Photoelectric conversion element and photoelectric conversion device including the same

Abstract

The present disclosure provides a photoelectric conversion element, which includes a first electrode 3, a second electrode 7, a photoelectric conversion layer 5 disposed between the first electrode 3 and the second electrode 7, and a reflective layer 6 disposed between one of the first electrode 3 and the second electrode 7 and the photoelectric conversion layer 5, wherein the wavelength at which the reflectance of the reflective layer 6 in the visible light region is maximum is within a wavelength range where the optical absorption coefficient of the photoelectric conversion layer 5 is 1 / 5 or more of its maximum value in the visible light region.

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion element and a photoelectric conversion device including the photoelectric conversion element. Background Art

[0002] In order to solve the problem of fossil energy depletion and global environmental problems caused by the use of fossil energy, research on renewable clean alternative energy sources such as solar, wind, and hydropower has been actively carried out. In particular, the interest in solar cells that directly convert sunlight into electricity has increased significantly. A solar cell is a cell that absorbs light energy from sunlight and generates a current-voltage through the photovoltaic effect, which is a phenomenon of generating electrons and holes.

[0003] Currently, n-p diode type single-crystalline silicon (Si)-based solar cells with a light energy conversion efficiency exceeding 20% are well-known and are used in practice for solar photovoltaic power generation. In addition, perovskite solar cells using a compound having a perovskite-type structure in the active layer have attracted attention due to their high power generation efficiency and low cost, and many studies have been conducted on such solar cells. In addition, the color of the active layer of a solar cell can be changed by controlling the halogen ratio in the active layer. It is expected that this will be applied to solar cells that are colorful and aesthetically pleasing.

[0004] Non-Patent Document 1 describes a solar cell using an organic hybrid perovskite compound, and describes that a colored solar cell can be obtained by controlling the bandgap of the perovskite.

[0005] Patent Document 1 describes a photoelectric conversion element using TiO2, SnO, or ZnO as an electron transport material.

[0006] Patent Document 2 describes a photoelectric conversion element using a perovskite compound as a material for the active layer, and describes that the photoelectric conversion element uses N-alkyl perylene tetracarboxylic diimide as an electron transporting compound in the electron transport layer.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: PCT Japanese Translation Patent Publication No. 2015-535390

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2019-106401

[0011] Non-Patent Documents

[0012] Non-Patent Document 1: Jun Hong Noh et al., Chemical Management for Colorful, Efficient, and Stable Inorganic-Organic Hybrid Nanostructured Solar Cells, Nano Letter. 2013, 13, 4, 1764-1769 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] There is still room for further improvement in the photoelectric conversion efficiency of the solar cells described in Non-Patent Document 1 and Patent Documents 1 and 2.

[0015] Solutions for Solving the Problems

[0016] The present invention has been completed in view of the above problems, and its object is to provide a photoelectric conversion element with high photoelectric conversion efficiency.

[0017] <<First Embodiment>>

[0018] The photoelectric conversion element according to this embodiment includes a first electrode, a second electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and a reflective layer disposed between one of the first electrode and the second electrode and the photoelectric conversion layer. The wavelength at which the reflectance of the reflective layer is maximum in the visible light region is within the wavelength range where the light absorption coefficient of the photoelectric conversion layer is 1 / 5 or more of the maximum light absorption coefficient in the visible light region.

[0019] <<Second Embodiment>>

[0020] The photoelectric conversion element of this embodiment sequentially includes an anode, a first layer containing a perovskite compound, a second conductive layer, and a cathode.

[0021] The second layer is disposed between the cathode and the first layer.

[0022] The second layer contains at least conductive particles, and the conductive particles include core particles and a conductive coating layer having a composition or material different from that of the core particles.

[0023] <<Third Embodiment>>

[0024] The first photoelectric conversion element of this embodiment has a first layer containing a perovskite compound between the anode and the cathode, and a second layer between the cathode and the first layer. The second layer contains a polymer compound combined with an electron transporting compound.

[0025] The second photoelectric conversion element of the present embodiment has a first layer containing a perovskite compound between the anode and the cathode, and a second layer between the cathode and the first layer.

[0026] The second layer contains at least one of the structures represented by the following formulas (E-1) to (E-3) and at least one of the structures represented by the following formulas (P-1) to (P-5).

[0027]

[0028] (In formulas (E-1) to (E-3), R 101 to R 106 , R 201 to R 210 , and R 301 to R 304 each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. One or both of R 101 to R 106 , one or both of R 201 to R 210 , and one or both of R 301 to R 304 are single bonds. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.)

[0029]

[0030] (In formulas (P-1) to (P-5), * represents a bonding site.)

[0031] The third photoelectric conversion element of the present embodiment has a first layer containing a perovskite compound between the anode and the cathode, and a second layer between the cathode and the first layer. The second layer contains at least one of the structure represented by the following formula (U1) and the structure represented by the following formula (U2).

[0032]

[0033] (In formulas (U1) and (U2), R 1 and R 3 each independently represents a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms in the main chain, or a substituted or unsubstituted phenylene group.

[0034] R 2represents a single bond, a substituted or unsubstituted alkylene group with 1 to 10 carbon atoms in the main chain, or a substituted or unsubstituted phenylene group. The substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group, or a halogen atom. The substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group, or a halogen-substituted alkyl group.

[0035] R 9 represents a hydrogen atom or an alkyl group.

[0036] A 1 represents any one of the groups represented by the following formulas (A-1) to (A-6).

[0037] B 1 represents a group represented by any one of the following formulas (B-1) to (B-3).

[0038] D 1 represents a group represented by the following formula (D) with 5 to 15 carbon atoms in the main chain.

[0039] E 1 represents a divalent group represented by any one of the following formulas (E-1) to (E-3).

[0040]

[0041] (In formula (A-5), R 10 represents a hydrogen atom or an alkyl group.)

[0042]

[0043] (In formulas (B-1) to (B-3), R 6 and R 7 each independently represent an alkylene group with 1 to 5 carbon atoms in the main chain, an alkylene group with 1 to 5 carbon atoms in the main chain substituted by an alkyl group having 1 to 5 carbon atoms, an alkylene group substituted by a benzyl group with 1 to 5 carbon atoms in the main chain, an alkylene group substituted by an alkoxycarbonyl group with 1 to 5 carbon atoms in the main chain, or an alkylene group substituted by a phenyl group with 1 to 5 carbon atoms in the main chain. One of the carbon atoms in the main chain of the alkylene group can be replaced by O, S, NH, or NR 15 (R 15 is an alkyl group).

[0044] R 2 represents a single bond, a substituted or unsubstituted alkylene group with 1 to 10 carbon atoms in the main chain, or a substituted or unsubstituted phenylene group. The substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group, or a halogen atom. The substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group, or a halogen-substituted alkyl group.

[0045] R 12represents a hydrogen atom or an alkyl group.

[0046] Ar 2 represents a substituted or unsubstituted phenylene group. The substituents of the substituted phenylene group are a halogen atom, a nitro group, a hydroxyl group, a cyano group, an alkyl group or a haloalkyl group.

[0047] A 1 and A 2 represent any one of the groups represented by the following formulas (A-1) to (A-5).

[0048] E 1 represents a divalent group represented by any one of the following formulas (E-1) to (E-3).

[0049] o, p and q are each independently 0 or 1, and the sum of o, p and q is 1 to 3.

[0050] The arrow points to the side bonded to R 3 .)

[0051]

[0052] (In formula (D), R 4 , R 5 , R 6 and R 7 each independently represent an alkylene group having 1 to 5 carbon atoms in the main chain, an alkylene group having 1 to 5 carbon atoms in the main chain substituted with an alkyl group having 1 to 5 carbon atoms, a benzyl-substituted alkylene group having 1 to 5 carbon atoms in the main chain, an alkoxycarbonyl-substituted alkylene group having 1 to 5 carbon atoms in the main chain, or a phenyl-substituted alkylene group having 1 to 5 carbon atoms in the main chain. One of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH or NR 15 (R 15 is an alkyl group).

[0053] Ar 1 and Ar 2 each independently represent a substituted or unsubstituted phenylene group. The substituents of the substituted phenylene group are a halogen atom, a nitro group, a hydroxyl group, a cyano group, an alkyl group or a haloalkyl group.

[0054] A 2 represents a group represented by any one of the following formulas (A-1) to (A-6).

[0055] l, m, n, o, p and q are each independently 0 or 1, and the sum of l, m and n and the sum of o, p and q are 1 to 3.)

[0056]

[0057] (In formulas (E-1) to (E-3), R101 to R 106 , R 201 to R 210 and R 301 to R 304 each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. One or both of R 101 to R 106 , one or both of R 201 to R 210 , and one or both of R 301 to R 304 are single bonds. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.)

[0058] The fourth photoelectric conversion element of this embodiment has a first layer containing a perovskite compound between the anode and the cathode, and a second layer between the cathode and the first layer. The second layer contains at least one of the structure represented by the following formula (C1) and the structure represented by the following formula (C2).

[0059]

[0060] (In formulas (C1) and (C2), R 11 to R 16 and R 22 to R 25 each independently represents a hydrogen atom, a methylene group, a monovalent group represented by -CH2OR 2 (R 2 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms), a group represented by the following formula (i), or a group represented by the following formula (ii). At least one of R 11 to R 16 and at least one of R 22 to R 25 are groups represented by the following formula (i), and at least one of R 11 to R 16 and at least one of R 22 to R 25 are groups represented by the following formula (ii).

[0061] R 21 represents an alkyl group, a phenyl group, or an alkyl-substituted phenyl group.)

[0062]

[0063] (In formula (i), R 61 represents a hydrogen atom or an alkyl group.)

[0064] Y 1 represents a single bond, an alkylene group or a phenylene group.)

[0065] F 1 represents a divalent group represented by any one of the following formulas (F1) to (F4).

[0066] * represents the side bonded to N in the above formula (C1) or the side bonded to N in the above formula (C2).)

[0067]

[0068] (In formula (ii), F 2 represents a divalent group represented by any one of the following formulas (F1) to (F4).

[0069] α represents an alkylene group having 1 to 6 carbon atoms in the main chain, an alkylene group having 1 to 6 carbon atoms in the main chain and substituted with an alkyl group having 1 to 6 carbon atoms, an alkylene group substituted with a benzyl group having 1 to 6 carbon atoms in the main chain, an alkylene group substituted with an alkoxycarbonyl group having 1 to 6 carbon atoms in the main chain, or an alkylene group substituted with a phenyl group having 1 to 6 carbon atoms in the main chain. One of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH or NR 1 (R 1 is an alkyl group having 1 to 6 carbon atoms).)

[0070] β represents a phenylene group, a phenylene group substituted with an alkyl group having 1 to 6 carbon atoms, a phenylene group substituted with a nitro group, or a phenylene group substituted with a halogen.)

[0071] γ represents an alkylene group having 1 to 6 carbon atoms in the main chain, or an alkylene group having 1 to 6 carbon atoms in the main chain and substituted with an alkyl group having 1 to 6 carbon atoms.)

[0072] r, s and t are each 0 or 1.)

[0073] E 1 represents a divalent group represented by any one of the following formulas (E-1) to (E-3).

[0074] * represents the side bonded to N in the above formula (C1) or the side bonded to N in the above formula (C2).)

[0075]

[0076] (In formulas (E-1) to (E-3), R 101 to R 106 、R 201 to R210 , and R 301 to R 304 each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. One or both of R 101 to R 106 , one or both of R 201 to R 210 , and one or both of R 301 to R 304 are single bonds. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.)

[0077] Effects of the Invention

[0078] The present invention can provide a photoelectric conversion element with high photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 shows an example of a photoelectric conversion element according to an embodiment of the present invention.

[0080] Figure 2 shows an example of a colorimetric method according to an embodiment of the present invention.

[0081] Figure 3 is a cross-sectional view in the thickness direction schematically showing a configuration example of a photoelectric conversion element according to an embodiment of the present invention.

[0082] Figure 4A is a diagram showing a configuration example of a photoelectric conversion element according to an embodiment of the present invention.

[0083] Figure 4B is a diagram showing a configuration example of a photoelectric conversion element according to an embodiment of the present invention.

[0084] Figure 4C is a diagram showing a configuration example of a photoelectric conversion element according to an embodiment of the present invention.

[0085] Figure 5 shows an example of a movable body including a photoelectric conversion element according to an embodiment of the present invention.

[0086] Figure 6 shows an example of a building material including a photoelectric conversion element according to an embodiment of the present invention.

[0087] Figure 7A ​​​​​​​​​Shows the spectrum of Example 1-1.

[0088] Figure 7B Shows the spectrum of Example 1-1. Detailed Description

[0089] <<Photoelectric Conversion Element>>

[0090] <First Embodiment>

[0091] The first embodiment of the present invention will be described in detail below. The photoelectric conversion element according to this embodiment includes a first electrode, a second electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and a reflective layer disposed between one of the first electrode and the second electrode and the photoelectric conversion layer. The wavelength at which the reflectance of the reflective layer is maximum in the visible light region is within the wavelength range where the light absorption coefficient of the photoelectric conversion layer is 1 / 5 or more of the maximum light absorption coefficient in the visible light region. The inventors have found through research that such a configuration can result in a photoelectric conversion element with high photoelectric conversion efficiency. In this embodiment, the "photoelectric conversion layer" may also be referred to as the "functional layer" or the "active layer".

[0092] The photoelectric conversion layer may include a charge transport layer.

[0093] Preferably, the reflective layer contains particles with a volume average particle diameter of 50 nm to 600 nm. Such a reflective layer can reflect blue light more strongly than other light. Therefore, the amount of light absorbed by the functional layer increases, thereby improving the photoelectric conversion efficiency.

[0094] Reflecting blue light from the reflective layer means that the functional layer appears red. More specifically, it means that the light reflected from the reflective layer and transmitted through the photoelectric conversion layer can have an L*c*h* color space of 20 ≤ L*, 30 ≤ c*, and 0 ≤ h* ≤ 90. The color space can be 47 ≤ c*, can be 20 ≤ L*, 42 ≤ c*, and 0 ≤ h* ≤ 50, or can be 20 ≤ L*, 47 ≤ c*, and 50 ≤ h* ≤ 90.

[0095] In this embodiment, the functional layer may include a layer that absorbs light and separates charges; thus, the functional layer can be a photoelectric conversion layer. Preferably, the functional layer can absorb light having a wavelength at which the reflective layer shows a higher reflectance compared to other wavelengths. In addition, the material of the functional layer can be an organic material, an inorganic material, or a material containing perovskite. The functional layer can be made of a mixture of these materials.

[0096] ​The reflective layer according to the present embodiment has a high reflectivity for the wavelength of light with a high absorptivity by the functional layer. More specifically, the particle size of the particles contained in the reflective layer is 50 nm to 600 nm. Preferably, the particle size is 70 nm to 500 nm, and more preferably 90 nm to 400 nm. The particle size of the particles contained in the reflective layer can be measured as the volume average particle size.

[0097] The photoelectric conversion element according to the present embodiment includes a first electrode, a second electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and a reflective layer. The wavelength at which the reflectivity in the visible light region is maximum is within the wavelength range of the light absorbed by the photoelectric conversion layer. More preferably, the wavelength at which the reflectivity is maximum is within the wavelength range where the light absorption coefficient of the photoelectric conversion layer is 1 / 5 or more of the maximum light absorption coefficient in the visible light region. Even more preferably, the wavelength at which the reflectivity is maximum is within the wavelength range where the light absorption coefficient of the photoelectric conversion layer is more than half of the maximum light absorption coefficient in the visible light region.

