the starting monomer compound used in the polymerization, the formed polymer may contain repeating units derived from impurities. In the present invention, the term "homopolymer" as described above means a polymer containing repeating units derived from one type of monomer, but may contain repeating units derived from impurities. In the present invention, it is preferable that the polythiophene derivative is a homopolymer in which substantially all repeating units are the repeating units represented by the above formula (1), and more preferably a homopolymer in which the repeating units are the repeating units represented by the above formula (1-1).

[0033] The weight-average molecular weight of the polythiophene derivative represented by the formula (1) is preferably about 1,000 to 1,000,000, more preferably about 5,000 to 100,000, and even more preferably about 10,000 to about 50,000. By setting the weight-average molecular weight to be not less than the lower limit, good conductivity can be obtained, and by setting it to be not more than the upper limit, the solubility in a solvent is improved. The weight-average molecular weight is a polystyrene-equivalent value determined by gel permeation chromatography.

[0034] In the composition of the present invention, the polythiophene derivative containing the repeating unit represented by the formula (1) may be used alone or in combination of two or more compounds. In addition, as the polythiophene derivative containing the repeating unit represented by the formula (1), a commercially available product or a product polymerized by a known method using a thiophene derivative or the like as a starting material may be used, but in any case, it is preferable to use a product purified by a method such as reprecipitation or ion exchange. By using a purified product, the characteristics of a perovskite photoelectric conversion element provided with a thin film obtained from the composition containing the compound can be further enhanced.

[0035] As the organic silane compound, alkoxysilane is preferable, and trialkoxysilane and tetraalkoxysilane are more preferable. Examples of the above alkoxysilane include tetraethoxysilane (TEOS), tetramethoxysilane, tetraisopropoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, and the like. In the present invention, among these, TEOS, tetramethoxysilane, and tetraisopropoxysilane can be preferably used. These organic silane compounds can be used alone or in combination of two or more.

[0036] The compounding amount of the organosilane compound is preferably 0.1 to 10 times, more preferably 0.5 to 7 times, and even more preferably 1.0 to 5 times in terms of mass ratio with respect to the above conductive polymer, and when including an electron-accepting dopant substance described later, with respect to the total amount of the conductive polymer and the electron-accepting dopant substance. By setting the compounding amount of the organosilane compound within the above range, the stability of the obtained photoelectric conversion element can be improved.

[0037] In the perovskite photoelectric conversion element, the ionization potential of the hole collection layer is preferably a value close to the ionization potential of the p-type semiconductor material (perovskite semiconductor material) in the active layer. The absolute value of the difference is preferably 0 to 1 eV, more preferably 0 to 0.5 eV, and even more preferably 0 to 0.2 eV. Therefore, the charge transport composition of the present invention may contain an electron-accepting dopant substance for the purpose of adjusting the ionization potential of the charge transport thin film obtained by using this. The electron-accepting dopant substance is not particularly limited as long as it is soluble in at least one solvent to be used.

[0038] Specific examples of the electron-accepting dopant substance include inorganic strong acids such as hydrogen chloride, sulfuric acid, nitric acid, and phosphoric acid; Lewis acids such as aluminum(III) chloride (AlCl3), titanium(IV) chloride (TiCl4), boron tribromide (BBr3), boron trifluoride ether complex (BF3·OEt2), iron(III) chloride (FeCl3), copper(II) chloride (CuCl2), antimony(V) pentachloride (SbCl5), arsenic(V) pentafluoride (AsF5), phosphorus pentafluoride (PF5), tris(4-bromophenyl)aluminum hexachloroantimonate (TBPAH); organic strong acids such as benzenesulfonic acid, tosylic acid, hydroxybenzenesulfonic acid, 5-sulfosalicylic acid, dodecylbenzenesulfonic acid, polystyrenesulfonic acid, and camphorsulfonic acid; and organic oxidants such as 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and iodine. Among these, polystyrenesulfonic acid is preferred. These may be used alone or in combination of two or more.

[0039] In addition, other additives may be blended in the composition of the present invention as long as the object of the present invention can be achieved. As the type of the additive, it can be appropriately selected from known ones according to the desired effect and used.

