Photoelectric conversion element, its manufacturing method, and power generation device

Abstract

To provide a photoelectric conversion element, a manufacturing method thereof, and a power generation device in which peeling between a buffer layer and an active layer is suppressed.SOLUTION: A photoelectric conversion element 100 includes an active layer 103 and a buffer layer 104, and the buffer layer 104 is an organic semiconductor compound having a hole-transporting ability, containing a dopant, and having a structural unit represented by the formula (1). In the formula (1), X has at least one aromatic ring group in the main chain selected from divalent, optionally substituted, single aromatic ring groups and condensed aromatic ring groups, and R1 and R2 independently represent hydrogen or an optionally substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention mainly relates to a photoelectric conversion element, a manufacturing method thereof, and a power generation device. [Background technology]

[0002] Photoelectric conversion elements are known that have an active layer, a buffer layer, etc., disposed between a pair of electrodes. In order to improve the photoelectric conversion efficiency, the use of organic-inorganic hybrid semiconductor materials as the active layer has been considered, and in particular, compounds having a perovskite structure have attracted attention.

[0003] In such photoelectric conversion elements, an organic semiconductor compound or the like is used as a buffer layer having a hole transporting ability. Patent Document 1 discloses a technology relating to a photoelectric conversion element that achieves improved charge mobility and reduced ionization potential by using a hole transport material containing a specific enamine structure. Patent Document 2 discloses a technology relating to a photoelectric conversion element that achieves excellent retention of photoelectric conversion efficiency by using a specific polytriarylamine-based semiconductor compound. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-181882 A [Patent Document 2] JP 2019-175970 A Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in the above-mentioned Patent Documents 1 and 2, in the field of photoelectric conversion elements, materials for buffer layers have been developed with the aim of improving charge mobility, durability of photoelectric conversion efficiency, etc. While material development focusing on improving such electrical properties has been widely carried out, material development focusing on improving structural features has hardly been carried out, and there is room for improvement. Problems based on structural features include, for example, interlayer delamination. When delamination occurs between the buffer layer and the active layer, hole transport between the layers is suppressed, and the electrodes are not connected as designed, causing high resistance, insulation, or a decrease in parallel resistance, resulting in a decrease in photoelectric conversion efficiency. Therefore, an object of the present invention is to provide a photoelectric conversion element in which peeling between the buffer layer and the active layer is suppressed, a method for producing the same, and a power generation device including the photoelectric conversion element. [Means for solving the problem]

[0006] As a result of intensive research aimed at solving the above problems, the inventors have found that the above problems can be solved by incorporating an organic semiconductor compound having a specific structure in the buffer layer, and have thus completed the present invention.

[0007] Embodiments of the present invention include, but are not limited to, the following. [1] A pair of electrodes consisting of an upper electrode and a lower electrode; an active layer located between the pair of electrodes and containing an organic-inorganic hybrid semiconductor compound; A photoelectric conversion element having a buffer layer located between the pair of electrodes, The buffer layer contains an organic semiconductor compound having a hole transporting ability and a dopant for the organic semiconductor compound, The organic semiconductor compound has a structural unit represented by the following formula (1): Photoelectric conversion element. [ka] (In the above formula (1), X represents a group having at least one divalent aromatic ring group A selected from a divalent monoaromatic ring group which may have a substituent and a divalent fused aromatic ring group which may have a substituent in at least the main chain, and the number of divalent aromatic ring groups A which are consecutively bonded to each other in the main chain is 3 or less; R 1 and R 2 each independently represents hydrogen or an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. [2] The photoelectric conversion element according to [1], wherein the number of divalent aromatic ring groups A connected consecutively by bonding to each other in the main chain of X in the formula (1) is 2 or less. [3] The photoelectric conversion element according to [1] or [2], wherein X in the formula (1) has a biphenylene group, which may have a substituent, at least in the main chain. [4] The photoelectric conversion element according to any one of [1] to [3], characterized in that the group constituting the main chain of X in the formula (1) is composed of one or more groups selected from the group consisting of a methylene group in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group, a divalent amino group substituted with a monovalent aromatic hydrocarbon ring group, and the divalent aromatic ring group A. [5] The photoelectric conversion element according to any one of [1] to [4], characterized in that the proportion of the total weight of structural units that can be represented by the structural unit represented by formula (1) in one molecule of the organic semiconductor compound is 5% by weight or more and 95% by weight or less. [6] The photoelectric conversion element according to any one of [1] to [5], wherein the structural unit represented by the formula (1) is a repeating structural unit represented by the following formula (2): [ka] (In the above formula (2), X, R 1 and R 2 represents X and R in the formula (1). 1 and R 2 and n represents 1 to 10,000. [7] The dopant is an organic compound containing trivalent iodine, The photoelectric conversion element according to any one of items 1] to [6]. [8] The photoelectric conversion element according to [7], wherein the dopant is a diaryliodonium salt. [9] The photoelectric conversion element according to any one of [1] to [8], wherein the organic-inorganic hybrid semiconductor compound is a compound having a perovskite structure.

[10] A method for producing a photoelectric conversion element according to any one of [1] to [9], a lamination step of laminating at least the pair of electrodes, the active layer, and the buffer layer to obtain a laminate; and A method for producing a photoelectric conversion element, comprising a serialization step of serializing the laminate by laser processing.

[11] A power generation device comprising the photoelectric conversion element according to any one of [1] to [9]. Effect of the Invention

[0008] According to the present invention, it is possible to provide a photoelectric conversion element in which peeling between the buffer layer and the active layer is suppressed, a manufacturing method thereof, and an energy harvesting device having the photoelectric conversion element, particularly an energy harvesting device for low illumination intensity. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view that illustrates a schematic diagram of a photoelectric conversion element according to an embodiment. [Diagram 2] 1 is a cross-sectional view illustrating a schematic diagram of a solar cell according to an embodiment. [Diagram 3] 1 is a cross-sectional view illustrating a schematic diagram of a solar cell module according to an embodiment. [Figure 4] FIG. 13 is a diagram for explaining scribing by laser irradiation in an embodiment. [Diagram 5] 1 is an optical microscope image of a processed surface that was scribed by laser irradiation of a laminate produced in an example (a photograph substituting a drawing). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. In addition, the present invention can be modified and carried out as desired without departing from the gist of the present invention. In this specification, the notation "~" indicates a range including the numbers before and after it. In addition, when describing two or more objects together, the term "independently" is used to mean that the two or more objects may be the same or different.

