Photoelectric conversion element and photoelectric conversion device

Abstract

To provide a photoelectric conversion element with improved durability when the element is driven. [Solution] A photoelectric conversion element comprising a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer, wherein the electron transport layer contains a cured product of a composition containing an organic electron transport compound, and the LUMO level of the organic electron transport compound is -4.40 eV or more and -3.70 eV or less.

Description

[Technical Field]

[0001] This disclosure relates to a photoelectric conversion element and a photoelectric conversion device. [Background technology]

[0002] In order to address the depletion of fossil fuels and the environmental problems caused by their use, research is actively being conducted on renewable and clean alternative energy sources such as solar, wind, and hydroelectric power.

[0003] Among these, there is growing interest in solar cells, which directly convert sunlight into electrical energy. Here, a solar cell refers to a battery that absorbs light energy from sunlight and generates current-voltage using the photovoltaic effect, which generates electrons and holes.

[0004] Currently, np diode type silicon (Si) single-crystal based solar cells with light energy conversion efficiencies exceeding 20% ​​are widely known and actually used in photovoltaic power generation. However, these have the problem of high cost per unit of power due to the need for high-temperature processing and the high price of the material itself. Furthermore, there are supply issues from the perspective of silicon resources.

[0005] 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 using a so-called roll-to-roll method on sheet substrates, which is expected to reduce costs.

[0006] However, further improvements in power generation efficiency and durability are desired for the practical application of organic solar cells. In particular, perovskite solar cells, which have a perovskite structure crystal as the photoelectric conversion layer, are being developed for practical use because of their excellent photoelectric conversion characteristics. Fullerene compounds are often used as electron transport layer materials in perovskite solar cells, but because they are extremely expensive, the development of cheaper alternative materials is underway.

[0007] For example, Patent Document 1 describes a technique using perylenediimide compounds and naphthalenediimide compounds as electron transport compounds, and Patent Document 2 describes a technique that achieves excellent conversion efficiency by polymerizing perylenediimide compounds and naphthalenediimide compounds with a crosslinking agent and a resin. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-106401 [Patent Document 2] Japanese Patent Publication No. 2022-2293 [Non-patent literature]

[0009] [Non-Patent Document 1] J.Mater.Chem.A,2017,5,12811-12821 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] According to the inventors' studies, it was found that the photoelectric conversion elements described in Patent Documents 1 and 2 have room for improvement in the surface properties of the electron transport layer and the conversion efficiency when the elements are driven for a long period of time. Therefore, the object of this disclosure is to provide a photoelectric conversion element with improved durability when the element is driven. [Means for solving the problem]

[0011] The above objectives are achieved by the following disclosure. That is, this disclosure is: A photoelectric conversion element comprising a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer, The electron transport layer contains a cured product of a composition containing an organic electron transport compound, The photoelectric conversion element is characterized in that the LUMO level of the organic electron transport compound is between -4.40 eV and -3.70 eV. Furthermore, this disclosure relates to a photoelectric conversion device equipped with the above-mentioned photoelectric conversion element. [Effects of the Invention]

[0012] According to this disclosure, a photoelectric conversion element with improved durability can be provided when a cured product of a composition containing an organic electron-transporting compound having a LUMO level of -4.40 eV to -3.70 eV is used in the electron transport layer. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view in the thickness direction of a first embodiment of the photoelectric conversion element of the present disclosure. [Figure 2] This is a schematic perspective view showing one embodiment of a mobile body equipped with a photoelectric conversion element of the present disclosure. [Figure 3] This is a schematic perspective view showing one embodiment of a building material equipped with a photoelectric conversion element of the present disclosure. [Modes for carrying out the invention]

[0014] <One Embodiment> One embodiment is a photoelectric conversion element. The photoelectric conversion element disclosed herein is A photoelectric conversion element comprising a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer, The electron transport layer contains a cured product of a composition containing an organic electron transport compound, The organic electron-transporting compound is characterized in that its LUMO level is between -4.40 eV and -3.70 eV. The explanation is as follows.

[0015] As a result of their investigation, the inventors have found that the above configuration results in a photoelectric conversion element with excellent durability. Although the details of why a photoelectric conversion element with excellent durability is obtained in this disclosure are not clear, it is thought to be as follows.

[0016] As an alternative to expensive fullerenes, compounds with broad molecular structure and high electron-transporting capacity due to π-π stacking have been developed as electron-transporting compounds. However, it has been reported that these compounds have strong cohesive forces, leading to aggregation and crystallization of molecules, resulting in poor smoothness and coverage as electron transport layers.

[0017] Non-patent document 1 uses a perylenediimide compound with high planarity, and reports that aggregation occurs, resulting in poor smoothness. Patent document 2 polymerizes perylenediimide compounds or naphthalenediimide compounds with a crosslinking agent and resin, suppressing aggregation of electron-transporting compounds. However, it is believed that prolonged operation generates strong internal stress within the electron-transport layer due to high cohesive forces, which causes cracks and pinholes, worsening smoothness.

[0018] This disclosure uses electron-transporting compounds with a LUMO level between -4.40 eV and -3.70 eV, which is a deeper LUMO level compound compared to the electron-transporting compounds described in Patent Document 2. Electron-transporting compounds with deeper LUMO levels are more energetically stable, and the interactions between electron-transporting compounds are not excessively strong.

[0019] Therefore, while π-π stacking improves electron transport capacity, it maintains its smoothness without the occurrence of aggregation or cracks even after long-term operation. This is the reason for its excellent durability.

[0020] Furthermore, if the electron-transporting compound has heteroatoms, it can also have a passivation effect on the perovskite layer. When using a single-molecule passivation compound, a problem is that the compound migrates to the perovskite layer during long-term operation, destroying the perovskite crystal. In this disclosure, since the electron-transporting compound that also has a passivation effect is polymerized, it does not migrate even during long-term operation and does not destroy the perovskite crystal.

[0021] In this disclosure, an electron-transporting compound may be described as a compound that can efficiently transport electrons, as an N-type semiconductor compound, or as a compound whose Fermi level approaches the conduction band or lowest unoccupied orbital (LUMO).

[0022] Furthermore, in this disclosure, the electron transport layer may be described as a layer containing a cured product of a composition containing an electron transport compound that efficiently transports electrons, or a layer containing a cured product of a composition containing an N-type semiconductor compound, or a layer containing a cured product of a composition in which the Fermi level is close to the conduction band or the lowest unoccupied orbital (LUMO).

[0023] The present disclosure will be described in detail below with reference to preferred embodiments. The present disclosure is not limited to the embodiments described below, and the scope of the present disclosure also includes modifications, improvements, etc., to the extent appropriate to the embodiments described below, based on the ordinary knowledge of a person skilled in the art, without departing from the spirit of the present disclosure.

[0024] In this specification, the term "layer" refers not only to layers with clear boundaries or flat, thin films, but also to layers with gradually changing elemental concentrations and layers that can combine with other layers to form complex, interwoven structures.

[0025] Furthermore, elemental analysis of the layers can be performed, for example, by conducting TOF-SIMS / FE-TEM / EDS line analysis measurements of the cross-section of the photoelectric conversion element to confirm the elemental distribution of specific elements. Analysis of each layer may also be performed by peeling off the completed photoelectric conversion element, exposing the layer to be analyzed, and then measuring it.

