JP2024060579A - Photoelectric conversion element - Google Patents

Abstract

[Problem] It is an object of the present invention to provide a photoelectric conversion element that has a high initial conversion efficiency and that is less prone to deterioration (drop) in conversion efficiency when used continuously for a long period of time. In order to achieve this, the following photoelectric conversion element is provided. [Solution] This photoelectric conversion element has a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal with a perovskite structure that is disposed between the first electrode and the second electrode, and is characterized in that the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode that contains a phthalocyanine compound and an aromatic ring compound having a hydroxyl group that is different from the phthalocyanine compound. [Selected Figure] Figure 1

Description

The present invention relates to a photoelectric conversion element.

In order to solve the problem of fossil energy depletion and the global environmental problems caused by the use of fossil energy, active research is being conducted on renewable and clean alternative energy sources such as solar energy, wind power, and hydroelectric power. Among them, interest in solar cells that directly convert sunlight into electrical energy is increasing. Here, a solar cell refers to a cell that generates a current-voltage by utilizing the photovoltaic effect in which light energy is absorbed from sunlight and electrons and holes are generated.
Currently, n-p diode type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% are widely known and are actually used for photovoltaic power generation. However, these require high-temperature processing and the material itself is expensive, so they have the problem of high cost per unit of power. In addition, there is a supply problem in terms of silicon resources.
On the other hand, solar cells using organic materials (hereinafter referred to as "organic solar cells") do not require high-temperature processing, and can be produced by a so-called roll-to-roll method using a sheet-like substrate, which allows for cost reduction. Further improvement in power generation efficiency and durability is desired for practical use of organic solar cells. In particular, as a photoelectric conversion layer, crystals with a perovskite structure (including perovskite crystals) have excellent photoelectric conversion properties, and are therefore being developed as materials for practical use of solar cells. For example, Patent Document 1 describes an increase in open-circuit voltage by having fullerene C60 as an intermediate layer on the upper layer of the perovskite. Patent Document 2 describes an improvement in durability by having an intermediate layer containing thiocyanic acid on the perovskite layer. Patent Document 3 describes an improvement in photoelectric conversion efficiency by having an intermediate layer containing 2-phenylethylammonium bromide on the perovskite layer.

JP 2020-13982 A JP 2019-71500 A JP 2022-27575 A

According to the investigations of the present inventors, the photoelectric conversion elements described in Patent Documents 1 to 3 have a problem in that the surface changes of the crystals with a perovskite structure cannot be suppressed when a current is passed through them, and the conversion efficiency deteriorates (drops) when used continuously for a long period of time.
SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a photoelectric conversion element which has high initial conversion efficiency and which is less prone to deterioration (dropping) in conversion efficiency when used continuously for a long period of time.

A first aspect of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure disposed between the first electrode and the second electrode,
The present invention is characterized in that a charge transport layer (including a hole transport layer or an electron transport layer) is provided between the photoelectric conversion layer and the first electrode, the charge transport layer including a phthalocyanine compound (including a metal-free phthalocyanine or a metal phthalocyanine, or a phthalocyanine derivative derived from the metal-free or metal phthalocyanine) and an aromatic ring compound having a hydroxy group that is different from the phthalocyanine compound.
A second aspect of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode,
The electroluminescent device is characterized in that a charge transport layer containing a hole transporting compound and an aromatic ring compound represented by the following general formula [1] is provided between the photoelectric conversion layer and the first electrode.

(In the above general formula [1], R ₁ to R ₄ are each independently within each repeating unit and each independently for every n repeating units, and are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, n is an integer of 3 to 20, and one molecule has at least one hydroxyl group.)

The present invention provides a photoelectric conversion element that suppresses the decrease in conversion efficiency even when used continuously for a long period of time.

1 is a schematic cross-sectional view in a thickness direction of a first embodiment of a photoelectric conversion element of the present invention. FIG. 2 is a schematic cross-sectional view in the thickness direction of a second embodiment of a photoelectric conversion element of the present invention. FIG. 1 is a perspective view showing a typical example of an application of a photoelectric conversion element of the present invention as a moving object. FIG. 11 is a perspective view that illustrates a schematic diagram of another example of an application of the photoelectric conversion element of the present invention as a building material.

First and Second Embodiments
The photoelectric conversion element of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure disposed between the first electrode and the second electrode, and a charge transport layer is provided between the photoelectric conversion layer and the first electrode. The charge transport layer according to the present invention has either of the following characteristics (1) or (2).
(1) A phthalocyanine compound and an aromatic ring compound having a hydroxyl group, which is different from the phthalocyanine compound. In the present invention, the phthalocyanine compound includes phthalocyanine and phthalocyanine derivatives (compounds derived from phthalocyanine).
(2) The electroluminescent device contains a hole transporting compound and an aromatic ring compound having a calixarene structure.

First, the above item (1) will be explained.
As a result of investigations, the present inventors have found that by having the charge transport layer of (1) above, a photoelectric conversion element having excellent surface stability of the crystal of the perovskite structure can be obtained. Although the details of the reason why high stability is obtained in the present invention are not clear, it is considered as follows.