[0011] <1. Photoelectric conversion element> The photoelectric conversion element according to one embodiment of the present invention (also simply referred to as a "photoelectric conversion element") is A pair of electrodes including an upper electrode and a lower electrode; an active layer located between the pair of electrodes and containing an organic-inorganic hybrid semiconductor compound; A photoelectric conversion element having a buffer layer located between the pair of electrodes, The buffer layer contains an organic semiconductor compound having a hole transporting ability and a dopant for the organic semiconductor compound, The photoelectric conversion element is characterized in that the organic semiconductor compound has a structural unit represented by formula (1) described below.

[0012] Fig. 1 is a cross-sectional view showing a schematic example of a photoelectric conversion element according to the present embodiment. In the photoelectric conversion element 100 shown in Fig. 1, a lower electrode 101, an active layer 103, and an upper electrode 105 are arranged in this order. In the photoelectric conversion element 100, a buffer layer 102 existing between the lower electrode 101 and the active layer 103 is made of an organic semiconductor compound having a hole transporting ability and and a hole transport layer containing a dopant for the organic semiconductor compound. However, the photoelectric conversion element 100 may have a buffer layer 104 between the upper electrode 105 and the active layer 103, and in this case, the buffer layer 104 may be the hole transport layer. As shown in FIG. 1, the photoelectric conversion element 100 may have a base material 106, and may have other layers such as an insulator layer and a work function tuning layer.

[0013] [1-1. Buffer layer] The photoelectric conversion element has a buffer layer located between a pair of electrodes, and the buffer layer containing the organic semiconductor compound having hole transport ability and a dopant for the organic semiconductor compound is a layer serving as a hole transport layer, and as described above, in FIG. 1, it is the buffer layer 102 or the buffer layer 104 located between the active layer 103 and at least one of the pair of electrodes 101 and 105. However, when forming the hole transport layer by a coating method, the active layer 103 may be immersed in the coating solvent and may affect the active layer 103, so that the hole transport layer is preferably located between the lower electrode 101 and the active layer 103. The buffer layer other than the hole transport layer may be a layer serving as an electron transport layer. Note that the buffer layer provided between the anode and the active layer may be called a hole transport layer, and the buffer layer provided between the cathode and the active layer may be called an electron transport layer.

[0014] [1-1-1. Buffer layer (hole transport layer)] The buffer layer as a hole transport layer is not particularly limited as long as it contains an organic semiconductor compound having hole transport ability and a dopant for the organic semiconductor compound, and may contain other substances within the range in which the effects of the present invention can be obtained. In the case of a nip stacked photoelectric conversion element, the hole transport layer makes it easy to control the amount of transported charges. Hereinafter, in this section, the buffer layer is also referred to as the hole transport layer.

[0015] (Organic semiconductor compounds) The organic semiconductor compound having a hole transporting ability contained in the buffer layer (hole transport layer) is not particularly limited as long as it has a structural unit represented by the following formula (1).

[0016] [ka]

[0017] In the above formula (1), X represents a group having at least one divalent aromatic ring group A selected from a divalent monoaromatic ring group which may have a substituent and a divalent fused aromatic ring group which may have a substituent in at least the main chain, and the number of divalent aromatic ring groups A which are continuous by bonding to each other in the main chain is 3 or less, but from the viewpoint of suppressing peeling (interlayer peeling) between the active layer and the hole transport layer, the number of continuous divalent aromatic ring groups A is preferably 2 or less. When the number of divalent aromatic ring groups A which are continuous by bonding to each other in the main chain of X is 3 or less, Since the organic semiconductor compound becomes flexible, the hole transport layer flexibly deforms in accordance with the deformation of the active layer that occurs during processing and other steps in the manufacture of the photoelectric conversion element, peeling between the hole transport layer and the active layer can be suppressed. The divalent aromatic ring A is at least one group selected from a divalent monoaromatic ring group which may have a substituent, and a divalent condensed aromatic ring group which may have a substituent. Examples of the divalent monoaromatic ring group include a phenylene group, a furanylene group, a thiophenylene group, a pyrrolene group, a pyrazolene group, an imidazolene group, an oxadiazolene group, a pyridinylene group, a pyrazinylene group, a pyridazinylene group, a pyrimidinylene group, and a triazinylene group. Examples of the divalent condensed aromatic ring group include a naphthalenylene group, an anthracenylene group, a phenanthrenylene group, a dihydrophenanthrenylene group, a triphenylenylene group, an acenaphthenylene group, a fluoranthenylene group, a naphthacenylene group, a fluorenylene group, a spirobifluorenylene group, a pyrenylene group, a perylenylene group, a chrysenylene group, an indenylene group, a fluoranthenylene group, a benzofluoranthenylene group, a benzofuranylene group, a benzothiophenylene group, an indolene group, a carbazolenylene group, Examples of such an alkyl group include a pyrroloimidazolene group, a pyrrolopyrazolene group, a pyrrolopyrrolene group, a thienopyrrolene group, a thienothiophenylene group, a furopyrrolene group, a furofuranylene group, a thienofuranylene group, a benzoisoxazolene group, a benzoisothizolene group, a benzimidazolene group, a quinolenyl group, a isoquinolinylene group, a cinolinylene group, a quinoxalenylene group, a phenanthridinylene group, a benzimidazolene group, a perimidinylene group, a quinazolinylene group, a quinazolinonylene group, and an azulenylene group. Among the above divalent monoaromatic ring group and divalent condensed aromatic ring group, the divalent aromatic ring A is preferably a phenyl group which may have a substituent from the viewpoint of suppressing delamination, and particularly preferably a phenyl group which does not have a substituent. Since the molecular size of the condensed aromatic ring group is larger than that of the phenylene group and the flexibility is low, delamination is likely to occur, so it is preferable that the organic semiconductor compound does not have a condensed aromatic ring group. However, when comparing the reduction in flexibility caused by X having a condensed aromatic ring group with the reduction in flexibility caused by X having a group in which the number of consecutive divalent aromatic ring groups A is 4 or more by bonding to each other in the main chain, the reduction in flexibility caused by the latter reason is greater. In addition, in the formula (1), from the viewpoints of adjusting the HOMO while ensuring molecular flexibility, it is preferable that X has a biphenylene group in the main chain in which two phenylene groups are bonded to each other.