[0026] Figure 1 is a schematic cross-sectional view showing the configuration of one embodiment of the photoelectric conversion element of the present invention. Figure 1 will be described below. The photoelectric conversion element 1 has, in this order, a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5 containing a perovskite crystal structure, a hole transport layer 6, and a first electrode 7. The first electrode 7 and the second electrode 3 function as a positive electrode and a negative electrode, respectively, and current can be extracted by connecting both electrodes to an external circuit as appropriate.

[0027] The photoelectric conversion layer 5 is excited by light incident through the second electrode 3 and the electron transport layer 4, or by light incident from the first electrode 7 side through the hole transport layer 6, generating electrons or holes. As a result, the photoelectric conversion layer 5 generates an electric current between the first electrode 7 and the second electrode 3.

[0028] Alternatively, a tandem structure forming a series circuit may be created by repeatedly stacking the layers from the second electrode 3 to the first electrode 7 to provide multiple photoelectric conversion layers 5. In this embodiment, either the first electrode 7 or the second electrode 3 may be made to be in contact with the substrate 2. The following describes the components that make up the photoelectric conversion element of the present invention.

[0029] [Photoelectric conversion element] The photoelectric conversion element of the present disclosure comprises a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer.

[0030] The photoelectric conversion element of this disclosure has an electron transport layer containing a cured product of a composition containing an organic electron transport compound. The organic electron transport compound can be cured by adding a crosslinking agent. If the electron transport layer of this disclosure contains additives as a composition, the composition may be considered to become a cured product. The chemical substances of this disclosure can be identified by nuclear magnetic resonance (NMR) spectrometers or mass spectrometers (e.g., MALDI-TOF-MS or GC-MS).

[0031] Furthermore, to improve photoelectric conversion efficiency, a tandem type with stacked photoelectric conversion elements may be used. The type of photoelectric conversion element to be stacked is not limited to perovskite solar cells that use perovskite crystals as the photoelectric conversion layer, but also includes silicon solar cells, CIGS solar cells, etc.

[0032] Methods for forming the photoelectric conversion layer and charge transport layer of the photoelectric conversion element disclosed herein include coating methods and vapor deposition methods. Examples of coating methods include immersion coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method involves preparing the coating solution for each layer, which will be described later, coating the layers in the desired order, and drying them. These film formation methods can be selected according to the requirements of each layer.

[0033] The following explains each layer. 〔substrate〕 The photoelectric conversion element 1 of this disclosure may include a substrate 2, such as a transparent glass substrate like soda-lime glass or alkali-free glass, a ceramic substrate, or a transparent plastic substrate. When light is taken in from the second electrode 3 side, the substrate 2 can be made of an opaque material, and when light is taken in from the first electrode 7 side, the substrate 2 is made of a transparent material.

[0034] 〔electrode〕 The photoelectric conversion element disclosed herein has a first electrode and a second electrode. The materials of the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. Examples include metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloys, lithium, magnesium, carbon, carbon nanotubes, aluminum, magnesium-silver mixtures, magnesium-indium mixtures, aluminum-lithium alloys, Al / Al2O3 mixtures, Al / LiF mixtures, and the like.

[0035] Examples of transparent electrode materials include conductive transparent materials such as CuI, ITO (indium tin oxide), SnO2, AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimond-doped tin oxide), as well as conductive transparent polymers.

[0036] These materials may be used individually or in combination of two or more. The first electrode 7 and the second electrode 3 may have at least one electrode on the light incidence side be a transparent electrode, and the other electrode may be a transparent electrode or a reflective layer made of a light-reflective material, or it may be a transparent electrode with a reflective layer on the side opposite to the light incidence side. When the second electrode 3 is on the light incidence side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer.

[0037] The electrodes may be patterned electrodes. Furthermore, the photoelectric conversion element of this disclosure may have a passivation layer formed on the first electrode 7. The passivation material is not particularly limited, but Al2O3 is preferred from the viewpoint of electrode surface treatment.

[0038] [Photoelectric conversion layer] The photoelectric conversion layer 5 has a perovskite crystal structure. The perovskite crystal used in this disclosure is preferably represented by the following general formula [1]. A o B p X q [1] In the above general formula [1], A is a cation, B is a cation, and X is an anion.

[0039] o, p, and q satisfy 0 ≤ o ≤ 10, 0 ≤ p ≤ 10, and 0 ≤ q ≤ 20, respectively, and A, B, and X may be composed of a single material or two or more materials may be used in combination. Additives may be added within the range in which the above general formula holds.

[0040] The above general formula generally forms a three-dimensional perovskite crystal. However, if the constituent cation A is large enough to fit within the three-dimensional perovskite crystal, it can form a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal possessing properties of both two and three dimensions, a two-layer crystal with three-dimensional and two-dimensional perovskite structures, or a mixed three-dimensional / two-dimensional perovskite crystal, all of which function as photoelectric conversion layers.

[0041] A two-layer crystal of 3D and 2D perovskite refers to a crystal in which 3D and 2D perovskite crystals are stacked as independent, separate layers, while a mixed 3D-2D perovskite refers to a crystal in which regions or domains of both 2D or 2.5D layered and 3D perovskite crystals are mixed.

[0042] Crystals of two-dimensional perovskites or 2.5-dimensional perovskite structures may form RP (Ruddlesden-Popper), DJ (Dion-Jacobson), or ACI (Alternating cations in the interlayer) type perovskite structures.

[0043] The cation A in the above general formula [1] is not particularly limited. The cation A may or may not have substituents, and specific examples include the following formulas (C1) to (C96).

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] Furthermore, while the inorganic atoms are not particularly limited, lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms may be used individually, or two or more may be used in combination.

[0049] In the general formula [1] above, B is a cation atom, and examples include 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, bismuth, and silver are preferred from the viewpoint of the stability of the perovskite crystal structure. These atoms may be used individually or in combination of two or more.

[0050] In the above general formula [1], X is a halogen or chalcogen atom, such as chlorine, bromine, iodine, oxygen, sulfur, selenium, tellurium, or polonium. These halogen or chalcogen atoms may be used individually or in combination of two or more.

[0051] In particular, halogen atoms are preferred because the inclusion of halogens in the structure makes the perovskite crystals more soluble in organic solvents, enabling their application to inexpensive printing methods and the like. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite crystals.

[0052] Specifically, three-dimensional perovskites, two-dimensional perovskites, and mixed three-dimensional-two-dimensional perovskites include MAPbI3, FAPbCl3, FAPbI3, MAPbI x Br 3-x , MAPbI x Cl 3-x , Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3, {Cs x1 (FA x2 MA 1-x2 ) 1-x1} x3 Pb(I x4 Br 1-x4 ) x5 , Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 , (FAPbI3) 0.95 (MAPbBr3) 0.05 , (FAPbI3) 0.85 (MAPbBr3) 0.15 , CsPbI3, CsPbBr3, Cs x (MA) 1-x PbI3, Cs x (FA) 1-x PbI3, MA x (FA) 1-x PbI3, MA 0.17 FA 0.83 Pb(I 0.83 Br 0.17 )3, Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 , Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 , Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 , (PEA)2(MA)2Pb3I 10 , (PTA)2(MA)4Pb5I 16 , (PEA)2(MA)4Pb5I 16(ThMA)2(MA)2Pb3I 10 , (3BBA)2(MA)2Pb3I 10 (ThMA)2(FA)4Pb5I 16 , (4FPEA)2(FA 0.3 MA 0.7 )4Pb5I 16 (PDMA)FA2Pb3I 10 (3AMPY)(MA)3Pb4I 13 (PDMA)MA5Pb6I 19 (PDMA)MA3Pb4I 13 , (BA 0.9 PEA 0.1 )2MA4Pb5I 16 , (BA 0.9 PEA 0.1 )2MA3Pb4I 13 (BA)2MA2Pb3I 10 (BA)2MA3Pb4I 13 (BA)2MA4Pb5I 16 (BA)2MA3Pb4I 13 , CsSnBr3, CsSnI3, FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I3, FAMASnGeI3, FASnBr3, FASnI3, MA2Sn3I8, MASnBr3, MASnGeI3, and MASnI3 are preferred.