[0098] In other words, in the spectrum of the reflectivity of the reflective layer with respect to the wavelength, the wavelength corresponding to the maximum reflectivity is within the wavelength range of the light absorbed by the photoelectric conversion layer. In addition, it can also be said that the maximum peak of the spectrum is within the above range.

[0099] In view of this, the spectrum can be in the visible light region, or in the visible light region, ultraviolet light region, and infrared light region. More specifically, the spectrum can be in the region of 250 nm to 1100 nm.

[0100] Now, the present embodiment will be described with reference to the accompanying drawings. [[ID=ID=13]]

[0101] Figure 1 FIG. shows an example of the photoelectric conversion element 1 according to the present embodiment. The first electrode 3, charge transport layer 4, photoelectric conversion layer 5, reflective layer 6, and second electrode 7 are provided on the substrate 2. The first electrode 3 and the second electrode 7 can be an anode or a cathode. A current is generated in the configuration where the first electrode 3 and the second electrode 7 are connected to an external circuit.

[0102] The positions of the first electrode 3 and the second electrode 7 can be interchanged.

[0103] For example, the photoelectric conversion layer 5 is excited by the light incident through the substrate 2, the first electrode 3, and the charge transport layer 4 to generate electrons or holes. Therefore, the photoelectric conversion layer 5 generates a current between the first electrode 3 and the second electrode 7. The charge transport layer 4 is a layer provided between the photoelectric conversion layer 5 and the two electrodes, and may not be provided in some cases. The charge transport layer 4 and the photoelectric conversion layer 5 can be in a form of being repeatedly stacked. This form can be called a tandem structure.

[0104] In the manufacture of a photoelectric conversion element, the following method can be used: prepare the coating solution described below for each layer, apply it according to the desired layer sequence, and then dry it. In this case, the coating solution can be applied by dip coating, spray coating, inkjet coating, roller coating, die coating, knife coating, curtain coating, wire bar coating, ring coating, or spin coating.

[0105] [Support substrate]

[0106] The supporting substrate is preferably a substrate on which an electrode (anode or cathode) can be provided on its main surface and made of a material that does not undergo chemical changes when forming a functional layer of the photoelectric conversion element.

[0107] Examples of the material of the support substrate include glass, plastic, polymer film, and silicon.

[0108] In a photoelectric conversion element configured to extract light from the support substrate side, a highly light-transmitting substrate is suitable as the support substrate.

[0109] A photoelectric conversion element placed on an opaque support substrate cannot receive light through the support substrate. Therefore, the electrode further from the support substrate is preferably transparent or translucent. When using an opaque support substrate, a transparent or translucent electrode is placed so that the electrode further from the support substrate can receive light through it.

[0110] [electrode]

[0111] The electrodes are made of conductive materials. Examples of materials for the electrodes include metals, inorganic compounds such as metal oxides, and organic compounds such as conductive polymers.

[0112] The electrodes may be defined by a single layer or a stack of multiple layers.

[0113] The first electrode or the second electrode may be an anode, and the other may be a cathode. Preferably, at least one of the anode and the cathode is transparent or translucent.

[0114] The first electrode and the second electrode receive charges generated in the functional layer, and these charges are extracted to the outside as electric energy.

[0115] Examples of transparent or translucent electrode materials include conductive metal oxides and metals. When the electrode material is opaque, the material can be thinned to a light-transmitting thickness, thereby making the electrode act as a transparent or translucent electrode. Specifically, transparent or translucent electrode materials include, for example, indium oxide, zinc oxide, tin oxide, and composite materials thereof, such as ITO, IZO, FTO and NESA, gold, platinum, silver, copper and aluminum.

[0116] There is no particular limitation on the method for forming the counter electrodes (anode and cathode). For example, the electrodes can be formed on the layer or the support substrate on which the electrodes should be formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method, a coating method, or the like.

[0117] [Functional layer]

[0118] The functional layer is provided between the first electrode and the second electrode. The functional layer may include a photoelectric conversion layer that converts the absorbed light into charges. The photoelectric conversion layer may be referred to as an active layer. The functional layer may include a charge transport layer. The charge transport layer may be referred to as a hole transport layer or an electron transport layer according to its function.

[0119] The functional layer may be in contact with both the first electrode and the second electrode or one of them.

[0120] [Hole transport layer]

[0121] Preferably, the photoelectric conversion element according to the present embodiment has a hole transport layer between the photoelectric conversion layer and the anode.

[0122] The hole transport layer serves to transport holes from the photoelectric conversion layer to the anode. The hole transport layer also serves to reduce the transport of electrons from the photoelectric conversion layer to the anode to suppress the recombination of electrons and holes, thereby reducing the decrease in photoelectric conversion efficiency. The hole transport layer is preferably in contact with the anode.

[0123] The hole transport materials for forming the hole transport layer include inorganic materials such as CuI and CuNCS, and organic hole transport materials disclosed in paragraphs 0209 to 0212 of Japanese Patent Application Laid-Open No. 2001-291534, and there is no particular limitation. Preferred organic hole transport materials include, for example, conductive polymers such as polythiophene, polyaniline, polypyrrole, and polysilane; spiro compounds in which two rings share a central atom of a tetrahedral structure such as C or Si; aromatic amine compounds such as triarylamine; benzophenanthrene compounds; nitrogen-containing heterocyclic compounds; and liquid crystal cyano compounds.

[0124] The hole transport material is preferably an organic hole transport material that can be coated as a solution and then become solid. Specific examples of such materials include 2,2',7,7'-tetra-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (also known as Spiro-OMeTAD), poly(3-hexylthiophene-2,5-diyl), 4-(diethylamino)benzaldehyde diphenylhydrazone, and polyethylenedioxythiophene (PEDOT).

[0125] There is no particular limitation on the thickness of the hole transport layer, but it is preferably 50 μm or less, more preferably 1 nm to 10 μm, even more preferably 5 nm to 5 μm, and particularly preferably 10 nm to 1 μm. The thickness can be measured by observing the cross section of the photoelectric conversion element under a scanning electron microscope (SEM).

[0126] The hole transport layer can be formed by preparing a coating liquid for a conductive layer containing the above material and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of the solvent for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0127] [Photoelectric conversion layer]

[0128] The photoelectric conversion layer of the photoelectric conversion element according to the present embodiment may contain a compound having a perovskite-type structure (perovskite compound).

[0129] The perovskite compound preferably has an organic-inorganic hybrid structure in which an organic and an inorganic compound are components of a perovskite-type structure.

[0130] The organic-inorganic perovskite compound is preferably a compound represented by the general formula R-M-X3.

[0131] In the general formula R-M-X3, R represents an organic molecule and is preferably represented by C l N m H n (l, m, and n are each a positive integer).

[0132] Specific examples of such R include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, ethylbutylamine, imidazole, azole, pyrrole, aziridine, azirine, azetidine, azete, imidazoline, carbazole; and their ions (e.g., methylammonium (CH3NH3 + ) etc.) and phenethylammonium. Among them, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, their ions, and phenethylammonium are preferred. Particularly, methylamine, ethylamine, propylamine, and their ions are preferred.

[0133] In the general formula R-M-X3, M represents a metal atom, and examples include lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. These metals can be used alone or in combination.

[0134] In the general formula R-M-X3, X represents a halogen atom or a chalcogen atom. Examples include chlorine, bromine, iodine, sulfur, and selenium. These halogen or chalcogen atoms can be used alone or in combination. Among them, halogen atoms are preferred because the presence of halogen atoms in the structure of the organic-inorganic perovskite compound makes the organic-inorganic perovskite compound soluble in organic solvents and enables it to be applied to inexpensive printing methods, etc. In addition, iodine is more preferred because iodine narrows the band gap of the organic-inorganic perovskite compound.

[0135] The organic-inorganic perovskite compound preferably has a cubic crystal structure in which the metal atom M is at the body center, the organic molecule R is at each vertex, and the halogen or chalcogen atom X is at the face center. Although the details are not clear, it is speculated that this structure makes it easy for the octahedra in the lattice to change their orientation, thereby increasing the electron mobility in the organic-inorganic perovskite compound and thus improving the photoelectric conversion efficiency.

[0136] The organic-inorganic perovskite compound is preferably a crystalline semiconductor. The organic-inorganic perovskite compound as a crystalline semiconductor increases the electron mobility and improves the photoelectric conversion efficiency. A crystalline semiconductor refers to a semiconductor in which scattering peaks can be detected by measurements such as X-ray diffraction.

[0137] The thickness of the part made of the organic-inorganic perovskite compound can be 5 nm to 5000 nm. When the thickness is 5 nm or more, the light absorption amount increases and the photoelectric conversion efficiency is further improved. When the thickness is 5000 nm or less, the region with low charge separation efficiency can be reduced, thereby improving the photoelectric conversion efficiency.

[0138] More preferably, the thickness of the part made of the perovskite compound is 10 nm to 1000 nm, and further preferably 20 nm to 500 nm.

[0139] The active layer can be formed by preparing a coating liquid for the active layer containing the above materials and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of the solvent for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0140] The coating liquid can be prepared by mixing two liquids with different compositions.

[0141] [Reflection layer]

[0142] The photoelectric conversion element according to this embodiment includes a reflection layer that reflects incident light. The reflection layer is provided between the functional layer and the first or second electrode.

[0143] The reflective layer is, for example, a stacked layer formed in the order of a first electrode, a charge transport layer, a photoelectric conversion layer, a reflective layer, and a second electrode, and reflects light not completely absorbed by the photoelectric conversion layer to enable the perovskite layer to absorb the light again, thereby effectively improving the light absorption efficiency of the entire element.

[0144] To ensure that the light reflected from the reflective layer is easily absorbed by the photoelectric conversion layer, the reflective layer contains particles with a volume average particle diameter of 50 nm to 600 nm. The particle diameter of the particles contained in the reflective layer is preferably 70 nm to 500 nm, and particularly preferably 90 nm to 400 nm.

[0145] The refractive index of the particles is preferably 1.3 to 3.0, more preferably 1.8 to 3.0, and even more preferably 2.3 to 3.0. The aspect ratio of the particles is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.0.

[0146] There is no particular limitation on the material of the particles. Examples of metal compounds include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, barium sulfate, strontium titanate, barium titanate, and potassium niobate. Examples of metals include aluminum, nickel, iron, nickel-chromium alloy, copper, zinc, and silver. Examples of resin particles include acrylic resins, fluororesins, polystyrene resins, polyethylene resins, and silicone resins.

[0147] The particles may have a coating layer made of a conductive material. Examples of conductive materials include metal-based materials such as metal oxides, aluminum, palladium, iron, copper, and silver; and composite materials subjected to electrolytic, spraying, or mixed vibration surface treatment. Among them, metal oxides are preferred. The metal oxide is preferably any one selected from tin oxide, zinc oxide, and titanium oxide. When these metal oxides are appropriately reduced to have an oxygen-deficient type structure or appropriately doped, these metal oxides can contribute to increasing the current density. When using tin oxide, tin oxide is preferably doped with an element selected from niobium, tantalum, phosphorus, tungsten, and fluorine. When using zinc oxide, zinc oxide is preferably doped with element aluminum or gallium. When using titanium oxide, titanium oxide is preferably doped with element niobium or tantalum.

[0148] In this embodiment, the aspect ratio of the particles is measured by a scanning electron microscope as described below. The particles to be measured are observed under a scanning electron microscope S-4800 (manufactured by Hitachi, Ltd.), and the major axis and minor axis of 100 particles randomly selected from the obtained image by observation are measured, and then their arithmetic mean is calculated.

[0149] In this embodiment, the refractive index of the particles is defined as the value measured using CARGILLE standard refractive index liquids manufactured by Cargille Laboratories. The specific measurement method is as follows: Place the particles on a glass slide and drop the refractive index liquid. Mix the particles and the refractive index liquid thoroughly and irradiate from below with a sodium lamp. Observe the outline of the particles from above. When the outline is invisible, the refractive index of the particles is considered equal to the refractive index of the refractive index liquid. For the resin forming the film, the refractive index is defined as the value measured according to JIS K7142, Plastics - Method for the determination of refractive index.

[0150] In addition, the refractive index of the resin forming the film is defined as the value obtained using an Abbe refractometer DR - A1 (trade name, manufactured by ATAGO Co., Ltd.).

[0151] The reflective layer according to this embodiment may contain, in addition to the particles, a binder. Examples of the binder include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, and alkyd resin.

[0152] The use of the binder can form a dense and uniform reflective layer, thereby forming a uniform interface between the reflective layer and the active layer, thereby improving the electron transport ability. However, an excessive content of the binder resin will reduce the electron transport ability within the reflective layer.

[0153] The weight ratio of the particles to the resin (particles / resin) in the reflective layer is preferably from 100 / 1 to 2 / 1, more preferably from 95 / 1 to 4 / 1, and even more preferably from 90 / 1 to 10 / 1.

[0154] The average thickness of the reflective layer is preferably from 50 nm to 1000 nm, and more preferably from 70 nm to 500 nm.

[0155] The reflective layer can be formed by preparing a coating liquid for the reflective layer containing the above materials and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of the solvent for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0156] In order to disperse the particles in the coating liquid for the reflective layer, a paint mixer, a sand mill, a ball mill, or a high - speed liquid collision disperser can be used. The conductive layer coating liquid prepared by dispersion can be filtered to remove impurities and used as the coating liquid for the reflective layer.

[0157] In this embodiment, as Figure 2The measured hue is shown. Specifically, a coating film of a reflective layer 22 and a photoelectric conversion layer 23 is successively formed on an aluminum sheet 21, and the surface of the coating film is irradiated with light from a spectrocolorimeter 24 at an angle of 45 degrees with respect to the vertical axis of the coating film surface. L*, c*, and h* are thus determined from the spectral reflectance at 90 degrees with respect to the coating film surface. A perovskite layer can be used as the photoelectric conversion layer, and RM200QC (manufactured by X-Rite Inc.) can be used as the spectrocolorimeter.

[0158] <Second Embodiment>

[0159] The inventors have found through research that a photoelectric conversion element including an anode, a first layer containing a perovskite compound, a second conductive layer, and a cathode in this order has improved photoelectric conversion efficiency when the second layer contains conductive particles produced by coating core particles with a conductive material.

[0160] It is not clear how the second embodiment of the present invention produces such an effect, but the following mechanism is speculated. Coating the core particles with a conductive material creates an interaction between the conductive material and the core particles, and the conduction band energy level of the conductive material is close to the conduction band energy level of the perovskite compound in the first layer. Therefore, electron injection from the first layer to the second layer is promoted to increase the current density. This may be the reason for the improvement in photoelectric conversion efficiency.

[0161] The second embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiments, and includes any modifications or variations of the following embodiments made within the scope and spirit of the present invention based on the knowledge of those skilled in the art.

[0162] Figure 3 The configuration of an embodiment of the photoelectric conversion element according to the present invention is schematically shown.