[0018] In the present specification, the substituent in the expression of an alkyl group which may have a substituent or an aliphatic hydrocarbon group which may have a substituent includes a halogeno group, -C≡N, -NH3, -C(=O)OH, -C(=O)OR', -C(=O)R', -SH, -SiRa R b R c , -BH, -SeH, a monovalent aliphatic hydrocarbon ring group, a monovalent aromatic hydrocarbon ring group, a monovalent aromatic heterocyclic group, or the like, or a combination thereof; R', R a , R b , R c each independently represents hydrogen or an alkyl group having 1 to 20 carbon atoms. Except for the expression of an alkyl group which may have a substituent, or an aliphatic hydrocarbon group which may have a substituent, the substituent in the expression "which may have a substituent" is a halogeno group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, an alkynyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, -C≡N, -NH3, -C(=O)OH, -C(=O)OR', -C(=O)R', -SH, -SiR a R b R c , -BH, -SeH, a monovalent aliphatic hydrocarbon ring group, a monovalent aromatic hydrocarbon ring group, a monovalent aromatic heterocyclic group, or the like, or a combination thereof; R', R a , R b , R c each independently represents hydrogen or an alkyl group having 1 to 20 carbon atoms.

[0019] The group constituting the main chain of X in formula (1) is a methylene group having at least one hydrogen atom substituted with a monovalent aromatic hydrocarbon ring group, a divalent amino group having at least one hydrogen atom substituted with a monovalent aromatic hydrocarbon ring group, group, and the divalent aromatic ring group A. The type of the monovalent aromatic hydrocarbon ring group is not particularly limited, and can be, for example, a group derived from a 6-membered single ring or 2-5 condensed rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring, or a group having a substituent thereof. From the viewpoint of suppressing delamination, however, a phenyl group or a p-tolyl group is preferable.

[0020] In the above formula (1), R 1 and R 2 each independently represents hydrogen or an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. From the viewpoint of suppressing delamination, R 1 and R 2 At least one of R is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, 1 and R 2 are each preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and further preferably R 1 and R 2 are preferably the same. The number of carbon atoms in the aliphatic hydrocarbon group having 1 to 20 carbon atoms is preferably 2 to 16, more preferably 3 to 12, further preferably 4 to 9, and particularly preferably 5 to 7, from the viewpoint of suppressing delamination.

[0021] The proportion of the total weight of structural units that can be represented by the structural unit represented by formula (1) in one molecule of the organic semiconductor compound is not particularly limited, but from the viewpoint of suppressing delamination, it is usually 5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more, and may be 100% by weight or less, or may be 95% by weight or less.

[0022] The structural unit represented by the above formula (1) is preferably a repeating structural unit represented by the following formula (2).

[0023] [ka]

[0024] In the above formula (2), X and R 1 and R 2 represents X and R in the above formula (1), including the preferred conditions. 1 and R 2 is synonymous with. In the above formula (2), n represents 1 to 10,000, and from the viewpoint of suppressing delamination, it is preferably 2 to 10,000, more preferably 3 to 10,000, even more preferably 4 to 10,000, and particularly preferably 5 to 10,000. In this specification, when there are multiple types of structures that can be described as structures constituting formula (2), each is treated as a separate structural unit. For example, A-((B) p -(C) q ) r In the case of the structure represented by -D, n above is p or q, and not r.

[0025] Specifically, the organic semiconductor compound having the structural unit represented by the above formula (2) can be a compound having the following structure: In these formulas, n has the same meaning as n in the above formula (2).

[0026] [ka]

[0027] [ka]

[0028] The number average molecular weight (Mn) of the organic semiconductor compound is not particularly limited, but from the viewpoint of suppressing interlayer delamination and ensuring solubility in a solvent, it is usually 5,000 or more, preferably 5,500 or more, more preferably 6,000 or more, even more preferably 6,500 or more, and particularly preferably 7,000 or more, and is usually 100,000 or less, preferably 90,000 or less, more preferably 80,000 or less, even more preferably 70,000 or less, and particularly preferably 60,000 or less. The weight average molecular weight (Mw) of the organic semiconductor compound is not particularly limited, but from the viewpoint of suppressing interlayer delamination and ensuring solubility in a solvent, it is usually 5,000 or more, preferably 5,500 or more, more preferably 6,000 or more, even more preferably 6,500 or more, and particularly preferably 7,000 or more, and is usually 100,000 or less, preferably 95,000 or less, and more preferably 90,000 or less. It is preferably 85,000 or less, more preferably 85,000 or less, and particularly preferably 80,000 or less.

[0029] The content of the organic semiconductor compound in the hole transport layer is not particularly limited, but from the viewpoint of suppressing delamination, it is usually 5% by weight or more, preferably 10% by weight or more, more preferably 20% by weight or more, even more preferably 30% by weight or more, particularly preferably 40% by weight or more, and may be 100% by weight or less. When the photoelectric conversion element has a plurality of buffer layers, it is sufficient that any one of the layers corresponding to the hole transport layer satisfies the above content range.

[0030] The synthesis method of the above-mentioned organic semiconductor compound is not particularly limited, and can be synthesized by combining known methods. For example, it can be synthesized by a method such as that described in JP-A-2009-263665, and can be synthesized by oxidative polymerization of triarylamine monomers or coupling reaction using a transition metal catalyst.

[0031] The content and structure of the components in the hole transport layer, including the organic semiconductor compound having the structural unit represented by the above formula (1) and the dopant described below, are, for example, 1 It can be analyzed by H-NMR.

[0032] (Dopant) The buffer layer as a hole transport layer contains a dopant for the organic semiconductor compound, but the form is not particularly limited. The dopant is a substance for optimizing the electrical conductivity and hole transport ability of the hole transport layer with respect to the active layer. Substances that can be used as dopants include boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, and organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane. The dopant preferably undergoes a charge transfer reaction with at least one organic semiconductor compound before or after the formation of the hole transport layer. As the dopant, a hypervalent iodine compound is preferred in that it has excellent solubility and produces an electron-accepting active site that functions as an oxidizing agent by heating or the like.

[0033] It is known that the hypervalent iodine compound acts as a dopant for an organic semiconductor compound and exhibits electron-accepting properties (i.e., acts as an oxidizing agent). In addition, an electron-accepting dopant can improve the electrical conductivity or hole transport ability of a semiconductor compound by removing electrons from the semiconductor compound. In this way, the hypervalent iodine compound can improve the charge transport properties of a semiconductor compound.