[0040] As the solvent used for preparing the charge transport composition, a highly soluble solvent that can dissolve the conductive polymer and the electron-accepting dopant substance well can be used. The highly soluble solvent can be used alone or as a mixture of two or more, and the amount used can be 5 to 100% by mass based on the total amount of the solvent used in the composition.

[0041] Examples of such highly soluble solvents include organic solvents such as water; alcohol solvents such as ethanol, 2-propanol, 1-butanol, 2-butanol, s-butanol, t-butanol, 1-methoxy-2-propanol, etc., and amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Among these, at least one selected from water and alcohol solvents is preferred, and water, ethanol, and 2-propanol are more preferred.

[0042] Both the charge transport material and the electron-accepting dopant material are either completely dissolved in the above solvent or in a state of being uniformly dispersed.

[0043] The solid content concentration of the charge transport composition of the present invention is appropriately set in consideration of factors such as the viscosity and surface tension of the composition, and the thickness of the thin film to be produced, etc. Usually, it is about 0.1 to 20.0% by mass, preferably 0.5 to 15.0% by mass, and more preferably 1.0 to 10.0% by mass. Here, the solid content of the solid content concentration means components other than the solvent contained in the charge transport composition of the present invention.

[0044] Also, the mass ratio of the charge transport material to the electron-accepting dopant material is appropriately set in consideration of the charge transport properties to be exhibited, the types of charge transport materials, etc. Usually, for 1 of the charge transport material, the electron-accepting dopant material is 0 to 10, preferably 0.1 to 8.0, and more preferably 0.2 to 7.0.

[0045] And the viscosity of the charge transport composition used in the present invention is appropriately adjusted according to the coating method in consideration of factors such as the thickness of the thin film to be produced and the solid content concentration. Usually, it is about 0.1 to 50 mPa·s at 25°C.

[0046] When preparing the charge transport composition of the present invention, as long as the solid content is uniformly dissolved or dispersed in the solvent, the charge transport substance, the organosilane compound, the electron-accepting dopant substance, the solvent, etc. can be mixed in any order. That is, for example, after dissolving a polythiophene derivative as a conductive polymer in a solvent, dissolving an electron-accepting dopant substance in the solution, after dissolving an electron-accepting dopant substance in a solvent, dissolving a polythiophene derivative in the solution, or after mixing a polythiophene derivative and an electron-accepting dopant substance and then introducing the mixture into a solvent to dissolve it, any of these methods can be adopted as long as the solid content is uniformly dissolved or dispersed in the solvent.

[0047] Also, usually, the preparation of the charge transport composition is carried out in an inert gas atmosphere at normal temperature and pressure. However, as long as the compounds in the composition do not decompose or the composition does not change significantly, it may be carried out in an air atmosphere (in the presence of oxygen), or it may be carried out while heating.

[0048] The charge transport composition described above is Reverse In the case of a stacked perovskite solar cell, on the anode, Forward In the case of a stacked perovskite solar cell, by coating and firing on the active layer, the hole collection layer of the present invention can be formed. However, as a preferred embodiment in the present invention, Reverse It is of a stacked type. In coating, considering the viscosity and surface tension of the composition, the desired thickness of the thin film, etc., an optimal one can be selected from various wet process methods such as the drop casting method, spin coating method, blade coating method, dip coating method, roll coating method, bar coating method, die coating method, inkjet method, printing method (letterpress, intaglio, lithography, screen printing, etc.). Also, usually, the coating is carried out in an inert gas atmosphere at normal temperature and pressure. However, as long as the compounds in the composition do not decompose or the composition does not change significantly, it may be carried out in an air atmosphere (in the presence of oxygen), or it may be carried out while heating.

[0049] The film thickness is not particularly limited, but in any case, it is preferably about 0.1 to 500 nm, and more preferably about 1 to 100 nm. As a method for changing the film thickness, there are methods such as changing the solid content concentration in the composition or changing the amount of solution during coating.