[0163] Figure 3 FIG. is a cross-sectional view of the photoelectric conversion element taken along the thickness direction (lamination direction), in which an anode 102, a charge transport layer 103, a first layer 104, a second layer 105, and a cathode 106 are laminated on a substrate 101. A current is generated between the anode 102 and the cathode 106 through an external circuit. The first layer 104 is excited by light obtained from the substrate 101 side or the cathode 106 side to generate electrons or holes; therefore, the first layer is a photoelectric conversion layer that generates a current between the anode 102 and the cathode 106, that is, a so-called active layer. The charge transport layer 103 is provided between the first layer 104 and the two electrodes 102 and 106, but is not necessarily an essential component. The first layer 104 may have a series structure defined by multiple layers. Although Figure 3A configuration is shown in which the anode 102 is disposed on the substrate 101 side, and the cathode 106 may be disposed on the substrate 101 side, and the second layer 105, the first layer 104, the charge transport layer 103, and the anode 102 are sequentially stacked thereon. Hereinafter, the first layer 104 will be referred to as the active layer 104.

[0164] The photoelectric conversion element of the present embodiment can be produced by preparing coating liquids for the respective layers described later, coating the coating liquids in a desired order, and drying the coating liquids. At this time, the coating liquids can be coated by dip coating, spray coating, inkjet coating, roll coating, die coating, knife coating, curtain coating, wire bar coating, loop coating, or spin coating.

[0165] <Substrate>

[0166] The substrate 101 is preferably a substrate on which an electrode (the anode 102 in the case of Figure 3 ) can be provided on its main surface and is made of a material that does not chemically change when forming the functional layers of the photoelectric conversion element. Examples of the material of the substrate include glass, plastic, polymer film, and silicon. When light is obtained from the substrate 101 side, the substrate 101 uses a transparent material.

[0167] <Electrode>

[0168] The electrodes 102 and 106 are made of a conductive material. Examples of the materials of the electrodes 102 and 106 include metals, inorganic compounds such as metal oxides, and organic compounds such as conductive polymers. The electrodes 102 and 106 may be defined by a single layer or a laminate of multiple layers.

[0169] When light is obtained from the substrate 101 side, the electrode on the substrate 101 side (the anode 102 in the case of Figure 3 ) is preferably made of a material with high transparency so that the photoelectric conversion element can function effectively. On the other hand, when light is obtained from the side opposite to the substrate 101 (the cathode 106 side in the case of Figure 3 ), the electrode on the side opposite to the substrate 101 (the cathode 106 side in the case of Figure 3 ) is made of a material with high transparency.

[0170] Examples of transparent or semi-transparent electrode materials include conductive metal oxides and metals. When the electrode material is opaque, the material can be thinned to a light-transmitting thickness so that the electrode functions as a transparent or semi-transparent electrode. Specific examples of transparent or semi-transparent electrode materials include, for example, indium oxide, zinc oxide, tin oxide, and their composites such as ITO, IZO, FTO, and NESA, gold, platinum, silver, copper, and aluminum.

[0171] There is no limitation on the method for forming the counter electrodes 102 and 106. For example, the electrodes can be formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method, a coating method, or the like.

[0172] <Hole transport layer>

[0173] In the present embodiment, the charge transport layer 103 between the anode 102 and the active layer 104 is preferably a hole transport layer.

[0174] The hole transport layer 103 functions to transport holes from the active layer 104 to the anode 102. In addition, the hole transport layer functions to suppress the inflow of electrons from the active layer 104 into the anode 102 to suppress the recombination of electrons and holes, thereby preventing a decrease in the photoelectric conversion efficiency. The hole transport layer is preferably in contact with the anode.

[0175] Examples of hole transport materials that can form the hole transport layer 103 include conductive polymers such as polythiophene, polyaniline, polypyrrole, and polysilane; spiro compounds in which two rings share a central atom of a tetrahedral structure such as C or Si; aromatic amine compounds such as triarylamine; benzophenanthrene compounds; nitrogen-containing heterocyclic compounds; and liquid crystal cyano compounds.

[0176] Specific examples of hole transport materials include 2,2',7,7'-tetra-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (also known as Spiro-OMeTAD), poly(3-hexylthiophene-2,5-yl), 4-(diethylamino)benzaldehyde diphenylhydrazone, and polyethylenedioxythiophene (PEDOT). The hole transport layer 103 can contain additives such as lithium bis(trifluoromethanesulfonyl)imide or tert-butylpyridine (TBP).

[0177] The thickness of the hole transport layer 103 is preferably, but not particularly limited to, 1 μm or less, more preferably 100 nm to 600 nm. This thickness can be measured by observing the cross-section of the photoelectric conversion element under a scanning electron microscope (SEM).

[0178] The hole transport layer 103 can be formed by preparing a coating liquid containing the above materials and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of solvents for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0179] <Active layer>

[0180] The active layer contains a compound having a perovskite-type structure (perovskite compound). The perovskite compound preferably has an organic-inorganic hybrid structure in which an organic and an inorganic compound are components of the perovskite-type structure, and particularly preferably a compound represented by the general formula RMX3.

[0181] In the general formula RMX3, R represents organic molecules such as methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, etc., and their ions. M represents metal atoms such as Cu, Ni, Mn, Fe, Co, Pd, Ge, Sn, Pb, and Eu. These metals can be used alone or in combination. Additionally, X represents halogen atoms such as chlorine, bromine, iodine, or fluorine. These halogen atoms can be used alone or in combination.

[0182] The organic-inorganic perovskite compound is preferably a crystalline semiconductor. The organic-inorganic perovskite compound as a crystalline semiconductor improves the mobility of electrons and enhances the photoelectric conversion efficiency. A crystalline semiconductor refers to a semiconductor in which scattering peaks can be detected by measurements such as X-ray diffraction.

[0183] The thickness of the active layer 104 is preferably, but not particularly limited to, 2 μm or less, and more preferably 200 nm to 1 μm.

[0184] The active layer 104 can be formed by preparing a coating liquid containing materials and solvents capable of forming a perovskite compound through a chemical reaction, forming a coating film of the liquid, and drying the coating film. Examples of solvents for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0185] <Conductive layer>

[0186] In the present embodiment, the conductive layer 105 disposed between the active layer 104 and the cathode 106 is an electron transport layer and contains conductive particles produced by coating core particles with a conductive material. The core particles are different from the conductive material forming the coating layer in composition or material.

[0187] In the present embodiment, examples of the conductive material forming the coating layer of the conductive particles include metal-based materials such as metal oxides, aluminum, palladium, iron, copper, and silver; composite materials subjected to electrolytic, spraying, or mixed vibration surface treatment; carbon black; and carbon black-based materials. Among them, carbon black and metal oxides are preferred. Metal oxides are more preferred. The metal oxide is preferably any one selected from tin oxide, zinc oxide, and titanium oxide.

[0188] Furthermore, such metal oxides can contribute to increasing the current density when appropriately reduced to have an oxygen-deficient structure or appropriately doped. When using tin oxide, tin oxide is preferably doped with elements selected from niobium, tantalum, phosphorus, tungsten, and fluorine. When using zinc oxide, zinc oxide is preferably doped with element aluminum or gallium. When using titanium oxide, titanium oxide is preferably doped with element niobium or tantalum.

[0189] The amount of the doping element of the metal oxide is preferably 0.5 to 10.0% by mass in the coating layer. When the dopant content is less than 0.5% by mass, the effect of increasing the current density may be insufficient. On the contrary, a dopant content exceeding 10.0% by mass may easily cause leakage in the photoelectric conversion element. Preferably, the dopant content is 1.0 to 7.0% by mass in the coating layer.

[0190] In the present embodiment, the material of the core particles of the conductive particles may be a metal compound, a metal, carbon black, a resin, or the like. Examples of the metal compound include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, barium sulfate, strontium titanate, barium titanate, and potassium niobate. Examples of the metal include aluminum, nickel, iron, nickel-chromium alloy, copper, zinc, and silver. Examples of the resin include acrylic resin, fluororesin, polystyrene resin, polyethylene resin, and silicone resin.

[0191] Various forms of particles, such as spherical, polyhedral, ellipsoidal, flaky, and needle-shaped, can be used as the core particles. Among them, from the viewpoint of electron injection at the interface between the active layer and the conductive layer, spherical, polyhedral, or ellipsoidal core particles are preferably used. More preferably, the core particles are spherical or polyhedral close to spherical.

[0192] In the present embodiment, the aspect ratio of the conductive particles represented by the ratio (a / b) of the average major axis diameter a to the average minor axis diameter b is preferably 3.0 or less. An aspect ratio of 3.0 or less is preferred because such an aspect ratio improves the electron injection efficiency from the active layer to the conductive layer 105.

[0193] Preferably, both the average major axis diameter a and the average minor axis diameter b of the conductive particles are 50 nm to 600 nm. When the average major axis diameter a and the average minor axis diameter b are 50 nm or more, the conductive particles are less likely to aggregate again after preparing the coating liquid for the conductive layer. In addition, when the average major axis diameter a and the average minor axis diameter b are 600 nm or less, the surface of the conductive layer 105 is less likely to be roughened. A conductive layer 105 with a rough surface easily causes leakage. More preferably, in the present embodiment, the average major axis diameter a and the average minor axis diameter b of the conductive particles are 50 nm to 400 nm.

[0194] In the present embodiment, the average major axis diameter a and the average minor axis diameter b of the conductive particles are measured by a scanning electron microscope. Specifically, the conductive particles to be measured are observed under a scanning electron microscope "S-4800" (manufactured by Hitachi, Ltd.), and the major axis diameters and minor axis diameters of 100 conductive particles randomly selected from the obtained image are measured, and then their arithmetic mean is calculated.

[0195] Preferably, the average major axis diameter and the average minor axis diameter of the core particles are 1 to 50 times, more preferably 5 to 20 times, the average thickness of the coating layer.

[0196] The conductive layer according to the present embodiment may be made only of the above-described conductive particles, but may also contain a binder in addition to the conductive particles. Examples of the binder include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, and alkyd resins. In the present embodiment, the conductive layer 105 preferably contains 20% by volume or more of the above-described conductive particles. When the content of the conductive particles is less than 20% by volume, the distance between the conductive particles increases, and the current density tends to decrease accordingly. Therefore, for the conductive layer 105 containing the conductive particles and the binder resin, the content of the binder resin in the conductive layer 105 is 80% by volume or less.

[0197] The average thickness of the conductive layer 105 is preferably 0.1 μm to 1.0 μm, and more preferably 0.1 μm to 0.5 μm.

[0198] The conductive layer 105 can be formed by preparing a coating liquid for a conductive layer containing the above-described conductive particles, a solvent, and optionally the above-described binder resin, forming a coating film of the coating liquid, and drying the coating film. Examples of the solvent for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. In order to disperse the conductive particles in the coating liquid for a conductive layer, a method using a paint stirrer, a sand mill, a ball mill, or a high-speed liquid collision disperser can be used. The coating liquid for a conductive layer prepared by dispersion can be filtered to remove unnecessary materials.

[0199] <Third Embodiment>

[0200] Hereinafter, the third embodiment of the present invention will be described in detail.

[0201] The inventors of the present invention found through their research that a configuration having a first layer containing a perovskite compound between the anode and the cathode and a second layer having the characteristics of the present embodiment between the cathode and the first layer improves the photoelectric conversion efficiency.

[0202] It is not clear how this embodiment produces such an effect, but the present inventors speculate the following mechanism. The present inventors believe that the two effects produced by imparting any feature of this embodiment to the second layer containing the electron transporting compound improve the photoelectric conversion efficiency. One of them may be that the electron transporting compound enhances electron extraction. The present inventors believe that by making the energy levels of the perovskite compound and the electron transporting compound coincide, electrons move rapidly, thereby improving the photoelectric conversion efficiency. Another may be to promote the formation of the first layer provided on the second layer, thereby improving the crystallinity of the first layer. Possibly, the feature of this embodiment imparted to the second layer promotes interface formation and forms a surface with wettability imparting affinity to the first layer, thereby promoting crystal growth. The present inventors believe that the improved crystallinity of the first layer increases light absorption and enables the generated charges to move effectively, thereby improving the photoelectric conversion efficiency.

[0203] The photoelectric conversion element of this embodiment has a first layer containing a perovskite compound between the anode and the cathode, and a second layer between the cathode and the first layer.

[0204] Figures 4A to 4C A diagram showing an example of the configuration of the photoelectric conversion element according to this embodiment. Figure 4A A plan view when viewed from the cathode side. Figure 4B is Figure 4A the a-a' cross-sectional view of. Figure 4C is Figure 4A the b-b' cross-sectional view of. In the Figures 4A to 4C photoelectric conversion element shown, a substrate 216, an anode 211, a third layer 212, a first layer 213, a second layer 214, and a cathode 215 are formed in sequence. A current is generated between the anode 211 and the cathode 215 through an external circuit. In this case, the first layer 213 is a photoelectric conversion layer that is excited by light entering through the substrate 216, the anode 211, and the third layer 212 or through the cathode 215 and the second layer 214 to generate electrons or holes and generate a current between the anode 211 and the cathode 215. The third layer 212 is a layer between the first layer 213 and the anode 211, and is not necessarily a necessary layer. The first layer 213 may be a tandem structure including multiple layers.

[0205] In the manufacture of the photoelectric conversion element of this embodiment, a method in which coating liquids for the following respective layers are prepared in the order of the desired respective layers, coated, and then dried can be used. In this method, the coating liquid can be coated by dip coating, spraying, inkjet coating, dispensing coating, roll coating, die coating, knife coating, curtain coating, wire bar coating, loop coating, or spin coating.

[0206] <Substrate 216>

[0207] The substrate 216 is preferably a substrate on which electrodes can be provided on its main surface and made of a material that does not chemically change when forming the functional layers of the photoelectric conversion element. Examples of the material for supporting the substrate include glass, plastic, polymer film, and silicon.

[0208] <Electrodes (anode 211, cathode 215)>

[0209] The electrodes are made of a conductive material. Examples of the material for the electrodes include metals, inorganic compounds such as metal oxides, and organic compounds such as conductive polymers. The electrodes can be defined by a single layer or a stack of multiple layers.

[0210] In the photoelectric conversion element of the present embodiment, the perovskite compound in the first layer 213 absorbs the light entering through either electrode to generate electrons and holes. The electrons thus generated reach the cathode 215, and the holes reach the anode 211. The electrons and holes are extracted from the photoelectric conversion element as electric energy (current). In order for the photoelectric conversion element to function effectively, the incident light must reach the first layer 213 through the substrate 216. A highly transparent material is suitable for the substrate 216 and the electrodes. In a photoelectric conversion element configured to obtain light from the substrate 216 side, a highly light-transmissive material is suitable for the substrate 216 and the electrodes on the substrate 216. In a photoelectric conversion element configured to obtain light from the electrode side farther from the substrate 216, a highly light-transmissive material is suitable for the electrode farther from the substrate 216.

[0211] Examples of the transparent or semi-transparent electrode materials include conductive metal oxides and metals. When the electrode material is opaque, the material can be thinned to a light-transmissive thickness so that the electrode functions as a transparent or semi-transparent electrode. Specific examples of the transparent or semi-transparent electrode materials include, for example, indium oxide, zinc oxide, tin oxide, and their composites such as ITO, IZO, FTO, and NESA, gold, platinum, silver, copper, and aluminum.

[0212] There is no limitation on the method for forming the electrodes. For example, the electrodes can be formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or a coating method, etc.

[0213] <The third layer 212>

[0214] Preferably, the photoelectric conversion element according to the present embodiment has a third layer 212 between the first layer 213 and the anode 211. The third layer 212 can be a hole transport layer.