By forming a film of the phthalocyanine compound in a particle state, high crystallinity is maintained, and the inherent charge transport ability of the phthalocyanine can be expressed. Furthermore, in the previous study by the present inventors, when the photoelectric conversion layer contains a perovskite compound, submicron-scale unevenness occurs on the surface, and it is presumed that by filling the concaves of such unevenness with phthalocyanine compound particles, the interface bonding is improved and high photoelectric conversion efficiency can be obtained. However, it was found that the lamination of phthalocyanine compound particles cannot suppress the change in the crystal surface of the perovskite structure when electricity is applied. In the present invention, the charge transport layer having the phthalocyanine compound particles contains an aromatic ring compound having a hydroxyl group different from the phthalocyanine compound, thereby making it possible to suppress the deterioration of the crystal of the perovskite structure. It is presumed that the aromatic ring compound having a hydroxyl group enters between the phthalocyanine compound particles and the crystal of the perovskite structure. Since the crystal of the perovskite structure is a hydrogen-bonding crystal, it is thought that the aromatic ring compound having a hydroxyl group interacts with the crystal surface of the perovskite structure through hydrogen bonding. It is believed that by interacting with the crystal surface of this perovskite structure, when the crystal of the perovskite structure changes to a stable state when an electric current is passed through it, the crystal surface is chemically fixed by the above interaction, thereby suppressing changes to the crystal surface.

The present inventors believe that the aromatic ring compound having a hydroxyl group can interact with the crystal surface of the perovskite structure by combining it with a phthalocyanine compound. It is presumed that the aromatic ring of the aromatic ring compound having a hydroxyl group interacts with the surface of the phthalocyanine compound because the condensed rings of the phthalocyanine compound strongly interact with each other. As a result, it is believed that the hydroxyl group of the aromatic ring compound having a hydroxyl group interacts more strongly with the crystal direction of the perovskite structure. From the viewpoint of the strength of the interaction with the crystal surface of the perovskite structure, when the content of the phthalocyanine compound contained in the charge transport layer is 100 parts by mass, it is preferable that the content (parts by mass) of the aromatic ring compound having a hydroxyl group in the charge transport layer is in the range of 0.5 parts by mass to 50 parts by mass. In addition, from the viewpoint of molecular size, the aromatic ring compound having a hydroxyl group preferably has a molecular weight of 10,000 or less in order to facilitate interaction with the crystal surface of the perovskite structure.

It was also found that when the number of hydroxyl groups in the aromatic ring compound is greater than the number of hydroxyl groups in the phthalocyanine compound, the aromatic ring compound and the crystal surface of the perovskite structure are more likely to interact with each other, and changes in the crystal surface are more likely to be suppressed. In the present invention, it is preferable that the number of hydroxyl groups in the aromatic ring compound is greater than the number of hydroxyl groups in the phthalocyanine compound. In particular, from the viewpoint of the strength of hydrogen bonds, the number of hydroxyl groups in the aromatic ring compound having hydroxyl groups is more preferably 3 or more, and particularly preferably 4 or more. Since the hydrogen bond density with the crystal surface of the perovskite structure is increased, it is more preferable that the aromatic ring compound having hydroxyl groups has a cyclic structure, and it is preferable that the aromatic ring compound has a calixarene structure such as calix-4 arene or calix-8 arene. It was found that a combination of multiple calix-4 arenes is particularly excellent.

In the present invention, the charge transport layer may contain one type of aromatic ring compound, but preferably contains multiple types of aromatic ring compounds. Specifically, the aromatic ring compound having a calixarene structure preferably used in the present invention is preferably a compound represented by the following general formula [1].

In the above general formula [1], R ₁ to R ₄ are each independently in each repeating unit and each independently for every n repeating units, and are each hydrogen, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, where n is an integer of 3 to 20, and has at least one hydroxyl group in one molecule. The present invention also relates to a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure disposed between the first electrode and the second electrode, characterized in that the photoelectric conversion element has a charge transport layer containing a hole transport compound and an aromatic ring compound represented by the above general formula [1] between the photoelectric conversion layer and the first electrode. In the present invention, the compound can be analyzed based on data measured by a nuclear magnetic resonance (NMR) spectrometer to determine the structure.

The organic group may be a group represented by the general formula -Y-Ar, where -Y- is -CH=N-, -CH=CH- or -N=N-, and Ar is a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted heterocyclic group.

Examples of the aromatic hydrocarbons exemplified as R ₁ to R ₄ and the aromatic hydrocarbons exemplified as Ar include benzene, naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, etc. Examples of the heterocycles exemplified as Ar include furan, thiophene, pyridine, indole, benzothiazole, carbazole, benzocarbazole, acridone, dibenzothiophene, benzoxazole, benzotriazole, oxathiazole, thiazole, phenazine, cinnoline, benzocinnoline, etc.

In addition, examples of the substituents which the aromatic hydrocarbon groups exemplified as R ₁ to R ₄ may have and the substituents which Ar may have include alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group; alkoxy groups such as a methoxy group and an ethoxy group; dialkylamino groups such as a dimethylamino group and a diethylamino group; alkoxycarbonyl groups such as a methoxycarbonyl group and an ethoxycarbonyl group; halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom; a hydroxy group, a nitro group, a cyano group, and a halomethyl group.

In the aromatic ring compound having a calixarene structure represented by the above general formula [1], n is preferably 4 or 8. It is also preferred that R ₁ is independently a halogen atom or a hydroxyl group for every n repeating units, and at least one R ₁ is a hydroxyl group. It is also preferred that R ₃ is independently a nitrophenylazo group or a dinitrophenylazo group for every n repeating units.

Specific examples of aromatic ring compounds having a calixarene structure that are preferably used in the present invention are listed below. In the present invention, it is preferable that the charge transport layer contains, as an aromatic ring compound, at least one selected from the group consisting of a compound represented by the following formula [C-1], a compound represented by the following formula [C-2], a compound represented by the following formula [C-3], and a compound represented by the following formula [C-4], and it is more preferable that the charge transport layer contains, as an aromatic ring compound, a compound represented by the following formula [C-1], a compound represented by the following formula [C-2], a compound represented by the following formula [C-3], and a compound represented by the following formula [C-4].