[0034] A hypervalent iodine compound is a compound containing hypervalent iodine, and is defined as a compound containing iodine with an oxidation number of +3 or more. For example, the dopant can be an iodine(III) compound or an iodine(V) compound. An iodine(V) compound containing pentavalent iodine can be, for example, a periodinane compound such as Dess-Martin periodinane. In addition, an iodine(III) compound containing trivalent iodine can be a compound having a structure in which iodobenzene is oxidized, such as (diacetoxyiodo)benzene, or a diaryliodonium salt. In terms of showing good electron accepting properties and being less likely to cause a reverse reaction when the molecule is destroyed in the oxidation process, the dopant is preferably an organic compound containing trivalent iodine, and more preferably a diaryliodonium salt.

[0035] Diaryliodonium salts are compounds in which the + -Ar]X - Here, each of the two Ar represents an aryl group. The aryl group (aromatic group) is not particularly limited, and may be, for example, any of those already listed for the organic semiconductor compound. X - is any Represents an anion. X - Examples of the anion include a halide ion, a trifluoroacetate ion, a tetrafluoroborate ion, and a tetrakis(pentafluorophenyl)borate ion. X- is preferably an anion having a fluorine atom, since it has high solubility and the reaction for producing the coating liquid can proceed smoothly.

[0036] Preferred examples of the dopant include those represented by general formula (I). In formula (I), X - represents any anion, specific examples of which are as described above. [R 11 -I + -R 12 ]X - (I)

[0037] In formula (I), R 11 and R 12are each independently a monovalent organic group. Examples of the monovalent organic group include an aliphatic group or an aromatic group. Examples of the aliphatic group include an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aliphatic heterocyclic group having 4 to 20 carbon atoms. For example, the aliphatic group may be an alkyl group including a cycloalkyl group, an alkenyl group, or an alkynyl group, and specific examples thereof include a methyl group, an ethyl group, a butyl group, a cyclohexyl group, or a tetrahydrofuryl group.

[0038] Examples of the aromatic group include an aromatic hydrocarbon group having 6 to 20 carbon atoms and an aromatic heterocyclic group having 2 to 20 carbon atoms. For example, the aromatic group includes a phenyl group, a naphthyl group, a biphenyl group, a thienyl group, a pyridyl group, and the like.

[0039] The aliphatic and aromatic groups may have a substituent, which is not particularly limited and may include a halogen atom, a hydroxyl group, a cyano group, an amino group, a carboxyl group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a thio group, a seleno group, an aromatic hydrocarbon group, and an aromatic heterocyclic group.

[0040] R 11 and R 12 R is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably a phenyl group. Here, it is preferable that the aromatic hydrocarbon group does not have a substituent or has an alkyl group having 1 to 6 carbon atoms. 11 and R 12 is particularly preferably a phenyl group having an alkyl group at the para position.

[0041] The content of the dopant in the hole transport layer is not particularly limited, but from the viewpoint of imparting electrical conductivity, it is usually 0.001% by weight or more, preferably 0.002% by weight or more, more preferably 0.003% by weight or more, even more preferably 0.004% by weight or more, particularly preferably 0.005% by weight or more, and may be 100% by weight or less. In addition, in the hole transport layer, the content ratio of the dopant to the organic semiconductor compound having a structural unit represented by the above formula (1) (dopant / organic semiconductor compound) is not particularly limited, but from the viewpoint of imparting electrical conductivity and hole transport ability, it is usually 0.001 or more, preferably 0.002 or more, more preferably 0.003 or more, even more preferably 0.004 or more, and particularly preferably 0.005 or more, and is usually 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. When the photoelectric conversion element has a plurality of buffer layers, it is sufficient that any one of the layers corresponding to the hole transport layer satisfies the above content range.

[0042] (Other substances) The buffer layer serving as a hole transport layer may contain substances other than the above organic semiconductor compound and dopant, for example, a crosslinking agent, a curing agent, a thickener, and the like.

[0043] [1-1-2. Buffer layer (electron transport layer)] The photoelectric conversion element may have a buffer layer as an electron transport layer in addition to the above-mentioned buffer layer as a hole transport layer. The mode is not particularly limited, and any material capable of improving the efficiency of extracting electrons from the active layer to the cathode may be used, and known materials may be used. Specifically, inorganic compounds, organic compounds, or organic-inorganic perovskite compounds according to the present invention described in known documents such as WO 2013 / 171517, WO 2013 / 180230, or JP 2012-191194 may be mentioned. For example, inorganic compounds include salts of alkali metals such as lithium, sodium, potassium, or cesium, and metal oxides such as zinc oxide, titanium oxide, aluminum oxide, or indium oxide. Examples of the organic compound include bathocuproine (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato)aluminum (Alq3), boron compounds, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic anhydride (NTCDA), perylenetetracarboxylic anhydride (PTCDA), fullerene compounds, and phosphine compounds having a double bond with an element of Group 16 of the periodic table, such as phosphine oxide compounds or phosphine sulfide compounds.

[0044] The thickness of the buffer layer as a hole transport layer and the thickness of the buffer layer as an electron transport layer are not particularly limited and can be appropriately set depending on the application, but in one embodiment, they can be 0.5 nm or more, in another embodiment, 1 nm or more, and in yet another embodiment, 5 nm or more, while in one embodiment, they can be 1 μm or less, in another embodiment, 500 nm or less, in another embodiment, 200 nm or less, and in yet another embodiment, 150 nm or less. When the film thickness of the buffer layer is within the above range, the mobility efficiency of carriers of holes and electrons is easily improved, and the photoelectric conversion efficiency can be improved.

[0045] In addition, the buffer layer as the hole transport layer and the buffer layer as the electron transport layer are not limited in the layer formation method, and the formation method can be selected according to the characteristics of the material. For example, the buffer layer can be formed by preparing a coating solution containing the above-mentioned organic semiconductor compound, a dopant, and a solvent, and using a wet film formation method such as a spin coating method or an inkjet method. The buffer layer can also be formed by a dry film formation method such as a vacuum deposition method.

[0046] [1-2.Active layer] The photoelectric conversion element 100 is located between a pair of electrodes, contains an organic-inorganic hybrid semiconductor compound, and has an active layer 103 that performs photoelectric conversion. When the photoelectric conversion element 100 receives light, the light is absorbed by the active layer 103 to generate carriers, and the generated carriers are extracted from the lower electrode 101 and the upper electrode 105. An organic-inorganic hybrid semiconductor material refers to a material in which an organic component and an inorganic component are combined at the molecular level or nano level, and which exhibits semiconductor properties.