[0050] Hereinafter, a method for manufacturing a perovskite solar cell using the charge transport composition of the present invention as a composition for forming a hole collection layer will be described, but it is not limited thereto. (1) Reverse Laminated perovskite solar cell [formation of anode layer]: A step of forming a layer of an anode material on the surface of a transparent substrate to manufacture a transparent electrode As the anode material, inorganic oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO), metals such as gold, silver, and aluminum, and highly charge-transporting organic compounds such as polythiophene derivatives and polyaniline derivatives can be used. Among these, ITO is most preferred. Further, as the transparent substrate, a substrate made of glass or a transparent resin can be used. The method for forming the layer of the anode material (anode layer) is appropriately selected according to the properties of the anode material. Usually, in the case of a poorly soluble, poorly dispersible sublimable material, a dry process such as a vacuum evaporation method or a sputtering method is selected, and in the case of a solution material or a dispersion material, considering the viscosity and surface tension of the composition, the desired thickness of the thin film, etc., the most suitable one is adopted from the above-described various wet process methods.

[0051] In addition, a commercially available transparent anode substrate can also be used. In this case, from the viewpoint of improving the yield of the device, it is preferable to use a substrate that has been subjected to a smoothing treatment. When using a commercially available transparent anode substrate, the method for manufacturing the perovskite solar cell of the present invention does not include the step of forming an anode layer. When forming a transparent anode substrate using an inorganic oxide such as ITO as the anode material, it is preferably washed with a detergent, alcohol, pure water, etc. before laminating the upper layer and then used. Further, it is preferably subjected to a surface treatment such as UV ozone treatment or oxygen-plasma treatment immediately before use. When the anode material is mainly composed of an organic substance, the surface treatment may not be performed.

[0052] [Formation of hole-trapping layer]: A step of forming a hole-trapping layer on the formed anode material layer According to the above method, a hole-trapping layer is formed on the anode material layer using the charge transport composition of the present invention

[0053] [Formation of active layer]: A step of forming an active layer on the formed hole-trapping layer In the present invention, as the active layer, an active layer containing a perovskite semiconductor compound is used The perovskite semiconductor compound refers to a semiconductor compound having a perovskite structure. As the perovskite semiconductor compound, known compounds can be used and are not particularly limited. For example, the general formula A + M 2+ X - represented by 3, or the general formula A + 2M 2+ X - represented by 4. Here, A + represents a monovalent cation, M 2+ represents a divalent cation, and X - represents a monovalent anion

[0054] Examples of the monovalent cation A + include cations containing Group 1 and Groups 13 to 16 elements of the periodic table. Among these, cesium ions, rubidium ions, ammonium ions that may have substituents, or phosphonium ions that may have substituents are preferred

[0055] Examples of the ammonium ion which may have a substituent include, for example, a primary ammonium ion or a secondary ammonium ion. The above-mentioned substituent is not particularly limited, but an alkylammonium ion or an arylammonium ion is preferable. In particular, in order to avoid steric hindrance, a monoalkylammonium ion having a three-dimensional crystal structure is more preferable. The number of carbon atoms of the alkyl group contained in the above alkylammonium ion is preferably 1 to 30, more preferably 1 to 20, and still more preferably 1 to 10. The number of carbon atoms of the aryl group contained in the above arylammonium ion is preferably 6 to 30, more preferably 6 to 20, and still more preferably 6 to 12.

[0056] Monovalent cation A + Specific examples thereof include methylammonium ion, ethylammonium ion, isopropylammonium ion, n-propylammonium ion, isobutylammonium ion, n-butylammonium ion, t-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium ion, guanidinium ion, formamidinium ion, acetamidinium ion, imidazolium ion and the like. The above cation A + can be used alone or in combination of two or more.

[0057] Divalent cation M 2+ is preferably a divalent metal cation or a metalloid cation, and more preferably a cation of a Group 14 element of the periodic table. Specific examples of the divalent cation M include a lead cation (Pb 2+ ), a tin cation (Sn 2+ ), a germanium cation (Ge 2+ ) and the like. In the present invention, from the viewpoint of obtaining a photoelectric conversion element having excellent stability, it is preferable to contain a lead cation. The above cation M 2+ can be used alone or in combination of two or more.