As aromatic ring compounds having a hydroxyl group that are different from phthalocyanine compounds, aromatic ring compounds having a non-cyclic structure can be used in addition to aromatic ring compounds having a calixarene structure. Specific examples include phenol, 1-naphthol, benzyl alcohol, cresol, benzenetriol, carboxylic acid, hydroquinone, benzoic acid, phthalic acid, terephthalic acid, and catecholamine.

In the present invention, the phthalocyanine compound is preferably a metal phthalocyanine compound. The phthalocyanine compound used in the present invention may have a metal ligand, and examples of the coordinated metal include Ga, Cu, Ti, and Zn, and among them, Ga is preferred from the viewpoint of crystallinity. From the viewpoint of interaction with an aromatic ring compound having a hydroxy group, the phthalocyanine compound is more preferably a gallium phthalocyanine compound, and is particularly preferably a hydroxygallium phthalocyanine compound.

The present inventors have also discovered that, in addition to the phthalocyanine compound, a combination of a hole transporting compound and an aromatic ring compound having a calixarene structure represented by the above general formula [1] allows the aromatic ring compound to interact with the crystal surface of the perovskite structure, chemically stabilizing the surface. That is, the charge transport layer of (2) above. As the aromatic ring compound having a calixarene structure, calix-4-arene in which n in the general formula [1] is 4 is preferable. In addition, a compound in which R ₁ in the general formula [1] is independently a halogen atom or a hydroxyl group for each of n repeating units, at least one R ₁ is a hydroxyl group, and R ₃ is independently a nitrophenylazo group or a dinitrophenylazo group for each of n repeating units is preferable. In particular, a mixture of a plurality of calix-4-arenes is preferable from the viewpoint of affinity with the hole transporting compound.

The hole transport compound to be combined with the aromatic ring compound having a calixarene structure is not particularly limited, but spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene) and PTAA (poly(triarylamine)) are preferred.

As explained above, the effects of the present invention can be achieved by each component exerting a synergistic effect.

The following describes in detail the embodiments of the present invention. The present invention is not limited to the following embodiments, and the scope of the present invention also includes appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of a person skilled in the art, provided that the modifications and improvements do not deviate from the spirit of the present invention.

In this specification, the term "layer" refers not only to a layer with clear boundaries or a flat thin-film layer, but also to a layer with a gradually changing concentration gradient of contained elements, or to a layer that can combine with other layers to form a complex and intricate structure. Elemental analysis of a layer can be performed, for example, by performing TOF-SIMS/FE-TEM/EDS line analysis measurement of a cross section of a photoelectric conversion element to confirm the elemental distribution of a specific element.

1 is a schematic cross-sectional view in the thickness direction of a first embodiment of a photoelectric conversion element of the present invention. A second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 8, a hole transport layer 6, and a first electrode 7 are provided on a substrate 2. The first electrode 7 is an anode, and the second electrode 3 is a cathode. A current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.
FIG. 2 is a schematic cross-sectional view in the thickness direction of a second embodiment of a photoelectric conversion element of the present invention.

The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or through the first electrode 7, the hole transport layer 6, and the charge transport layer 8, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a voltage between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and the two electrodes 3 and 7, and may not be formed in some cases. The photoelectric conversion element of the present invention may be in a form in which a plurality of electron transport layers 4, photoelectric conversion layers 5, and hole transport layers 6 are stacked, and an electrode may be provided as necessary. The photoelectric conversion elements to be stacked may be photoelectric conversion elements having silicon, CIGS, or the like. Such a form is sometimes called a tandem structure. Each member is described below.

〔substrate〕
The photoelectric conversion element 1 of the present invention may include a substrate 2, examples of which include a transparent glass substrate such as soda-lime glass or alkali-free glass, a ceramic substrate, a transparent plastic substrate, etc. When light is taken in from the first electrode 7 side, an opaque material can be used for the substrate 2, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material. In addition, both the first electrode 7 and the second electrode 3 may be made of a transparent material.

〔electrode〕
The materials of the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al/Al ₂ O ₃ mixture, and Al/LiF mixture can be mentioned. Examples of transparent electrode materials include conductive transparent materials such as CuI, ITO (indium tin oxide), SnO ₂ , AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimony-doped tin oxide), and conductive transparent polymers. These materials may be used alone, or two or more of them may be used in combination. At least one of the electrodes on the light incident side of the first electrode 7 and the second electrode 3 is a transparent electrode, and the other may be a transparent electrode or a reflective layer formed of a light-reflective material. When the first electrode 7 is on the light incident side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The transparent electrode may be a patterned electrode.

[Photoelectric Conversion Layer]
The photoelectric conversion layer 5 has a crystal having a perovskite structure. The crystal having a perovskite structure used in the present invention is preferably a crystal of a compound represented by the following general formula [2], which is easily hydrogen-bonded on the surface.
R-M-X ₃ [2]
In the above general formula [2], R is either an organic molecule or an inorganic atom, or both, M is a metal atom, and X is a halogen atom or a chalcogen atom.
In the above general formula [2], for example, in the case of an organic molecule, R is preferably represented by C _p N _m H _n (wherein p, m, and n are all positive integers). Specific examples of the amine include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, ethylbutylamine, imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, imidazoline, carbazole, aniline, pyridine, methylcarboxyamine, ethylcarboxyamine, propylcarboxyamine, butylcarboxyamine, pentylcarboxyamine, hexylcarboxyamine, formamidinium, guanidine ions (e.g., methylammonium (CH ₃ NH ₃ ), etc.), and phenethylammonium. Among them, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, aniline, pyridine, propylcarboxyamine, butylcarboxyamine, pentylcarboxyamine, formamidinium, guanidine ion, and phenethylammonium are preferred, and methylamine, ethylamine, propylamine, pentylcarboxyamine, formamidinium, and guanidine ion are more preferred. Inorganic atoms are not particularly limited, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms may be used alone or in combination of two or more.