[0047] The organic-inorganic hybrid semiconductor material is preferably a compound having a perovskite structure (hereinafter, sometimes referred to as a perovskite semiconductor compound). The perovskite semiconductor compound refers to a semiconductor compound having a perovskite structure. There are no particular limitations on the perovskite semiconductor compound, but examples of the perovskite semiconductor compound include those described in Galasso et al. The perovskite semiconductor compound can be selected from those listed in Structure and Properties of Inorganic Solids, Chapter 7 - Perovskite type and related structures. For example, the perovskite semiconductor compound can be an AMX3 type compound represented by the general formula AMX3, or an A2MX4 type compound represented by the general formula A2MX4. Here, M represents a divalent cation, A represents a monovalent cation, and X represents a monovalent anion.

[0048] There is no particular limitation on the monovalent cation A, but those described in the above book by Galasso can be used. More specific examples include cations containing elements of Groups 1 and 13 to 16 of the periodic table. Among these, cesium ion, rubidium ion, potassium ion, ammonium ion which may have a substituent, or phosphonium ion which may have a substituent are preferred. Examples of ammonium ions which may have a substituent include primary ammonium ions and secondary ammonium ions. There is no particular limitation on the substituent. Specific examples of ammonium ions which may have a substituent include alkylammonium ions and arylammonium ions. In particular, in order to avoid steric hindrance, monoalkylammonium ions which form a three-dimensional crystal structure are preferred, and from the viewpoint of improving stability, it is preferred to use alkylammonium ions substituted with one or more fluorine groups. In addition, a combination of two or more types of cations can be used as the cation A.

[0049] Specific examples of the monovalent cation A include a methylammonium ion, a methylammonium monofluoride ion, a methylammonium difluoride ion, a methylammonium trifluoride ion, an ethylammonium ion, an isopropylammonium ion, an n-propylammonium ion, an isobutylammonium ion, an n-butylammonium ion, a t-butylammonium ion, a dimethylammonium ion, a diethylammonium ion, a phenylammonium ion, a benzylammonium ion, a phenethylammonium ion, a guanidinium ion, a formamidinium ion, an acetamidinium ion, and an imidazolium ion.

[0050] There is no particular limitation on the divalent cation M, but it is preferably a divalent metal cation or semimetal cation. Specific examples include cations of elements in Group 14 of the periodic table, and more specific examples include lead cations (Pb 2+ ), tin cation (Sn 2+ ), germanium cation (Ge 2+) can be mentioned. In addition, a combination of two or more kinds of cations can be used as the cation M. From the viewpoint of obtaining a stable photoelectric conversion element, it is particularly preferable to use a lead cation or two or more kinds of cations including a lead cation.

[0051] Examples of monovalent anions X include halide ions, acetate ions, nitrate ions, sulfate ions, borate ions, acetylacetonate ions, carbonate ions, citrate ions, sulfur ions, tellurium ions, thiocyanate ions, titanate ions, zirconate ions, 2,4-pentanedionate ions, and silicofluoride ions. In order to adjust the band gap, X may be one type of anion or a combination of two or more types of anions. In one embodiment, X may be a halide ion, or a combination of a halide ion and another anion. Examples of halide ions X include chloride ions, bromide ions, and iodide ions. From the viewpoint of not widening the band gap of the semiconductor too much, it is preferable to mainly use iodide ions or bromide ions, but iodide ions and bromide ions may be combined in an appropriate ratio.

[0052] Preferred examples of the perovskite semiconductor compound include organic-inorganic perovskite semiconductor compounds, particularly halide-based organic-inorganic perovskite semiconductor compounds. 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 , and CH3NH3Pb (1-y) Sn y Br ( 3-x) Cl x and the above compounds in which CFH2NH3, CF2HNH3, or CF3NH3 is used instead of CH3NH3. Here, x is an arbitrary value of 0 or more and 3 or less, and y is an arbitrary value of 0 or more and 1 or less.

[0053] The active layer 103 may contain two or more kinds of perovskite semiconductor compounds. For example, two or more kinds of perovskite semiconductor compounds in which at least one of A, B, and X is different may be included in the active layer 103. The active layer 103 may also have a laminated structure formed of a plurality of layers containing different materials or having different components.

[0054] The amount of the perovskite semiconductor compound contained in the active layer 103 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, so that good semiconductor characteristics can be obtained. There is no particular upper limit. The active layer 103 may contain an additive in addition to the perovskite semiconductor compound. Examples of the additive include inorganic compounds such as halides, oxides, or inorganic salts such as sulfides, sulfates, nitrates, or ammonium salts, or organic compounds.

[0055] There is no particular limit to the thickness of the active layer 103. In terms of being able to absorb more light, the thickness of the active layer 103 is 10 nm or more in one embodiment, 50 nm or more in another embodiment, 100 nm or more in yet another embodiment, and 120 nm or more in yet another embodiment. On the other hand, in terms of reducing the series resistance or increasing the charge extraction efficiency, the thickness of the active layer 103 is 1500 nm or less in one embodiment, 1200 nm or less in another embodiment, and 800 nm or less in yet another embodiment.

[0056] The method for forming the active layer 103 is not particularly limited, and any method can be used. Specific examples include a coating method and a vapor deposition method (or a co-evaporation method). The coating method can be used because the active layer 103 can be easily formed. For example, a method can be used in which a coating liquid containing a perovskite semiconductor compound or a precursor thereof is applied, and the active layer 103 is formed by heating and drying as necessary. In addition, after applying such a coating liquid, a solvent in which the perovskite semiconductor compound has low solubility can be further applied to precipitate the perovskite semiconductor compound.

[0057] The precursor of the perovskite semiconductor compound refers to a material that can be converted into a perovskite semiconductor compound after the coating liquid is applied. As a specific example, a perovskite semiconductor compound precursor that can be converted into a perovskite semiconductor compound by heating can be used. For example, a coating liquid can be prepared by mixing a compound represented by the general formula AX, a compound represented by the general formula MX2, and a solvent, and heating and stirring the mixture. By applying this coating liquid and drying it by heating, an active layer 103 containing a perovskite semiconductor compound represented by the general formula AMX3 can be prepared. The solvent is not particularly limited as long as it dissolves the perovskite semiconductor compound and the additives, and examples thereof include organic solvents such as N,N-dimethylformamide.

[0058] Any method can be used as a method for applying the coating liquid, and examples thereof include spin coating, inkjet coating, doctor blade coating, drop casting, reverse roll coating, gravure coating, kiss coating, roll brush coating, spray coating, air knife coating, wire barber coating, pipe doctor coating, impregnation / coating, and curtain coating.