[0215] The third layer 212 functions to transport holes from the first layer 213 to the anode 211. In addition, the third layer functions to suppress the inflow of electrons from the first layer 213 into the anode 211 to inhibit the recombination of electrons and holes, thereby preventing the decrease in the photoelectric conversion efficiency. The third layer 212 is preferably in contact with the anode 211.

[0216] Hole transporting materials that can form the third layer 212 include conductive polymers such as polythiophene, polyaniline, polypyrrole, and polysilane; spiro compounds in which two rings share a central atom of a tetrahedral structure such as C or Si; aromatic amine compounds such as triarylamine; benzophenanthrene compounds; nitrogen-containing heterocyclic compounds; and liquid crystal cyano compounds. Specific examples of hole transporting materials include 2,2',7,7'-tetra-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (also known as Spiro-OMeTAD), poly(3-hexylthiophene-2,5-diyl), 4-(diethylamino)benzaldehyde diphenylhydrazone, and polyethylenedioxythiophene (PEDOT).

[0217] The third layer 212 may contain additives such as lithium bis(trifluoromethanesulfonyl)imide or tert-butylpyridine (TBP).

[0218] The thickness of the third layer 212 is preferably, but not particularly limited to, less than 1 μm, more preferably 200 nm to 60 μm. The thickness can be measured by observing the cross-section of the photoelectric conversion element under a scanning electron microscope (SEM).

[0219] The third layer 212 can be formed by preparing a coating liquid for a conductive layer containing the above materials and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of solvents for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0220] <The first layer 213>

[0221] The first layer 213 contains a perovskite compound (a compound having a perovskite-type structure). The first layer 213 can be an active layer, a functional layer, or a photoelectric conversion layer.

[0222] The perovskite compound preferably has an organic-inorganic hybrid structure in which an organic and an inorganic compound are components of a perovskite-type structure.

[0223] The organic-inorganic perovskite compound is preferably a compound represented by the general formula RMX3.

[0224] In the general formula RMX3, R represents organic molecules such as methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, and their ions.

[0225] In the general formula RMX3, M represents metal atoms such as Cu, Ni, Mn, Fe, Co, Pd, Ge, Sn, Pb, and Eu. These metals can be used alone or in combination.

[0226] In the general formula RMX3, X represents halogen atoms such as chlorine, bromine, iodine, or fluorine. These halogen atoms can be used alone or in combination.

[0227] The organic-inorganic perovskite compound is preferably a crystalline semiconductor. The organic-inorganic perovskite compound as a crystalline semiconductor increases the electron mobility and improves the photoelectric conversion efficiency. A crystalline semiconductor refers to a semiconductor in which scattering peaks can be detected by measurement such as X-ray diffraction.

[0228] The thickness of the portion partially composed of the organic-inorganic perovskite compound is preferably, but not particularly limited to, 2 μm or less, more preferably 200 nm to 1 μm.

[0229] The first layer 213 can be formed by preparing a coating liquid for a conductive layer containing the above materials and a solvent, forming a coating film of the liquid, and drying the coating film. Examples of the solvent for the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. In particular, from the viewpoints of improving the solubility of the material of the first layer 213 and improving the crystallinity, aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide are preferred.

[0230] <Second layer 214>

[0231] The photoelectric conversion element according to the present embodiment has a second layer 214 between the first layer 213 and the cathode 215. The second layer 214 can be an underlayer or a conductive layer.

[0232] [First photoelectric conversion element]

[0233] In the first photoelectric conversion element, the second layer 214 contains a polymer compound, and the polymer compound is combined with an electron transporting compound.

[0234] Examples of the electron transporting compound contained in the second layer 214 include oxadiazole derivatives, anthraquinone dimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoquinone dimethane and its derivatives, fluorenone derivatives, diphenyl dicyanoethylene and its derivatives, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline and its derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, polyfluorene and its derivatives, fullerene-based and its derivatives, phenanthrene derivatives such as bathocuproine, naphthalenetetracarboxylic diimide and its derivatives, perylenetetracarboxylic diimide and its derivatives, and pyromellitic diimide and its derivatives. In particular, naphthalenetetracarboxylic diimide and its derivatives, perylenetetracarboxylic diimide and its derivatives, and pyromellitic diimide and its derivatives are preferred.

[0235] The second layer 214 can be a cured film formed by curing a curable resin, and the electron transporting compound can be bonded to the chain of the resin forming the cured film.

[0236] [Second photoelectric conversion element]

[0237] In the second photoelectric conversion element, the second layer 214 contains at least one of the structures represented by formulas (E-1) to (E-3) and at least one of the structures represented by formulas (P-1) to (P-5). The second layer 214 is a layer (cured layer) containing at least one of the structures represented by formulas (E-1) to (E-3) and at least one of the structures represented by formulas (P-1) to (P-5). In other words, the second layer 214 includes a cured film (polymer) having at least one of the structures represented by formulas (E-1) to (E-3) and at least one of the structures represented by formulas (P-1) to (P-5).

[0238]

[0239] In formulas (E-1) to (E-3), R 101 to R 106 , R 201 to R 210 , and R 301 to R 304 each independently represent a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. One or both of R 101 to R 106 , one or both of R ... 201 to R 210 , and one or both of R 301 to R 304 are single bonds. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.

[0240]

[0241] In formulas (P-1) to (P-5), * represents a bonding site.

[0242] The single bond can be a single bond that binds to the chain of the resin forming the second layer 214, and the structure represented by formulas (P-1) to (P-5) can be a part of the resin chain.

[0243] Tables 1 to 5 show specific examples of formulas (E-1) to (E-3). In Tables 1 to 5, each bonding site is represented by a dotted line. Each of the specific examples shown in Tables 1 to 5 is the E 1 specific structure of the specific example represented by the corresponding number shown in Tables 6 to 11 or Tables 12 to 19. Therefore, Tables 1 to 5 may repeatedly show the same structure.

[0244] [Table 1]

[0245]

[0246] [Table 2]

[0247]

[0248] [Table 3]

[0249]

[0250] [Table 4]

[0251]

[0252] [Table 5]

[0253]

[0254] For example, the second layer 214 can be formed as described below. First, a crosslinking agent, a resin having a polymerizable functional group capable of reacting with the crosslinking agent, and an electron transporting compound having a polymerizable functional group capable of reacting with the crosslinking agent are dissolved in a solvent to prepare a coating solution. A coating film of the coating solution is formed and thermally cured to produce the second layer 214. Thermal curing is preferred because the reaction can proceed more uniformly when the reaction is carried out during drying.

[0255] [Electron Transporting Compound]

[0256] The electron transporting compound is preferably a naphthalenetetracarboxylic diimide derivative, a perylenetetracarboxylic diimide derivative, or a pyromellitic diimide derivative. In addition, the electron transporting compound preferably has a polymerizable functional group capable of reacting with the crosslinking agent. Examples of the polymerizable functional group include a hydroxyl group, a thiol group, a carboxyl group, an amino group, an isocyanate group, and an acrylic group.

[0257] Derivatives having the structure represented by (E-1) (electron transport material derivatives) can be synthesized by known synthesis methods, such as those described in U.S. Patent Nos. 4442193, 4992349, and 5468583 and Chemistry of Materials, Vol. 19, No. 11, 2703-2705 (2007). In addition, such derivatives can be synthesized by the reaction of naphthalenetetracarboxylic dianhydride with a monoamine derivative from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan, or Johnson Matthey Japan G.K.

[0258] In order for an electron transporting material to have polymerizable functional groups (such as hydroxyl groups, thiol groups, amino groups, or carboxyl groups) capable of reacting with a crosslinking agent, for example, such polymerizable functional groups can be directly introduced into derivatives having the (E-1) structure, or a structure having a polymerizable functional group or a functional group that can be used as a precursor of a polymerizable functional group can be introduced. In the latter method, for example, a cross-coupling reaction using a palladium catalyst and a base can be used to introduce a functional group-containing aryl group into a halogenated naphthalene tetracarboxylic diimide derivative, or a cross-coupling reaction using an FeCl3 catalyst and a base can be used to introduce a functional group-containing alkyl group into a halogenated naphthalene tetracarboxylic diimide derivative. Alternatively, after lithiation, an epoxide and CO2 can be allowed to act on the derivative to introduce a hydroxyalkyl group or a carboxyl group. In the former method, for example, as a raw material for synthesizing a naphthalene tetracarboxylic diimide derivative, a naphthalene tetracarboxylic dianhydride derivative or a monoamine derivative having a polymerizable functional group or a functional group that can be used as a precursor of a polymerizable functional group can be used.

[0259] Derivatives having the structure represented by (E-2) or (E-3) can be synthesized by, for example, known methods described in Journal of the American Chemical Society, Vol. 129, No. 49, 15259-78 (2007). In addition, such derivatives can be synthesized by the reaction of perylene tetracarboxylic dianhydride (E-2) or pyromellitic dianhydride (E-3) available from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan, or Johnson Matthey Japan G.K. with a monoamine derivative.

[0260] In the method of introducing such polymerizable functional groups into derivatives having the (E-2) or (E-3) structure, the polymerizable functional groups can be directly introduced into the derivatives, or a structure having a polymerizable functional group or a functional group that can be used as a precursor of a polymerizable functional group can be introduced. In the latter method, for example, a halogenated compound of a perylene tetracarboxylic diimide derivative or a pyromellitic diimide derivative can be subjected to a cross-coupling reaction using a palladium catalyst and a base or a cross-coupling reaction using an FeCl3 catalyst and a base. In the former method, for example, a perylene tetracarboxylic dianhydride derivative or a monoamine derivative having a polymerizable functional group or a functional group that can be used as a precursor of a polymerizable functional group can be used as a raw material for synthesizing a perylene diimide derivative.

[0261] Examples of electron transporting compounds having polymerizable functional groups include the following.

[0262]

[0263]

[0264]

[0265]

[0266]

[0267]

[0268]

[0269]

[0270]

[0271] [Third Photoelectric Conversion Element]

[0272] In the third photoelectric conversion element, the second layer 214 contains at least one of the structure represented by the formula (U1) and the structure represented by the formula (U2). The second layer 214 is a layer (cured layer) containing at least one of the structure represented by the formula (U1) and the structure represented by the formula (U2). In other words, the second layer 214 includes a cured film (polymer) having at least one of the structure represented by the formula (U1) and the structure represented by the formula (U2).

[0273]

[0274] In the formulas (U1) and (U2), R 1 and R 3 each independently represents an alkylene group having 1 to 10 carbon atoms in the main chain which may be substituted or unsubstituted, or a phenylene group which may be substituted or unsubstituted.

[0275] R 2 represents a single bond, an alkylene group having 1 to 10 carbon atoms in the main chain which may be substituted or unsubstituted, or a phenylene group which may be substituted or unsubstituted. The substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group or a halogen atom. The substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group, or a halogen-substituted alkyl group.

[0276] R 9 represents a hydrogen atom or an alkyl group.

[0277] A 1 represents any one of the groups represented by the formulas (A-1) to (A-6).

[0278] B 1 represents any one of the groups represented by the formulas (B-1) to (B-3).

[0279] D1 A group represented by formula (D) and having 5 to 15 atoms in the main chain. From the viewpoint of improving the photoelectric conversion efficiency, the number of atoms in the main chain represented by formula (D) is more preferably 10 to 15. D 1 The number of atoms in the main chain of refers to the number of atoms in the shortest chain between the left and right ends of formula (D). For example, the main chain of p-phenylene has 4 atoms. The main chain of m-phenylene has 3 atoms. The main chain of o-phenylene has 2 atoms.

[0280] E 1 Represents a divalent group represented by any one of formulas (E-1) to (E-3).

[0281] In formulas (U1) and (U2), E 1 On the right side represents a hydrogen atom, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group, or a bonding site. One of the carbon atoms in the main chain of the substituted or unsubstituted alkyl group may be replaced by O, S, NH, or NR 16 (R 16 is an alkyl group). The substituent of the substituted aryl group may be an alkyl group, a halogen atom, a nitro group, or a cyano group. The substituent of the substituted alkyl group may be an alkyl group, an aryl group, a halogen atom, a nitro group, or a cyano group. In the case of a bonding site, a substituted or unsubstituted arylene group, or a substituted or unsubstituted alkylene group binds to D 1 other than E 1 in the structure represented by (U1) and (U2).

[0282]

[0283] In formula (A-5), R 10 represents a hydrogen atom or an alkyl group.

[0284]

[0285] In formulas (B-1) to (B-3), R 6 and R 7 each independently represent an alkylene group having 1 to 5 atoms in the main chain, an alkylene group having 1 to 5 atoms in the main chain and substituted by an alkyl group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 atoms in the main chain substituted by benzyl, an alkylene group having 1 to 5 atoms in the main chain substituted by an alkoxycarbonyl group, or an alkylene group having 1 to 5 atoms in the main chain substituted by a phenyl group. One of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH, or NR 15 (R 15 is an alkyl group).

[0286] R 2represents a single bond, a C1-C10 alkylene group with a substituted or unsubstituted main chain, or a substituted or unsubstituted phenylene group. The substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group, or a halogen atom. The substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group, or a halogen-substituted alkyl group.

[0287] R 12 represents a hydrogen atom or an alkyl group.

[0288] Ar 2 represents a substituted or unsubstituted phenylene group. The substituent of the substituted phenylene group is a halogen atom, a nitro group, a hydroxyl group, a cyano group, an alkyl group, or a haloalkyl group.

[0289] A 1 and A 2 represents any one of the groups represented by formulae (A-1) to (A-5).

[0290] E 1 represents a divalent group represented by any one of formulae (E-1) to (E-3).

[0291] o, p, and q are each independently 0 or 1, and the sum of o, p, and q is 1 to 3.

[0292] The arrow points to the side bonded to R 3 .

[0293] In (B-2), on the right side of E 1 represents a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkyl group, heterocyclic group, or bonding site. The substituent of the substituted aryl group can be an alkyl group, a halogen atom, or a nitro group. In the case of the bonding site, a substituted or unsubstituted arylene or alkylene group is bonded to D 1 other than E 1 in the structures represented by (U1) and (U2). In formula (B-3), the right side of CH2 is bonded to the side chain of the resin in the second layer 214.

[0294] In formula (B-2), R 6 、R 7 、Ar 2 、A 2 、o, p, and q can be the same as or different from R 6 、R 7 、Ar 2 、A 2 、o, p, and q in formula (D). E 1 in formula (B-2) can be the same as or different from E 1 in formulae (U1) and (U2). In formula (B-3), R 2 and A 1can be the same as or different from R in formula (U1) and (U2) respectively 2 and A 1 respectively.

[0295]

[0296] In formula (D), R 4 , R 5 , R 6 and R 7 are each independently an alkylene group having 1 to 5 carbon atoms in the main chain, an alkylene group having 1 to 5 carbon atoms in the main chain substituted with an alkyl group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 carbon atoms in the main chain substituted with a benzyl group, an alkylene group having 1 to 5 carbon atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 5 carbon atoms in the main chain substituted with a phenyl group. One of the carbon atoms in the main chain of the alkylene group can be replaced by O, S, NH or NR 15 (R 15 is an alkyl group). More preferably, R 4 , R 5 , R 6 and R 7 are each independently an alkylene group having 1 to 5 carbon atoms in the main chain, or an alkylene group having 1 to 5 carbon atoms in the main chain substituted with a methyl group or an ethyl group.