The above M is a metal atom, such as lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of electron orbital overlap. These metal atoms may be used alone or in combination of two or more.

The X is a halogen atom or a chalcogen atom, such as chlorine, bromine, iodine, sulfur, and selenium. These halogen atoms or chalcogen atoms may be used alone or in combination of two or more. Among them, halogen atoms are preferred because the organic-inorganic perovskite compound is easily soluble in an organic solvent by containing a halogen in the structure, and can be applied to inexpensive printing methods and the like. Furthermore, iodine is more preferred because the energy band gap of the organic-inorganic perovskite compound is narrowed.
Specifically, _MAPbI3 , _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ , and _CsPbI3 are preferred. Note that "MA" _stands for methylammonium, _and "FA" stands for formamidinium.

The organic-inorganic perovskite compound preferably has a cubic crystal structure in which a metal atom M is located at the body center, an organic molecule R at each vertex, and a halogen atom or chalcogen atom X is located at the face center. Although the details are not clear, it is presumed that the presence of such a structure makes it easy to change the orientation of the octahedrons in the crystal lattice, thereby increasing the mobility of electrons in the organic-inorganic perovskite compound and improving the photoelectric conversion efficiency of the photoelectric conversion element.

The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor means a semiconductor in which a scattering peak can be detected by measuring the X-ray scattering intensity distribution. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound is increased, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 1000 nm or less. If the thickness is 5 nm or more, light can be sufficiently absorbed, and if the thickness is 1000 nm or less, the generated charges can be transported to each electrode. A more preferred lower limit is 10 nm or more, a more preferred upper limit is 700 nm, an even more preferred lower limit is 15 nm, and an even more preferred upper limit is 500 nm.

[Charge Transport Layer]
The photoelectric conversion element 1 of the present invention has a charge transport layer 8 between the photoelectric conversion layer 5 and the first electrode 7. In the present invention, it is preferable that the charge transport layer is in contact with the photoelectric conversion layer. As described above, the charge transport layer 8 contains either a phthalocyanine compound and an aromatic ring compound having a hydroxyl group different from the phthalocyanine compound, or a hole transport compound and an aromatic ring compound having a calixarene structure.

The thickness of the charge transport layer 8 is preferably 20 nm or more and 800 nm or less. If the thickness is 20 nm or more, it is easy to sufficiently cover the photoelectric conversion layer 5 and charge transport can be performed smoothly, and if the thickness is 800 nm or less, it is easy to transport charges well to each electrode. More preferably, it is 50 nm or more and 600 nm or less, and even more preferably, it is 50 nm or more and 400 nm or less.

[Hole transport layer]
In the present invention, it is preferable to have a hole transport layer 6 between the charge transport layer 8 and the first electrode 7 from the viewpoint of film compatibility of the charge transport layer.
The material of the hole transport layer 6 is not particularly limited, and examples thereof include spirofluorene compounds, triphenylamine compounds, chrysene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, etc. In particular, from the viewpoint of compatibility with the film interface, it is preferable that the compound has an aromatic ring, and as the hole transport compound, Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferable.

[Electron Transport Layer]
In the photoelectric conversion element of the present invention, as shown in FIG. 1, an electron transport layer 4 may be disposed between the second electrode 3 and the photoelectric conversion layer 5 .

The material of the electron transport layer 4 is not particularly limited, and examples thereof include N-type conductive polymers, N-type low molecular weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc., and specific examples thereof include cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc.

The thickness of the electron transport layer 4 has a preferred lower limit of 1 nm and a preferred upper limit of 2000 nm. If the thickness is 1 nm or more, holes can be blocked sufficiently, and if the thickness is 2000 nm or less, it is unlikely to become a resistance during electron transport, and the photoelectric conversion efficiency is high. A more preferred lower limit of the thickness is 3 nm, a more preferred upper limit is 1000 nm, an even more preferred lower limit is 5 nm, and an even more preferred upper limit is 500 nm.

[Photoelectric conversion device]
A photoelectric conversion device can be constructed by using a plurality of photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can also be called a photoelectric conversion module. The photoelectric conversion elements may be stacked to increase the output voltage. The photoelectric conversion device has the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current to alternating current. The photoelectric conversion device may have a storage unit connected to the photoelectric conversion element. The storage unit is not limited as long as it can store electricity. For example, a secondary battery using lithium ions or the like, an all-solid-state battery, an electric double layer capacitor, etc. can be mentioned.

<Application Examples>
[Mobile object]
The moving body of the present invention is preferably equipped with the above-mentioned photoelectric conversion element. FIG. 3 is a perspective view showing a typical example of an application of a moving body equipped with the photoelectric conversion element of the present invention. The moving body 30 has the photoelectric conversion element 31 of the present invention and a vehicle 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position on the vehicle 32 where it can receive external light. If the moving body 30 is an automobile, it may be disposed on the roof. The electric energy obtained by the photoelectric conversion element 31 may be used as the power source for the moving body 30 or as the power source for other electric devices. The electric energy generated from the power source of the moving body 30 may be used to power the photoelectric conversion element 31. If the moving body 30 is an automobile, frictional energy generated by braking may be converted into electric energy and used to control the photoelectric conversion element 31.

The moving body 30 may be, for example, an automobile, a ship, an aircraft, or a drone. The configuration of the body 32 of the moving body 30 is not particularly limited, but it is preferably made of a high-strength material.

