JP2022145231A - Photoelectric conversion element, manufacturing method thereof, and power generation device - Google Patents

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 The present invention mainly relates to a photoelectric conversion element, a manufacturing method thereof, and a power generation device.

2. Description of the Related Art As a photoelectric conversion element, one in which an active layer, a buffer layer, and the like are arranged between a pair of electrodes is known. For the purpose of improving the photoelectric conversion efficiency, the use of an organic-inorganic hybrid semiconductor material as an active layer has been studied, and in particular, compounds having a perovskite structure have attracted attention.

An organic semiconductor compound or the like is used as a buffer layer having a hole-transporting ability in such a photoelectric conversion device. , discloses a technology related to a photoelectric conversion device that achieves improved charge mobility and reduced ionization potential, and Patent Document 2 discloses an improvement in photoelectric conversion efficiency by using a specific polytriarylamine-based semiconductor compound. A technique relating to a photoelectric conversion element having excellent retention rate is disclosed.

JP 2018-181882 A JP 2019-175970 A

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 for the purpose of improving charge mobility, durability of photoelectric conversion efficiency, and the like. While material development focusing on such improvement in electrical properties has been widely carried out, material development focusing on improvement in structural characteristics has hardly been carried out, and there is room for improvement. Problems based on structural features include, for example, delamination. If delamination occurs between the buffer layer and the active layer, the transport of holes between layers will be suppressed, and the electrodes will not be connected as designed, resulting in high resistance, insulation, or a decrease in parallel resistance. , the photoelectric conversion efficiency decreases.
Accordingly, an object of the present invention is to provide a photoelectric conversion element in which peeling between a buffer layer and an active layer is suppressed, a method for manufacturing the same, and a power generation device having the photoelectric conversion element.

As a result of intensive studies aimed at solving the above problems, the present inventors have found that the above problems can be solved by including an organic semiconductor compound having a specific structure in the buffer layer, and have completed the present invention. I came to let you.

（上記式（１）において、Ｘは、置換基を有していてよい２価の単芳香環基、及び置換基を有していてよい２価の縮合芳香環基から選択される少なくも１つの２価の芳香環基Ａを少なくとも主鎖に有し、かつ、該主鎖において互いに結合することで連続する２価の芳香環基Ａの数が３以下である基を表し；Ｒ^１及びＲ^２は、独立に、水素、又は置換基を有していてもよい炭素数１～２０の脂肪族炭化水素基を表す。）
［２］ 前記式（１）におけるＸの主鎖において、互いに結合することで連続する２価の芳香環基Ａの数が２以下である、［１］に記載の光電変換素子。
［３］ 前記式（１）におけるＸが、置換基を有していてよいビフェニレン基を少なくとも主鎖に有することを特徴とする、［１］又は［２］に記載の光電変換素子。
［４］ 前記式（１）におけるＸの主鎖を構成する基が、少なくとも１つの水素が１価の芳香族炭化水素環基で置換されたメチレン基、１価の芳香族炭化水素環基で置換された２価のアミノ基、及び前記２価の芳香環基Ａよりなる群から選択される１以上の基から構成されることを特徴とする、［１］～［３］のいずれかに記載の光電変換素子。
［５］ 前記有機半導体化合物１分子中の、前記式（１）で表される構造単位で表され得る構造単位の全重量の割合が、５重量％以上９５重量％以下であることを特徴とする、［１］～［４］のいずれかに記載の光電変換素子。
［６］ 前記式（１）で表される構造単位が、下記式（２）で表される繰り返し構造単位であることを特徴とする、［１］～［５］のいずれかに記載の光電変換素子。

（上記式（２）において、Ｘ、Ｒ^１及びＲ^２は、前記式（１）におけるＸ、Ｒ^１及びＲ^２と同義であり；ｎは、１～１００００を表す。）
［７］ 前記ドーパントが、３価のヨウ素を含む有機化合物であることを特徴とする、［
１］～［６］のいずれかに記載の光電変換素子。
［８］ 前記ドーパントが、ジアリールヨードニウム塩であることを特徴とする、［７］に記載の光電変換素子。
［９］ 前記有機無機ハイブリッド型半導体化合物が、ペロブスカイト構造を有する化合物であることを特徴とする、［１］～［８］のいずれかに記載の光電変換素子。
［１０］ ［１］～［９］のいずれかに記載の光電変換素子の製造方法であって、
少なくとも前記一対の電極、前記活性層、及び前記バッファ層を積層して積層体を得る積層工程、及び
前記積層体を、レーザー加工によって直列化する直列化工程を有することを特徴とする、光電変換素子の製造方法。
［１１］ ［１］～［９］のいずれかに記載の光電変換素子を有することを特徴とする、発電デバイス。 Embodiments of the invention include, but are not limited to:
[1] a pair of electrodes composed 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;
and a buffer layer positioned between the pair of electrodes,
the buffer layer contains an organic semiconductor compound having hole-transporting ability and a dopant for the organic semiconductor compound, and
characterized in that the organic semiconductor compound has a structural unit represented by the following formula (1),
Photoelectric conversion element.