[0058] Monovalent anion X - Examples of the monovalent anion X include halide ions, acetate ions, nitrate ions, acetylacetonate ions, thiocyanate ions, and 2,4-pentanedionate ions, etc., and halide ions are preferred. The above anion X - can be used alone or in combination of two or more.

[0059] Examples of the halide ions include chloride ions, bromide ions, and iodide ions, etc. In the present invention, from the viewpoint of not overly widening the band gap of the semiconductor, it is preferable to contain iodide ions.

[0060] As the perovskite semiconductor compound, for example, an organic-inorganic perovskite semiconductor compound is preferred, and a halide-based organic-inorganic perovskite semiconductor compound is more preferred. Specific examples of the perovskite semiconductor compound include CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CH3NH3SnI3, CH3NH3SnBr3, CH3NH3SnCl3, CH3NH3PbI (3-x) Cl x 、CH3NH3PbI (3-x) Br x 、CH3NH3PbBr (3-x) Cl x 、CH3NH3Pb (1-y) Sn y I3、CH3NH3Pb (1-y) Sn y Br3、CH3NH3Pb (1-y) Sn y Cl3、CH3NH3Pb (1-y) Sn y I (3-x) Cl x 、CH3NH3Pb (1-y) Sn y I (3-x) Br x 、CH3NH3Pb (1-y) Sn y Br (3-x) Cl x and so on. Here, x represents any number from 0 to 3, and y represents any number from 0 to 1.

[0061] From the viewpoint of improving the photoelectric conversion efficiency, as the perovskite semiconductor compound, it is preferable to use a semiconductor compound having an energy band gap of 1.0 to 3.5 eV.

[0062] The active layer may contain two or more types of perovskite semiconductor compounds. For example, among the above A + , M 2+ and X - , two or more types of perovskite semiconductor compounds in which at least one of them is different may be included in the active layer.

[0063] From the viewpoint of obtaining good photoelectric conversion characteristics, the content of the perovskite semiconductor compound in the active layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. There is no particular limitation on the upper limit, but it is usually 100% by mass or less.

[0064] In addition, the active layer may contain other additives as necessary. Examples of the additives that can be used in the present invention include surfactants, charge imparting agents, 1,8-diiodooctane, N-cyclohexyl-2-pyrrolidone, and the like. From the viewpoint of obtaining good PCE, the content of these additives in the active layer is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. There is no particular limitation on the lower limit, but it is usually 0% by mass or more.

[0065] Similar to the above, the method for forming the active layer is also selected as the most suitable one from the various wet process methods described above in consideration of the viscosity and surface tension of the composition, the desired thickness of the thin film, and the like.

[0066] [Formation of electron collection layer]: The step of forming an electron collection layer on the formed active layer If necessary, an electron collection layer may be formed between the active layer and the cathode layer for the purpose of, for example, improving the efficiency of charge transfer. Examples of materials for forming the electron collection layer include fullerenes, lithium oxide (Li2O), magnesium oxide (MgO), alumina (Al2O3), lithium fluoride (LiF), sodium fluoride (NaF), magnesium fluoride (MgF2), strontium fluoride (SrF2), cesium carbonate (Cs2CO3), lithium 8 - quinolinolate (Liq), sodium 8 - quinolinolate (Naq), bathocuproine (BCP), 4,7 - diphenyl - 1,10 - phenanthroline (BPhen), polyethyleneimine (PEI), ethoxylated polyethyleneimine (PEIE), and the like.

[0067] Among fullerenes, fullerene and its derivatives are preferred, but not particularly limited. Specifically, fullerenes and their derivatives having a basic skeleton such as C60, C70, C76, C78, C84, etc. are included. In the fullerene derivative, the carbon atoms in the fullerene skeleton may be modified with any functional group, and these functional groups may be bonded to each other to form a ring. The fullerene derivative includes a fullerene - bonded polymer. A fullerene derivative having a functional group with high affinity for the solvent and high solubility in the solvent is preferred.