[0053] In the above specific examples, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylenedimethaneammonium, "TTDMA" represents thieno[3,2-b]thiophene-2,5-diyldimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, and "BA" represents butylammonium.

[0054] Depending on the purpose, the A site, B site, and X site in the above general formula may be adjusted to be too small or too large, and the combinations of x1 to x5 may be changed according to the purpose. Examples of the combinations of x1 to x5 are shown in Table 1.

[0055] Particularly preferred ranges are 0.03 ≤ x1 ≤ 0.10, 0.80 ≤ x2 ≤ 0.96, 0.95 ≤ x3 ≤ 1.05, 0.80 ≤ x4 ≤ 0.96, and 2.95 ≤ x5 ≤ 3.05. MACl may also be included as the material for forming the perovskite crystal.

[0056] [Table 1]

[0057] The perovskite crystal described above preferably has a cubic crystal structure in which a metal atom B is located at the body center, organic molecules A are located at each vertex, and halogen atoms X are located at the face centers. Although the details are not clear, it is presumed that having such a structure allows the orientation of octahedra within the crystal lattice to change easily, thereby increasing the electron mobility in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0058] The organic-inorganic perovskite compounds used in this disclosure are preferably crystalline semiconductors. A crystalline semiconductor is a semiconductor in which the X-ray scattering intensity distribution can be measured and a scattering peak can be detected. When the organic-inorganic perovskite compound is a crystalline semiconductor, the electron mobility in the organic-inorganic perovskite compound is increased, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

[0059] The thickness of the photoelectric conversion layer according to this disclosure is preferably 5 nm or more and 2000 nm or less. If the thickness is 5 nm or more, light can be absorbed sufficiently, and if it is 2000 nm or less, the generated charge can be transported to each electrode. A more preferable lower limit is 50 nm or more, a more preferable upper limit is 1200 nm, an even more preferable lower limit is 100 nm, and an even more preferable upper limit is 1000 nm.

[0060] Furthermore, the photoelectric conversion element of this disclosure may have a passivation layer formed in or adjacent to the photoelectric conversion layer 5. The passivation material is not particularly limited and includes organic salts, inorganic salts, ionic liquids, and resins. The conductivity of the passivation material is not particularly limited and may be either insulating or conductive.

[0061] As organic salts, compounds composed of at least one cation selected from the group consisting of compounds represented by formulas (C1) to (C96) and at least one anion selected from the group consisting of compounds represented by the following formulas (A1) to (A29) are preferred.

[0062] [ka]

[0063] The material of the inorganic salt is not particularly limited, but a compound composed of at least one cation selected from the group consisting of metal atoms and at least one anion selected from the group consisting of compounds represented by formulas (A1) to (A29) is preferred.

[0064] Examples of metal atoms include copper, silver, zinc, gallium, bismuth, sodium, potassium, lithium, vanadium, manganese, iron, cobalt, nickel, germanium, arsenic, selenium, lead, tin, iridium, platinum, osmium, cesium, barium, rubidium, molybdenum, and ruthenium.

[0065] The material of the ionic liquid is not particularly limited, but a compound composed of at least one cation selected from the group consisting of compounds represented by the following formulas (ILC1) to (ILC10) and at least one anion selected from the group consisting of compounds represented by the following formulas (ILA1) to (ILA17) is preferred.

[0066] [ka]

[0067] R 01 ~R 04 Each of these independently represents a hydrogen atom, an optional alkyl group, or an optional aryl group.

[0068] The resin material is not particularly limited and may have substituents, including polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polystyrene (PS), polyimide (PI), fluororesin (PVDF), polyurethane (PU), silicone resin (PDMS), epoxy resin, nanocomposite resin, PEDOT:PSS, poly(9,9-dioctylfluorene-artenalyl) (PFN), P3HT, poly(fluorene-co Phenylene (PFP), polyvinylcarbazole (PVK), polythiophene (PTh), polyaniline (PANI), polybithiophene (PBTh), polydioxythiophene (PDT), polyoxyethylene (PEO), polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyfumaric acid (PFA), polysuccinic acid (PSA), polyadipic acid (PAdA), polycaprolactam (PCL), polyisophthalic acid (PIPA), polyterephthalic acid (PT) A) Examples include polynaphthalenedicarboxylic acid (PNA), polyamide-imide (PAI), polysilsesquioxane (POSS), polyphenol resin (PF), polycarbonate (PC), poly(styrene-butadiene) (PSB), polysilyl ether (PSE), poly(ether-imide) (PEI), polyvinylpyrrolidone (PVP), polyacrylic acid ester (PAE), polydimethylaminoethyl methacrylate (PDMAEMA), polytrifluoroethylene (PTFE), polyoxymethylene (POM), polyesterimide (PEI), polyacrylonitrile (PAN), polyvinyl acetal (PVAH), polyolefin ether (PIE), polyacetal (PA), polysulfone (PSU), polyurea urethane (PUU), and polyolefin (PO), with polyvinyl acetal, polyolefin, polymethyl methacrylate, polyurethane, polyvinyl alcohol, and polyvinyl butyral being particularly preferred.

[0069] [Hole transport layer] In the photoelectric conversion element of this disclosure, a hole transport layer 6 may be arranged between the first electrode 7 and the photoelectric conversion layer 5, as shown in Figure 1. The thickness of the hole transport layer is preferably 0.1 nm or more and 1000 nm or less, more preferably 0.1 nm or more and 500 nm or less, and particularly preferably 0.1 nm or more and 200 nm or less.

[0070] The hole transport layer can be formed by preparing a coating solution for the hole transport layer containing the above-mentioned materials and solvents, forming this coating film on an ITO electrode, and drying it. Examples of solvents that can be used in the coating solution include amide solvents, aproton solvents, alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0071] Among these solvents, amide solvents, aproton solvents, alcohol solvents, or aromatic hydrocarbon solvents are preferred. Furthermore, in this disclosure, from the viewpoint of the compatibility of the hole transport layer 6 film, a second charge transport layer may be further provided between the hole transport layer 6 and the first electrode 7.

[0072] The material of the hole transport layer 6 or the second charge transport layer is not particularly limited, and examples 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, phenothiazine compounds, triazaalkene compounds, cyclooctatetraene compounds, squalate compounds, and the like.

[0073] In particular, it is preferable that the compound has an aromatic ring from the viewpoint of compatibility at the membrane interface, and Spiro-OMeTAD, PTAA, phenothiazine compounds, carbazole compounds, triphenylamine compounds, triazaalkene compounds, cyclooctatetraene compounds, and squalate compounds are preferred. Furthermore, a passivation material may be provided in or on the hole transport layer 6. The passivation material is not particularly limited and includes organic salts, inorganic salts, ionic liquids, and resins. The conductivity of the passivation material is not particularly limited and may be either insulating or conductive.

[0074] As organic salts, compounds composed of at least one cation selected from the group consisting of compounds represented by formulas (C1) to (C96) and at least one anion selected from the group consisting of compounds represented by formulas (A1) to (A29) are preferred.