(In the above formula (1), X is at least one selected from a divalent monovalent aromatic ring group which may have a substituent and a divalent condensed aromatic ring group which may have a substituent R ¹ and R ² independently represents hydrogen or an optionally substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms.)
[2] The photoelectric conversion device according to [1], wherein in the main chain of X in the formula (1), the number of divalent aromatic ring groups A that are continuous by bonding to each other is 2 or less.
[3] The photoelectric conversion device according to [1] or [2], wherein X in formula (1) has at least a biphenylene group which may have a substituent in the main chain.
[4] The group constituting the main chain of X in the formula (1) is a methylene group in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group, or a monovalent aromatic hydrocarbon ring group. Any one of [1] to [3], characterized by being composed of one or more groups selected from the group consisting of a substituted divalent amino group and the divalent aromatic ring group A The photoelectric conversion device described.
[5] The ratio of the total weight of structural units that can be represented by the structural unit represented by the formula (1) in one molecule of the organic semiconductor compound is 5% by weight or more and 95% by weight or less. The photoelectric conversion element according to any one of [1] to [4].
[6] The photoelectric device according to any one of [1] to [5], wherein the structural unit represented by formula (1) is a repeating structural unit represented by formula (2) below. conversion element.

(In the above formula (2), X, R ¹ and R ² have the same definitions as X, R ¹ and R ² in the above formula (1); n represents 1 to 10000.)
[7] The dopant is an organic compound containing trivalent iodine, [
1] The photoelectric conversion element according to any one of [6].
[8] The photoelectric conversion device of [7], wherein the dopant is a diaryliodonium salt.
[9] The photoelectric conversion device 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 manufacturing the photoelectric conversion element according to any one of [1] to [9],
A photoelectric conversion comprising: 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. A method of manufacturing an element.
[11] A power generation device comprising the photoelectric conversion element according to any one of [1] to [9].

INDUSTRIAL APPLICABILITY According to the present invention, a photoelectric conversion element in which peeling between a buffer layer and an 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 are provided. can do.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which represents typically the photoelectric conversion element as one Embodiment. 1 is a cross-sectional view schematically showing a solar cell as one embodiment; FIG. 1 is a cross-sectional view schematically showing a solar cell module as one embodiment; FIG. It is a figure for demonstrating the scribing by laser irradiation in an Example. FIG. 4 is an optical microscope image of a processed surface scribed by laser irradiation of a laminate manufactured in Example (photograph substituting for drawing). FIG.

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 to these. In addition, the present invention can be arbitrarily changed and implemented without departing from the gist thereof.
In this specification, the description represented by "-" shall represent the range including the numbers described before and after it.
In addition, the term "independently" used when describing two or more objects together means that the two or more objects may be the same or different.

<1. Photoelectric conversion element>
A photoelectric conversion device according to an embodiment of the present invention (also simply referred to as a “photoelectric conversion device”) is
a pair of electrodes composed 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;
and a buffer layer positioned between the pair of electrodes,
the buffer layer contains an organic semiconductor compound having hole-transporting ability and a dopant for the organic semiconductor compound, and
The photoelectric conversion device is characterized in that the organic semiconductor compound has a structural unit represented by formula (1) described later.

FIG. 1 is a cross-sectional view schematically showing an example of a photoelectric conversion element according to this 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, the buffer layer 102 present between the lower electrode 101 and the active layer 103 is a hole transport layer containing an organic semiconductor compound having hole transport ability and a dopant for the organic semiconductor compound. can do. 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 above-mentioned hole transport layer. Also, as shown in FIG. 1, the photoelectric conversion element 100 may have a substrate 106 and may have other layers such as an insulator layer and a work function tuning layer.

[1-1. buffer layer]
A photoelectric conversion element has a buffer layer positioned between a pair of electrodes, and the buffer layer containing the organic semiconductor compound having a hole-transporting ability and the dopant for the organic semiconductor compound is a layer as a hole-transporting layer. is the buffer layer 102 or 104 positioned between the active layer 103 and at least one of the pair of electrodes 101 and 105 in FIG. However, when the hole transport layer is formed by a coating method, the active layer 103 may be immersed in the coating solvent, which may affect the active layer 103. and the active layer 103 .
A buffer layer separate from the hole-transport layer may be a layer as an electron-transport layer. A buffer layer provided between the anode and the active layer is sometimes called a hole transport layer, and a buffer layer provided between the cathode and the active layer is sometimes called an electron transport layer.

[1-1-1. Buffer layer (hole transport layer)]
The buffer layer as a hole-transporting layer is not particularly limited as long as it contains an organic semiconductor compound having a hole-transporting ability and a dopant for the organic semiconductor compound. you can stay In the case of the nip stacked photoelectric conversion device, the hole transport layer facilitates control of the amount of transported charge. Hereinafter, in this item, the buffer layer is also referred to as a hole transport layer.