[0068] Examples of the functional group in the fullerene derivative include, for example, a hydrogen atom, a hydroxyl group, a halogen atom such as a fluorine atom or a chlorine atom, an alkyl group such as a methyl group or an ethyl group, an alkenyl group such as a vinyl group, a cyano group, an alkoxy group such as a methoxy group or an ethoxy group, an aromatic hydrocarbon group such as a phenyl group or a naphthyl group, an aromatic heterocyclic group such as a thienyl group or a pyridyl group, and the like. Specifically, hydrogenated fullerenes such as C60H36 and C70H36, oxide fullerenes such as C60 and C70, and fullerene metal complexes are included. As the fullerene derivative, it is more preferable to use methyl [6,6] - phenyl C61 butyrate (

[60] PCBM) or methyl [6,6] - phenyl C71 butyrate (

[70] PCBM).

[0069] The method for forming the electron collection layer is the same as above. When the electron collection material is a poorly soluble sublimable material, various dry processes described above are selected. When it is a solution material or a dispersion material, considering the viscosity and surface tension of the composition, the thickness of the desired thin film, etc., the most suitable one is adopted from the various wet process methods described above.

[0070] [Formation of cathode layer]: A step of forming a cathode layer on the formed electron collection layer Examples of the cathode material include metals such as aluminum, magnesium-silver alloy, aluminum-lithium alloy, lithium, sodium, potassium, cesium, calcium, barium, silver, and gold, inorganic oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO), and high charge transport organic compounds such as polythiophene derivatives and polyaniline derivatives. A plurality of cathode materials can be laminated or mixed for use. The method for forming the cathode layer is the same as above. When the cathode layer material is a poorly soluble and poorly dispersible sublimable material, various dry processes described above are selected. When it is a solution material or a dispersion material, considering the viscosity and surface tension of the composition, the thickness of the desired thin film, etc., the most suitable one is adopted from the various wet process methods described above.

[0071] [Formation of carrier blocking layer] If necessary, a carrier blocking layer may be provided between any layers for the purpose of controlling the rectification of the photocurrent, etc. When providing a carrier blocking layer, usually, an electron blocking layer is inserted between the active layer and the hole collection layer or the anode, and a hole blocking layer is inserted between the active layer and the electron collection layer or the cathode in many cases, but this is not the limit. Examples of the material for forming the hole blocking layer include titanium oxide, zinc oxide, tin oxide, bathocuproine (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen), etc. Examples of the material for forming the electron blocking layer include triarylamine-based materials such as N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (α-NPD) and poly(triarylamine) (PTAA).

[0072] The method for forming the carrier block layer is the same as above. When the carrier block layer material is a poorly soluble, poorly dispersible sublimable material, various dry processes described above are selected. When it is a solution material or a dispersion liquid material, considering the viscosity and surface tension of the composition, the thickness of the desired thin film, etc., the optimum one is adopted from among the various wet process methods described above.

[0073] (2) Forward Stacked perovskite solar cell [Formation of cathode layer]: A step of forming a layer of a cathode material on the surface of a transparent substrate to manufacture a transparent cathode substrate As the cathode material, in addition to those exemplified for the stacked anode material above, fluorine-doped tin oxide (FTO) can be mentioned. As the transparent substrate, those exemplified for the stacked anode material above can be mentioned. Reverse Reverse Reverse Regarding the method for forming the layer of the cathode material (cathode layer), when it is a poorly soluble, poorly dispersible sublimable material, the dry process described above is selected. When it is a solution material or a dispersion liquid material, considering the viscosity and surface tension of the composition, the thickness of the desired thin film, etc., the optimum one is adopted from among the various wet process methods described above. Also, in this case, a commercially available transparent cathode substrate can be preferably used. From the viewpoint of improving the yield of the device, it is preferable to use a substrate that has been subjected to a smoothing treatment. When using a commercially available transparent cathode substrate, the manufacturing method of the perovskite solar cell of the present invention does not include the step of forming the cathode layer. When forming a transparent cathode substrate using an inorganic oxide as the cathode material, Reverse The same cleaning treatment and surface treatment as those for the stacked anode material may be performed.

