Photoelectric conversion element, and photoelectric conversion device

Abstract

To provide a photoelectric conversion element and a photoelectric conversion device having improved photoelectric conversion efficiency.SOLUTION: A photoelectric conversion element has a first electrode, a second electrode, and a photoelectric conversion layer arranged between the first electrode and the second electrode and including the crystal of a perovskite structure. The photoelectric conversion element has a hole transport layer including a compound having a specific structure between the photoelectric conversion layer and the first electrode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion element and a photoelectric conversion device.

Background Art

[0002] In order to solve the problem of depletion of fossil energy and the environmental problems of the earth caused by the use of fossil energy, research on renewable and clean alternative energy sources such as solar energy, wind power, and hydropower has been actively conducted. Among them, the interest in solar cells that directly convert sunlight into electrical energy is increasing. Here, a solar cell means a battery that absorbs light energy from sunlight and generates a current-voltage by utilizing the photovoltaic effect in which electrons and holes are generated. Currently, n-p diode type silicon (Si) single crystal-based solar cells having a light energy conversion efficiency exceeding 20% are widely known and are actually used for solar power generation. However, these have a problem that the cost per unit power is high because they require a high-temperature treatment process and the price of the material itself is also high. Also, from the perspective of silicon resources, there is a problem in supply.

[0003] On the other hand, a solar cell using an organic material (hereinafter referred to as "organic solar cell") does not require a high-temperature treatment process, can be produced in a so-called roll to roll manner on a sheet-like substrate, and cost reduction can be expected. However, for the practical application of organic solar cells, further improvement in power generation efficiency and durability is desired. For the purpose of enhancing the function of selectively transporting holes and improving the photoelectric conversion efficiency, the development of hole transport materials used for the hole transport layer has been promoted. For example, Patent Document 1 and Non-Patent Document 1 describe that the photoelectric conversion efficiency is improved by providing a hole transport layer containing a compound having a specific structure. In addition, a perovskite type solar cell having a perovskite structure crystal as a photoelectric conversion layer is particularly being developed for the practical application of organic solar cells because of its excellent photoelectric conversion properties.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Document

[0005]

Non-Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] According to the studies of the present inventors, in a photoelectric conversion element having a photoelectric conversion layer containing a perovskite-structured crystal, in a photoelectric conversion element using the compounds described in Patent Document 1 and Non-Patent Document 1 in the hole transport layer, the photoelectric conversion efficiency was insufficient. Therefore, an object of the present invention is to provide a photoelectric conversion element and a photoelectric conversion device in which the photoelectric conversion efficiency is improved by using a compound having a specific structure in the hole transport layer.

MEANS FOR SOLVING THE PROBLEMS

[0007] The above object is achieved by the following present invention. That is, the photoelectric conversion element according to the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, characterized in that it has a hole transport layer containing a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode.

Chemical formula

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a photoelectric conversion element with improved photoelectric conversion efficiency and a photoelectric conversion device.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] 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 perovskite structure crystal disposed between the first electrode and the second electrode, and has a hole transport layer containing a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode. [Chemical formula] In formula (1), R 1 and R 2 each represent a linear or branched alkyl group having 1 to 6 carbon atoms, and R 3 to R 22 each independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group having 1 to 18 carbon atoms which may have a substituent, an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent. The substituent that each functional group may have is a halogeno group, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 18 carbon atoms, an amino group having an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 36 carbon atoms, or a heterocyclic group having 5 to 36 ring-forming atoms.

[0011] As a result of investigations, the present inventors have found that a photoelectric conversion element having a hole transport layer containing the compound represented by the formula (1) between the photoelectric conversion layer and the first electrode results in a photoelectric conversion element with improved photoelectric conversion efficiency. In the present invention, although the details of the reason why a photoelectric conversion element with improved photoelectric conversion efficiency is obtained are not clear, it is considered as follows. The compound represented by the formula (1) has a structure having the following characteristics (A) and (B). (A) Nitrogen atoms are directly bonded to the carbon atoms at the 2-position and 7-position of the fluorene skeleton (B) The α-carbon atom of the malonic ester is bonded to the carbon atom at the 9-position of the fluorene skeleton via a carbon-carbon double bond By having the structure of the characteristic (A), it is suggested by DFT calculation that the electron distribution of the highest occupied molecular orbital (HOMO) spreads over the whole molecule. It is considered that the hole transport ability in the hole transport layer is improved by the spread of the electron distribution of HOMO over the whole molecule. Also, by having the structure of the characteristic (B), it is suggested by DFT calculation that the dipole moment of the molecule increases and it has a high polarity. By using such a highly polar hole transport compound in the hole transport layer, the interaction between the hole transport layer and the photoelectric conversion layer is improved, so it is considered that the efficiency of holes generated in the photoelectric conversion layer moving to the hole transport layer is improved. As in the above mechanism, by the synergistic effect of the characteristics (A) and (B), it becomes possible to achieve the effects of the present invention.