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

In the above formula (1), X is at least one selected from a divalent monovalent aromatic ring group which may have a substituent and a divalent condensed aromatic ring group which may have a substituent Represents a group having at least a divalent aromatic ring group A in the main chain and having 3 or less continuous divalent aromatic ring groups A by bonding to each other in the main chain, but the active layer and From the viewpoint of suppressing delamination (delamination) from the hole transport layer, the number of consecutive divalent aromatic ring groups A is preferably 2 or less. When the number of continuous divalent aromatic ring groups A that are bonded to each other in the main chain of X is 3 or less,
Since the organic semiconductor compound becomes flexible, the hole transport layer is flexibly deformed according to the deformation of the active layer that is deformed in the process such as processing in the manufacture of the photoelectric conversion element, so that the hole transport layer and the active layer are easily deformed. It is possible to suppress the occurrence of peeling between them.
The above divalent aromatic ring A is at least one divalent single aromatic ring group which may have a substituent and a divalent condensed aromatic ring group which may have a substituent is the base.
Examples of divalent monoaromatic ring groups 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, or A triazinylene group and the like can be mentioned.
Examples of divalent condensed aromatic ring groups include naphthalenylene group, anthracenylene group, phenanthrenylene group, dihydrophenanthrenylene group, triphenylenine group, acenaphthenylene group, fluoranthenylene group, naphthalenylene group, fluorenylene group, spirobifluorenylene group, pyrenylene group, perylenylene group, chrysenylene group, indenylene group, fluoranthenylene group, or benzofluoranthenylene group, benzofuranylene group, benzothiophenylene group, indolene group, carbazolene group, pyrroloyimidazolene 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, an 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.
The divalent aromatic ring A is a phenyl group which may have a substituent from the viewpoint of suppressing delamination among the above divalent single aromatic ring groups and divalent condensed aromatic ring groups. is preferred, and a phenyl group having no substituent is particularly preferred. Since a condensed aromatic ring group has a larger molecular size and lower flexibility than a phenylene group, delamination is likely to occur, so the organic semiconductor compound preferably does not have a condensed aromatic ring group. However, the reduction in flexibility due to X having a condensed aromatic ring group, and the flexibility due to 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 Compared to the decrease in flexibility, the decrease in flexibility due to the latter reason is greater.
In formula (1), X preferably has a biphenylene group in which two phenylene groups bond to each other in its main chain from the viewpoint of HOMO adjustment and the like while ensuring molecular flexibility.

In this specification, the substituent in the expression of an alkyl group optionally having substituents or an aliphatic hydrocarbon group optionally having substituents means a halogeno group, —C≡N, —NH ₃ , -C(=O)OH, -C(=O)OR', -C(=O)R', -SH, -SiR ^a R ^b R ^c , -BH ₂ , -SeH, monovalent aliphatic carbonization A hydrogen ring group, a monovalent aromatic hydrocarbon ring group, a monovalent aromatic heterocyclic group, or the like, or ^a combination thereof, wherein R', Ra, ^Rb , and ^Rc are independently hydrogen, or represents an alkyl group having 1 to 20 carbon atoms.
The substituent in the expression "optionally having a substituent" except in the expression of an alkyl group which may have a substituent or an aliphatic hydrocarbon group which may have a substituent, halogeno group, alkyl group having 1 to 20 carbon atoms, alkenyl group having 1 to 20 carbon atoms, alkynyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, —C≡N, —NH ₃ , —C( =O)OH, -C(=O)OR', -C(=O)R', -SH, -SiR ^a R ^b R ^c , -BH ₂ , -SeH, monovalent aliphatic hydrocarbon ring group , a monovalent aromatic hydrocarbon ring group, a monovalent aromatic heterocyclic group, or a combination thereof, and R′, R ^a , R ^b , and R ^c are independently hydrogen or the number of carbon atoms represents an alkyl group of 1 to 20;

The group constituting the main chain of X in formula (1) is a methylene group in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group, a 2 in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group It is preferably composed of one or more groups selected from the group consisting of a divalent amino group and the divalent aromatic ring group A.
The type of the monovalent aromatic hydrocarbon ring group is not particularly limited, and examples thereof include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, and triphenylene ring. , an acenaphthene ring, a fluoranthene ring, a fluorene ring, a 6-membered monocyclic ring or a group derived from 2 to 5 condensed rings, or a group having a substituent, but from the viewpoint of suppressing delamination , phenyl group or p-tolyl group.

In the above formula (1), R ¹ and R ² independently represent hydrogen or an optionally substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, from the viewpoint of suppressing delamination. Therefore, at least one of R ¹ and R ² is preferably an optionally substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, and both R ¹ and R ² are independently substituted It is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a group, and more preferably R ¹ and R ² are 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, more preferably 4 to 9, from the viewpoint of suppressing delamination. More preferably, 5 to 7 is particularly preferable.

The ratio of the total weight of structural units that can be represented by the structural unit represented by the 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. is preferably 10% by weight or more, more preferably 15% by weight or more, further preferably 20% by weight or more, may be 100% by weight or less, and may be 95% by weight or less. you can

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

In formula (2) above, X, R ¹ and R ² are synonymous with X, R ¹ and R ² in formula (1) above, including preferred conditions.
In the above formula (2), n represents 1 to 10,000, but from the viewpoint of suppressing delamination, it is preferably 2 to 10,000, more preferably 3 to 10,000, and 4 to 10,000. is more preferred, and 5 to 10,000 is particularly preferred.
In this specification, when there are a plurality of 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 1 -D, n above is either p or q, not r.

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

The number average molecular weight (Mn) of the organic semiconductor compound is not particularly limited, but is usually 5000 or more, preferably 5500 or more, preferably 6000, from the viewpoint of suppressing delamination and ensuring solubility in a solvent. more preferably 6,500 or more, particularly preferably 7,000 or more, and usually 100,000 or less, preferably 90,000 or less, and more preferably 80,000 or less. , 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 is usually 5000 or more, preferably 5500 or more, preferably 6000, from the viewpoint of suppressing delamination and ensuring solubility in a solvent. more preferably 6,500 or more, particularly preferably 7,000 or more, and usually 100,000 or less, preferably 95,000 or less, and more preferably 90,000 or less. , is more preferably 85,000 or less, and particularly preferably 80,000 or less.