[0074] [Formation of electron collection layer]: A step of forming an electron collection layer on the formed cathode If necessary, an electron collection layer may be formed between the active layer and the cathode layer for the purpose of, for example, improving the efficiency of charge transfer. As the material for forming the electron collection layer, those described above ReverseIn addition to those exemplified by the laminated material, zinc oxide (ZnO), titanium oxide (TiO), tin oxide (SnO), etc. can be mentioned. Regarding the method for forming the electron collection layer, in the case of a poorly soluble, poorly dispersible sublimable material, the dry process described above is selected. In the case of a solution material or a dispersion material, considering the viscosity and surface tension of the composition, the desired thickness of the thin film, etc., the most suitable one is adopted from among the various wet process methods described above. Also, a method of forming a precursor layer of an inorganic oxide on the cathode using a wet process (particularly the spin coating method or the slit coating method) and then baking to form a layer of the inorganic oxide can also be adopted.

[0075] [Formation of the active layer]: The step of forming an active layer on the formed electron collection layer As the active layer, an active layer containing the perovskite semiconductor compound described above is formed. The method for forming the active layer is also the same as the method described for the laminated active layer above. Reverse

[0076] [Formation of the hole collection layer]: The step of forming a hole collection layer on the layer of the formed active layer material According to the above method, a hole collection layer is formed on the layer of the active layer material using the composition of the present invention.

[0077] [Formation of the anode layer]: The step of forming an anode layer on the formed hole collection layer As the anode material, the same ones as the laminated anode material described above can be mentioned. Also, as the method for forming the anode layer, Reverse it is the same as that of the laminated cathode layer. Reverse

[0078] [Formation of the carrier blocking layer] Reverse Similar to the laminated element, if necessary, a carrier blocking layer may be provided between any layers for the purpose of controlling the rectifying property of the photocurrent, etc. As the material for forming the hole blocking layer and the material for forming the electron blocking layer, the same ones as those described above can be mentioned. The method for forming the carrier blocking layer is also the same as that described above.

[0079] The perovskite solar cell device fabricated by the method exemplified above was introduced back into the glove box to perform a sealing operation in an inert gas atmosphere such as nitrogen in order to prevent device degradation due to the atmosphere, and it was possible to exhibit the function as a solar cell or measure the solar cell characteristics in the sealed state. As the sealing method, a concave glass substrate with a UV-curable resin attached to the end is attached to the film formation surface side of the perovskite solar cell device in an inert gas atmosphere, and the resin is cured by UV irradiation, or a film sealing type sealing is performed by a method such as sputtering under vacuum.

Examples

[0080] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The devices used are as follows. (1) Solar simulator: OTENTOSUN-III manufactured by Spectral Instruments Co., Ltd. (2) Source measure unit: 2401 manufactured by Keithley Instruments Co., Ltd. (3) Film thickness measurement device: DEKTAK XT manufactured by Bulker (4) Photoelectron spectrometer: AC-2 manufactured by Riken Keiki Co., Ltd.

[0081] [1] Preparation of composition for hole collection layer [Example 1-1] 2,462 mg of PEDOT-PSS (manufactured by Heraeus, model number AI4083, PEDOT:PSS = 1:6, solid content concentration: 1.3 to 1.7% by mass) was dissolved in 2,425 mg of ethanol, and 113 mg of TEOS (manufactured by Tama Chemical Industry Co., Ltd.) was added to prepare a dark blue solution. The obtained dark blue liquid was filtered through a 0.45 μm syringe filter to obtain a composition A for hole collection layer (solid content concentration: 3.0% by mass). The above solid content concentration is a value calculated by setting the solid content concentration of PEDOT:PSS to 1.5% by mass and taking the total amount of TEOS as the solid content (hereinafter the same).

[0082] [Example 1-2] A composition B for a hole collection layer (solid content concentration: 2.3% by mass) was obtained in the same manner as in Example 1, except that the amount of TEOS was changed to 80 mg.

[0083] [Example 1-3] A composition C for a hole collection layer (solid content concentration: 1.9% by mass) was obtained in the same manner as in Example 1, except that the amount of TEOS was changed to 60 mg.