[0297] Ar 1 and Ar 2 each independently represent a substituted or unsubstituted phenylene group. The substituents of the substituted phenylene group are a halogen atom, a nitro group, a hydroxyl group, a cyano group, an alkyl group or a haloalkyl group. Preferably, Ar 1 and Ar 2 are unsubstituted phenylene groups.

[0298] A 2 represents a group represented by any one of formulas (A-1) to (A-6).

[0299] l, m, n, o, p and q are each independently 0 or 1, and the sum of l, m and n and the sum of o, p and q are 1 to 3.

[0300]

[0301] In formulas (E-1) to (E-3), R 101 to R 106 , R 201 to R 210 , and R 301 to R 304Each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R 101 to R 106 either one or both of, R 201 to R 210 either one or both of, and R 301 to R 304 either one or both of are a single bond. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group or a carbonyl group.

[0302] In the structure represented by formula (U1), R 2 in formula (U1) binds to the structure X surrounded by a dotted line.

[0303] This structure X may be a part corresponding to the resin chain. The same applies to formula (U2).

[0304]

[0305] The present inventors believe that two effects of the second layer 214 containing the structures represented by formulas (U1) and (U2) improve the photoelectric conversion efficiency. One of them may be that the electron transporting compound (E 1 ) and the carbamate bond enhance the electron extraction. The carbamate bond and the electron transporting compound have an electron-withdrawing property. Therefore, the present inventors believe that electrons move rapidly from the perovskite compound, thereby improving the photoelectric conversion efficiency. The other may be to promote the formation of the first layer 213 provided on the second layer 214, thereby improving the crystallinity of the first layer 213. Possibly, the features imparted to the second layer 214 in this embodiment promote interface formation and form a surface having wettability that imparts affinity to the first layer 213 and promotes crystal growth. The present inventors believe that the improved crystallinity of the first layer 213 increases light absorption, enables the generated charges to move effectively, and therefore, improves the photoelectric conversion efficiency.

[0306] Preferably, the second layer 214 contains the structures represented by formulas (U1) and (U2) in an amount of 30% by mass to 100% by mass based on the total mass of the second layer 214.

[0307] The amounts of the structures represented by the formulas (U1) and (U2) in the second layer 214 can be analyzed by common analytical methods. Exemplary analytical methods will be described below. The amount of the structure represented by the formula (U1) in the bottom layer is determined by FT-IR using the KBr-tab method. A calibration curve based on the absorption of the isocyanurate structure is prepared using samples prepared by adding tris(2-hydroxyethyl) isocyanurate to KBr powder in different ratios, and the amount of the structure represented by the formula (U1) in the second layer 214 can be calculated from the calibration curve. The same applies to the formula (U2).

[0308] In addition, the structures represented by the formulas (U1) and (U2) can be measured by methods such as solid-state 13 13C-NMR, mass spectrometry, MS spectroscopy with pyrolysis GC analysis, and characteristic absorption measurement by infrared spectroscopic analysis to identify the second layer 214. For example, solid-state 13 13C-NMR can be performed using a CMX-300 Infinity manufactured by Chemagnetics under the following conditions: observed nucleus: 13 13C, reference substance: polydimethylsiloxane, number of accumulations: 8192, pulse sequence: CP / MAS, DD / MAS, pulse width: 2.1 μs (DD / MAS), 4.2 μs (CP / MAS), contact time: 2.0 ms, and sample rotation rate: 10 kHz. In mass spectrometry analysis, the molecular weight is measured using a mass spectrometer (MALDI-TOF MS, Ultraflex manufactured by Bruker Daltonics) under the following conditions: acceleration voltage: 20 kV, mode: reflector, molecular weight standard: fullerene C60. The structures can be identified using the peak top values obtained therefrom.

[0309] In addition to the structures represented by the formulas (U1) and (U2), the second layer 214 may further contain various resins, crosslinking agents, organic particles, inorganic particles, metal oxide particles, leveling agents, and catalysts for promoting curing, etc., to improve the film-forming property and the photoelectric conversion efficiency. However, with respect to the total mass of the second layer 214, the sum of these constituent components is preferably less than 50% by mass, more preferably less than 20% by mass. The thickness of the second layer 214 is preferably from 10 nm to 1.0 μm.

[0310] Specific examples of the structures represented by the formulas (U1) and (U2) will be given below, but these examples do not limit the present invention. In Tables 6 to 11, each bonding site is represented by a dotted line. A single bond is represented by "SB". The left-right direction of the formulas (U1) and (U2) is the same as that of each structure shown in Tables 6 to 11. In addition, in all the compounds exemplified in Tables 6 to 11, R in the formulas (U1) and (U2) 9 and R 12is a hydrogen atom. R in formula (B-2) 6 , R 7 , Ar 2 , A 2 , o, p, and q are the same as R 1 in D 6 , R 7 , Ar 2 , A 2 , o, p, and q. Specific examples of E 1 in formulas (U1) and (U2) are represented by the corresponding numbers in Tables 1 to 5.

[0311] [Table 6]

[0312]

[0313] [Table 7]

[0314]

[0315] [Table 8]

[0316]

[0317] [Table 9]

[0318]

[0319] [Table 10]

[0320]

[0321] [Table 11]

[0322]

[0323] For example, the second layer 214 can be formed as described below. First, an isocyanate compound (crosslinking agent), a resin having a polymerizable functional group capable of reacting with the isocyanate group of the isocyanate compound, and an electron transporting compound having a polymerizable functional group capable of reacting with the isocyanate group of the isocyanate compound are dissolved in a solvent to prepare a coating solution. A coating film of the coating solution is formed and thermally cured to produce the second layer 214. Thermal curing is preferred because the reaction can proceed more uniformly when the reaction is carried out during drying.

[0324] [Isocyanate Compound]

[0325] The isocyanate compound is preferably an isocyanate compound in which the isocyanate group is protected by a blocking agent such as an oxime (blocked isocyanate compound). The blocked isocyanate compound is heated together with a resin and an electron transporting compound to initiate an addition reaction to separate the blocking agent and a crosslinking reaction proceeds. Thus, a cured product containing structures represented by formulas (U1) and (U2) is produced.

[0326] Examples of the blocking agent include active methylene compounds such as ethyl acetate and acetylacetone; thiol compounds such as butanethiol and dodecyl mercaptan; amide compounds such as acetanilide and acetamide; lactam compounds such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; imide compounds such as succinimide and maleimide; imidazole compounds such as imidazole and 2-methylimidazole; urea compounds such as urea, thiourea, and ethyleneurea; oxime compounds such as formamide oxime, acetamide oxime, acetone oxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, and cyclohexanone oxime; and amine compounds such as diphenylamine, aniline, carbazole, ethyleneimine, and polyethyleneimine. These blocking agents can be used alone or in combination. Among these blocking agents, oxime compounds such as methyl ethyl ketoxime, lactam compounds such as ε-caprolactam, and imidazole compounds such as 2-methylimidazole are preferred in view of versatility, ease of production, processability, and thermal curing temperature.

[0327] Next, examples of the isocyanate compound will be given below.

[0328]

[0329]

[0330] The isocyanate compound has an isocyanate group (molar amount = I) at a molar ratio (I / H) of preferably 0.5 to 5.0 with respect to the total moles (= H) of the polymerizable functional groups of the resin and the polymerizable functional groups of the electron transporting compound. A molar ratio (I / H) of 0.5 to 5.0 is preferred because the isocyanate group can react effectively with the polymerizable functional groups to increase the crosslink density.

[0331] [Electron Transporting Compound]

[0332] Details of the electron transporting compound having a polymerizable functional group capable of reacting with an isocyanate group have been described in the [Electron Transporting Compound] of the above [Second Photoelectric Conversion Element].

[0333] [Resin]

[0334] The polymerizable functional groups of the resin are preferably hydroxyl groups, carboxyl groups, amide groups or thiol groups. More preferably, hydroxyl groups or amide groups that can effectively react with isocyanate groups. Therefore, polyol resins, polyvinylphenolic resins and polyamide resins having two or more hydroxyl groups or amide groups are preferably used as the resin. Regarding the molecular weight of the resin, the weight average molecular weight (Mw) is preferably in the range of 5,000 to 1,500,000.

[0335] Preferably, the cured product containing the structures represented by the formulas (U1) and (U2) further contains the structure represented by the following formula (2). Therefore, the resin should have the structure shown in the following formula (2). The structure represented by the formula (2) improves the adhesiveness of the second layer 214 to the lower layer and the upper layer and the thickness uniformity of the second layer 214, thereby improving the photoelectric conversion efficiency.

[0336]

[0337] In formula (2), R 8 represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. The substituents of the substituted alkyl group are alkyl groups, aryl groups or halogen atoms.

[0338] [Solvent]

[0339] The solvent for preparing the coating liquid for forming the second layer 214 can be arbitrarily selected from, for example, alcohol-based, aromatic-based solvents, halogenated hydrocarbons, ketones, keto-alcohols, ethers, and esters, etc. More specifically, examples that can be used include organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene and toluene. These solvents can be used alone or in combination.

[0340] [Confirmation of curability]

[0341] For example, check whether the second layer 214 is cured as described below. A coating film of the coating liquid for forming the second layer 214 containing an isocyanate compound, a resin and an electron transport material is formed on an aluminum plate with a Meyer rod, and the coating film is dried by heating at 160 °C for 40 minutes to obtain the second layer 214. The obtained second layer 214 is immersed in a mixed solvent of cyclohexanone / ethyl acetate = 1 / 1 for 2 minutes, and then dried at 160 °C for 5 minutes. Measure the mass of the second layer 214 before and after immersion, and confirm that there is no elution (mass difference: within ±2%).

[0342] [Fourth photoelectric conversion element]

[0343] The second layer 214 of the fourth photoelectric conversion element contains at least one of the structure represented by formula (C1) and the structure represented by formula (C2). The second layer 214 is a layer (cured layer) containing at least one of the structures represented by formula (C1) and formula (C2). In other words, the second layer 214 contains a cured film (polymer) having at least one of the structures represented by formula (C1) and formula (C2).

[0344]

[0345] In formula (C1) and (C2), R 11 to R 16 and R 22 to R 25 each independently represents a hydrogen atom, a methylene group, a monovalent group represented by -CH2OR 2 (R 2 represents a hydrogen atom or an alkyl group having 1 to 10 carbons), a group represented by formula (i), or a group represented by formula (ii). At least one of R 11 to R 16 and at least one of R 22 to R 25 is a group represented by formula (i), and at least one of R 11 to R 16 and at least one of R 22 to R 25 is a group represented by formula (ii).

[0346] R 21 represents an alkyl group, a phenyl group, or an alkyl-substituted phenyl group.

[0347]

[0348] In formula (i), R 61 represents a hydrogen atom or an alkyl group.

[0349] Y 1 represents a single bond, an alkylene group, or a phenylene group.

[0350] F 1 represents a divalent group represented by any one of formulas (F1) to (F4).

[0351] * represents the side bonded to N in formula (C1) or the side bonded to N in formula (C2).

[0352]

[0353] In formula (ii), F 2 represents a divalent group represented by any one of formulas (F1) to (F4).

[0354] α represents an alkylene group having 1 to 6 atoms in the main chain, an alkylene group having 1 to 6 atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms, an alkylene group having 1 to 6 atoms in the main chain substituted with a benzyl group, an alkylene group having 1 to 6 atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 6 atoms in the main chain substituted with a phenyl group. One of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH or NR 1 (R 1 Preferably, α is an alkylene group having 1 to 5 atoms in the main chain, or an alkylene group having 1 to 5 atoms in the main chain and substituted by an alkyl group having 1 to 4 carbon atoms.

[0355] β represents a phenylene group, a phenylene group substituted by an alkyl group having 1 to 6 carbon atoms, a nitro-substituted phenylene group, or a halogen-substituted phenylene group.

[0356] Preferably, β is phenylene.

[0357] γ represents an alkylene group having 1 to 6 atoms in the main chain, or an alkylene group having 1 to 6 atoms in the main chain and substituted with an alkyl group having 1 to 6 carbon atoms.

[0358] Preferably, γ is an alkylene group having 1 to 5 atoms in the main chain, or an alkylene group having 1 to 5 atoms in the main chain and substituted with an alkyl group having 1 to 4 carbon atoms.

[0359] r, s, and t are each 0 or 1.

[0360] E 1 represents a divalent group represented by any one of formulae (E-1) to (E-3).

[0361] * represents the side bonded to N in formula (C1) or the side bonded to N in formula (C2).

[0362] When the main chain of formula (ii) is substituted by E 1 When the number of atoms other than E is less than 12, the distance between the triazine ring and the electron transporting portion is moderate, and their interaction enables smooth electron transport. This is preferred in terms of improving photoelectric conversion efficiency. More preferably, in the main chain of formula (ii), except for E 1 The number of atoms other than 2 to 9.

[0363]

[0364] In formulas (E-1) to (E-3), R 101 to R 106 、R 201 to R 210 , and R 301 to R304 each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R 101 to R 106 one or both of, R 201 to R 210 one or both of and R 301 to R 304 one or both of is a single bond. The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or a carbonyl group. The substituent of the substituted aryl group or the substituted heterocyclic group is a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.

[0365] The structure represented by formula (C1) includes a moiety derived from a melamine compound, and the structure represented by formula (C2) includes a moiety derived from a guanamine compound. The moiety derived from a melamine compound or the moiety derived from a guanamine compound is bonded to a group represented by formula (i) or a group represented by formula (ii). The group represented by formula (i) is a moiety derived from a resin. The group represented by formula (ii) has an electron transporting moiety represented by any one of (E-1) to (E-3).

[0366] The present inventors believe that two effects of the second layer 214 including the structures represented by formulas (C1) and (C2) improve the photoelectric conversion efficiency. One of them may be that the binding of the electron transporting compound (E 1 ) to the structures represented by formulas (C1) and (C2) enhances electron extraction. Each of the melamine compound and the guanamine compound has a triazine ring structure. The triazine ring is inherently electron-deficient. The present inventors believe that the coexistence of the electron transporting compound and such a triazine ring enables electrons to move rapidly from the perovskite compound, thereby improving the photoelectric conversion efficiency. Another may be to promote the formation of the first layer 213 provided on the second layer 214, thereby improving the crystallinity of the first layer 213. Possibly, the features of the present embodiment imparted to the second layer 214 promote interface formation and form a surface having wettability imparting affinity to the first layer 213, and promote crystal growth. The present inventors believe that the improved crystallinity of the first layer 213 increases light absorption, enabling the generated charges to move effectively, and thus improving the photoelectric conversion efficiency.

[0367] The structure represented by formula (C1) and the structure represented by formula (C2) are each bonded to at least one of the group represented by formula (i) and at least one of the group represented by formula (ii). When other groups that are not bonded to the group represented by formula (i) or the group represented by formula (ii) are methylene groups, the structure may be bonded to the melamine structure or the guanamine structure via a methylene group.

[0368]

[0369] Preferably, the second layer 214 contains the structures represented by formula (C1) and formula (C2) in a proportion of 30% by mass to 100% by mass based on the total mass of the second layer 214.

[0370] The amount of the structure represented by formula (C1) or (C2) in the second layer 214 can be analyzed by conventional analysis methods. Exemplary analysis methods will be described below. The amount of the structure represented by formula (C1) or (C2) is determined by FT-IR using the KBr-tab method. A calibration curve based on the absorption of the triazine ring is prepared using samples prepared by adding melamine or guanamine to KBr powder in different proportions, and the amount of the structure represented by formula (C1) or (C2) in the second layer 214 can be calculated from the calibration curve.