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, and 20% by weight or more. more preferably 30% by weight or more, particularly preferably 40% by weight or more, and may be 100% by weight or less.
In addition, when the photoelectric conversion element has a plurality of buffer layers, any one layer corresponding to the hole transport layer among them may satisfy the above content range.

The method for synthesizing the organic semiconductor compound described above is not particularly limited, and can be synthesized by combining known methods. For example, it can be synthesized by the method described in JP-A-2009-263665, and can be synthesized by oxidative polymerization of a triarylamine monomer or a coupling reaction using a transition metal catalyst.

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

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

This hypervalent iodine compound is known to act as a dopant for organic semiconductor compounds and exhibit electron acceptability (that is, act as an oxidizing agent). Also, the electron-accepting dopant can improve the conductivity or hole-transporting ability of the semiconductor compound by removing electrons from the semiconductor compound. Thus, hypervalent iodine compounds can improve the charge transport properties of semiconductor compounds.

A hypervalent iodine compound is a compound containing hypervalent iodine and is defined as a compound containing iodine having an oxidation number of +3 or higher. For example, the dopant can be an iodine (III) compound or an iodine (V) compound. The iodine (V) compound containing pentavalent iodine can be, for example, a periodinane compound such as Dess-Martin periodinane. Examples of iodine (III) compounds containing trivalent iodine include compounds having a structure in which iodobenzene is oxidized, such as (diacetoxyiodo)benzene, and diaryliodonium salts. The dopant is preferably an organic compound containing trivalent iodine, more preferably a diaryliodonium salt, in that it exhibits good electron-accepting properties and is less likely to cause a reverse reaction if the molecule is destroyed during the oxidation process. .

A diaryliodonium salt is a salt having the [Ar-I ⁺ -Ar]X ^- structure. Here, two Ars each represent an aryl group. The aryl group (aromatic group) is not particularly limited and can be, for example, those already mentioned for the organic semiconductor compounds. X ⁻ represents any anion. X ^- can be, for example, a halide ion, a trifluoroacetate ion, a tetrafluoroborate ion, a tetrakis(pentafluorophenyl)borate ion, or the like. X- is preferably an anion having a fluorine atom in that the solubility is high and the reaction for forming the coating liquid can proceed smoothly.

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

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

Examples of aromatic groups include aromatic hydrocarbon groups having 6 to 20 carbon atoms or aromatic heterocyclic groups having 2 to 20 carbon atoms. For example, aromatic groups include a phenyl group, a naphthyl group, a biphenyl group, a thienyl group, a pyridyl group, and the like.

In addition, said aliphatic group and aromatic group may have a substituent. Substituents which may be present are not particularly limited, but are halogen atoms, hydroxyl groups, cyano groups, amino groups, carboxyl groups, ester groups, alkylcarbonyl groups, acetyl groups, sulfonyl groups, silyl groups, and boryl groups. , nitrile group, alkyl group, alkenyl group, alkynyl group, alkoxy group, thio group, seleno group, aromatic hydrocarbon group, aromatic heterocyclic group and the like.

R ¹¹ and R ¹² are preferably aromatic hydrocarbon groups having 6 to 20 carbon atoms, more preferably phenyl groups. Here, the aromatic hydrocarbon group preferably has no substituent or has an alkyl group having 1 to 6 carbon atoms. R ¹¹ and R ¹² are particularly preferably phenyl groups having an alkyl group at the para-position.

The content of the dopant in the hole transport layer is not particularly limited, but from the viewpoint of imparting conductivity, it is usually 0.001% by weight or more, preferably 0.002% by weight or more, and preferably 0.003% by weight. % or more, 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 the hole transport layer, the content ratio of the dopant to the organic semiconductor compound having the structural unit represented by the above formula (1) (dopant/organic semiconductor compound) is not particularly limited. From the viewpoint of transportability, it is usually 0.001 or more, preferably 0.002 or more, more preferably 0.003 or more, further preferably 0.004 or more, and 0.005 or more. is particularly preferably, and is usually 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, further preferably 0.2 or less, and 0 .1 or less is particularly preferred.
In addition, when the photoelectric conversion element has a plurality of buffer layers, any one layer corresponding to the hole transport layer among them may satisfy the above content range.

(other substances)
The buffer layer as a hole transport layer may contain substances other than the above organic semiconductor compound and dopant, and may contain, for example, a cross-linking agent, a curing agent, a thickening agent, and the like.

[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 buffer layer as the hole transport layer described above. The mode is not particularly limited, and any material that can improve the efficiency of taking electrons from the active layer to the cathode can be used, and known materials can be used. Specifically, the inorganic compounds, organic compounds, or organic-inorganic perovskite compounds according to the present invention are described in known documents such as WO 2013/171517, WO 2013/180230, or JP-A-2012-191194. is 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 organic compounds include bathocuproine (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato)aluminum (Alq3), boron compounds, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic anhydride (NTCDA), Examples include perylenetetracarboxylic anhydride (PTCDA), fullerene compounds, and phosphine compounds having a Group 16 element of the periodic table and a double bond, such as phosphine oxide compounds or phosphine sulfide compounds.

The thickness of the buffer layer as the hole-transporting layer and the thickness of the buffer layer as the electron-transporting layer are not particularly limited and can be appropriately set according to the application. 0.5 nm or greater, in another embodiment 1 nm or greater, in yet another embodiment 5 nm or greater, while in one embodiment 1 μm or less, in another embodiment 500 nm or less, in yet another embodiment It may be 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 transfer efficiency of carriers such as holes and electrons can be easily improved, and the photoelectric conversion efficiency can be improved.