[0012] In the formula (1), R 3 ~R 22 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent, and it is preferable that R 5 , R 10 , R 15 , R 20 are each an alkoxy group having 1 to 20 carbon atoms which may have a substituent. By having such a substituent, the photoelectric conversion efficiency is improved.

[0013] Specific examples (exemplified compounds 1-1 to 1-12) of the compound represented by the formula (1) are given below, but the present invention is not limited thereto.

[0014] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry] [Chemistry]

[0015] Hereinafter, the present invention will be described in detail with reference to preferred embodiments. The present invention is not limited to the following embodiments, and those obtained by appropriately modifying or improving the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0016] In addition, in this specification, the term "layer" means not only a layer with a clear boundary or a flat thin film layer, but also a layer with a concentration gradient in which the contained elements gradually change, or a layer that can form a complex intertwined structure together with other layers. Further, elemental analysis of a layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis measurement on a cross-section of a photoelectric conversion element to confirm the elemental distribution of specific elements.

[0017] FIG. 1 is a cross-sectional view schematically showing the configuration of an embodiment of the photoelectric conversion element of the present invention. On a substrate 2, a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a hole transport layer 6, and a first electrode 7 are provided. One of the first electrode 7 and the second electrode 3 is a positive electrode and the other is a negative electrode, and a current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit. The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, the electron transport layer 4, or the first electrode 7 and the hole transport layer 6, generating electrons or holes. That is, the photoelectric conversion layer 5 generates a current 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. A form in which a plurality of the electron transport layer 4 and the photoelectric conversion layer 5 are stacked may also be used. Such a form can also be called a tandem structure. Further, as shown in FIG. 2, a photoelectric conversion element may be fabricated on the substrate 2 in the order of the first electrode 7, the hole transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3. The photoelectric conversion element of the present invention and each member constituting the photoelectric conversion element will be described below.

[0018] [Photoelectric Conversion Element] 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 perovskite structure crystal disposed between the first electrode and the second electrode, wherein a hole transport layer is provided between the photoelectric conversion layer and the first electrode. Further, in order to improve the photoelectric conversion efficiency, a tandem type in which photoelectric conversion elements are stacked may be used. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion element, such as a perovskite solar cell using a perovskite crystal in the photoelectric conversion layer, a silicon solar cell, and a CIGS solar cell. Examples of the method for forming each layer of the photoelectric conversion element of the present invention include a coating method and a vapor deposition method. Examples of the coating method include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen printing, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method is a method of preparing a coating solution for each layer to be described later, coating it in the desired layer order, and drying it. These film formation methods can select the desired method according to each layer. Hereinafter, each layer will be described.

[0019] 〔Substrate〕 The photoelectric conversion element 1 of the present invention may include a substrate 2, and examples thereof include a soda lime glass, a transparent glass substrate of non-alkali glass, a ceramic substrate, and a transparent plastic substrate. In FIG. 1, when light is taken in from the first electrode 7 side, the substrate 2 can use an opaque material, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0020] 〔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, carbon, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al2O3 mixture, and Al / LiF mixture can be mentioned. As the transparent electrode material, for example, 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), ATO (antimony-doped tin oxide), and conductive transparent polymers can be mentioned. These materials may be used alone or in combination of two or more. 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 may also serve as a reflective layer formed of a light-reflective material, or may be a transparent electrode provided with a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 may be used as a transparent electrode, and the substrate 2 may be used as a reflective layer. Note that the transparent electrode may be a patterned electrode.

[0021] 〔Photoelectric conversion layer〕 The photoelectric conversion layer 5 has a perovskite structure crystal. The perovskite structure crystal used in the present invention is preferably represented by the following formula [2]. ABX3 [2] In the above formula [2], A is a monovalent cation of an organic molecule or a metal atom, B is a divalent metal cation, and X is a monovalent halide anion. As A in the above formula [2], for example, in the case of an organic molecule, it is preferably represented by C p N m H n (p, m, and n are all positive integers). Specifically, methylammonium and formamidinium can be mentioned. Also, the inorganic atom is 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.