[0371] In addition, the structure represented by formula (C1) or (C2) can be measured by methods such as solid-state 13 C-NMR, mass spectrometry, MS spectrometry with pyrolysis GC analysis, and characteristic absorption measurement by infrared spectroscopic analysis to identify the second layer 214. For example, solid-state 13 C-NMR can be performed using a CMX-300Infinity manufactured by Chemagnetics under the following conditions: observed nucleus: 13 C, reference substance: polydimethylsiloxane, number of accumulations: 8192, pulse sequence: CP / MAS, DD / MAS, pulse width: 2.1 μs (DD / MAS), 4.2 μs (CP / MAS), contact time: 2.0 ms, and sample rotation rate: 10 kHz. In mass spectrometry analysis, the molecular weight is measured using a mass spectrometer (MALDI-TOF MS, Ultraflex manufactured by Bruker Daltonics) under the following conditions: acceleration voltage: 20 kV, mode: reflector, molecular weight standard: fullerene C60. The structure can be identified using the top value of the peak obtained thereby.

[0372] In addition to the structures represented by formula (U1) or (U2), the second layer 214 may further contain various resins, crosslinking agents, organic particles, inorganic particles, metal oxide particles, leveling agents, and catalysts for promoting curing, etc., to improve the film-forming property and the photoelectric conversion efficiency. However, based on the total mass of the second layer 214, the sum of these constituent components is preferably less than 50% by mass, more preferably less than 20% by mass. The thickness of the second layer 214 is preferably 10 nm to 1.0 μm.

[0373] Specific examples of the structure represented by formula (C1) or (C2) will be given below, but these examples do not limit the present invention. In each specific example, the number of atoms in the main chain of formula (ii) other than the electron transporting moiety E 1 is given. In Tables 12 to 19, each bonding site is represented by a dotted line. A single bond is represented as "SB". The left - right direction of the groups represented by formula (i) and formula (ii) is the same as that of each structure shown in Tables 12 to 19.

[0374] Specific examples of E in formula (ii) 1 are represented by the corresponding numbers in Tables 1 to 5.

[0375] [Table 12]

[0376]

[0377] [Table 13]

[0378]

[0379] [Table 14]

[0380]

[0381] [Table 15]

[0382]

[0383] [Table 16]

[0384]

[0385] [Table 17]

[0386]

[0387] [Table 18]

[0388]

[0389] [Table 19]

[0390]

[0391] For example, the second layer 214 can be formed as follows. First, a coating solution containing a melamine compound or a guanamine compound, a resin having a polymerizable functional group capable of reacting with the melamine or guanamine compound, and an electron transporting compound having a polymerizable functional group capable of reacting with the melamine or guanamine compound is coated to form a coating film. Then, the obtained coating film is thermally cured to produce the second layer 214.

[0392] [Melamine compound, Guanamine compound]

[0393] The melamine compound and the guanamine compound will now be described. The melamine compound or the guanamine compound is synthesized by a known method using, for example, melamine or guanamine and formaldehyde.

[0394] Specific examples of the melamine compound and the guanamine compound will be given below. Although the following specific examples are monomers, oligomers of the monomers may be included. From the viewpoint of improving the conversion efficiency, preferably, the monomer is included in a proportion of 10% by mass relative to the total mass of the monomer and the oligomer. Preferably, the degree of polymerization of the oligomer can be from 2 to 100. Two or more oligomers and monomers can be included together. Commercially available amine compounds include, for example, Super Melami No.90 (produced by NOF Corporation); Super Beckamine(R) series TD-139-60, L-105-60, L127-60, L110-60, J-820-60, and G-821-60 (all produced by DIC Corporation); U-VAN 2020 (produced by Mitsui Chemicals, Inc.); Sumitex Resin M-3 (produced by Sumitomo Chemical Company, Limited); NIKALAC series MW-30, MW-390, and MX-750LM (produced by Nippon Carbide Industries Co., Inc.). Commercially available guanamine compounds include, for example, Super Beckamine(R) series L-148-55, 13-535, L-145-60, and TD-126 (produced by DIC Corporation); and NIKALAC series BL-60 and BX-4000 (produced by Nippon Carbide Industries Co., Inc.).

[0395] Specific examples of the melamine compound will be given below.

[0396]

[0397]

[0398] Specific examples of the guanamine compound will be given below.

[0399]

[0400]

[0401]

[0402] The molar ratio (I:H) of the functional groups (molar number = I) of the melamine or guanamine compound to the total moles (= H) of the polymerizable functional groups of the resin and the electron transporting compound (a compound having a structure represented by any one of formulas (E-1) to (E-3)) is preferably from 1:0.5 to 1:3.0.

[0403] The molar ratio within this range is preferred because the proportion of the functional groups to be reacted is high.

[0404] [Electron transporting compound]

[0405] Details of the electron transporting compound having a polymerizable functional group capable of reacting with the melamine compound or guanamine compound are described in the [Electron transporting compound] of the above [Second Photoelectric Conversion Element]. The electron transporting compound is derived from the structure represented by E in formula (ii). 1 represented.

[0406] [Resin]

[0407] Now, a resin having a polymerizable functional group capable of reacting with the melamine compound or guanamine compound will be described. The resin has a group represented by formula (i). The resin can be obtained by polymerizing, for example, monomers having polymerizable functional groups (hydroxyl group, thiol group, amino group, carboxyl group, and methoxy group) that are commercially available from Sigma-Aldrich Japan or Tokyo Chemical Industry Co., Ltd.

[0408] The resin can also be purchased and used as it is. Examples of commercially available resins include polyether polyol resins such as AQD-457 and AQD-473 produced by Nippon Polyurethane Industry Co., Ltd., and SANNIX GP-400 and GP-700 produced by Sanyo Chemical Industries, Ltd.; polyester polyol resins such as Phthalkyd W2343 produced by Hitachi Chemical Company, Ltd., WATERSOL S-118, CD-520, BECKOLITE M-6402-50 and M-6201-40IM produced by DIC Corporation, HARIDIP WH-1188 produced by Harima Chemicals Group, Inc., and ES3604 and ES6538 produced by Japan U-pica co., ltd.; polyacrylic polyol resins such as BURNOCK WE-300 and WE-304 produced by DIC Corporation; polyvinyl alcohol resins such as KURARAY POVAL PVA-203 produced by Kuraray Co., Ltd.; polyvinyl acetal resins such as BX-1, BM-1, KS-1 and KS-5 produced by Sekisui Chemical Co., Ltd.; polyamide resins such as Toresin FS-350 produced by Nagase Chemtex Corporation; carboxyl group-containing resins such as AQUALIC produced by Nippon Shokubai Co., Ltd. and FINELEX SG2000 produced by Namariichi Co., Ltd.; polyamine resins such as LUCKAMIDE produced by DIC Corporation; and polythiol resins such as QE-340M produced by Toray Industries, Inc. Among them, from the viewpoints of polymerizability and the uniformity of the second layer 214, polyvinyl acetal resins and polyester polyol resins are preferred.

[0409] Preferably, the resin has a weight average molecular weight (Mw) of 5,000 to 300,000. The molecular weight of the resin can be determined, for example, by measuring with a gel permeation chromatograph "HLC-8120" manufactured by Tosoh Corporation and calculating in terms of polystyrene conversion.

[0410] The methods for determining functional groups in the resin include, for example, titrating carboxyl groups with potassium hydroxide, amino groups with sodium nitrite, hydroxyl groups with acetic anhydride and potassium hydroxide, mercapto groups with 5,5'-dithiobis(2-nitrobenzoic acid), and the method using a calibration curve obtained from the IR spectra of samples with functional groups introduced in different ratios.

[0411] Next, specific samples of the resin will be given below.

[0412] [Table 20]

[0413]

[0414] [Solvent]

[0415] The solvent for preparing the coating liquid for forming the second layer 214 can be arbitrarily selected from, for example, alcohol-based, aromatic solvents, halogenated hydrocarbons, ketones, keto-alcohols, ethers, and esters, etc. More specifically, for example, examples that can be used include organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene. These solvents can be used alone or in combination.

[0416] [Confirmation of curability]

[0417] For example, check whether the second layer 214 is cured as follows. Form a coating film of the coating liquid for forming the second layer 214 containing a melamine compound or a guanamine compound, a resin, and an electron transporting material on an aluminum plate with a Meyer rod, and dry the coating film by heating at 160 °C for 40 minutes to obtain the second layer 214. Immerse the obtained second layer 214 in a mixed solvent of cyclohexanone / ethyl acetate = 1 / 1 for 2 minutes, and then dry at 160 °C for 5 minutes. Measure the mass of the second layer 214 before and after immersion, and confirm that there is no dissolution (mass difference: within ±2%).

[0418] [[Photoelectric conversion device]]

[0419] The photoelectric conversion device includes a photoelectric conversion element according to an embodiment of the present invention.

[0420] Among them, a device connecting multiple elements can also be called a photoelectric conversion module. These elements can be arranged one above the other to increase the output voltage. In addition, the photoelectric conversion device includes a photoelectric conversion element according to an embodiment of the present invention and an inverter. The inverter can be a converter that converts direct current into alternating current. The photoelectric conversion device can include a power storage unit connected to the photoelectric conversion element. The power storage unit stores electricity and has no other limitations. Examples of the power storage unit include secondary batteries using lithium ions, etc., all-solid-state batteries, and electric double-layer capacitors.

[0421] Figure 5 Figure 5 shows an example of a mobile body according to the present embodiment. The mobile body 30 includes a photoelectric conversion element 31 according to an embodiment of the present invention, and a main body frame 32 provided with the photoelectric conversion element. The photoelectric conversion element 31 is located at a position in the main body frame 32 where external light can be received. In the mobile body 30 which is an automobile, the photoelectric conversion element may be located on the roof. The electric energy obtained by the photoelectric conversion element 31 can supply power to the mobile body 30 or other electrical devices. The electric energy generated by the power of the mobile body 30 can be used to supply power to the photoelectric conversion element 31. In the mobile body 30 which is an automobile, the frictional energy generated by braking can be converted into electric energy and used to control the photoelectric conversion element 31.

[0422] The mobile body 30 can be, for example, an automobile, a ship, an airplane, or a drone.

[0423] There is no particular limitation on the main body frame 32 of the mobile body 30, but it is preferably made of a high-strength material.

[0424] Figure 6 Figure 6 shows an example of a building material according to the present embodiment. The building material can be the roof of a building. The building material 40 includes a photoelectric conversion element 41 according to an embodiment of the present invention, a protective member 42 for protecting the photoelectric conversion element, a heat dissipation member 43, and an exterior finish 44.

[0425] Therefore, the building material according to the present embodiment includes the photoelectric conversion element 41 and the protective member 42 or the heat dissipation member 43 according to the present invention.

[0426] The building material 40 according to the present embodiment may include a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When the building material is used for a roof or the like, sunlight can increase the temperature of the photoelectric conversion element 41, thereby reducing the photoelectric conversion efficiency. Using the heat dissipation member 43 can reduce the reduction of the photoelectric conversion efficiency. The heat dissipation member 43 can be a metal, an alloy, a liquid metal, or a liquid resin, etc.

[0427] The building material 40 according to the present embodiment has an exterior finish 44. The exterior finishes 44a and 44b can emit different colors or the same color. The exterior finishes 44a and 44b can be composed of the same member or different members. The exterior finish 44 can use paint and a transparent substrate. Preferably, it has low light absorption and high heat shielding performance.

[0428] The designability of the building material 40 according to the present embodiment is excellent because it includes a photoelectric conversion layer containing perovskite. In addition, the building material has a high photoelectric conversion efficiency because it includes a reflective layer. Therefore, the photoelectric conversion efficiency of the building material is excellent and the color is bright.

[0429] Examples

[0430] The present invention will be described in further detail with reference to the examples and comparative examples. The present invention is not limited by the following examples unless departing from the gist of the present invention. In the following examples, "parts" are based on mass unless otherwise specified.

[0431] <<First Embodiment>>

[0432] <Example of Selection and Production of Particles>

[0433] (Particles 1 to 8: Titanium Oxide Particles)

[0434] Titanium oxide (produced by Tayca Corporation) with a volume average particle size of 50 nm to 600 nm was used.

[0435] (Particle 9: Zinc Oxide Particle)

[0436] Zinc oxide with a volume average particle size of 200 nm (produced by Hakusui Tech Co., Ltd.) was used.

[0437] (Particle 10: Tin Oxide-Coated Titanium Oxide Particle)

[0438] Titanium oxide particles with a volume average particle size of 200 nm were used as core particles.

[0439] 200 g of the core particles were dispersed in water to prepare a 2 L aqueous suspension, and then heated to 70 °C. A stannic acid solution A prepared by dissolving 226.2 g of tin chloride (SnCl4·5H2O) in 500 mL of a 3 mol / L hydrochloric acid solution, and a basic solution B prepared by dissolving 5.2 g of sodium tungstate (Na2WO4·2H2O) in 500 mL of a 5 mol / L sodium hydroxide solution were simultaneously added dropwise (parallel addition) to the suspension over 6 hours to adjust the pH of the suspension to 2 to 3. After the addition was completed, the suspension was filtered, and the product was rinsed and dried at 110 °C for 8 hours. The dried product was heat-treated in a nitrogen stream (1 L / min) at 650 °C for 1 hour to produce Particle 10.

[0440] (Particle 11: Nb-Doped Titanium Oxide-Coated Titanium Oxide Particle)

[0441] Titanium oxide particles with a volume average particle size of 200 nm were used as core particles.

[0442] Prepare a titanium-niobium sulfuric acid solution containing 33.7 g of titanium (calculated as TiO2) and 2.9 g of niobium (calculated as Nb2O5). Disperse 100 g of core particles in pure water to prepare a 1 L suspension, and then heat it to 60 °C. Dropwise add the titanium-niobium sulfuric acid solution and 10 mol / L sodium hydroxide over 3 hours to adjust the pH of the suspension to 2 to 3. After adding the entire volume, adjust the pH to near neutral, and add a flocculant to cause the solids to settle. Remove the supernatant and filter the residue. Wash the residue and dry it at 110 °C to obtain an intermediate containing 0.1 wt% of the organic matter derived from the flocculant based on C. Bake the intermediate in nitrogen at 800 °C for 1 hour to produce Particle 11.

[0443] [Table 21]

[0444] Particle No. Material Particle Size Coating Material Coating Thickness Aspect Ratio Refractive Index Particle 1 Titanium Oxide 50 None None 1.0 2.4 Particle 2 Titanium Oxide 70 None None 1.2 2.5 Particle 3 Titanium Oxide 120 None None 1.3 2.5 Particle 4 Titanium Oxide 150 None None 2.2 2.7 Particle 5 Titanium Oxide 180 None None 1.3 2.7 Particle 6 Titanium Oxide 200 None None 2.4 2.7 Particle 7 Titanium Oxide 300 None None 1.9 2.8 Particle 8 Titanium Oxide 600 s None 2.3 2.7 None Particle 9 200 Zinc Oxide None 1.5 2.4 None Particle 10 200 Titanium Oxide 20 2.6 2.8 Tin Oxide Particle 11 200 Titanium Oxide 30 2.4 2.7

[0445] <Preparation Example of Coating Liquid for Reflective Layer>

[0446] In the case where no binder is added to the reflective layer, a solution is obtained by dissolving in 1500 parts of 1-methoxy-2-propanol as a solvent. To this solution, add 30 parts of the above-mentioned particles, and in a vertical sand mill using 1500 parts of glass beads with an average diameter of 1.0 mm as a dispersion medium, disperse the particles in the solution at a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s) at a dispersion liquid temperature of 23 °C ± 3 °C for 4 hours. Remove the glass beads from the obtained dispersion liquid with a sieve to obtain a coating for the reflective layer.