In addition, there is no limitation on the layer formation method for both the buffer layer as the hole transport layer and the buffer layer as the electron transport layer, 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 liquid containing the above-described organic semiconductor compound, dopant, and 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-forming method such as a vacuum deposition method.

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

The organic-inorganic hybrid semiconductor material is preferably a compound having a perovskite structure (hereinafter sometimes referred to as a perovskite semiconductor compound). A perovskite semiconductor compound refers to a semiconductor compound having a perovskite structure. Although there are no particular restrictions on the perovskite semiconductor compound, for example, Galasso et al.
Structures and Properties of Inorganic Solids, Chapter 7 - Perovskite types and related structures. For example, perovskite semiconductor compounds include those of the AMX ₃ type, represented by the general formula AMX ₃ , or those of the A ₂ MX ₄ type, represented by the general formula A ₂ MX ₄ . Here, M denotes a divalent cation, A denotes a monovalent cation, and X denotes a monovalent anion.

Although there is no particular limitation on the monovalent cation A, those described in the above-mentioned 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 ions, rubidium ions, potassium ions, optionally substituted ammonium ions, and optionally substituted phosphonium ions are preferred. Examples of optionally substituted ammonium ions include primary ammonium ions and secondary ammonium ions. There are no particular restrictions on the substituents, either. Specific examples of optionally substituted ammonium ions include alkylammonium ions and arylammonium ions. In particular, in order to avoid steric hindrance, a monoalkylammonium ion having a three-dimensional crystal structure is preferable, and from the viewpoint of improving stability, it is preferable to use an alkylammonium ion substituted with one or more fluorine groups. A combination of two or more cations can also be used as the cation A.

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

Although the divalent cation M is not particularly limited, it is preferably a divalent metal cation or metalloid cation. Specific examples include cations of Group 14 elements of the periodic table, and more specific examples include lead cations (Pb ²⁺ ), tin cations (Sn ²⁺ ), and germanium cations (Ge ²⁺ ). A combination of two or more cations can also be used as the cation M. From the viewpoint of obtaining a stable photoelectric conversion device, it is particularly preferable to use lead cations or two or more kinds of cations containing lead cations.

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, titanates. ions, zirconate ions, 2,4-pentanedionate ions, silicofluoride ions, and the like. In order to adjust the bandgap, X may be one type of anion or a combination of two or more types of anions. In one embodiment, X includes halide ions or combinations of halide ions and other anions. Examples of halide ions X include chloride ions, bromide ions, iodide ions, and the like. From the viewpoint of not widening the bandgap 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.

Preferred examples of perovskite semiconductor compounds include organic-inorganic perovskite semiconductor compounds, particularly halide-based organic-inorganic perovskite semiconductor compounds. _{Specific examples} of _{perovskite semiconductor compounds include CH3NH3PbI3 , CH3NH3PbBr3 , CH3NH3PbCl3 , CH3NH3SnI3 , CH3NH3SnBr3 , CH3NH3SnCl3 .} , CH ₃ NH ₃ PbI _(3-x) Cl _x , CH ₃ NH ₃ PbI _(3-x) Br _x , CH ₃ NH ₃ PbBr _(3-x) Cl _x , CH ₃ NH ₃ Pb _(1-y) Sn _y I ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y Br ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y Cl ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y I _{(3 -x)} Cl _x , CH ₃ NH ₃ Pb _(1-y) Sn _y I _(3-x) Br _x , and CH ₃ NH ₃ Pb _(1-y) Sn _y Br _(
3-x) Cl _x , and the above compounds using CFH ₂ NH ₃ , CF ₂ HNH ₃ or CF ₃ NH ₃ instead of CH ₃ NH ₃ , and the like. Note that x is 0 or more and 3 or less, and y is any value of 0 or more and 1 or less.

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

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 still more preferably 80% by mass or more so as to obtain good semiconductor characteristics. be. There is no particular upper limit. Also, the active layer 103 may contain an additive in addition to the perovskite semiconductor compound. Examples of additives include inorganic or organic compounds, such as halides, oxides, or inorganic salts such as sulfides, sulfates, nitrates or ammonium salts.

There is no particular limitation on the thickness of the active layer 103 . In order 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 another embodiment, and 120 nm or more in another embodiment. is. On the other hand, 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 still another embodiment in order to reduce the series resistance or improve the charge extraction efficiency. is.

A 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). A coating method can be used because the active layer 103 can be easily formed. For example, there is a method of forming the active layer 103 by applying a coating liquid containing a perovskite semiconductor compound or a precursor thereof and drying it by heating as necessary. In addition, after applying such a coating liquid, a perovskite semiconductor compound can be precipitated by further applying a solvent in which the perovskite semiconductor compound has a low solubility.

A perovskite semiconductor compound precursor refers to a material that can be converted into a perovskite semiconductor compound after application of a coating liquid. 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, followed by heating and stirring. The active layer 103 containing the perovskite semiconductor compound represented by the general formula AMX ₃ can be produced by applying this coating liquid and heat-drying it. The solvent is not particularly limited as long as it dissolves the perovskite semiconductor compound and the additive, and examples thereof include organic solvents such as N,N-dimethylformamide.