[0059] [1-3. Electrode] The photoelectric conversion element 100 has a pair of electrodes. The electrodes have a function of collecting holes and electrons generated by light absorption in the active layer 103. The photoelectric conversion element 100 has a pair of electrodes. One of the pair of electrodes is called the upper electrode and the other is called the lower electrode. When the photoelectric conversion element 100 has a substrate or is provided on a substrate, the electrode closer to the substrate can be called the lower electrode and the electrode farther from the substrate can be called the upper electrode. Also, a transparent electrode can be called the lower electrode and an electrode less transparent than the lower electrode can be called the upper electrode. The photoelectric conversion element 100 shown in FIG. 1 has a lower electrode 101 and an upper electrode 105.

[0060] The pair of electrodes may be an anode suitable for collecting holes and a cathode suitable for collecting electrons. In this case, the photoelectric conversion element 100 may have a forward configuration in which the lower electrode 101 is an anode and the upper electrode 105 is a cathode, or may have an inverted configuration in which the lower electrode 101 is a cathode and the upper electrode 105 is an anode.

[0061] Depending on the application, one or both of the pair of electrodes may be light-transmitting. Light-transmitting means that 40% or more of sunlight is transmitted through the electrode. In addition, it is preferable that the sunlight transmittance of the transparent electrode is 70% or more, so that more light passes through the transparent electrode and reaches the active layer 103. The light transmittance can be measured with a spectrophotometer (for example, U-4100 manufactured by Hitachi High-Technologies Corporation).

[0062] There are no particular limitations on the constituent members and manufacturing method of the lower electrode 101 and the upper electrode 105, or the anode and the cathode, and well-known techniques can be used. For example, the members and manufacturing methods described in known documents such as WO 2013 / 171517, WO 2013 / 180230, or JP 2012-191194 A can be used.

[0063] [1-4. Base material] The photoelectric conversion element 100 usually has a substrate 106 that serves as a support. However, the photoelectric conversion element according to this embodiment does not necessarily have to have the substrate 106. The material of the substrate 106 is not particularly limited as long as it does not significantly impair the effects of the present invention, and for example, materials described in publicly known documents such as WO 2013 / 171517, WO 2013 / 180230, or JP 2012-191194 A can be used.

[0064] <2. Method for manufacturing photoelectric conversion element> A method for manufacturing a photoelectric conversion element according to another embodiment of the present invention (also simply referred to as a "method for manufacturing a photoelectric conversion element") is a method for manufacturing the above-mentioned photoelectric conversion element, characterized in that it includes a stacking step of stacking at least the pair of electrodes, the active layer, and the buffer layer to obtain a stack, and a serialization step of serializing the stack by laser processing. The above-mentioned manufacturing method may include a step other than the above-mentioned lamination step and serialization step.

[0065] [Lamination process] The method for laminating each layer is not particularly limited. For example, each layer can be laminated by coating on a substrate, and then heated to dry and laminate. The coating method is not particularly limited, and examples thereof include wire bar coating, blade coating, die coating, reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, pipe doctor coating, impregnation coating, curtain coating, flexographic printing, and inkjet printing. The heating (also called annealing) conditions are not particularly limited, and the heating temperature is usually 40°C or more and 600°C or less, preferably 70°C or more and 300°C or less, and more preferably 100°C or more and 200°C or less, from the viewpoint of improving the adhesion between layers and preventing thermal decomposition of the material, and the heating time is usually 1 minute or more and 300 minutes or less, preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 30 minutes or less. The heating atmosphere is not particularly limited, and the heating may be performed in air or in an inert gas atmosphere. The above heating and drying methods are not particularly limited, and may be performed using an oven or the like, and may be performed in a batch system or a continuous system.

[0066] The above-mentioned lamination, heating, and drying can be performed in a batch process by a roll-to-roll method. The roll-to-roll method is a method in which a flexible substrate wound in a roll shape is unwound and processed while being transported intermittently or continuously until it is wound up by a winding roll. According to the roll-to-roll method, it is possible to process a long substrate of the order of km in a batch process, so the roll-to-roll method is more suitable for mass production than the sheet-to-sheet method. On the other hand, when each layer is formed by the roll-to-roll method, there is a high possibility that partial peeling may occur due to the contact between the film formation surface and the roll due to its structure, but by using the material of the hole transport layer according to this embodiment, peeling between the active layer and the buffer layer can be suppressed.

[0067] The size of the roll that can be used in the roll-to-roll method is not particularly limited as long as it can be handled by the manufacturing device of the roll-to-roll method, but the upper limit of the outer diameter is preferably 5 m or less, more preferably 3 m or less, and more preferably 1 m or less. On the other hand, the lower limit is preferably 10 cm or more, more preferably 20 cm or more, and more preferably 30 cm or more. The upper limit of the outer diameter of the roll core is preferably 4 m or less, more preferably 3 m or less, and more preferably 0.5 m or less. On the other hand, the lower limit is preferably 1 cm or more, more preferably 3 cm or more, more preferably 5 cm or more, more preferably 10 cm or more, and particularly preferably 20 cm or more. It is preferable that these diameters are less than the above upper limit in terms of high handleability of the roll, and it is preferable that they are more than the lower limit in terms of low possibility that the layer formed in each process will be destroyed by bending stress. The lower limit of the width of the roll is preferably 5 cm or more, more preferably 10 cm or more, and more preferably 20 cm or more. On the other hand, the upper limit is preferably 5 m or less, more preferably 3 m or less, and more preferably 2 m or less. A width equal to or less than the upper limit is preferable in terms of ease of handling of the roll, while a width equal to or greater than the lower limit is preferable in terms of greater freedom in the size of the photoelectric conversion element 100 .

[0068] [Serialization process] The method of serialization is not particularly limited as long as it is performed by laser processing, and examples thereof include a method of processing the laminate obtained by the lamination step by laser scribing or mechanical scribing. A layer having a specific pattern shape may also be formed by mask deposition or screen printing. From the viewpoint of ensuring a larger effective element area, it is preferable to perform patterning by laser scribing, which is capable of fine processing. In general, in laser processing, a load is applied to the surface irradiated with the laser, and peeling may occur between the layers. In particular, if the heat treatment in the lamination process is insufficient, peeling is more likely to occur on the inside of the laminate than on the outside. However, by using the material of the hole transport layer according to this embodiment, peeling between the active layer and the buffer layer can be suppressed. The conditions for laser processing are not particularly limited. For example, the width of the groove formed by the laser is usually 5 μm or more and 1000 μm or less, and may be 10 μm or more and 500 μm or less, or may be 25 μm or more and 300 μm or less, the wavelength of the laser used is usually 200 nm or more and 1200 nm or less, and may be 250 nm or more and 900 nm or less, or may be 300 nm or more and 600 nm or less, and the energy density is usually 0.01 J / cm 2 More than 10J / cm 2 Less than 0.05 J / cm 2 More than 5J / cm 2 It may be less than 0.1 J / cm 2 More than 1J / cm 2 It may be the following.