[0447] In the case where the reflective layer contains a binder, a solution is obtained by dissolving a phenolic resin or a polyamide resin as a binder in 1500 parts of 1-methoxy-2-propanol as a solvent. In the obtained solution, add the above-prepared particles to the selected resin in any weight ratio, and in a vertical sand mill using 1500 parts of glass beads with an average diameter of 1.0 mm as a dispersion medium, disperse the particles in the solution at a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s) at a dispersion liquid temperature of 23 °C ± 3 °C for 4 hours. Remove the glass beads from the obtained dispersion liquid with a sieve to obtain a coating for the reflective layer.

[0448] <Preparation Example of Coating Liquid for Photoelectric Conversion Layer>

[0449] (Coating 1: MAPbI3 Coating)

[0450] Dissolve 4 parts of lead iodide and 1.4 parts of methylammonium iodide in 4.5 parts of dimethylformamide as a solvent by stirring at 60 °C for 24 hours.

[0451] (Coating 2: MAPbBr3 Coating)

[0452] Dissolve 3.4 parts of lead bromide and 1 part of methylammonium bromide in 4.5 parts of dimethylformamide as a solvent by stirring at 60 °C for 24 hours.

[0453] (Coatings 3 to 5: MAPbI (1-x) Br x Coatings)

[0454] Prepare each coating by mixing Coating 1 and Coating 2 at the weight ratios shown in Table 22.

[0455] [Table 22]

[0456]

[0457] <Example 1-1>

[0458] On an ITO glass substrate, dissolve Spiro-OMeTAD (180 mg), which is a hole transport material, in chlorobenzene (1 mL) in an N2 atmosphere. Add tert-butylpyridine (TBP, 17.5 μL) and an acetonitrile solution (37.5 μL) prepared by dissolving lithium bis(trifluoromethanesulfonyl)imide (170 mg) in acetonitrile (1 mL) to the chlorobenzene solution to prepare a hole transport material solution. Coating the resulting solution onto the perovskite layer by spin coating. After coating, bake the coated film at 100 °C for 10 minutes to form a 300-nm-thick hole transport layer.

[0459] Next, form a film of Coating 4 for the photoactive conversion layer on the hole transport layer by spin coating, and bake the coated film at 100 °C for 10 minutes to form a 300-nm-thick photoactive conversion layer.

[0460] Subsequently, form a film of a coating prepared by dispersing Particles 6 and phenolic resin in a weight ratio of 80 / 1 on the photoactive conversion layer by spin coating. Bake the coated film at 130 °C for 30 minutes to form a 300-nm-thick reflective layer.

[0461] Then, form a gold electrode with a thickness of 80 nm and an area of 0.09 cm 2 on the reflective layer by vacuum deposition, thereby obtaining a photoactive conversion element.

[0462] <Example 1-2>

[0463] Overlap and form each layer up to the photoactive conversion layer in the same manner as in Example 1-1, and form a film of a coating in which Particles 6 are dispersed by spin coating. Bake the coated film at 130 °C for 30 minutes to form a 300-nm-thick reflective layer. Then, form an 80-nm-thick gold electrode on the reflective layer by vacuum deposition, thereby completing the photoactive conversion element.

[0464] <Example 1-3 to 1-19>

[0465] Layers up to the charge transport layer were formed by overlapping in the same manner as in Example 1-1, and a film of the coating material for the photoelectric conversion layer shown in Table 23 was formed by spin coating. The coated film was fired at 100 °C for 10 minutes to form an active layer with a thickness of 300 nm. Subsequently, a coated film of the coating material in which the particles shown in Table 23 were dispersed was formed by spin coating. The coated film was fired at 130 °C for 30 minutes to form a reflective layer with a thickness of 300 nm. Then, a gold electrode with a thickness of 80 nm and an area of 0.09 cm 2 was formed on the reflective layer by vacuum deposition to complete the photoelectric conversion element.

[0466] <Example 1-20>

[0467] A photoelectric conversion element was produced in the same manner as in Example 1-1, except that the weight ratio of Particle 6 to phenolic resin was 100 / 1.

[0468] <Example 1-21>

[0469] A photoelectric conversion element was produced in the same manner as in Example 1-1, except that the weight ratio of Particle 6 to phenolic resin was 2 / 1.

[0470] <Example 1-22>

[0471] A photoelectric conversion element was produced in the same manner as in Example 1-20, except that polyamide was used as the binder resin.

[0472] <Example 1-23>

[0473] A photoelectric conversion element was produced in the same manner as in Example 1-21, except that polyamide was used as the binder resin.

[0474] <Comparative Example 1-1>

[0475] A photoelectric conversion element was produced in the same manner as in Example 1-1, except that titanium oxide with a volume average particle diameter of 30 nm was used instead of Particle 6.

[0476] <Comparative Example 1-2>

[0477] A photoelectric conversion element was produced in the same manner as in Example 1-2, except that titanium oxide with a volume average particle diameter of 30 nm was used instead of Particle 6.

[0478] <Comparative Example 1-3>

[0479] A photoelectric conversion element was produced in the same manner as in Example 1-14, except that titanium oxide with a volume average particle diameter of 30 nm was used instead of Particle 6.

[0480] <Evaluation>

[0481] The photovoltaic conversion elements produced in the examples and comparative examples were evaluated as follows.

[0482] (The wavelength α at which the reflectance of the reflective layer in the visible light region is maximum)

[0483] Nb-Doped Titanium Oxide and Figure 7A shows the spectrum of the element of Example 1-1. Figure 7B is the reflection spectrum of the reflective layer, Figure 7A is the absorption spectrum of the photovoltaic conversion layer. Figure 7B shows that the wavelength α at which the reflectance of the reflective layer in the visible light region (360 nm to 830 nm) is maximum is 656 nm. In addition, Figure 7A Figure 7B shows that the light absorption coefficient of the photovoltaic conversion layer in the visible light region reaches a maximum value of 1.92 (A.U.) at 360 nm. The light absorption coefficient at the wavelength α (656 nm) is 0.64 (A.U.). Therefore, in the element of Example 1-1, the wavelength α is within the range where the light absorption coefficient of the photovoltaic conversion layer is more than 1 / 5 of the maximum value in the visible light region.

[0484] In addition, in the elements of other examples, the wavelength α is within the range where the light absorption coefficient of the photovoltaic conversion layer is more than 1 / 5 of the maximum value in the visible light region.

[0485] In contrast, in the elements of the comparative examples, the wavelength α is outside the range where the light absorption coefficient of the photovoltaic conversion layer is more than 1 / 5 of the maximum value in the visible light region.

[0486] (Evaluation of power generation efficiency)

[0487] A power supply (Model 236, manufactured by KEITHLEY Instruments) was connected between the electrodes of the photovoltaic conversion element. Using a sunlight simulator (manufactured by Yamashita Denso Corporation), the element was continuously irradiated with light from the glass substrate side at an intensity of 100 mW / cm 2 to measure the generated current and voltage to evaluate the photovoltaic conversion efficiency.

[0488] [Table 23]

[0489]

[0490] As described above, the photovoltaic conversion element according to the present invention shows a higher photovoltaic conversion efficiency compared with the comparative examples. In addition, as measured, the elements of the examples not only have excellent photovoltaic conversion efficiency but also have bright colors.

[0491] <<Second Embodiment>>

[0492] [Preparation of Conductive Particles]

[0493] (Conductive Particle 1)

[0494] Titanium oxide particles with an average major axis diameter a and an average minor axis diameter b both of 50 nm are used as core particles. A titanium-niobium sulfuric acid solution containing 33.7 g of titanium (calculated as TiO2) and 2.9 g of niobium (calculated as Nb2O5) is prepared. 100 g of core particles are dispersed in pure water to prepare a 1 L suspension, and then heated to 60 °C. The titanium-niobium sulfuric acid solution and 10 mol / L sodium hydroxide are added dropwise over 3 hours such that the pH of the suspension is 2 to 3. After adding the entire volume, the pH is adjusted to near neutral, and a flocculant is added to cause the solids to settle. The supernatant is removed, and the residue is filtered. The residue is washed and dried at 110 °C to obtain an intermediate containing 0.1 mass% of organic matter derived from the flocculant based on C. The intermediate is fired in nitrogen at 800 °C for 1 hour to produce Conductive Particle 1.

[0495] (Conductive Particles 2 to 6)

[0496] Except for changing the average major axis diameter a and the average minor axis diameter b of the core particles, Conductive Particles 2 to 6 shown in Table 24 are prepared in the same manner as the preparation process of Conductive Particle 1.

[0497] (Conductive Particle 7)

[0498] Except for changing the coating conditions such that the average major axis diameter a and the average minor axis diameter b are both 250 nm, Conductive Particle 7 is prepared in the same manner as the preparation process of Conductive Particle 2.

[0499] (Conductive Particle 8)

[0500] Titanium oxide particles with an average major axis diameter a and an average minor axis diameter b both of 200 nm are used as core particles. 200 g of core particles are dispersed in water to prepare a 2 L aqueous suspension, and then heated to 70 °C. A stannic acid solution prepared by dissolving 226.2 g of tin chloride (SnCl4·5H2O) in 500 mL of 3 mol / L hydrochloric acid solution and 5 mol / L sodium hydroxide solution are added dropwise simultaneously (added in parallel) to the suspension over 6 hours such that the pH of the suspension is 2 to 3. After the addition is complete, the suspension is filtered, and the product is rinsed and dried at 110 °C for 8 hours. The dried product is heat-treated in a nitrogen stream (1 L / min) at 650 °C for 1 hour to produce Conductive Particle 8.

[0501] (Conductive Particle 9)

[0502] The conductive particles 9 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8, except that orthophosphoric acid was added to the stannic acid solution so that the amount of the dopant (calculated as P2O5) was 5.0% by mass.

[0503] (Conductive particles 10)

[0504] The conductive particles 10 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8, except that tantalum(V) chloride was added to the stannic acid solution so that the amount of the dopant was 5.0% by mass (calculated as Ta2O5).

[0505] (Conductive particles 11)

[0506] The conductive particles 11 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8, except that niobium(V) chloride was added to the stannic acid solution so that the amount of the dopant (calculated as Nb2O5) was 5.0% by mass.

[0507] (Conductive particles 12)

[0508] The conductive particles 12 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8, except that sodium tungstate dihydrate was added to the stannic acid solution so that the amount of the dopant (calculated as WO3) was 5.0% by mass.

[0509] (Conductive particles 13)

[0510] The conductive particles 13 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8, except that sodium fluoride was added to the stannic acid solution so that the amount of the dopant (calculated as F) was 1.0% by mass.

[0511] (Conductive particles 14)

[0512] Titanium oxide particles with both an average major axis diameter a and an average minor axis diameter b of 200 nm were used as core particles. 250 g of the core particles were dispersed in water to prepare a 2 L aqueous suspension, which was then heated to 50 °C. An aqueous zinc chloride solution prepared by dissolving 161.5 g of zinc chloride (ZnCl2) in 3 L of water and a 5 mol / L sodium hydroxide solution were simultaneously added dropwise (parallel addition) to the suspension over 2 hours so that the pH of the suspension was 10. After the addition was completed, the suspension was filtered, and the product was rinsed and dried at 110 °C for 12 hours. The dried product was heat-treated in a nitrogen stream (1 L / min) at 550 °C for 1 hour to produce the conductive particles 14.

[0513] (Conductive particles 15)

[0514] The conductive particles 15 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 14, except that aluminum(III) chloride was added to the stannic acid solution so that the amount of the dopant (calculated as Al2O3) was 3.0% by mass.

[0515] (Conductive particles 16)

[0516] The conductive particles 16 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 14, except that gallium(III) chloride was added to the stannic acid solution so that the amount of the dopant (calculated as Ga2O3) was 3.0% by mass.

[0517] (Conductive particles 17)

[0518] The conductive particles 17 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 8, except that barium sulfate particles with both an average major axis diameter a and an average minor axis diameter b of 300 nm were used as the core particles.

[0519] (Conductive particles 18)

[0520] The conductive particles 18 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 17, except that orthophosphoric acid was added to the stannic acid solution so that the amount of the dopant (calculated as P2O5) was 5.0% by mass.

[0521] (Conductive particles 19)

[0522] The conductive particles 19 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 1, except that strontium titanate particles with both an average major axis diameter a and an average minor axis diameter b of 100 nm were used as the core particles.

[0523] (Conductive particles 20)

[0524] The conductive particles 20 shown in Table 24 were prepared in the same manner as in the preparation process of the conductive particles 1, except that barium titanate particles with both an average major axis diameter a and an average minor axis diameter b of 150 nm were used as the core particles.

[0525] (Conductive particles 21)

[0526] Strontium titanate particles with both an average major axis diameter a and an average minor axis diameter b of 100 nm were used as the core particles. While the muller was running, 140 mg of methylhydrogenpolysiloxane was added to 7 g of the core particles. The materials were mixed and stirred at a linear load of 588 N / cm (60 kg / cm) for 30 minutes. The stirring speed at this time was 22 rpm. While the muller was running, 7 g of carbon black particles (volume average particle diameter: 20 nm, volume resistivity: 1.0×10 2Ω·cm, pH 8.0). The material was further mixed and stirred for 60 minutes under a line load of 588 N / cm (60 kg / cm). As a result, carbon black adhered to the surface of the strontium titanate particles coated with methylhydrogenpolysiloxane. Then, the obtained particles were dried in a dryer at 80 °C for 60 minutes, thereby preparing the conductive particles 21 shown in Table 24.

[0527] (Conductive particles 22 and 23)

[0528] Strontium titanate particles with both an average major axis diameter a and an average minor axis diameter b of 100 nm were used as core particles. A 10-nm-thick copper coating film was formed on the surface of the strontium titanate particles by electroless plating, thereby preparing the conductive particles 22 shown in Table 24. Similarly, a 10-nm-thick silver coating film was formed by electroless plating, thereby obtaining the conductive particles 23 shown in Table 24.

[0529] (Conductive particles 24)

[0530] Except that silica particles with both an average major axis diameter a and an average minor axis diameter b of 150 nm were used as core particles, the conductive particles 24 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8.

[0531] (Conductive particles 25)

[0532] Except that alumina particles with both an average major axis diameter a and an average minor axis diameter b of 250 nm were used as core particles, the conductive particles 25 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 8.

[0533] (Conductive particles 26)

[0534] Except that silica particles with both an average major axis diameter a and an average minor axis diameter b of 150 nm were used as core particles, the conductive particles 26 shown in Table 24 were prepared in the same manner as the preparation process of the conductive particles 21.

[0535] (Conductive particles 27 to 29)

[0536] As the conductive particles for the comparative example, as shown in Table 24, tin oxide particles with both an average major axis diameter a and an average minor axis diameter b of 200 nm, zinc oxide particles with both an average major axis diameter a and an average minor axis diameter b of 150 nm, and carbon black particles with a volume average particle size of 20 nm were prepared.