[0022] If the cation of A that constitutes is too large to fit within the crystal of the three-dimensional perovskite structure, a crystal of a two-dimensional perovskite structure, a crystal of a 2.5-dimensional perovskite structure having both two-dimensional and three-dimensional properties, a two-layer crystal of three-dimensional and two-dimensional perovskite structures, or a crystal of a mixed three-dimensional·two-dimensional perovskite structure is formed, and all of them function as a photoelectric conversion layer. The two-layer crystal of three-dimensional and two-dimensional perovskite structures refers to a crystal in which crystals of three-dimensional and two-dimensional perovskite structures are stacked as independent and separate layers. The crystal of a mixed three-dimensional·two-dimensional perovskite structure refers to a crystal having a structure in which both regions or domains of a two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystal are mixed.

[0023] The crystal of a two-dimensional perovskite structure or the crystal of a 2.5-dimensional perovskite structure is preferably represented by the following formulas [3] to [5]. R’2A n-1 B n X 3n+1 [3] R’’A n-1 B n X 3n+1 [4] R’’’A n B n X 3n+1 [5] The above formulas [3] to [5] form perovskite structures of the RP (Ruddlesden-Popper) type for [3], the DJ (Dion-Jacobson) type for [4], and the ACI (Alternating cations in the interlayer) type for [5], respectively.

[0024] R’, R’’, and R’’’ in the above formulas [3] to [5] are large cations that cannot fit into the three-dimensional perovskite structure. For example, in the case of organic molecules, C p N m H nIt is preferably represented by (where p, m, and n are all positive integers). Also, A may or may not have a substituent. Specifically, ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexanediammonium, iso-butylammonium, 3-(nonafluoro-tert-butoxy)propylammonium, 1,3-propanediammonium, 1,5-pentamethylenediamine, 1,8-octyldiammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidinium, propylammonium, propargylammonium, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium, cyclohexylammonium, 4-fluorophenethylammonium, 4-fluorophenethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophenedimethylammonium, phenylpropylammonium, 1,4-phenylenedimethanammonium, 3-phenyl-2-propen-1-ammonium, phenylbutylammonium, 4-tert-butyl-benzylammonium, 3-(aminomethyl)piperidinium, 4-(aminomethyl)piperidinium are preferred.

[0025] In the formulas [2] to [5], B 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, europium. Among them, from the viewpoint of the overlap of electron orbits, lead, tin, and bismuth are preferable. These metal atoms may be used alone or in combination of two or more.

[0026] In the formulas [2] to [5], X is a halogen atom, such as chlorine, bromine, iodine. These halogen atoms may be used alone or in combination of two or more. Among them, since the crystal of the perovskite structure becomes easily soluble in an organic solvent by containing a halogen in the structure and can be applied to an inexpensive printing method or the like, a halogen atom is preferable. Further, since the energy band gap of the crystal of the perovskite structure becomes narrow, iodine is more preferable.

[0027] Specifically, the three-dimensional perovskite, two-dimensional perovskite, and mixed three-dimensional / two-dimensional perovskite include MAPbI3, FAPbCl 3、 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 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, CsPbBr 3、 Cs x (MA) 1-x PbI3, Cs x (FA) 1-x PbI3, MA x (FA) 1-x PbI 3, 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, (pF-PEA)2(FA 0.3 MA 0.7 )4Pb5I 16 ,(PDMA)FA2Pb3I 10, (3AMPY)(MA)3Pb4I 13 ,(PDMA)MA5Pb6I 19 ,(PDMA)MA3Pb4I 13 ,(TTDMA)MA3Pb4I 13 ,(TTDMA)MA4Pb5I 16 ,(BA 0.9 PEA 0.1 )2MA4Pb5I 16 、(BA 0.9 PEA 0.1 )2MA3Pb4I 13 、(4FPEA)2MA3Pb4I 13 、(4FPEA)2MA4Pb5I 16 (BA)2MA2Pb3I 10 、(BA)2MA3Pb4I 13 、(TEA)2MA2Pb3I 10 、(BA)2MA4Pb5I16 、 (BA)2MA3Pb4I 13 is preferred. 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-phenylenedimethanammonium, "TTDMA" represents thieno[3,2-b]thiophene-2,5-diyl dimethanammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0028] The crystal of the perovskite structure preferably has a cubic crystal structure in which metal atom B is at the body center, organic molecule A is at each vertex, and halogen atom or X is at the face center. Although the details are not clear, having such a structure allows the orientation of the octahedrons in the crystal lattice to easily change, so it is presumed that the mobility of electrons in the perovskite structure crystal increases and the photoelectric conversion efficiency of the photoelectric conversion element improves.