[0075] As inorganic salts, compounds composed of at least one cation selected from the group consisting of metal atoms and at least one anion selected from the group consisting of compounds represented by formulas (A1) to (A29) are preferred.

[0076] Examples of metal atoms include copper, silver, zinc, gallium, bismuth, sodium, potassium, lithium, vanadium, manganese, iron, cobalt, nickel, germanium, arsenic, selenium, lead, tin, iridium, platinum, osmium, cesium, barium, rubidium, molybdenum, and ruthenium.

[0077] The material of the ionic liquid is not particularly limited, but a compound composed of at least one cation selected from the group consisting of compounds represented by formulas (ILC1) to (ILC10) and at least one anion selected from the group consisting of compounds represented by formulas (ILA1) to (ILA17) is preferred. 01 ~R 04 Each of these independently represents a hydrogen atom, an optional alkyl group, or an optional aryl group.

[0078] The resin material is not particularly limited and may have substituents, including polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polystyrene (PS), polyimide (PI), fluororesin (PVDF), polyurethane (PU), silicone resin (PDMS), epoxy resin, nanocomposite resin, PEDOT:PSS, poly(9,9-dioctylfluorene-artenalyl) (PFN), P3HT, poly(fluorene-co Phenylene (PFP), polyvinylcarbazole (PVK), polythiophene (PTh), polyaniline (PANI), polybithiophene (PBTh), polydioxythiophene (PDT), polyoxyethylene (PEO), polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyfumaric acid (PFA), polysuccinic acid (PSA), polyadipic acid (PAdA), polycaprolactam (PCL), polyisophthalic acid (PIPA), polyterephthalic acid (PT) A) Examples include polynaphthalenedicarboxylic acid (PNA), polyamide-imide (PAI), polysilsesquioxane (POSS), polyphenol resin (PF), polycarbonate (PC), poly(styrene-butadiene) (PSB), polysilyl ether (PSE), poly(ether-imide) (PEI), polyvinylpyrrolidone (PVP), polyacrylic acid ester (PAE), polydimethylaminoethyl methacrylate (PDMAEMA), polytrifluoroethylene (PTFE), polyoxymethylene (POM), polyesterimide (PEI), polyacrylonitrile (PAN), polyvinyl acetal (PVAH), polyolefin ether (PIE), polyacetal (PA), polysulfone (PSU), polyurea urethane (PUU), and polyolefin (PO), with polyvinyl acetal, polyolefin, polymethyl methacrylate, polyurethane, polyvinyl alcohol, and polyvinyl butyral being particularly preferred.

[0079] [Electron transport layer] In this disclosure, the electron transport layer 4 contains a cured product of a composition containing an electron transport compound, wherein the LUMO level of the electron transport compound (organic electron transport compound) is preferably between -4.40 eV and -3.70 eV, and between -4.00 eV and -3.75 eV, and is disposed between the second electrode 3 and the photoelectric conversion layer 5.

[0080] The preferred thickness of the electron transport layer 4 is 1 nm at the lower limit and 2000 nm at the upper limit. If the thickness of the electron transport layer 4 is 1 nm or more, holes can be sufficiently blocked, and if it is 2000 nm or less, it will not be a resistance during electron transport, and the photoelectric conversion efficiency will be high. A more preferred lower limit for the thickness is 1 nm, a more preferred upper limit is 1000 nm, an even more preferred lower limit is 1 nm, and an even more preferred upper limit is 500 nm.

[0081] The electron-transporting compound is preferably a compound selected from phthalocyanine derivatives, triazine derivatives, phenanthroline derivatives, pyrene derivatives, perylenediimide derivatives, naphthalenediimide derivatives, azaacene derivatives, and indasenodithiophene derivatives as a non-fullerene derivative, and more preferably a compound selected from perylenediimide derivatives, naphthalenediimide derivatives, azaacene derivatives, and indasenodithiophene derivatives.

[0082] Furthermore, more preferably, the photoelectric conversion element of the present disclosure is an organic electron transport compound which is at least one compound selected from the compounds represented by the following formula (E1), the compounds represented by the following formula (E2), the compounds represented by the following formula (E3), and the compounds represented by the following formula (E4). [ka] [ka] [ka] [ka] In formulas (E1) to (E4), R 11 to R 20 , R 21 to R 26 , R 31 to R 34 , and R 41 to R 48 each independently represent a functional group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 28 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 28 carbon atoms, a hydroxy group, a carboxy group, an amino group, a thiol group, a halogen atom, a cyano group, and a nitro group. At this time, R 11 to R 20 , R 21 to R 26 , R 31 to R 34 , and R 41 to R 48 may have adjacent groups bonded to each other to jointly form a ring. Provided that at least one of R 11 to R 20 is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, at least one of R 21 to R 26 is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, at least one of R 31 to R 34 is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, and at least one of R 41 to R 48 is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group.

[0083] In the photoelectric conversion element of the present disclosure, in the above formulas (E1) to (E4), R 11 to R 20 , R 21 to R 26 , R 31 to R 34 , and R 41 to R48 Preferably, each of these is independently a group represented by the following formula (1). -(R a ) m -(R b ) n -R c (1) (In equation (1), m and n are independently either 0 or 1.) In formula (1), R a R in formula (1) represents an alkylene group having 1 to 10 substituted or unsubstituted carbon atoms, or an arylene group having 6 to 14 substituted or unsubstituted carbon atoms. c or R in equation (2) d They may be connected to each other to form a ring. In formula (1), R b represents an oxygen atom, a sulfur atom, or a group represented by the following formula (2). [ka] (In formula (2), R d R represents a hydrogen atom, or an alkyl group having 1 to 4 substituted or unsubstituted carbon atoms. In this case, R in formula (1) a or R in equation (1) c They may be connected together to form a ring. In formula (1), R c R represents a hydrogen atom, an alkyl group having 1 to 10 substituted or unsubstituted carbon atoms, an aryl group having 6 to 14 substituted or unsubstituted carbon atoms, or an arylalkyl group having 7 to 18 substituted or unsubstituted carbon atoms. In this case, R in formula (1) a or R in equation (2) d They may be connected to each other to form a ring. The substituents that the alkylene group and the alkyl group may have are a hydroxyl group, a carboxyl group, an amino group, a thiol group, an alkoxy group having 1 to 3 carbon atoms, and an alkoxycarbonyl group having 2 to 4 carbon atoms. The substituents that the arylene group, the aryl group, and the arylalkyl group may have are alkyl groups having 1 to 3 carbon atoms, hydroxyl groups, hydroxyalkyl groups having 1 to 3 carbon atoms, carboxyl groups, amino groups, thiol groups, alkoxy groups having 1 to 3 carbon atoms, alkoxycarbonyl groups having 2 to 4 carbon atoms, halogen atoms, cyano groups, and nitro groups. However, R 11 ~R 20 One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R 21 ~R 26 One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R 31 ~R 34 One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R 41 ~R 48 One or more of these groups contain a functional group selected from the group consisting of hydroxyl groups, carboxyl groups, amino groups, and thiol groups.

[0084] Specifically, examples include the compounds shown in Tables 2-5.

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] [Table 5]

[0089] Furthermore, from the viewpoint of passivation effect, it is preferable that the electron-transporting compound (organic electron-transporting compound) contains heteroatoms with a number of atoms of 6 to 20, and more preferably contains heteroatoms with a number of atoms of 8 to 16.