[0069] [3. Photoelectric conversion characteristics] The photoelectric conversion characteristics of the photoelectric conversion element 100 can be obtained as follows. The photoelectric conversion element 100 is irradiated with light of an appropriate spectrum at a certain irradiation intensity, and the current-voltage characteristics are measured. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short-circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained. As an example, the current-voltage characteristics at each illuminance can be measured by irradiating the photoelectric conversion element 100 with white LED light with a color temperature of 5000K at an appropriate irradiation intensity (illuminance).

[0070] The photoelectric conversion element according to this embodiment has excellent power generation efficiency in a low illuminance range (10 to 5000 lux), and can achieve a photoelectric conversion efficiency of 20% or more when using a light source such as white LED light. Also, the photoelectric conversion efficiency at 200 lux can be achieved to be 25% or more. There is no particular upper limit to this efficiency, and the higher the efficiency, the better. The photoelectric conversion efficiency (PCE) is the ratio of the output (maximum output) at the optimum operating point of the current-voltage curve of the photoelectric conversion element measured with a given irradiated light to the total energy of the irradiated light (for example, 100 mW / cm for sunlight with an intensity of AM1.5G).2 ) (%)

[0071] [4. Power generation devices] In one embodiment, the above-mentioned photoelectric conversion element 100 is suitably used as a power generation device, particularly as a solar cell for use in low-illuminance environments such as indoors. Specifically, the photoelectric conversion element according to this embodiment is advantageous in low-illuminance environments because peeling between the buffer layer and the active layer can be suppressed, thereby suppressing unnecessary high resistance and reduction in insulation or parallel resistance. FIG. 2 is a cross-sectional view showing a schematic configuration of a solar cell according to one embodiment of the present invention, and FIG. 2 shows a solar cell which is a solar cell according to one embodiment of the present invention. As shown in FIG. 2, the thin-film solar cell 14 according to this embodiment includes a weather-resistant protective film 1, an ultraviolet-cutting film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, a solar cell element 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10, in this order. The thin-film solar cell 14 according to this embodiment has the above-mentioned photoelectric conversion element as the solar cell element 6. Then, light is irradiated from the side where the protective film 1 is formed (lower side in FIG. 2), and the solar cell element 6 generates electricity. It is not necessary for the thin-film solar cell 14 to have all of these components, and necessary components can be selected arbitrarily. In this specification, a low illuminance environment means 10 to 5000 lux, typically around 200 lux.

[0072] There are no particular limitations on the components constituting the photoelectric conversion element and the manufacturing method thereof, and well-known techniques can be used. For example, techniques described in known documents such as WO 2013 / 171517, WO 2013 / 180230, or JP 2012-191194 A can be used.

[0073] There is no limitation on the use of the solar cell according to this embodiment, particularly the above-mentioned thin-film solar cell 14, and it can be used for any purpose. For example, the solar cell according to one embodiment can be used as a solar cell for building materials, a solar cell for automobiles, a solar cell for interior decoration, a solar cell for railways, a solar cell for ships, a solar cell for airplanes, a solar cell for spacecraft, a solar cell for home appliances, a solar cell for mobile phones, or a solar cell for toys. As described above, since it has excellent conversion efficiency in a low illuminance environment, it can be suitably applied to energy harvesting applications in particular.

[0074] The solar cell according to this embodiment, particularly the above-mentioned thin-film solar cell 14, may be used as it is, or may be used as a component of a solar cell module. For example, as shown in Fig. 3, a solar cell module 13 including the solar cell according to this embodiment, particularly the above-mentioned solar cell 14, on a substrate 12 may be fabricated, and this solar cell module 13 may be installed at the place of use. EXAMPLES

[0075] The features of the present invention will be described in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

[0076] <Example 1> [Preparation of Coating Solution for Electron Transport Layer] Ultrapure water was added to a 15% by mass aqueous dispersion of tin (IV) oxide (manufactured by Alfa Aesar) to prepare a 7.5% by mass aqueous dispersion of tin oxide.

[0077] [Preparation of coating solution for active layer] Lead iodide (II) was weighed into a vial and introduced into the glove box. N,N-dimethylformamide was added as a solvent so that the concentration of lead iodide (II) was 1.3 mol / L, and then the mixture was heated and stirred at 100°C for 1 hour to prepare coating solution 1 for the active layer. Next, formamidine hydrobromide (FABr), methylamine hydrobromide (MABr), and methylamine hydrochloride (MACl) were weighed out in a mass ratio of 7.25:1:1.5 into another vial and introduced into the glove box. By adding isopropyl alcohol as a solvent, active layer coating solution 2 with a total concentration of FABr, MABr, and MACl of 0.49 mol / L was prepared.

[0078] [Synthesis of organic semiconductor compounds] According to the synthesis method described in JP 2019-173032 A, an organic semiconductor compound (A-1) represented by the following formula (A-1) was synthesized. Mw: 38300 PDI: 1.3.

[0079] [ka]

[0080] [Preparation of Coating Solution for Hole Transport Layer] 64 mg of the organic semiconductor compound (A-1) and 2.6 mg of 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (TPFB, manufactured by TCI) were weighed into a vial and introduced into a glove box. 1.6 mL of orthodichlorobenzene was added as a solvent. Next, the resulting mixture was heated and stirred at 150°C for 1 hour to prepare a coating solution for a hole transport layer.

[0081] [Fabrication of photoelectric conversion element] Glass with patterned indium tin oxide (ITO) transparent conductive film (bottom electrode) The substrate (Geomatec Corporation) was ultrasonically cleaned using ultrapure water, dried by nitrogen blowing, and treated with UV-ozone.

[0082] Next, the coating solution for the electron transport layer prepared as above was spin-coated on the substrate at room temperature at a speed of 2000 rpm to form an electron transport layer with a thickness of about 35 nm, and then the substrate was heated on a hot plate at 150° C. for 10 minutes.