[0084] [Example 1-4] A composition D for a hole collection layer (solid content concentration: 1.3% by mass) was obtained in the same manner as in Example 1, except that the amount of TEOS was changed to 30 mg.

[0085] [2] Fabrication and Evaluation of Perovskite Solar Cells [Example 2-1] Lead iodide (PbI2) and methylammonium iodide (CH3NH3I) were each dissolved in dimethyl sulfoxide (DMSO) at a concentration of 1 M to prepare a perovskite precursor solution. On the other hand, on a glass substrate formed with a positive electrode made of indium tin oxide (ITO) with a film thickness of 100 nm, the composition A for a hole collection layer was applied by spin coating and annealed at 200 °C to form a hole collection layer A with a film thickness of 71 nm. The substrate on which this hole collection layer was formed was carried into a glove box purged with nitrogen. Then, the precursor solution prepared above was dropped onto the hole collection layer A through a filter with a pore size of 0.45 μm, and after rotating the substrate at 500 rpm for 10 seconds and then at 6,000 rpm for 30 seconds for spin coating, a perovskite precursor film was formed. Next, an immersion tank filled with deoxygenated toluene (second solvent) was temperature-adjusted to 25 °C on a cool plate. While stirring this solvent, the substrate on which the perovskite precursor film was formed was immersed in the solvent for 2 minutes. Then, the substrate was taken out and annealed at 90 °C for 5 minutes to produce a perovskite film. On this perovskite film, by vacuum evaporation method, 1×10 -4An organic layer and an electrode were formed at a vacuum degree of Pa. First, on the perovskite film, fullerene (C 60 ) was deposited with a thickness of 30 nm, and on top of that, BCP was deposited with a thickness of 10 nm to form a two-layer organic layer. Further, Ag was deposited with a thickness of 100 nm on top of that to form an electrode. The obtained laminate (substrate / ITO anode / hole collection layer / perovskite film / C 60 layer / BCP layer / Ag cathode) was housed in a glass sealing tube and sealed with a UV curable resin to obtain a solar cell.

[0086] [Example 2-2] A solar cell was fabricated using the same procedure as in Example 2-1, except that Composition B for hole collection layer was used as the hole collection layer.

[0087] [Example 2-3] A solar cell was fabricated using the same procedure as in Example 2-1, except that Composition C for hole collection layer was used as the hole collection layer.

[0088] [Example 2-4] A solar cell was fabricated using the same procedure as in Example 2-1, except that Composition D for hole collection layer was used as the hole collection layer.

[0089] [Comparative Example 2-1] A solar cell was fabricated using the same procedure as in Example 2-1, except that PEDOT-PSS (manufactured by Heraeus, model number AI4083) was used as the hole collection layer.

[0090] [3]Characteristic Evaluation Regarding the perovskite solar cells fabricated in Examples 2-1 to 2-4 and Comparative Example 2-1 above, using a solar simulator, simulated sunlight of AM1.5 was irradiated at an irradiance of 100 mW / cm 2 , and the short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and PCE were evaluated. The results are shown in Table 1. Note that the PCE [%] was calculated by the following formula. PCE [%] = Jsc [mA / cm 2〕×Voc〔V〕×FF÷ Incident light intensity (100〔mW / cm 2 〕)×100

[0091]

Table 1

[0092] From the results in Table 1, it can be seen that by using the composition for the hole - collecting layer of the present invention, a perovskite solar cell having very stable characteristics can be obtained.

[0093] [4] Fabrication of a substrate with a hole - collecting layer for chemical resistance evaluation [Example 2 - 5] On a glass substrate on which a film made of indium tin oxide (ITO) with a thickness of 100 nm was formed, the composition A for the hole - collecting layer was applied by spin - coating, and a hole - collecting layer with a thickness of 71 nm was formed by annealing at 200 °C to fabricate a substrate with a hole - collecting layer. Three such substrates with a hole - collecting layer were fabricated.

[0094] [Comparative Example 2 - 2] A hole - collecting layer with a thickness of 40 nm was formed in the same procedure as in Example 2 - 5 except that PEDOT - PSS (manufactured by Heraeus, model number AI4083) was used as the composition for forming the hole - collecting layer to fabricate a substrate with a hole - collecting layer. Three such substrates with a hole - collecting layer were fabricated.