[0090] In the photoelectric conversion element of the present invention, the content of the organic electron transport compound in the composition is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 80% by mass or less, based on the total mass of solids in the composition. In this disclosure, the content can be confirmed by nuclear magnetic resonance (NMR) spectrometer or mass spectrometer (e.g., MALDI-TOF-MS or GC-MS).

[0091] The LUMO level of the electron-transporting compound can be measured by cyclic voltammetry (CV). An example of the measurement conditions is as follows: electrochemical analyzer ALS600F (BSA), DMF solvent, supporting electrolyte: tetrabutylammonium perchlorate, working electrode: glassy carbon electrode, reference electrode: silver-silver chloride electrode, auxiliary electrode: platinum electrode, sweep rate: 50 mV / s. The LUMO level is calculated from the half-wave potential of the measured redox potential and the vacuum level of the reference electrode.

[0092] Furthermore, in this disclosure, a second electron transport layer may be provided between the electron transport layer 4 and the second electrode 3, from the viewpoint of the compatibility of the electron transport layer 4 film. The material of the second electron transport layer is not particularly limited and includes, for example, 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. Specifically, examples include cyano group-containing polyphenylene vinylene, boron-containing polymers, vasocuproin, vasophenanthroline, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium dioxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc. In particular, tin oxide may be reacted with tin(2) chloride, tin(4) chloride, tin(2) chloride dihydrate, or tin(4) chloride pentahydrate.

[0093] The electron transport layer composition may contain a crosslinking agent, and any known material can be used as the crosslinking agent. Specifically, examples include compounds described in "Crosslinking Agent Handbook" edited by Shinzo Yamashita and Tosuke Kaneko, published by Taiseisha (1981).

[0094] The photoelectric conversion element of the present disclosure preferably contains a composition that includes at least one compound selected from the group consisting of isocyanate compounds, melamine compounds, and guanamine compounds.

[0095] The crosslinking agent is preferably an acid anhydride derivative, a phenol compound, a polyamine compound, an isocyanate compound having an isocyanate group or a blocked isocyanate group, or an amine compound having an N-methylol group or an alkyl etherified N-methylol group, and more preferably an isocyanate compound having an isocyanate group or a blocked isocyanate group, or an amine compound having an N-methylol group or an alkyl etherified N-methylol group.

[0096] These crosslinking agents produce many -NH- and -C(=O)- structures after polymerization. These structures form complex hydrogen bonds, which is thought to alleviate the aggregation of electron-transporting compounds. Furthermore, when the electron-transporting layer is in contact with the perovskite layer, these structures strongly interact with the perovskite crystal, resulting in high adhesion between layers and mitigating internal stress caused by thermal volume changes in the perovskite crystal. These effects further stabilize the smoothness of the electron-transporting layer during long-term use. Isocyanate compounds having 3 to 6 isocyanate groups or blocked isocyanate groups are even more preferable.

[0097] Examples of isocyanate compounds include, but are not limited to, the isocyanate compounds listed below. Furthermore, multiple isocyanate compounds may be used in combination.

[0098] Examples include triisocyanate benzene, triisocyanate methylbenzene, triphenylmethane triisocyanate, lysine triisocyanate, tolylene diisocyanate, biuret modified, biuret-type isocyanate, allophanate modified, and adduct modified with trimethylolpropane or pentaerythritol. A blocked isocyanate group is a group having the structure -NHCOZ1 (where Z1 is a protecting group). Z1 can be any protecting group that can be introduced into an isocyanate group.

[0099] Examples of commercially available isocyanate compounds include isocyanate-based crosslinking agents such as Duranate MFK-60B, SBA-70B, 17B-60P, SBN-70D, SBB-70P (manufactured by Asahi Kasei Corporation), Cosmonate TM-20, TM-50 (manufactured by Mitsui Chemicals, Inc.), and Bronate 1227EV, 1232P, 1902V, 1961V (manufactured by Daiei Sangyo Co., Ltd.).

[0100] Amine compounds having multiple (three or more) N-methylol groups or alkyl etherified N-methylol groups are more preferred. Examples include methylolated melamine, methylolated guanamine, methylolated urea derivatives, methylolated ethyleneurea derivatives, methylolated glycoluryl, compounds in which the methylol moiety is alkyl etherified, and derivatives thereof. Methylolated melamine and methylolated guanamine are even more preferred.

[0101] Examples of commercially available amine compounds include melamine compounds such as Yuban 20SB, 2020, 60R, and 360 (manufactured by Mitsui Chemicals, Inc.), and Nikalac MW-30M, MW-11, and MX-750 (manufactured by Sanwa Chemical Co., Ltd.). Examples of guanamine compounds include Nikalac BL-60 and BX-4000 (manufactured by Sanwa Chemical Co., Ltd.).

[0102] The electron transport layer composition may further contain an electron transport material, a crosslinking agent, and a resin having functional groups polymerizable by the crosslinking agent. Examples of resins include polyacetal resins, polyvinyl acetal resins, polyolefin resins, polyester resins, polyether resins, and polyamide resins. Examples of functional groups polymerizable by the crosslinking agent include hydroxyl groups, carboxyl groups, amino groups, and thiol groups.

[0103] The photoelectric conversion element of the present disclosure preferably contains an organic electron transport compound that contains at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

[0104] The photoelectric conversion element of the present disclosure preferably contains a resin having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

[0105] Examples of commercially available resins having functional groups that can be polymerized with the aforementioned crosslinking agent include Bekkolite AL-4298-60, AS-019, Polylite OD-X-2420, OD-X-688 (manufactured by DIC Corporation), Esrec BX-1, BM-1, KS-5 (manufactured by Sekisui Chemical Co., Ltd.), Gosenex Z-100, Z-220, LW-100, LW-200 (manufactured by Mitsubishi Chemical Corporation), ARUFON UH-2000, UH-2041, UC-3000, UC-3080 (manufactured by Toagosei Co., Ltd.), and Hyros-X NS-2092, ZS-1417, X-1, X-210, BS-2060 (manufactured by Seikoh PMC Co., Ltd.). The weight-average molecular weight of the resin having polymerizable functional groups with the aforementioned crosslinking agent is more preferably in the range of 5,000 to 400,000. More preferably, it is in the range of 5,000 to 300,000.

[0106] In addition to the polymers described above, the electron transport layer may also contain organic particles, inorganic particles, leveling agents, etc., to enhance film-forming properties and electrical characteristics. However, the content of these in the electron transport layer is preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the electron transport layer.

[0107] One method for forming an electron transport layer is to form a coating film of an electron transport layer coating solution containing the above-mentioned substances and then dry the coating film. When polymerizing these compositions during the drying of the coating film of the electron transport layer coating solution, the polymerization reaction (curing reaction) is accelerated by applying heat or light energy. Examples of solvents used in the electron transport layer coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon solvents.

[0108] Furthermore, from the viewpoint of electron injection, an electron injection layer may be provided on top of the electron transport layer or a second electron transport layer. The material of the electron injection layer is not particularly limited, but bathocuproine and bathophenanthroline are preferred, for example.

[0109] <Application Examples> Examples of applications of this disclosure include photoelectric converters, mobile devices, and building materials. [Photoelectric converter] The photoelectric conversion device disclosed herein comprises a photoelectric conversion element disclosed herein. A photoelectric conversion device can be configured by using multiple photoelectric conversion elements disclosed herein. When multiple photoelectric conversion elements are connected together, such a photoelectric conversion device may also be called a photoelectric conversion cell or a photoelectric conversion module.