Any method can be used as a method for applying the coating liquid, and examples include spin coating, ink jet method, doctor blade method, drop casting method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, A spray coating method, an air knife coating method, a wire barber coating method, a pipe doctor method, an impregnation/coating method, a curtain coating method, or the like can be used.

[1-3. electrode]
The photoelectric conversion element 100 has a pair of electrodes. The electrode has 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 which is called an upper electrode and the other is called a lower electrode. When the photoelectric conversion element 100 has a substrate or is provided on a substrate, an electrode closer to the substrate can be called a lower electrode, and an electrode farther from the substrate can be called an upper electrode. Also, the transparent electrode can be called a lower electrode, and the electrode having a lower transparency than the lower electrode can be called an upper electrode. A photoelectric conversion element 100 shown in FIG. 1 has a lower electrode 101 and an upper electrode 105 .

As the pair of electrodes, an anode suitable for collecting holes and a cathode suitable for collecting electrons can be used. In this case, the photoelectric conversion element 100 may have a forward configuration in which the lower electrode 101 is the anode and the upper electrode 105 is the cathode, or a reverse configuration in which the lower electrode 101 is the cathode and the upper electrode 105 is the anode. It may have a mold configuration.

Either one of the pair of electrodes may be translucent, or both may be translucent, depending on the application. Having translucency refers to transmitting 40% or more of sunlight. In addition, it is preferable that the transparent electrode has a sunlight transmittance of 70% or more so that more light can pass through the transparent electrode and reach the active layer 103 . The light transmittance can be measured with a spectrophotometer (eg, U-4100 manufactured by Hitachi High-Tech).

There is no particular limitation on the lower electrode 101 and upper electrode 105, or the constituent members of the anode and cathode, and the manufacturing method thereof, and well-known techniques can be used. For example, members described in known documents such as International Publication No. 2013/171517, International Publication No. 2013/180230, or Japanese Patent Application Laid-Open No. 2012-191194 and manufacturing methods thereof can be used.

[1-4. Base material]
The photoelectric conversion element 100 usually has a base material 106 that serves as a support. However, the photoelectric conversion element according to this embodiment may not have the substrate 106 . The material of the base material 106 is not particularly limited as long as it does not significantly impair the effects of the present invention. can be used.

<2. Method for producing a photoelectric conversion element>
A method for manufacturing a photoelectric conversion element according to another embodiment of the present invention (also referred to simply as a "method for manufacturing a photoelectric conversion element") is the above method for manufacturing a photoelectric conversion element, comprising: at least the pair of electrodes; A method for manufacturing a photoelectric conversion element, comprising a lamination step of laminating an active layer and a buffer layer to obtain a laminate, and a serialization step of serializing the laminate by laser processing.
The manufacturing method described above may have processes other than the stacking process and the serialization process described above.

[Lamination process]
The method for laminating each layer is not particularly limited, and for example, each layer can be laminated by coating on a substrate and then dried by heating to 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, and pipe doctor method. , an impregnation/coating method, a curtain coating method, a flexographic printing method, an inkjet method, and the like.
The heating (also referred to as annealing) conditions are not particularly limited, and the heating temperature is usually 40° C. or higher and 600° C. or lower from the viewpoint of improving the adhesion between layers and preventing thermal decomposition of the material, The temperature is preferably 70°C or higher and 300°C or lower, more preferably 100°C or higher and 200°C or lower, and the heating time is usually 1 minute or longer and 300 minutes or shorter, and 5 minutes or longer and 120 minutes. It is preferably 10 minutes or more and 30 minutes or less.
The heating atmosphere is not particularly limited, and may be performed in air or in an inert gas atmosphere.
The heating and drying methods described above are not particularly limited, and may be carried out in an oven or the like, and may be carried out in a batch mode or a continuous mode.

The above lamination, heating, and drying can be carried out in batch processing by a roll-to-roll method. The roll-to-roll method is a method in which a flexible base material wound in a roll 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, long substrates on the order of km can be collectively processed, 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 generally a high risk of partial peeling due to contact between the film-forming surface and the roll due to its structure. By using the material for the hole transport layer according to the embodiment, peeling between the active layer and the buffer layer can be suppressed.

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 a roll-to-roll manufacturing apparatus, but the upper limit of the outer diameter is preferably 5 m or less, more preferably 3 m or less, more preferably 3 m or less. 1 m or less. On the other hand, the lower limit is preferably 10 cm or more, more preferably 20 cm or more, and still 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 even 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, still more preferably 10 cm or more, and particularly preferably 20 cm or more. It is preferable that these diameters are equal to or less than the above upper limit because the handleability of the roll is high. . The lower limit of the width of the roll is preferably 5 cm or more, more preferably 10 cm or more, and still 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. It is preferable that the width is equal to or less than the upper limit because the roll is easy to handle.