[Building Materials]
The building material of the present invention preferably includes the above-mentioned photoelectric conversion element. Fig. 4 is a perspective view showing a schematic diagram of another example of an application of a building material including the photoelectric conversion element of the present invention. The building material 40 may be the roof of a building. The building material 40 of the application example includes the photoelectric conversion element 41 of the present invention, a protective member 42 for protecting the photoelectric conversion element 41, a heat dissipation member 43, and exteriors 44a and 44b.

The building material 40 of the present invention may have a heat dissipation member 43 that has a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, the temperature of the photoelectric conversion element 41 may rise due to sunlight, and the photoelectric conversion efficiency may decrease. By using the heat dissipation member 43, the decrease in photoelectric conversion efficiency can be reduced. Examples of the heat dissipation member 43 include metal, alloy, liquid metal, liquid resin, etc.

The building material 40 of the present invention may also have exteriors 44a and 44b. The exteriors 44a and 44b may emit different colors or may be the same. 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior. A material with low light absorption and high heat insulation is preferable.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" refers to "parts by mass" unless otherwise specified.

[Preparation of Phthalocyanine Compound Particles]
Preparation of Particle 1
Step (1)
Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were put into a reaction vessel, and then heated to a temperature of 30° C. and maintained at this temperature. Next, 3.75 parts of gallium trichloride were put in at this temperature (30° C.). The water concentration of the mixed liquid at the time of putting in was 150 ppm. Then, the temperature was raised to 200° C. Next, under a nitrogen flow atmosphere, the mixture was reacted at a temperature of 200° C. for 4.5 hours, cooled, and when the temperature reached 150° C., the product was filtered. The obtained filtrate was dispersed and washed using N,N-dimethylformamide at a temperature of 140° C. for 2 hours, and then filtered. The obtained filtrate was washed with methanol and then dried to obtain chlorogallium phthalocyanine particles with a yield of 71%.

Step (2)
4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at a temperature of 10° C., dropped into 620 parts of ice water under stirring to reprecipitate, and filtered under reduced pressure using a filter press. At this time, No. 5C (manufactured by Advantec Co., Ltd.) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% ammonia water for 30 minutes, and then filtered using a filter press. Next, the obtained wet cake (filtrate) was dispersed and washed with ion-exchanged water, and then filtration using a filter press was repeated three times. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solid content of 23% by mass at a yield of 71%. The hydroxygallium phthalocyanine particles were dried using a hyper-dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Japan Biocon Co., Ltd.) to obtain hydroxygallium phthalocyanine particles (crystals) with a moisture content of 1.0% by mass or less.

Step (3)
Five parts of the hydroxygallium phthalocyanine (HOGaPc) particles were dispersed for six hours using a sand mill (K-800, manufactured by Igarashi Machinery Mfg. Co., Ltd. (now Imex Co., Ltd.), disk diameter 70 mm, number of disks 5) containing 5 parts of DMF (N,N-dimethylformamide) as a solvent and 5 parts of glass beads sealed therein, followed by filtration and drying to obtain Particle 1.

Example 1
[Formation of Electron Transport Layer]
A glass substrate with ITO (indium tin oxide) was cleaned, and tin (II) oxide adjusted to 3 mass % was applied thereon by spin coating, followed by heating at 150° C. for 30 minutes to form a thin-film electron transport layer having a thickness of 100 nm.

[Formation of photoelectric conversion layer]
A photoelectric conversion layer coating solution was prepared by dissolving 4 g of lead iodide and 1.4 g of methylammonium iodide in 4.5 g of dimethylformamide as a solvent and stirring and dissolving the mixture at 60° C. for 24 hours. This coating solution was spin-coated on the electron transport layer to form a photoelectric conversion layer of _MAPbI3 having a thickness of 500 nm.

[Formation of Charge Transport Layer]
0.05 g of the particles 1 was dispersed for 6 hours using a sand mill (K-800, manufactured by Igarashi Machinery Mfg. Co., Ltd. (now Imex Co., Ltd.), disk diameter 70 mm, number of disks 5) containing 4.95 g of 2-propanol as a solvent, 0.0001 g of phenol as an aromatic ring compound having a hydroxyl group, and 11 g of glass beads, to prepare a charge transport layer solution. The charge transport layer solution was spin-coated on the photoelectric conversion layer to form a charge transport layer having a thickness of 100 nm.

[Introduction of a hole transport layer]
180 mg of Spiro-OMeTAD as a hole transporting compound was dissolved in 1 mL of chlorobenzene. 37.5 μL of an acetonitrile solution obtained by dissolving 170 mg of lithium-bis(trifluoromethanesulfonyl)imide in 1 mL of acetonitrile was added to this chlorobenzene solution, and 17.5 μL of t-butylpyridine (TBP) were added and mixed to prepare a solution of the hole transporting compound. This was applied to the charge transporting layer by spin coating to form a hole transporting layer having a thickness of 200 nm.

[Formation of the first electrode]
A gold electrode having a thickness of 80 nm and an area of 0.09 cm ² was formed on the hole transport layer by vacuum deposition to obtain a photoelectric conversion element.

(Examples 2 to 5)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that 0.00025 g of an aromatic ring compound having a hydroxyl group was used in Example 2, 0.005 g in Example 3, 0.025 g in Example 4, and 0.04 g in Example 5.

(Examples 6 to 8)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to 1-naphthol and 0.0001 g was used in Example 6, 0.00025 g in Example 7, and 0.025 g in Example 8.

(Examples 9 to 12)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-1], and 0.0001 g was used in Example 9, 0.00025 g in Example 10, 0.0025 g in Example 11, and 0.005 g in Example 12.