[0110] The photoelectric conversion element may be stacked with photoelectric conversion elements having different absorption wavelengths to increase the output voltage. Furthermore, the photoelectric conversion device includes the photoelectric conversion element of this disclosure and an inverter. The inverter may be a converter that converts direct current to alternating current.

[0111] The photoelectric conversion device may have a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited to any device that can store electricity. Examples include secondary batteries using lithium ions, all-solid-state batteries, and electric double-layer capacitors. To provide functions such as maintaining or increasing the amount of incident light, a surface that is resistant to water and dirt, or a function to collect or guide light may be added.

[0112] [Mobile] The mobile body of the present disclosure has the above-described photoelectric conversion element. Figure 2 is a schematic perspective view showing one embodiment of the mobile body equipped with the photoelectric conversion element of the present disclosure. The mobile body 30 has the photoelectric conversion element 31 of the present disclosure and a body 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is positioned in a location on the body 32 that can receive ambient light.

[0113] If the mobile body 30 is an automobile, it may be placed on the roof. The electrical energy obtained by the photoelectric conversion element 31 may be used to power the mobile body 30 or other electrical equipment. The electrical energy generated from the power of the mobile body 30 may be used to power the photoelectric conversion element 31. If the mobile body 30 is an automobile, the frictional energy generated by the brakes may be converted into electrical energy and used to control the photoelectric conversion element 31.

[0114] The mobile body 30 may be, for example, an automobile, a motorcycle, a railway vehicle, a ship, a satellite, an airplane, or a drone. The structure of the mobile body 32 is not particularly limited, but it is preferably made of a high-strength material.

[0115] [Building materials] The building material of this disclosure has the above-described photoelectric conversion element. Figure 3 is a schematic perspective view showing one embodiment of the building material of this disclosure equipped with the photoelectric conversion element. The building material 40 may be the roof of a building. The building material 40 of this embodiment has the photoelectric conversion element 41 of this disclosure, a protective member 42 for protecting the photoelectric conversion element 41, a heat dissipation member 43, and exterior parts 44a, 44b.

[0116] The building material 40 of this disclosure may have a heat dissipation member 43 with a higher thermal conductivity than the photoelectric conversion element 41. When used on roofs, etc., the temperature of the photoelectric conversion element 41 may rise due to sunlight, which may reduce the photoelectric conversion efficiency. By using the heat dissipation member 43, the decrease in photoelectric conversion efficiency can be reduced. Examples of the heat dissipation member 43 include metals, alloys, liquid metals, liquid resins, etc.

[0117] Furthermore, the building material 40 of this disclosure may have exteriors 44a and 44b. Exteriors 44a and 44b may have different colors or the same color. 44a and 44b may be composed of the same material or different materials. As the exterior, paint or a transparent substrate may be used. It is preferable that the exterior has low light absorption and high heat shielding properties.

[0118] In addition to the above examples of applications, the following are some other examples of applications: Portable devices include calculators, sensors, and small solar panels. Wearable devices include eyeglasses, smartwatches, and portable medical devices. Sheet structures supported by multiple frames include tents, greenhouses, and truck beds. Fixed structures include road panels, floating panels, building materials that utilize the flexibility of the substrate, wall-type building materials, glass-type building materials, and mega solar panels.

[0119] <Manufacturing method for photoelectric conversion elements> The present invention provides a method for manufacturing a photoelectric conversion element, comprising the steps of: forming a first electrode; forming a second electrode; forming a photoelectric conversion layer containing a perovskite crystal between the first electrode and the second electrode; and forming an electron transport layer between the photoelectric conversion layer and the second electrode. The following describes each step of the manufacturing process.

[0120] [Steps for forming the first electrode and steps for forming the second electrode] In the process of forming the first electrode and the process of forming the second electrode, an appropriate method can be selected depending on the material of the first electrode and the material of the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering, vacuum deposition, CVD (vapor deposition), and SPD (spray pyrolysis deposition). The materials of the first and second electrodes are as described above. When either or both of the first and second electrodes are transparent electrodes, the thickness of the transparent electrode is preferably 0.03 μm or more and 3 μm or less. When manufacturing solar cells, cutting processes may be performed between each manufacturing step to form circuits. Examples of cutting processes include mechanical patterning and laser patterning.

[0121] [Modularization Process] When manufacturing solar cells, cutting processes may be performed between each manufacturing step to form circuits. Examples of cutting processes include mechanical patterning and laser patterning. Furthermore, the element with electrodes formed may be sealed. Examples of sealing methods include sealing with a resin or sealing with a film containing a resin. Examples of materials used for sealing include silazane, silicone rubber, resins having a siloxane skeleton, resins containing fluorine, and glass. Furthermore, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll-to-roll manner, the surface of the sealed elements may be given a hairline finish.

[0122] [Process for forming the photoelectric conversion layer] The photoelectric conversion layer formation process may include a step of applying a liquid containing the above-mentioned photoelectric conversion layer material. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, mold making, print transfer, immersion and pull-up, inkjet, spray, and vacuum deposition. From these options, appropriate choices are made depending on the characteristics of the photoelectric conversion layer to be fabricated, such as thickness control and orientation control. Annealing treatment may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere) to remove the solvent or dispersion medium from the liquid containing the material of the applied photoelectric conversion layer. The temperature of the annealing treatment is preferably 40°C to 300°C, and more preferably 50°C to 150°C. Annealing treatment is preferable because it can increase the contact area at the interface between the stacked layers, as the materials constituting each layer penetrate each other, which can increase the short-circuit current.

[0123] [Process for forming the electron transport layer] A preferred method for forming the electron transport layer is to apply a liquid containing the electron transport layer material described above. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, molding, print transfer, immersion and pull-up, inkjet, spray, and vacuum deposition. [Examples]

[0124] The present disclosure will be described in more detail below using examples and comparative examples. The present disclosure is not limited in any way by the following examples unless it exceeds the gist of the disclosure. In the following examples, "parts" refers to a mass basis unless otherwise specified.

[0125] (Example 1) [Hole transport layer formation] A square glass substrate with ITO, measuring 25 mm on each side, was cleaned. A 0.01 mM solution of 3PATAT-3C (manufactured by Tokyo Chemical Industry Co., Ltd.) was prepared in 100 mL of N,N-dimethylformamide (DMF), and this solution was applied to the substrate by spin coating. The substrate was then heated at 110°C for 10 minutes to form a thin film-like hole transport layer.

[0126] [Formation of the photoelectric conversion layer] 0.044 g of lead bromide, 0.392 g of formamidium iodide, 1.144 g of lead iodide, 0.0134 g of methylammonium bromide, and 0.0176 g of methylammonium chloride were dissolved in 1384 uL of DMF and 252.4 uL of dimethyl sulfoxide (DMSO) and stirred for 2 hours (Solution 1).

[0127] Furthermore, 0.036 g of cesium iodide was dissolved in 96.6 uL of DMSO and stirred for 2 hours (Solution 2). Then, the dissolved cesium iodide solution (Solution 2) was added to Solution 1 to prepare the photoelectric conversion layer coating solution. This coating solution was spin-coated onto the hole transport layer using a poor solvent method, and heated at 100°C for 10 minutes to obtain {Cs 0.05 (Fa 0.86 MA 0.14 ) 0.95} 0.98 Pb(I 0.95 Br 0.05 ) 2.98 A photoelectric conversion layer with a thickness of 600 nm was obtained.

[0128] [Formation of the passivation layer] 2-phenylethylamine hydroiodide was prepared in 2-propanol (IPA) at a concentration of 1 mg / mL. The solution was applied by spin coating to obtain a passivation layer.