[Serialization process]
The serialization method is not particularly limited as long as it is performed by laser processing, and examples thereof include a method in which the laminate obtained by the lamination process is processed by laser scribing, mechanical scribing, or the like. Alternatively, a layer having a specific pattern shape may be formed using mask deposition or screen printing. From the viewpoint of ensuring a wider effective element area, it is preferable to perform patterning by laser scribing, which enables fine processing.
Generally, in laser processing, a load is applied to the surface irradiated with the laser, and peeling may occur between layers. In particular, if the heat treatment in the lamination process is not sufficient, the inner side of the laminate is more likely to peel off than the outer side. However, by using the material for the hole transport layer according to the present embodiment, peeling between the active layer and the buffer layer can be suppressed.
The conditions for laser processing are not particularly limited, and for example, the width of the open groove formed by laser is usually 5 μm or more and 1000 μm or less, may be 10 μm or more and 500 μm or less, or 25 μm or more and 300 μm or less. Also, the wavelength of the laser to be used is usually 200 nm or more and 1200 nm or less, 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 0.01 J/cm ² or more and 10 J/cm ² or less, may be 0.05 J/cm ² or more and 5 J/cm ² or less, or 0.1 J/cm ² or more and 1 J/cm ² or less. good too.

[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 current-voltage characteristics are measured. From the resulting 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, by irradiating the photoelectric conversion element 100 with white LED light having a color temperature of 5000 K at an appropriate irradiation intensity (illuminance), the current-voltage characteristics at each illuminance can be measured.

The photoelectric conversion element according to the present embodiment is excellent in power generation efficiency in a low illuminance region (10 to 5000 lux), and can achieve a photoelectric conversion efficiency of 20% or more particularly when a light source such as white LED light is used. Also, the photoelectric conversion efficiency at 200 lux can be 25% or higher. There is no particular limit to the upper limit of this efficiency, and the higher the efficiency, the better.
The photoelectric conversion efficiency (PCE) is the output (maximum output) at the optimum operating point of the current-voltage curve of the photoelectric conversion element measured by a predetermined irradiation light, and the total amount of energy that the irradiation light has (for example, It is a value (%) divided by 100 mW/cm ² for sunlight with an intensity of AM 1.5G.

[4. power generation device]
In one embodiment, the photoelectric conversion element 100 described above is suitably used as a power generation device, especially as a solar cell for low-illuminance environments such as indoors. Specifically, the photoelectric conversion element according to the present embodiment can suppress delamination between the buffer layer and the active layer, thereby suppressing unnecessary increase in resistance and reduction in insulation or parallel resistance. environment.
FIG. 2 is a cross-sectional view schematically showing the 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 the present embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell. An element 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. The thin-film solar cell 14 according to this embodiment has the photoelectric conversion element described above 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 power. It should be noted that the thin-film solar cell 14 does not need to have all of these constituent members, and necessary constituent members can be arbitrarily selected.
In this specification, a low illumination environment means 10 to 5000 lux, typically around 200 lux.

There are no particular restrictions on these constituent members constituting the photoelectric conversion element and the method of manufacturing the same, and well-known techniques can be used. For example, techniques described in known documents such as International Publication No. 2013/171517, International Publication No. 2013/180230, and Japanese Patent Application Laid-Open No. 2012-191194 can be used.

Applications of the solar cell according to the present embodiment, particularly the thin-film solar cell 14 described above, are not limited and can be used for any application. For example, the solar cell according to one embodiment includes solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railroads, solar cells for ships, solar cells for airplanes, solar cells for spacecraft, solar cells for home appliances, and so on. It can be used as a battery, a solar cell for mobile phones or a solar cell for toys. As described above, it has excellent change efficiency in a low-illuminance environment, so it is particularly suitable for energy harvesting applications.

The solar cell according to this embodiment, particularly the thin-film solar cell 14 described above, 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 having the solar cell according to the present embodiment, particularly the above-described solar cell 14, on a substrate 12 is produced, and the solar cell module 13 is installed at a place of use. can be used.

EXAMPLES The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

<Example 1>
[Preparation of Coating Liquid for Electron Transport Layer]
An aqueous dispersion of 7.5% by mass of tin oxide was prepared by adding ultrapure water to a 15% by mass aqueous dispersion of tin (IV) oxide (manufactured by Alfa Aesar).

[Preparation of Active Layer Coating Solution]
Lead (II) iodide 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 (II) iodide was 1.3 mol/L, and then the mixture was heated and stirred at 100° C. for 1 hour to prepare active layer coating solution 1. .
Next, formamidine hydrobromide (FABr), methylamine hydrobromide (MABr), and methylamine hydrochloride (MACl) were mixed 7.25:1:1.5 in another vial. and introduced into the glove box. By adding isopropyl alcohol as a solvent thereto, an active layer coating liquid 2 having a total concentration of FABr, MABr and MACl of 0.49 mol/L was prepared.

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

[Preparation of Coating Liquid 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 placed in a glove box. introduced into 1.6 mL of ortho-dichlorobenzene was added thereto as a solvent. Next, the resulting mixed solution was heated and stirred at 150° C. for 1 hour to prepare a hole transport layer coating solution.

[Production of photoelectric conversion element]
A glass substrate (manufactured by Geomatec) with a patterned indium tin oxide (ITO) transparent conductive film (lower electrode) was subjected to ultrasonic cleaning using ultrapure water, drying by nitrogen blow, and UV-ozone treatment. gone.

Next, the electron transport layer coating liquid prepared as described above was spin-coated onto the substrate at room temperature at a speed of 2000 rpm to form an electron transport layer having a thickness of about 35 nm. After that, the substrate was heated on a hot plate at 150° C. for 10 minutes.

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

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 further heated on a hot plate at 90° C. for 5 minutes to remove holes. A transport layer (100 nm) was formed.
A laminate was produced as described above.

<Example 2>
Instead of the organic semiconductor compound (A-1), an organic compound (A-2) (Mw : 38100 PDI: 1.4) was used in the same manner as in Example 1 to prepare a laminate.