[0029] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor means a semiconductor in which the X-ray scattering intensity distribution is measured and scattering peaks can be detected. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound increases and the photoelectric conversion efficiency of the photoelectric conversion element improves.

[0030] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. If the thickness is 5 nm or more, light can be sufficiently absorbed, and if it is 2000 nm or less, the generated charges can be transported to each electrode. A more preferable lower limit is 50 nm, 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.

[0031] [Positive hole transport layer] In the present invention, as shown in FIGS. 1 and 2, a positive hole transport layer 6 is provided between the photoelectric conversion layer 5 and the first electrode 7. As described above, the positive hole transport layer 6 contains the compound represented by the formula (1). Also, for the purpose of improving the photoelectric conversion efficiency, a dopant (oxidizing agent) or a basic compound may be added. The thickness of the positive hole transport layer according to the present invention is preferably 10 nm or more and 1000 nm or less. If the thickness is 10 nm or more, holes can be sufficiently transported to the electrode, and if it is 1000 nm or less, it is difficult to cause resistance during hole transport, and the photoelectric conversion efficiency becomes high. A more preferable lower limit of the thickness of the positive hole transport layer is 50 nm, and a more preferable upper limit is 500 nm.

[0032] [Electron transport layer] In the photoelectric conversion element of the present invention, as shown in FIGS. 1 and 2, 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 organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc. Specifically, for example, cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic 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. can be mentioned. The thickness of the electron transport layer 4 preferably has a lower limit of 1 nm and an upper limit of 2000 nm. If this thickness is 1 nm or more, holes can be sufficiently blocked, and if it is 2000 nm or less, it is difficult to cause resistance during electron transport, and the photoelectric conversion efficiency becomes high. A more preferable lower limit of the thickness of the electron transport layer 4 is 3 nm, a more preferable upper limit is 1000 nm, a further more preferable lower limit is 5 nm, and a further more preferable upper limit is 500 nm.

[0033] [Photoelectric conversion device] By using a plurality of the photoelectric conversion elements of the present invention, a photoelectric conversion device can be configured. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can also be referred to as a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion elements may be stacked with elements having different absorption wavelengths in order to increase the output voltage. Further, 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 into alternating current. The photoelectric conversion device may have a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited as long as it can store electricity. For example, secondary batteries using lithium ions or the like, all-solid-state batteries, electric double layer capacitors, and the like can be mentioned.

[0034] [Moving body] FIG. 3 is a perspective view schematically showing an embodiment of a moving body provided 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 body 32 provided with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position where it can receive external light of the body 32. If the moving body 30 is an automobile, the photoelectric conversion element 31 may be disposed on the roof. The electric energy obtained by the photoelectric conversion element 31 may be used as the power of the moving body 30 or the power of other electric devices. The electric energy generated from the power of the moving body 30 may be used as the power of the photoelectric conversion element 31. If the moving body 30 is an automobile, the frictional energy generated by the brake may be converted into electric energy and used for the control of 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 material having high strength.

[0035] [Building materials] FIG. 4 is a perspective view schematically showing an embodiment of a building material provided with a photoelectric conversion element of the present invention. The building material 40 may be a roof of a building. The building material 40 of the present embodiment includes a photoelectric conversion element 41 of the present invention, a protective member 42 that protects 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 having a higher thermal conductivity than the photoelectric conversion element 41. When the photoelectric conversion element 41 is 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, it is possible to reduce the decrease in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include metals, alloys, liquid metals, and liquid resins. In addition, the building material 40 of the present invention may have exteriors 44a and 44b. The exterior 44a and the exterior 44b may emit different colors or the same color. 44a and 44b may be composed of the same member or different members. As the exterior member, paint or a transparent substrate may be used, and those with low light absorption and high heat insulation are preferred.

Example

[0036] Hereinafter, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, "parts" means based on mass unless otherwise specified.