[0129] [Formation of the electron transport layer] The electron transport layer coating solution was prepared using the following procedure and spin-coated onto the photoelectric conversion layer at 2500 rpm. The solution was then heated at 140°C for 30 minutes to deposit an electron transport layer with a thickness of approximately 20 nm. The electron transport layer coating solution was prepared considering the desorbing block groups, and the content of the electron transport compound after deposition was 60% by mass relative to the total mass of the electron transport layer.

[0130] 4.47 parts of the example compound (E1-1) from Table 2 as an electron transport compound, 0.37 parts of polyolefin resin (product name: UC-3920, manufactured by Toagosei Co., Ltd.), 0.37 parts of polyvinyl acetal resin (product name: KS-5Z, manufactured by Sekisui Chemical Co., Ltd.) as resins, and 4.79 parts of a blocked isocyanate compound (product name: SBB-70P, manufactured by Asahi Kasei Corporation) as a crosslinking agent were dissolved in a mixed solvent of 670 parts THF / 330 parts orthoxylene. Subsequently, the mixture was filtered under pressure using a Teflon® filter (product name: PF020) manufactured by ADVANTEC.

[0131] [Formation of electron injection layer] Vasocuproine (BCP) was prepared in IPA at a concentration of 0.5 mg / mL. This solution was applied by spin coating to obtain an electron injection layer.

[0132] [Formation of the second electrode] On the aforementioned electron injection layer, an area of ​​0.09 cm² 2 Ten Ag electrodes were formed to obtain a photoelectric conversion element.

[0133] 〔evaluation〕 [Smoothness] The smoothness of the fabricated photoelectric conversion element was evaluated using an atomic force microscope (AFM / SPM) (Oxford Instruments MFP-3D Origin), obtaining height images in AM-FM mode. The images were evaluated by image analysis, and the maximum surface roughness (Rz) was calculated and used as the initial value. For the AFM / SPM measurement conditions, a cantilever (OMCL-AC-160TS, Olympus Corporation) was used, and a 5 μm × 5 μm area was scanned with a scanning frequency of 1 Hz, 256 X data points, and 256 Y data points. Furthermore, the photoelectric conversion element underwent a 100-hour durability test while being exposed to 80°C nitrogen under 1 sun of irradiation, and was evaluated in the same manner. This value was taken as the value after durability testing.

[0134] Image evaluation was determined based on the following criteria. In this disclosure, evaluations of A and B after durability were judged to have achieved the effects of this disclosure, while evaluations of C were judged to have not achieved the effects of this disclosure. The evaluation results are shown in Table 6. A;Rz is less than 100nm. No cracks or pinholes. B:Rz is between 101nm and 150nm. No cracks or pinholes. C:Rz is 151nm or higher. Cracks and pinholes are present.

[0135] [Perovskite crystal diffraction peak intensity] The fabricated photoelectric conversion element was set in an X-ray diffractometer (Rigaku Corporation, RINT-TTRII) and X-ray diffraction measurements were performed. The measurement conditions were as follows: X-ray tube target: Cu, tube voltage: 50kV, tube current: 300mA, X-ray focus: line, X-ray wavelength: Kα1, optical system: parallel beam method, Kβ filter: none, incident monochromator: present, divergence slit: open, scattering slit: open, receiving slit: open, scanning axis: 2θ / θ, scanning range: 3°~60°, scanning speed: 4° / min, sampling interval: 0.02°, measurement method: continuous, detector: scintillation counter.

[0136] The diffraction peak intensity of the perovskite crystal, where the 2θ angle is around 14°, was measured and this value was used as the initial value. Furthermore, a photoelectric conversion element was subjected to a 100-hour endurance test under 1 sun irradiation while being blown with nitrogen at 80°C, and measurements were taken similarly. This value was used as the endurance value, and the decay rate from the initial value was calculated. The evaluation results are shown in Table 6.

[0137] [Conversion efficiency] A power supply (KEITHLEY, Model 236) was connected between the electrodes of the fabricated photoelectric conversion element, and the intensity was set to 100 mW / cm². 2The photoelectric conversion efficiency was measured by irradiating a constant amount of light using a solar simulator (manufactured by Yamashita Densou Co., Ltd.) and measuring the generated current and voltage. Measurements were also taken at 10 electrodes for each photoelectric conversion element, and the average value was used as the representative value for that element. This value was used as the initial value.

[0138] Furthermore, the photoelectric conversion element was subjected to a 100-hour durability test under 1 sun of irradiation while being blown with nitrogen at 80°C, and measurements were taken similarly. This value was taken as the value after durability testing, and the decay rate from the initial value was calculated. The evaluation results are shown in Table 6.

[0139] (Examples 2-26) Except for changing the type and content of the electron-transporting compound mixed into the coating solution for the electron transport layer and the crosslinking agent as shown in Table 6, a photoelectric conversion element was fabricated in the same manner as in Example 1 and evaluated in the same way. The results are shown in Table 6.

[0140] (Example 27) A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a second electron transport layer was formed using ZnO after the formation of the electron transport layer, and the same evaluation was performed. The results are shown in Table 6.

[0141] (Example 28) A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a second electron transport layer was formed using SnO after the electron transport layer deposition, and the same evaluation was performed. The results are shown in Table 6.

[0142] (Example 29) A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a second electron transport layer was formed using ZTO after the electron transport layer deposition, and the same evaluation was performed. The results are shown in Table 6.

[0143] (Example 30) A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a second electron transport layer was formed using the compound shown in formula (E5) below after the formation of the electron transport layer, and the same evaluation was performed. The results are shown in Table 6. The "content" shown in Table 6 refers to the ratio of the content of the organic electron transport compound in the composition to the total mass of solids in the composition. [ka]

[0144] (Example 31) A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a second electron transport layer was formed using the compound shown in formula (E6) below after the formation of the electron transport layer, and the same evaluation was performed. The results are shown in Table 6. [ka]

[0145] (Comparative Example 1) A photoelectric conversion element was fabricated and evaluated in the same manner as in Example 1, except that the coating solution for the electron transport layer was prepared using the following procedure. The results are shown in Table 7.

[0146] Ten parts of the compound represented by the above formula (E5) were dissolved in a mixed solvent of 1000 parts of orthoxylene as a coating solution for the electron transport layer. The mixture was then subjected to pressure filtration using an ADVANTEC Teflon® filter (product name: PF020).

[0147] (Comparative Example 2) A photoelectric conversion element was fabricated and evaluated in the same manner as in Example 1, except that the coating solution for the electron transport layer was prepared using the following procedure. The results are shown in Table 7.

[0148] Ten parts of the compound represented by the following formula (E7) were dissolved in a mixed solvent of 670 parts THF and 330 parts orthoxylene as a coating solution for the electron transport layer. The mixture was then pressure filtered using an ADVANTEC Teflon® filter (product name: PF020). [ka]

[0149] (Comparative Example 3) A photoelectric conversion element was fabricated in the same manner as in Comparative Example 2, except that a second electron transport layer was formed using ZnO after the electron transport layer deposition, and the same evaluation was performed. The results are shown in Table 7.

[0150] (Comparative Example 4) A photoelectric conversion element was fabricated in the same manner as in Comparative Example 2, except that a second electron transport layer was formed using SnO after the electron transport layer deposition, and the same evaluation was performed. The results are shown in Table 7.