(Example 13)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-1] and 0.005 g was used, and further, the hole transporting compound in the hole transport layer was changed to PTAA (CAS: 1333317-99-9, manufactured by Luminescence Technology Co., Ltd.).

(Example 14)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], _{0.005 g} of the compound was used, and the perovskite structure crystal was changed to _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ .

(Examples 15 to 17)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-1] and 0.015 g was used in Example 15, 0.025 g in Example 16, and 0.04 g in Example 17.

(Example 18)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-9] above and 0.005 g was used.

(Example 19)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that 0.005 g of an aromatic ring compound having a hydroxyl group, which was a mixture of an aromatic ring compound represented by the formula [C-1] and an aromatic ring compound represented by the formula [C-2] in a mass ratio of 1:1, was used.

(Examples 20 to 22)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.0001 g was used in Example 20, 0.00025 g in Example 21, and 0.005 g in Example 22. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 23)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], 0.005 g of which was used, and the perovskite structure crystal was changed to Sr ₂ Nb ₂ O _7. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 24)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], 0.005 g of which was used, and no hole transport layer was formed. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 25)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.005 g was used, and the order of film formation of the hole transport layer and the charge transport layer was reversed so that the hole transport layer was in contact with the photoelectric conversion layer. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Examples 26 and 27)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.025 g was used in Example 26 and 0.04 g was used in Example 27. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 28)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the aromatic ring compound having a hydroxy group was changed to an aromatic ring compound represented by the following formula [A-1] (CAS: 490-46-0, manufactured by Fuji Film Corporation) and an aromatic ring compound represented by the following formula [A-2] (CAS: 970-73-0, manufactured by Fuji Film Corporation), and 0.005 g of each was used. The mass ratio was [A-1]:[A-2]=1:1.

(Example 29)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that 0.005 g of a mixture of an aromatic ring compound represented by the formula [C-5] and an aromatic ring compound represented by the formula [C-6] in a mass ratio of 1:1 was used as the aromatic ring compound having a hydroxy group.

(Example 30)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that 0.005 g of a mixture of an aromatic ring compound represented by the formula [C-7] and an aromatic ring compound represented by the formula [C-8] in a mass ratio of 1:1 was used as the aromatic ring compound having a hydroxy group.

(Examples 31 to 33)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine (CuPc) and 0.0001 g of an aromatic ring compound having a hydroxyl group was used in Example 31, 0.005 g in Example 32, and 0.04 g in Example 33.

(Examples 34 and 35)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to 1-naphthol, and 0.00025 g was used in Example 34 and 0.025 g was used in Example 35.

(Examples 36 to 38)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.0001 g was used in Example 36, 0.0025 g in Example 37, and 0.005 g in Example 38.

(Example 39)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-1] in an amount of 0.005 g, and the hole transport compound was changed to PTAA.

(Example 40)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] ( _0.005 g _was used), and the perovskite structure crystal was changed to _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ .

(Examples 41 and 42)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.015 g was used in Example 41 and 0.04 g was used in Example 42.

(Example 43)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-9] and 0.005 g was used.

(Examples 44 and 45)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to copper phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.00025 g was used in Example 44 and 0.025 g was used in Example 45. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Examples 46 to 48)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine (ZnPc), and 0.0001 g of an aromatic ring compound having a hydroxyl group was used in Example 46, 0.005 g in Example 47, and 0.04 g in Example 48.

(Examples 49 and 50)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to 1-naphthol, and 0.00025 g was used in Example 49 and 0.025 g was used in Example 50.

(Examples 51 to 53)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.0001 g was used in Example 51, 0.0025 g in Example 52, and 0.005 g in Example 53.

(Example 54)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] (0.005 g was used), and the hole transporting compound in the hole transport layer was changed to PTAA.

(Example 55)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] ( _0.005 g _was used), and the perovskite structure crystal was changed to _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ .

(Examples 56 and 57)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.015 g was used in Example 56 and 0.04 g was used in Example 57.

(Example 58)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-9] and 0.005 g was used.

(Examples 59 and 60)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.00025 g was used in Example 59 and 0.025 g was used in Example 60. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Examples 61 to 63)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine (TiPc) and 0.0001 g of an aromatic ring compound having a hydroxyl group was used in Example 61, 0.005 g in Example 62, and 0.04 g in Example 63.

(Examples 64 and 65)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to 1-naphthol, and 0.00025 g was used in Example 64 and 0.025 g was used in Example 65.

(Examples 66 to 68)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.0001 g was used in Example 66, 0.0025 g in Example 67, and 0.005 g in Example 68.

(Example 69)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] (0.005 g was used), and the hole transporting compound in the hole transport layer was changed to PTAA.

(Example 70)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] ( _0.005 g _was used), and the perovskite structure crystal was changed to _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ .

(Examples 71 and 72)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.015 g was used in Example 71 and 0.04 g was used in Example 72.

(Example 73)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-9] and 0.005 g was used.

(Examples 74 and 75)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.00025 g was used in Example 74 and 0.025 g was used in Example 75. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Examples 76 to 78)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine (ClGaPc), and 0.0001 g of an aromatic ring compound having a hydroxyl group was used in Example 76, 0.005 g in Example 77, and 0.04 g in Example 78.

(Examples 79 and 80)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to 1-naphthol, and 0.00025 g was used in Example 79 and 0.025 g was used in Example 80.

(Examples 81 and 82)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.0001 g was used in Example 81 and 0.005 g was used in Example 82.

(Example 83)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.005 g of the compound was used, and further the hole transport compound in the hole transport layer was changed to PTAA.