[0037] <Synthesis of Exemplary Compound (1-2)> The exemplary compound (1-2) was synthesized by the following method. Into a reaction vessel, 2,7-dibromo-9-fluorenone (3.38 g, manufactured by Tokyo Chemical Industry), 4,4'-dimethoxydiphenylamine (5.04 g, manufactured by Tokyo Chemical Industry), palladium acetate (89.8 mg, manufactured by Tokyo Chemical Industry), 1,1'-bis(diphenylphosphino)ferrocene (332.6 mg, manufactured by Tokyo Chemical Industry), cesium carbonate (9.77 g, manufactured by Tokyo Chemical Industry), and toluene (300 mL) were charged, and the mixture was stirred under reflux heating for 18 hours in a nitrogen atmosphere. The reaction solution was returned to room temperature, filtered under reduced pressure, and washed with toluene. The filtrate was concentrated and purified by silica gel column chromatography (developing solvent: toluene) to obtain an intermediate represented by the following formula (A) as a purple powder (yield 44%). [Chemical formula] Subsequently, into a reaction vessel, the above intermediate (1.27 g), diethyl malonate (1.60 g, manufactured by Tokyo Chemical Industry), tetrahydrofuran (30 mL), and pyridine (5 mL) were charged, cooled to 0 °C with ice water, and titanium tetrachloride (3.79 g, manufactured by Tokyo Chemical Industry) was added dropwise. After the addition, the mixture was returned to room temperature and stirred for 18 hours. After completion of the reaction, water and ethyl acetate were added, and liquid separation was performed. The organic layer was washed with water and saturated brine and concentrated. The obtained crude product was purified by silica gel column chromatography (developing solvent: ethyl acetate / heptane = 1 / 3) to obtain the exemplified compound (1-2) as a purple powder (yield 71%).

[0038] [Manufacture of photoelectric conversion element] (Example 1) [Formation of electron transport layer] The glass substrate with an ITO film was washed, and a tin(II) oxide coating solution adjusted to 3 mass% was applied thereon by spin coating, and then heated at 150 °C for 30 minutes to form a thin film-like electron transport layer with a thickness of 15 nm.

[0039] [Formation of photoelectric conversion layer] 22.4 mg of lead bromide, 172 mg of formamidinium iodide, and 576 mg of lead iodide were dissolved in 600 μL of N,N-dimethylformamide and 160 μL of dimethyl sulfoxide, and stirred for 1 hour (Solution 1). Further, 389.72 mg of cesium iodide was dissolved in 1000 μL of dimethyl sulfoxide and stirred for 1 hour (Solution 2). Then, 40 μL of Solution 2 was added to Solution 1 to prepare a coating solution for the photoelectric conversion layer. By spin-coating this coating solution on the electron transport layer, a 500-nm-thick photoelectric conversion layer composed of Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.95 Br 0.05 )3 was formed.

[0040] [Formation of Hole Transport Layer] 0.15 g of the exemplified compound (1-2) was dissolved in 2.2 g of chlorobenzene to prepare a coating solution 1 for the hole transport layer. By spin-coating this coating solution on the photoelectric conversion layer, a 200-nm-thick hole transport layer was formed.

[0041] [Formation of First Electrode] An 80-nm-thick and 0.09 cm 2 gold electrode was formed on the hole transport layer by vacuum evaporation to obtain a photoelectric conversion device.

[0042] (Example 2) A photoelectric conversion device was obtained in the same manner as in Example 1, except that the exemplified compound (1-2) was changed to the compound represented by the exemplified compound (1-3) in the preparation of the coating solution 1 for the hole transport layer.

[0043] (Example 3) A photoelectric conversion device was obtained in the same manner as in Example 1, except that the exemplified compound (1-2) was changed to the compound represented by the exemplified compound (1-5) in the preparation of the coating solution 1 for the hole transport layer.

[0044] (Comparative Example 1) In the preparation of the coating liquid 1 for the hole transport layer, a photoelectric conversion element was obtained in the same manner as in Example 1, except that the exemplified compound (1-2) was changed to the compound represented by the formula (A).

[0045] (Comparative Example 2) In the preparation of the coating liquid 1 for the hole transport layer, a photoelectric conversion element was obtained in the same manner as in Example 1, except that the exemplified compound (1-2) was changed to the compound represented by the following formula (B). [Chemical Formula]

[0046] (Example 4) [Formation of Electron Transport Layer] The glass substrate with an ITO film was cleaned, and a tin(II) oxide coating liquid adjusted to 3% by mass was spin-coated thereon, followed by heating at 150 °C for 30 minutes to form a thin film-like electron transport layer with a thickness of 15 nm.