[0083] Furthermore, the substrate was introduced into a glove box, and 150 μL of active layer coating solution 1 heated to 100° C. was dropped onto the electron transport layer and spin-coated at a speed of 2000 rpm. Next, the substrate was annealed by heating on a hot plate at 100° C. for 10 minutes to form a lead iodide layer. Next, after the substrate returned to room temperature, active layer coating solution 2 (120 μL) was spin-coated onto the lead iodide layer at a speed of 2000 rpm and heated at 150° C. for 20 minutes to form an organic-inorganic perovskite active layer (thickness 650 nm).

[0084] Next, after the substrate returned to room temperature, the hole transport layer coating solution (120 μL) was spin-coated onto the active layer at a speed of 2000 rpm, and then heated on a hot plate at 90° C. for 5 minutes to form a hole transport layer (100 nm). In this manner, a laminate was produced.

[0085] <Example 2> A laminate was produced in the same manner as in Example 1, except that an organic compound (A-2) (Mw: 38100, PDI: 1.4) represented by the following formula (A-2) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0086] [ka]

[0087] <Example 3> A laminate was produced in the same manner as in Example 1, except that an organic compound (A-3) (Mw: 44,800 PDI: 1.4) represented by the following formula (A-3) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0088] [ka]

[0089] <Example 4> A laminate was produced in the same manner as in Example 1, except that an organic compound (A-4) (Mw: 37300 PDI: 1.4) represented by the following formula (A-4) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0090] [ka]

[0091] <Comparative Example 1> A laminate was produced in the same manner as in Example 1, except that an organic compound (B-1) (Mw: 43600 PDI: 1.3) represented by the following formula (B-1) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0092] [ka]

[0093] <Comparative Example 2> Instead of the organic semiconductor compound (A-1), A laminate was produced in the same manner as in Example 1, except that an organic compound (B-2) (Mw: 43600, PDI: 1.3) represented by the following formula (B-2) synthesized according to the synthesis method was used.

[0094] [ka]

[0095] <Comparative Example 3> A laminate was produced in the same manner as in Example 1, except that an organic compound (B-3) (Mw: 41900 PDI: 1.3) represented by the following formula (B-3) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0096] [ka]

[0097] <Comparative Example 4> A laminate was produced in the same manner as in Example 1, except that an organic compound (B-4) (Mw: 38600 PDI: 1.4) represented by the following formula (B-4) synthesized in accordance with the synthesis method described in JP-A-2019-173032 was used instead of the organic semiconductor compound (A-1).

[0098] [ka]

[0099] <Adhesion evaluation> For each laminated body, a Callisto manufactured by V Technology was used, with a wavelength of 1064 nm and an energy density of 0.5 J / cm. 2 The hole transport layer, active layer, and electron transport layer of the laminate were scribed by laser irradiation under the conditions shown in Figure 4. However, the thicknesses of the layers and the ratio of the scribe widths in Figure 4 are not shown in actual ratios. The observation direction arrow in Figure 4 indicates the observation direction in the optical microscope observation described below. FIG. 5 shows the results of observing each laminate scribed by laser irradiation from above with an optical microscope.

[0100] From FIG. 5, it was found that in the laminate using the organic semiconductor compound having the structural unit represented by the above formula (1), peeling between the active layer and the hole transport layer was suppressed as shown in FIG. 4(a), whereas in the laminate not using the organic semiconductor compound, peeling occurred between the active layer and the hole transport layer as shown in FIG. 4(b).

[0101] <Fabrication of photoelectric conversion element>

[0102] On the hole transport layer of the laminate obtained in each of the above-mentioned Examples, MoO3 was deposited to a thickness of about 10 nm by a resistance heating vacuum deposition method, followed by deposition of IZO to a thickness of about 30 nm and silver to a thickness of about 100 nm to form an upper electrode, thereby producing a photoelectric conversion element.

[0103] From the above examples, it can be seen that the present invention can provide a photoelectric conversion element in which peeling between the buffer layer and the active layer is suppressed, a manufacturing method thereof, and an energy harvesting device having the photoelectric conversion element, particularly an energy harvesting device for low illumination of 5,000 lux or less. [Explanation of symbols]

[0104] 100 Photoelectric conversion element 101 Lower electrode 102 Buffer Layer 103 Active layer 104 Buffer Layer 105 Upper electrode 106 Base material

Claims

1. A pair of electrodes including an upper electrode and a lower electrode; an active layer located between the pair of electrodes and containing an organic-inorganic hybrid semiconductor compound; A photoelectric conversion element having a buffer layer located between the pair of electrodes, the organic-inorganic hybrid semiconductor compound is a compound having a perovskite structure, The buffer layer contains an organic semiconductor compound having a hole transporting ability and a dopant for the organic semiconductor compound, The photoelectric conversion element, wherein the organic semiconductor compound has a structural unit represented by the following formula (1): 【Chemistry 1】 (In the above formula (1), X represents a group having at least one divalent aromatic ring group A selected from a divalent monoaromatic ring group which may have a substituent and a divalent fused aromatic ring group which may have a substituent at least in the main chain, and X represents one or more groups selected from the group consisting of a methylene group in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group, a divalent amino group substituted with a monovalent aromatic hydrocarbon ring group, and the divalent aromatic ring group A, and the number of consecutive divalent aromatic ring groups A bonded to each other in the main chain is 2 or less; R １ and R ２ each independently represents hydrogen or an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent.

2. 2. The photoelectric conversion element according to claim 1, wherein X in the formula (1) has a biphenylene group, which may have a substituent, at least in the main chain.

3. 3. The photoelectric conversion element according to claim 1, wherein the total weight ratio of the structural units that can be represented by the structural unit represented by formula (1) in one molecule of the organic semiconductor compound is 5% by weight or more and 95% by weight or less.

4. 4. The photoelectric conversion element according to claim 1, wherein the structural unit represented by the formula (1) is a repeating structural unit represented by the following formula (2): 【Chemistry 2】 (In the above formula (2), X, R １ and R ２ represents X and R in the formula (1). １ and R ２ and n represents 1 to 10,000.

5. 5. The photoelectric conversion element according to claim 1, wherein the dopant is an organic compound containing trivalent iodine.

6. 6. The photoelectric conversion element according to claim 5, wherein the dopant is a diaryliodonium salt.

7. A method for producing the photoelectric conversion element according to any one of claims 1 to 6, comprising the steps of: a lamination step of laminating at least the pair of electrodes, the active layer, and the buffer layer to obtain a laminate; and A method for producing a photoelectric conversion element, comprising a serialization step of serializing the laminate by laser processing.

8. A power generation device comprising the photoelectric conversion element according to any one of claims 1 to 6.

Images