[0151] (Comparative Example 5) A photoelectric conversion element was fabricated and evaluated in the same manner as in Example 1, except that the compound shown in formula (E8) below was used as the electron-transporting compound to be mixed into the coating solution for the electron transport layer. The results are shown in Table 7. [ka]

[0152] [Table 6]

[0153] [Table 7]

[0154] This embodiment includes the following configurations and methods. (Composition 1) A photoelectric conversion element comprising a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer, The electron transport layer contains a cured product of a composition containing an organic electron transport compound, A photoelectric conversion element characterized in that the LUMO level of the organic electron transport compound is between -4.40 eV and -3.70 eV. (Configuration 2) The photoelectric element according to claim 1, wherein the composition contains at least one compound selected from the group consisting of isocyanate compounds, melamine compounds, and guanamine compounds. (Composition 3) The photoelectric element according to claim 1 or 2, wherein the composition contains a resin having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group. (Composition 4) The photoelectric conversion element according to any one of claims 1 to 3, wherein the content of the organic electron transporting compound in the composition is 40% by mass or more and 90% by mass or less, relative to the total mass of solids in the composition. (Composition 5) The photoelectric conversion element according to any one of claims 1 to 4, wherein the organic electron transport compound contains at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group. (Composition 6) The photoelectric conversion element according to any one of claims 1 to 5, wherein the organic electron transporting compound is at least one compound selected from the group consisting of the compound represented by the following formula (E1), the compound represented by the following formula (E2), the compound represented by the following formula (E3), and the compound represented by the following formula (E4). [ka] [ka] [ka] [ka] (In formulas (E1) to (E4), R 11 ~R 20 , R 21 ~R 26 , R31 to R 34 , and R 41 to R 48 each independently represent a functional group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 28 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 28 carbon atoms, a hydroxy group, a carboxy group, an amino group, a thiol group, a halogen atom, a cyano group, and a nitro group. R 11 to R 20 , R 21 to R 26 , R 31 to R 34 , and R 41 to R 48 may have adjacent groups bonded to each other to jointly form a ring, provided that one or more of R 11 to R 20 are groups containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, one or more of R 21 to R 26 are groups containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, one or more of R 31 to R 34 are groups containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, and one or more of R 41 to R 48 are groups containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group.) (Configuration 7) In the above formula (E1) to the above formula (E4), R 11 to R 20 , R 21 to R 26 , R 31 to R 34 , and R 41 to R 48 each independently are a group represented by the following formula (1), the photoelectric conversion element according to claim 6. -(R a ) m -(R b )n -R c (1) (In formula (1), m and n are each independently 0 or 1. In formula (1), R a represents a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 14 carbon atoms. R in formula (1) c or R in formula (2) d may be linked to each other to jointly form a ring. In formula (1), R b represents an oxygen atom, a sulfur atom, or a group represented by the following formula (2).)

Chemical Formula

[0155] 1. Photoelectric conversion element 2 circuit boards 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6. Hole transport layer 7 First electrode 30 Mobile Units 31, 41 Photoelectric conversion element 32 aircraft 40 Building materials 42 Protective member 43 Heat dissipation components 44a, 44b Exterior

Claims

1. A photoelectric conversion element comprising a first electrode, a second electrode, a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode, and an electron transport layer disposed between the second electrode and the photoelectric conversion layer, The electron transport layer contains a cured product of a composition containing an organic electron transport compound, A photoelectric conversion element characterized in that the LUMO level of the organic electron transport compound is between -4.40 eV and -3.70 eV.

2. The photoelectric element according to claim 1, wherein the composition contains at least one compound selected from the group consisting of isocyanate compounds, melamine compounds, and guanamine compounds.

3. The photoelectric element according to claim 1, wherein the composition contains a resin having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

4. The photoelectric conversion element according to claim 1, wherein the content of the organic electron transporting compound in the composition is 40% by mass or more and 90% by mass or less, relative to the total mass of solids in the composition.

5. The photoelectric conversion element according to claim 1, wherein the organic electron transport compound contains at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

6. The photoelectric conversion element according to claim 1, wherein the organic electron transporting compound is at least one compound selected from the group consisting of the compound represented by the following formula (E1), the compound represented by the following formula (E2), the compound represented by the following formula (E3), and the compound represented by the following formula (E4). 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 (In Formulas (E1) to (E4), R １１ to R ２０ , R ２１ to R ２６ , R ３１ to R ３４ , and R ４１ to R ４８ each independently represent a functional group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 28 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 28 carbon atoms, a hydroxy group, a carboxy group, an amino group, a thiol group, a halogen atom, a cyano group, and a nitro group. R １１ to R ２０ , R ２１ to R ２６ , R ３１ to R ３４ , and R ４１ to R ４８ may be groups adjacent to each other that are linked together to jointly form a ring. Provided that at least one of R １１ to R ２０ is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, at least one of R ２１ to R ２６ is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, at least one of R ３１ to R ３４ is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group, and at least one of R ４１ to R ４８ is a group containing a functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a thiol group.)

7. In the above formulas (E1) to (E4), R １１ ~R ２０ , R ２１ ~R ２６ , R ３１ ~R ３４ , and R ４１ ~R ４８ The photoelectric conversion element according to claim 6, wherein each of the elements is independently a group represented by the following formula (1). -(R ａ ) ｍ -(R ｂ ) ｎ -R ｃ (1) (In equation (1), m and n are independently either 0 or 1.) In formula (1), R ａ R in formula (1) represents an alkylene group having 1 to 10 substituted or unsubstituted carbon atoms, or an arylene group having 6 to 14 substituted or unsubstituted carbon atoms. ｃ or R in formula (2) ｄ They may be connected to each other to form a ring. In formula (1), R ｂ (This represents an oxygen atom, a sulfur atom, or a group represented by the following formula (2).) 【Transformation 5】 (In formula (2), R ｄ R represents a hydrogen atom, or an alkyl group having 1 to 4 substituted or unsubstituted carbon atoms. In this case, R in formula (1) ａ or R in formula (1) ｃ They may be connected to each other to form a ring. In formula (1), R ｃ R in formula (1) represents a hydrogen atom, an alkyl group having 1 to 10 substituted or unsubstituted carbon atoms, an aryl group having 6 to 14 substituted or unsubstituted carbon atoms, or an arylalkyl group having 7 to 18 substituted or unsubstituted carbon atoms. ａ or R in formula (2) ｄ They may be connected to each other to form a ring. The substituents that the alkylene group and the alkyl group may have are a hydroxyl group, a carboxyl group, an amino group, a thiol group, an alkoxy group having 1 to 3 carbon atoms, and an alkoxycarbonyl group having 2 to 4 carbon atoms. The substituents that the arylene group, the aryl group, and the arylalkyl group may have are alkyl groups having 1 to 3 carbon atoms, hydroxyl groups, hydroxyalkyl groups having 1 to 3 carbon atoms, carboxyl groups, amino groups, thiol groups, alkoxy groups having 1 to 3 carbon atoms, alkoxycarbonyl groups having 2 to 4 carbon atoms, halogen atoms, cyano groups, and nitro groups. However, R １１ ~R ２０ One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R ２１ ~R ２６ One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R ３１ ~R ３４ One or more of these are groups containing a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group, R ４１ ~R ４８ One or more of these groups contain a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

8. The photoelectric conversion element according to claim 1, wherein the organic electron transport compound contains a heteroatom having 6 to 20 atoms.

9. The photoelectric conversion element according to claim 1, wherein the LUMO level of the organic electron transport compound is -4.00 eV or higher and -3.75 eV or lower.

10. A photoelectric conversion device comprising a photoelectric conversion element according to any one of claims 1 to 9.

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