<Example 3>
Instead of the organic semiconductor compound (A-1), an organic compound (A-3) (Mw : 44800 PDI: 1.4) was used in the same manner as in Example 1 to prepare a laminate.

<Example 4>
Instead of the organic semiconductor compound (A-1), an organic compound (A-4) (Mw : 37300 PDI: 1.4) was used in the same manner as in Example 1 to prepare a laminate.

<Comparative Example 1>
Instead of the organic semiconductor compound (A-1), an organic compound (B-1) (Mw : 43600 PDI: 1.3) was used in the same manner as in Example 1 to prepare a laminate.

<Comparative Example 2>
Instead of the organic semiconductor compound (A-1), an organic compound (B-2) (Mw : 43600 PDI: 1.3) was used in the same manner as in Example 1 to prepare a laminate.

<Comparative Example 3>
Instead of the organic semiconductor compound (A-1), an organic compound (B-3) (Mw : 41900 PDI: 1.3) was used in the same manner as in Example 1 to prepare a laminate.

<Comparative Example 4>
Instead of the organic semiconductor compound (A-1), an organic compound (B-4) (Mw : 38600 PDI: 1.4) was used in the same manner as in Example 1 to prepare a laminate.

<Adhesion evaluation>
Using Callisto manufactured by V-Technology Co., Ltd., each laminate was irradiated with a laser beam under the conditions of a wavelength of 1064 nm and an energy density of 0.5 J/cm ² for scribing. At this time, as shown in FIG. 4, the hole transport layer, active layer, and electron transport layer of the laminate were scribed by laser irradiation. However, the thickness of each layer and the ratio of the scribe width in FIG. 4 are not represented by actual ratios. In addition, the arrow of the observation direction in FIG. 4 represents the observation direction in observation with the following optical microscopes.
FIG. 5 shows the result of observing each laminate scribed by laser irradiation from above with an optical microscope.

From FIG. 5, it can be seen that in the laminate using the organic semiconductor compound having the structural unit represented by the above formula (1), peeling occurs between the active layer and the hole transport layer as shown in FIG. 4(a). On the other hand, it was found that in the laminated body not using the organic semiconductor compound, peeling occurred between the active layer and the hole transport layer as shown in FIG. 4(b).

<Production of photoelectric conversion element>

_MoO3 with a thickness of about 10 nm, then IZO with a thickness of about 30 nm and silver with a thickness of about 100 nm were vapor-deposited on the hole transport layer in the laminate obtained in each of the above examples by a resistance heating vacuum vapor deposition method, and the upper electrode was formed. was formed to fabricate a photoelectric conversion element.

From the above examples, it can be seen that, according to the present invention, a photoelectric conversion element in which delamination between the buffer layer and the active layer is suppressed, a method for manufacturing the same, and an energy harvesting device having the photoelectric conversion element, particularly at 5,000 lux or less. It can be seen that an energy harvesting device for low illumination can be provided.

100 photoelectric conversion element 101 lower electrode 102 buffer layer 103 active layer 104 buffer layer 105 upper electrode 106 substrate

Claims (11)

a pair of electrodes composed 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;
and a buffer layer positioned between the pair of electrodes,
the buffer layer contains an organic semiconductor compound having hole-transporting ability and a dopant for the organic semiconductor compound, and
A photoelectric conversion device, wherein the organic semiconductor compound has a structural unit represented by the following formula (1).

(In the above formula (1), X is at least one selected from a divalent monovalent aromatic ring group which may have a substituent and a divalent condensed aromatic ring group which may have a substituent R ¹ and R ² independently represents hydrogen or an optionally substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms.) 2. The photoelectric conversion device according to claim 1, wherein in the main chain of X in formula (1), the number of divalent aromatic ring groups A that are continuous by bonding to each other is 2 or less. 3. The photoelectric conversion device according to claim 1, wherein X in the formula (1) has at least a biphenylene group which may have a substituent in its main chain. A group constituting the main chain of X in the formula (1) is a methylene group in which at least one hydrogen is substituted with a monovalent aromatic hydrocarbon ring group, or a monovalent aromatic hydrocarbon ring group. The photovoltaic device according to any one of claims 1 to 3, comprising one or more groups selected from the group consisting of a divalent amino group and the divalent aromatic ring group A. conversion element. The ratio of the total weight of structural units that can be represented by the structural unit represented by the formula (1) in one molecule of the organic semiconductor compound is 5% by weight or more and 95% by weight or less. Item 5. The photoelectric conversion element according to any one of Items 1 to 4. 5. The photoelectric conversion device according to claim 1, wherein the structural unit represented by formula (1) is a repeating structural unit represented by formula (2) below.

(In the above formula (2), X, R ¹ and R ² have the same definitions as X, R ¹ and R ² in the above formula (1); n represents 1 to 10000.) 7. The photoelectric conversion device according to claim 1, wherein said dopant is an organic compound containing trivalent iodine. 8. The photoelectric conversion device according to claim 7, wherein the dopant is a diaryliodonium salt. 9. The photoelectric conversion device according to claim 1, wherein the organic-inorganic hybrid semiconductor compound is a compound having a perovskite structure. A method for manufacturing a photoelectric conversion element according to any one of claims 1 to 9,
A photoelectric conversion, comprising: 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. A method of manufacturing an element. A power generation device comprising the photoelectric conversion element according to any one of claims 1 to 9.

Images