[0047] [Formation of Photoelectric Conversion Layer] 22.4 mg of lead bromide, 172 mg of formamidinium iodide, and 576 mg of lead iodide were dissolved in 600 μL of N,N-dimethylformamide and 160 μL of dimethyl sulfoxide, and stirred for 1 hour (Solution 1). Further, 389.72 mg of cesium iodide was dissolved in 1000 μL of dimethyl sulfoxide and stirred for 1 hour (Solution 2). Then, Solution 2 (40 μL) was added to Solution 1 to prepare a coating liquid for the photoelectric conversion layer. By spin-coating this coating liquid on the electron transport layer, a photoelectric conversion layer with a thickness of 500 nm composed of Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.95 Br 0.05 )3 was formed.

[0048] [Formation of Hole Transport Layer] 0.15 g of the exemplary compound (1-2) was dissolved in 2.2 g of chlorobenzene. To this chlorobenzene solution, 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium-bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile and 36 μL of t-butylpyridine were added and mixed. Further, 58 μL of an acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile was mixed to prepare a coating solution 2 for the hole transport layer. By spin-coating this coating solution on the photoelectric conversion layer, a hole transport layer with a thickness of 200 nm was formed.

[0049] [Formation of the first electrode] On the hole transport layer, a gold electrode with a thickness of 80 nm and an area of 0.09 cm 2 was formed by vacuum evaporation to obtain a photoelectric conversion element.

[0050] [Evaluation] (Evaluation of photoelectric conversion efficiency) A power supply (model 236, manufactured by KEITHLEY) was connected between the electrodes of the photoelectric conversion element obtained in Example 1, and a constant light was irradiated using a solar simulator (manufactured by Yamashita Electric Co., Ltd.) with an intensity of 100 mW / cm 2 . The photoelectric conversion efficiency was evaluated by measuring the generated current and voltage. The same evaluation was also performed for Examples 2 to 4 and Comparative Examples 1 and 2. The results are shown in Tables 1 and 2.

[0051] [Table 1]

[0052] [Table 2]

[0053] The disclosure of this embodiment includes the following configurations. [Configuration 1] A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, wherein a hole transport layer containing a compound represented by the following formula (1) is provided between the photoelectric conversion layer and the first electrode. The photoelectric conversion element is characterized by having a hole transport layer containing a compound represented by the following formula (1). [Chemical formula] (In formula (1), R 1 and R 2 each represent a linear or branched alkyl group having 1 to 6 carbon atoms, and R 3 to R 22 each independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group having 1 to 18 carbon atoms which may have a substituent, an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent. The substituent that each functional group may have is a halogeno group, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 18 carbon atoms, an amino group having an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 36 carbon atoms, or a heterocyclic group having 5 to 36 ring-forming atoms.) (Constitution 2) In the formula (1), a compound in which R 3 to R 22 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent is contained in the hole transport layer. The photoelectric conversion element according to Constitution 1. (Configuration 3) In the formula (1), R 5 , R 10 , R 15 , R 20 is a compound in which each of them is an alkoxy group having 1 to 20 carbon atoms which may have a substituent, and the hole transport layer contains the compound, and the photoelectric conversion element according to Configuration 1 or 2.

Explanation of reference numerals

[0054] 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Hole transport layer 7 First electrode

Claims

1. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, wherein a hole transport layer containing a compound represented by the following formula (1) is provided between the photoelectric conversion layer and the first electrode. The photoelectric conversion element is characterized by this. 【Chemical 1】 (In formula (1), R １ and R ２ each represent a linear or branched alkyl group having 1 to 6 carbon atoms, and R ３ to R ２２ each independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group having 1 to 18 carbon atoms which may have a substituent, an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent. The substituent which each functional group may have is a halogeno group, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 18 carbon atoms, an amino group having an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 36 carbon atoms, or a heterocyclic group having 5 to 36 ring-forming atoms.)

2. In the formula (1), R ３ to R ２２ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having an alkyl group having 1 to 20 carbon atoms which may have a substituent, and the hole transport layer contains a compound represented by the above, and the photoelectric conversion element according to claim 1.

3. In the formula (1), R ５ , R １０ , R １５ , R ２０ is a compound in which each of them is an alkoxy group having 1 to 20 carbon atoms which may have a substituent, and the hole transport layer contains the compound. The photoelectric conversion element according to claim 1 or 2.

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