(Example 84)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] ( _{0.005 g} ) was used, and the perovskite structure crystal was changed to _Cs5 ( _MA0.17FA0.83 ) _95Pb ( _I0.83Br0.17 ) ₃ .

(Example 85)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1] and 0.04 g was used.

(Example 86)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-9] and 0.005 g was used.

(Examples 87 and 88)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to chlorogallium phthalocyanine, the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], and 0.00025 g was used in Example 87 and 0.025 g in Example 88. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 89)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to metal-free phthalocyanine (Pc), and the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], respectively, and 0.005 g was used. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Example 90)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to gallium phthalocyanine represented by the following formula [F-1], and the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], respectively, and 0.005 g was used. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Comparative Example 1)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to zinc phthalocyanine and no aromatic ring compound having a hydroxy group was used.

(Comparative Example 2)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to titanyl phthalocyanine and no aromatic ring compound having a hydroxy group was used.

(Comparative Example 3)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that no phthalocyanine compound was used.

(Comparative Example 4)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that no phthalocyanine compound was used and the aromatic ring compound having a hydroxy group was changed to the aromatic ring compound represented by the formula [C-1].

(Comparative Example 5)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that no phthalocyanine compound was used, and further, the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4]. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Examples 91 to 93)
Photoelectric conversion elements were obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to Spiro-OMeTAD, which is a hole transporting compound, and the aromatic ring compound having a hydroxyl group was changed to the aromatic ring compound represented by the formula [C-1], and 0.00025 g was used in Example 91, 0.005 g in Example 92, and 0.025 g in Example 93.

(Example 94)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to a hole transporting compound, Spiro-OMeTAD, and the aromatic ring compound having a hydroxyl group was changed to a mixture of the aromatic ring compounds represented by the formulas [C-1] to [C-4], respectively, and 0.005 g was used. The mass ratio was [C-1]:[C-2]:[C-3]:[C-4]=1:1:1:1.

(Comparative Example 6)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to 0.0001 g of Spiro-OMeTAD, which is a hole transporting compound.

(Comparative Example 7)
A photoelectric conversion element was obtained in the same manner as in Example 1, except that the phthalocyanine compound was changed to 0.04 g of Spiro-OMeTAD, which is a hole transporting compound.

[evaluation]
The photoelectric conversion elements obtained in each of the Examples and Comparative Examples were evaluated as follows.
(Power generation efficiency evaluation)
A power source (KEITHLEY, Model 236) was connected between the electrodes of the photoelectric conversion element, and a constant amount of light was irradiated using a solar simulator (Yamashita Denso) with an intensity of 100 mW/ ^cm2 , and the generated current and voltage were measured to evaluate the photoelectric conversion efficiency. Degradation was evaluated by continuously irradiating light of 2000 Lx and measuring the photoelectric conversion efficiency after 30 days. The stability of the element was evaluated by the attenuation rate of the conversion efficiency after 30 days (degradation rate after 30 days) relative to the initial conversion efficiency. The results are shown in Tables 1 to 4. In the tables, the "amount used" of the "aromatic ring compound having a hydroxyl group" indicates the amount (parts by mass) of the aromatic ring compound used when the amount of the phthalocyanine compound used is taken as 100 parts by mass.

Disclosure of the embodiments according to the present invention includes the following configurations.
(Configuration 1)
A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode,
a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a phthalocyanine compound and an aromatic ring compound having a hydroxyl group, the aromatic ring compound being different from the phthalocyanine compound.
(Configuration 2)
2. The photoelectric conversion element according to claim 1, wherein the number of hydroxy groups in the aromatic ring compound is greater than the number of hydroxy groups in the phthalocyanine compound.
(Configuration 3)
3. The photoelectric conversion element according to claim 1 or 2, wherein the aromatic ring compound has three or more hydroxy groups.
(Configuration 4)
3. The photoelectric conversion element according to claim 1 or 2, wherein the aromatic ring compound has four or more hydroxy groups.
(Configuration 5)
5. The photoelectric conversion element according to any one of configurations 1 to 4, wherein the charge transport layer contains a plurality of types of the aromatic ring compound.
(Configuration 6)
The photoelectric conversion element according to any one of configurations 1 to 5, wherein the aromatic ring compound is a compound represented by the following general formula [1]:
(In the above general formula [1], R ₁ to R ₄ are each independently within each repeating unit and each independently for every n repeating units, and are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, n is an integer of 3 to 20, and one molecule has at least one hydroxyl group.)
(Configuration 7)
The photoelectric conversion element according to the above-mentioned constitution 6, wherein n in the general formula [1] is 4 or 8.
(Configuration 8)
The photoelectric conversion element according to Structure 6 or 7, wherein R ₁ in the general formula [1] is independently a halogen atom or a hydroxyl group for every n repeating units, at least one R ₁ is a hydroxyl group, and R ₃ is independently a nitrophenylazo group or a dinitrophenylazo group for every n repeating units.
(Configuration 9)
The photoelectric conversion element according to any one of structures 1 to 8, wherein the charge transport layer contains, as the aromatic ring compound, at least one selected from the group consisting of a compound represented by the following formula [C-1], a compound represented by the following formula [C-2], a compound represented by the following formula [C-3], and a compound represented by the following formula [C-4]:
(Configuration 10)
The photoelectric conversion element according to Structure 9, wherein the charge transport layer contains, as the aromatic ring compound, a compound represented by the formula [C-1], a compound represented by the formula [C-2], a compound represented by the formula [C-3], and a compound represented by the formula [C-4].
(Configuration 11)
11. The photoelectric conversion element according to any one of configurations 1 to 10, wherein the aromatic ring compound has a molecular weight of 10,000 or less.
(Configuration 12)
12. The photoelectric conversion element according to any one of configurations 1 to 11, wherein the charge transport layer is in contact with the photoelectric conversion layer.
(Configuration 13)
13. The photoelectric conversion element according to any one of configurations 1 to 12, wherein the phthalocyanine compound is a metal phthalocyanine compound.
(Configuration 14)
14. The photoelectric conversion element according to any one of configurations 1 to 13, wherein the phthalocyanine compound is a gallium phthalocyanine compound.
(Configuration 15)
14. The photoelectric conversion element according to any one of configurations 1 to 13, wherein the phthalocyanine compound is a hydroxygallium phthalocyanine compound.
(Configuration 16)
The photoelectric conversion element according to any one of configurations 1 to 15, wherein the crystal having the perovskite structure is a crystal of a compound represented by the following general formula [2]:
R-M-X ₃ [2]
(In the above general formula [2], R is either an organic molecule or an inorganic atom, or both, M is a metal atom, and X is a halogen atom or a chalcogen atom.)
(Configuration 17)
The photoelectric conversion element according to any one of structures 1 to 16, wherein the content (parts by mass) of the aromatic ring compound in the charge transport layer is 0.5 parts by mass or more and 50 parts by mass or less when the content of the phthalocyanine compound is 100 parts by mass.
(Configuration 18)
18. The photoelectric conversion element according to any one of configurations 1 to 17, further comprising a hole transport layer between the charge transport layer and the first electrode.
(Configuration 19)
19. The photoelectric conversion element according to Structure 18, wherein the hole transport layer contains Spiro-OMeTAD as a hole transport compound.
(Configuration 20)
A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode,
A photoelectric conversion element comprising a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a hole transport compound and an aromatic ring compound represented by the following general formula [1]:
(In the above general formula [1], R ₁ to R ₄ are each independently within each repeating unit and each independently for every n repeating units, and are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, n is an integer of 3 to 20, and one molecule has at least one hydroxyl group.)