[0095] [5] Evaluation of chemical resistance 3 mL of dimethyl sulfoxide (DMSO) was dropped onto the hole - collecting layer of the substrate with a hole - collecting layer fabricated above, left standing for 10 seconds, and then spin - coated at 6,000 rpm for 30 seconds to form a DMSO liquid film. Thereafter, a DMSO - treated substrate was fabricated by drying at 200 °C for 10 minutes. Next, 3 mL of a DMSO solution of methylammonium iodide (MAI) adjusted to a concentration of 1 M was dropped onto the hole collection layer of another substrate with a hole collection layer, and after standing for 10 seconds, spin coating was performed at 6,000 rpm for 30 seconds to form an MAI(DMSO) liquid film on the hole collection layer. Further, after dropping 3 mL of DMSO and standing for 10 seconds, rinsing treatment was performed by spin coating at 6,000 rpm for 30 seconds while dropping 3 mL of DMSO. Next, an MAI(DMSO)-treated substrate was prepared by drying at 200 °C for 10 minutes. For the DMSO-treated substrate, MAI(DMSO)-treated substrate, and untreated substrate, the ionization potential of the hole collection layer was measured using a photoelectron spectrometer. The results are shown in Table 2.

[0096]

Table 2

[0097] From the results in Table 2, when the hole collection layer was formed using the composition of the comparative example, the ionization potential became shallower by 0.1 eV or more when exposed to MAI, whereas when the hole collection layer was formed using Composition A for the hole collection layer, the change in the ionization potential was small. The same tendency was also observed when exposed to DMSO.

Claims

1. An inverted perovskite photoelectric conversion device having an anode, a hole collection layer formed on the anode, and an active layer formed on the hole collection layer, wherein the hole collection layer comprises a charge transport material made of a conductive polymer, an organic silane compound, and a solvent, the conductive polymer is PEDOT-PSS, the organic silane compound is tetraalkoxysilane, the solvent contains water and at least one highly soluble solvent selected from the group consisting of ethanol, 2-propanol, 1-butanol, 2-butanol, s-butanol, t-butanol, and 1-methoxy-2-propanol, and is a thin film obtained from a charge transport composition for a perovskite photoelectric conversion device, and the active layer is a perovskite photoelectric conversion device containing a perovskite semiconductor compound.

2. The perovskite photoelectric conversion device according to claim 1, wherein the tetraalkoxysilane is at least one selected from the group consisting of tetraethoxysilane, tetramethoxysilane, and tetraisopropoxysilane.

3. A solar cell comprising the perovskite photoelectric conversion device according to claim 1 or 2.

4. A charge transport composition for a perovskite photoelectric conversion device for forming a hole collection layer of an inverted perovskite photoelectric conversion device having an anode, a hole collection layer formed on the anode, and an active layer formed on the hole collection layer, comprising a charge transport material made of a conductive polymer, an organic silane compound, and a solvent, the conductive polymer is PEDOT-PSS, the organic silane compound is tetraalkoxysilane, and the solvent contains water and at least one highly soluble solvent selected from the group consisting of ethanol, 2-propanol, 1-butanol, 2-butanol, s-butanol, t-butanol, and 1-methoxy-2-propanol.

5. The charge transport composition for a perovskite photoelectric conversion device according to claim 4, wherein the tetraalkoxysilane is at least one selected from the group consisting of tetraethoxysilane, tetramethoxysilane, and tetraisopropoxysilane.

6. The charge transporting composition for a perovskite photoelectric conversion element according to claim 4 or 5, wherein the compounding amount of the above-mentioned organic silane compound is 0.1 to 10 times in terms of mass ratio with respect to the above-mentioned conductive polymer.

7. The charge transporting composition for a perovskite photoelectric conversion element according to any one of claims 4 to 6, wherein the solid content concentration is 0.1 to 20.0% by mass.

8. The charge transporting composition according to any one of claims 4 to 7, wherein the above-mentioned perovskite photoelectric conversion element is a solar cell.

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