1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Hole transport layer 7 First electrode 8 Charge transport layer

Claims (20)

A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode,
a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a phthalocyanine compound and an aromatic ring compound having a hydroxyl group, the aromatic ring compound being different from the phthalocyanine compound. The photoelectric conversion element according to claim 1, wherein the number of hydroxyl groups in the aromatic ring compound is greater than the number of hydroxyl groups in the phthalocyanine compound. The photoelectric conversion element according to claim 1, wherein the number of hydroxyl groups in the aromatic ring compound is 3 or more. The photoelectric conversion element according to claim 1, wherein the number of hydroxyl groups in the aromatic ring compound is 4 or more. The photoelectric conversion element according to claim 1, wherein the charge transport layer contains multiple types of the aromatic ring compound. The photoelectric conversion element according to claim 1 , wherein the aromatic ring compound is a compound represented by the following general formula [1]:
(In the above general formula [1], R ₁ to R ₄ are each independently within each repeating unit and each independently for every n repeating units, and are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, n is an integer of 3 to 20, and one molecule has at least one hydroxyl group.) The photoelectric conversion element according to claim 6, wherein n in the general formula [1] is 4 or 8. The photoelectric conversion element according to claim 6, wherein R ₁ in the general formula [1] is independently a halogen atom or a hydroxyl group for every n repeating units, at least one R ₁ is a hydroxyl group, and R ₃ is independently a nitrophenylazo group or a dinitrophenylazo group for every n repeating units. The photoelectric conversion element according to claim 1, wherein the charge transport layer contains, as the aromatic ring compound, at least one selected from the group consisting of a compound represented by the following formula [C-1], a compound represented by the following formula [C-2], a compound represented by the following formula [C-3], and a compound represented by the following formula [C-4].
The photoelectric conversion element according to claim 9, wherein the charge transport layer contains, as the aromatic ring compound, a compound represented by the formula [C-1], a compound represented by the formula [C-2], a compound represented by the formula [C-3], and a compound represented by the formula [C-4]. The photoelectric conversion element according to claim 1, wherein the molecular weight of the aromatic ring compound is 10,000 or less. The photoelectric conversion element according to claim 1, wherein the charge transport layer is in contact with the photoelectric conversion layer. The photoelectric conversion element according to claim 1, wherein the phthalocyanine compound is a metal phthalocyanine compound. The photoelectric conversion element according to claim 1, wherein the phthalocyanine compound is a gallium phthalocyanine compound. The photoelectric conversion element according to claim 1, wherein the phthalocyanine compound is a hydroxygallium phthalocyanine compound. 2. The photoelectric conversion element according to claim 1, wherein the crystal having the perovskite structure is a crystal of a compound represented by the following general formula [2]:
R-M-X ₃ [2]
(In the above general formula [2], R is either an organic molecule or an inorganic atom, or both, M is a metal atom, and X is a halogen atom or a chalcogen atom.) The photoelectric conversion element according to claim 1, wherein the content (parts by mass) of the aromatic ring compound in the charge transport layer is 0.5 parts by mass or more and 50 parts by mass or less when the content of the phthalocyanine compound is 100 parts by mass. The photoelectric conversion element according to claim 1, having a hole transport layer between the charge transport layer and the first electrode. The photoelectric conversion element according to claim 18, wherein the hole transport layer contains Spiro-OMeTAD as a hole transport compound. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode,
A photoelectric conversion element comprising a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a hole transport compound and an aromatic ring compound represented by the following general formula [1]:
(In the above general formula [1], R ₁ to R ₄ are each independently within each repeating unit and each independently for every n repeating units, and are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted organic group, n is an integer of 3 to 20, and one molecule has at least one hydroxyl group.)

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