[0537] [Table 24]

[0538]

[0539] (Example 2-1)

[0540] Dissolve Spiro-OMeTAD (180 mg), which serves as a hole transporting material, in chlorobenzene (1 mL). Add tert-butylpyridine (TBP, 17.5 μL) and an acetonitrile solution (37.5 μL) prepared by dissolving lithium bis(trifluoromethanesulfonyl)imide (170 mg) in acetonitrile (1 mL) to the chlorobenzene solution to prepare a hole transporting material solution. Coating the hole transporting material solution onto an ITO glass substrate by spin coating in an N2 atmosphere and firing at 100 °C for 10 minutes to form a 300-nm-thick hole transporting layer.

[0541] Subsequently, dissolve 4 parts of lead iodide and 1.4 parts of methylammonium iodide in 4.5 parts of dimethylformamide as a solvent, and stir the solution at 60 °C for 24 hours to prepare a coating solution for the active layer. Form a film of this coating solution on the hole transporting layer by spin coating and fire at 100 °C for 10 minutes to form a 300-nm-thick active layer.

[0542] Dissolve 5 parts of a phenolic resin (phenolic resin monomer / oligomer) (trade name "Plyophen J-325", manufactured by DIC Corporation, resin solid content: 60% by mass, cured density: 1.3 g / cm 2 ) as a binder in 1500 parts of 1-methoxy-2-propanol as a solvent. Add 30 parts of conductive particles 1 to the resulting solution, and disperse the particles in the solution at a rotation speed of 1500 rpm (circumferential speed: 5.5 m / s) in a vertical sand mill using 1500 parts of glass beads with an average diameter of 1.0 mm as a dispersion medium at a dispersion liquid temperature of 23 °C ± 3 °C for 4 hours. Remove the glass beads from the resulting dispersion using a sieve to obtain a coating solution for the conductive layer.

[0543] Subsequently, coat the coating solution for the conductive layer onto the active layer by spin coating. After coating, fire the coating film at 150 °C for 10 minutes to form a 500-nm-thick conductive layer.

[0544] Then, form a gold electrode with a thickness of 80 nm and an area of 0.09 cm 2 on the conductive layer by vacuum deposition to complete the photoelectric conversion element.

[0545] Connect a power supply (type 236, manufactured by KEITHLEY Instruments) between the electrodes of the photoelectric conversion element. Continuously irradiate the element with light at an intensity of 100 mW / cm 2 using a sunlight simulator (manufactured by Yamashita Denso Corporation), and measure the generated current and voltage to evaluate the photoelectric conversion efficiency. The results of the short-circuit current density and the photoelectric conversion efficiency are shown in Table 25.

[0546] (Examples 2-2 to 2-26)

[0547] A photovoltaic conversion element was produced in the same manner as in Example 2-1, except that the conductive particles used for preparing the coating liquid for the conductive layer were replaced with the conductive particles 2 to 26 shown in Table 24. And the photovoltaic conversion efficiency was evaluated. The results of the short-circuit current density and the photovoltaic conversion efficiency are shown in Table 25.

[0548] (Example 2-27)

[0549] The coating liquid for the conductive layer was prepared as described below.

[0550] In a mixed solvent of 400 parts of methyl ethyl ketone and 700 parts of 1-butanol, 1 part of butyral resin (trade name: BM-1, produced by Sekisui Chemical Co., Ltd.) as a polyol resin and 1 part of blocked isocyanate resin (trade name: TPA-B80E, 80% solution, produced by Asahi Kasei Corp.) were dissolved to prepare a solution. By adding 20 parts of the conductive particles 2 shown in Table 24 to the obtained solution, and using 1100 parts of glass beads with an average diameter of 1.0 mm as a dispersion medium in a vertical sand mill, the particles were dispersed in the solution at a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s) for 4 hours in an atmosphere of 25°C ± 3°C to prepare the coating liquid for the conductive layer.

[0551] A photovoltaic conversion element was produced in the same manner as in Example 2-1, except that the coating liquid for the conductive layer prepared above was used. And the photovoltaic conversion efficiency was evaluated. The results of the short-circuit current density and the photovoltaic conversion efficiency are shown in Table 25.

[0552] (Example 2-28)

[0553] A photovoltaic conversion element was produced in the same manner as in Example 2-27, except that the conductive particles used for preparing the coating liquid for the conductive layer were replaced with the conductive particles 9 shown in Table 24. And the photovoltaic conversion efficiency was evaluated. The results of the short-circuit current density and the photovoltaic conversion efficiency are shown in Table 25.

[0554] (Example 2-29)

[0555] A photovoltaic conversion element was produced in the same manner as in Example 2-1, except that phenolic resin was not used when preparing the coating liquid for the conductive layer, and the conductive particles 2 shown in Table 24 were used as the conductive particles. And the photovoltaic conversion efficiency was evaluated. The results of the short-circuit current density and the photovoltaic conversion efficiency are shown in Table 25.

[0556] (Comparative Examples 2-1 to 2-3)

[0557] An optoelectronic conversion element was produced in the same manner as in Example 2-1, except that the conductive particles used for preparing the coating liquid for the conductive layer were replaced with any one of the conductive particles 27 to 29 shown in Table 24, and their optoelectronic conversion efficiencies were evaluated. The results of the short-circuit current density and the optoelectronic conversion efficiency are shown in Table 25.

[0558] In the elements of Comparative Examples 2-1 and 2-2, the wavelength α at which the reflectance of the reflective layer in the visible light region is maximum is outside the range where the light absorption coefficient of the optoelectronic conversion layer is 1 / 5 or more of the maximum value in the visible light region.

[0559] [Table 25]

[0560]

[0561] <<Third Embodiment>>

[0562] <Example 3-1>

[0563] In a mixed solvent of 50 parts of methyl ethyl ketone and 50 parts of dimethylacetamide, 3.27 parts of an exemplary compound (E-1-1) as an electron transporting compound, 6.2 parts of an exemplary compound (I-8) as an isocyanate compound, and 1.29 parts of butyral resin (trade name: BM-1, produced by Sekisui Chemical Co., Ltd.) as a resin were dissolved. To the resulting solution, 0.031 parts of dioctyltin dilaurate was added as a catalyst to prepare a coating liquid for the underlayer of the second layer 214. This coating liquid was applied onto an FTO glass substrate which is a substrate 216 provided with a cathode 215 by a spin coating method. After application, the coating film was heated at 160 °C for 30 minutes for polymerization (curing), thereby forming an underlayer with a thickness of 500 nm.

[0564] Then, a 1M solution was prepared by dissolving lead iodide as a metal halide compound in N,N-dimethylformamide (DMF). A coating film of this solution was formed on the underlayer by a spin coating method. Further, a 1M solution was prepared by dissolving methylammonium iodide as an amine compound in 2-propanol. The lead iodide coating film sample was immersed in this solution, and then fired in air at 100 °C for 10 minutes, thereby forming a perovskite layer with a thickness of 500 nm as the first layer 213.

[0565] Then, Spiro-OMeTAD (180 mg) as a hole transporting material was dissolved in chlorobenzene (1 mL). tert-Butylpyridine (TBP, 17.5 μL) and an acetonitrile solution (37.5 μL) prepared by dissolving lithium bis(trifluoromethanesulfonyl)imide (170 mg) in acetonitrile (1 mL) were added to the chlorobenzene solution to prepare a hole transporting material solution. The resulting solution was coated onto the perovskite layer by spin coating. After coating, the coated film was fired at 100 °C for 10 minutes to form a 300-nm-thick hole transporting layer as the third layer 212.

[0566] Then, an 80-nm-thick gold electrode as the anode 211 was formed on the hole transporting layer by vacuum deposition to fabricate a photoelectric conversion element.

[0567] [Evaluation]

[0568] [Structure of the bottom layer]

[0569] The structure of the bottom layer was analyzed as follows. The photoelectric conversion element for analyzing the bottom layer structure was immersed in a chlorobenzene solvent for 5 minutes, and ultrasonic waves were applied to the element to peel off the hole transporting layer. Then, the perovskite layer was polished with an abrasive belt (C2000, manufactured by FUJIFILM Corporation) and dried at 100 °C for 10 minutes. The resulting structure was used as the photoelectric conversion element for analyzing the bottom layer structure. For this photoelectric conversion element, it was confirmed by the FTIR-ATR method that the constituent components of the hole transporting layer and the perovskite layer did not remain on the bottom layer. A 5-mm square was cut out from the center of the photoelectric conversion element and used as a sample for analyzing the bottom layer structure. The number of atoms in the main chain of the structure represented by formula (U1) (specific examples in Tables 1 to 11) and the number of atoms in the D 1 structure were identified by the above solid-state 13 13C-NMR, mass spectrometry, MS spectrometry with pyrolysis GC analysis, and characteristic absorption measurement by infrared spectroscopy analysis, and are shown in Table 26.

[0570] [Power generation efficiency]

[0571] A power supply (type 236, manufactured by KEITHLEY Instruments) was connected between the electrodes of the photoelectric conversion element. Using sunlight simulation (manufactured by Yamashita Denso Corporation), the element was continuously irradiated with light at an intensity of 100 mW / cm 2 2, and the generated current and voltage were measured to evaluate the photoelectric conversion efficiency. The results of the short-circuit current density and the photoelectric conversion efficiency are shown in Table 26.

[0572] <Examples 3-2 to 3-73>

[0573] A photoelectric conversion element was produced in the same manner as in Example 3-1, except that the electron transporting compound and the isocyanate compound in the coating liquid for the underlayer used in Example 3-1 were replaced with those shown in Tables 26 and 27.

[0574] <Comparative Examples 3-1 to 3-3>

[0575] A photoelectric conversion element was produced in the same manner as in Example 3-1, except that the coating liquid for the underlayer used in Example 3-1 was replaced with a coating liquid shown in Table 28 that contains only an electron transporting compound and does not use an isocyanate compound or a resin.

[0576] <Comparative Example 3-4>

[0577] A photoelectric conversion element was produced in the same manner as in Example 3-1, except that the coating liquid for the underlayer used in Example 3-1 was replaced with a coating liquid shown in Table 28 that contains an isocyanate compound and a resin and does not use an electron transporting compound.

[0578] [Table 26]

[0579]

[0580] [Table 27]

[0581]

[0582] [Table 28]

[0583]

[0584] In Tables 26 to 28, the parts by mass of the electron transporting compound represent the amount (parts by mass) of the electron transporting compound in the coating liquid for the underlayer. The parts by mass of the isocyanate compound represent the amount (parts by mass) of the isocyanate compound in the coating liquid for the underlayer. The parts by mass of the resin represent the amount (parts by mass) of the resin in the coating liquid for the underlayer.

[0585] In the comparison between the examples and the comparative examples, as shown in Comparative Examples 3-1 to 3-3, the underlayer formed only of the electron transporting compound caused elution during the formation of the perovskite layer, and the film properties deteriorated significantly. This may be the reason why the characteristics of these samples as photoelectric conversion elements were not measured. In Comparative Example 3-4, electrons may not have been transferred from the perovskite layer due to the absence of the electron transporting compound.

[0586] <Example 3-74>

[0587] A coating solution for the bottom layer was prepared by dissolving 5 parts of an electron transporting compound (E-1-8), 3.5 parts of a melamine compound (C1-3), 3.4 parts of Resin 1, and 0.1 part of dodecylbenzenesulfonic acid as a catalyst in a mixed solvent of 100 parts of dimethylacetamide and 100 parts of methyl ethyl ketone. The coating solution was applied onto an FTO glass substrate by spin coating. After coating, the coated film was heated at 160 °C for 30 minutes for polymerization (curing) to form a 500-nm-thick bottom layer. The following operations were carried out in the same manner as in Example 3-1 to produce a photoelectric conversion element.

[0588] <Examples 3-75 to 3-141>

[0589] A photoelectric conversion element was produced in the same manner as in Example 3-74, except that the electron transporting compound and the melamine or guanamine compound used in the coating solution for the bottom layer of Example 3-74 were replaced as shown in Tables 29 and 30.

[0590] <Comparative Examples 3-5 to 3-7>

[0591] A photoelectric conversion element was produced in the same manner as in Example 3-74, except that the coating solution for the bottom layer used in Example 3-74 was replaced with a coating solution shown in Table 31 that contains only an electron transporting compound and does not use a melamine compound, a guanamine compound, or a resin.

[0592] <Comparative Example 3-8>

[0593] A photoelectric conversion element was produced in the same manner as in Example 3-74, except that the coating solution for the bottom layer used in Example 3-74 was replaced with a coating solution shown in Table 31 that contains a melamine or guanamine compound and a resin but does not contain an electron transporting compound.

[0594] [Table 29]

[0595]

[0596] [Table 30]

[0597]

[0598] [Table 31]

[0599]

[0600] In Tables 29 to 31, the parts by mass of the electron transporting compound represent the amount (parts by mass) of the electron transporting compound in the coating solution for the bottom layer. The parts by mass of the melamine or guanamine compound represent the amount (parts by mass) of the melamine or guanamine compound in the coating solution for the bottom layer. The parts by mass of the resin represent the amount (parts by mass) of the resin in the coating solution for the bottom layer.

[0601] In the comparison between the examples and the comparative examples, as shown in Comparative Examples 3-5 to 3-7, the underlayer formed only of the electron transporting compound caused elution during the formation of the perovskite layer, and the film properties were significantly deteriorated. This may be the reason why the characteristics of these samples as photoelectric conversion elements were not measured. In Comparative Example 3-8, electrons may not have been transferred from the perovskite layer due to the absence of the electron transporting compound.

[0602] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the claims are attached to disclose the scope of the present invention.

[0603] This application claims the benefit of Japanese Patent Application No. 2020-112744 filed on June 30, 2020, Japanese Patent Application No. 2020-096830 filed on June 3, 2020, Japanese Patent Application No. 2020-049504 filed on March 19, 2020, and Japanese Patent Application No. 2021-028128 filed on February 25, 2021, which are incorporated herein by reference in their entirety.

Claims

1. A photoelectric conversion element, comprising: A first layer containing a perovskite compound between an anode and a cathode; and a second layer between the cathode and the first layer, characterized in that the second layer contains at least one of a structure represented by the following formula (U1) and a structure represented by the following formula (U2), In formulas (U1) and (U2), R 1 and R 3 each independently represents a substituted or unsubstituted alkylene group having 1 to 10 atoms in the main chain, or a substituted or unsubstituted phenylene group, R 2 represents a single bond, an alkylene group with 1 to 10 carbon atoms in the main chain which is substituted or unsubstituted, or a substituted or unsubstituted phenylene group; the substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group or a halogen atom; the substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group, or a halogen-substituted alkyl group R 9 represents a hydrogen atom or an alkyl group, A 1 represents any one of the groups represented by the following formulas (A-1) to (A-6), B 1 represents a group represented by any one of the following formulas (B-1) to (B-3), D 1 A group represented by the following formula (D) and having 5 to 15 atoms in the main chain, E 1 represents a divalent group represented by any one of the following formulas (E-1) to (E-3), -O-(A-1) -S-(A-4) In formula (A-5), R 10 represents a hydrogen atom or an alkyl group, In formulas (B-1) to (B-3), R 6 and R 7 each independently represents an alkylene group having 1 to 5 carbon atoms in the main chain, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with an alkyl group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with a benzyl group, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with a phenyl group; one of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH or NR 15 wherein R 15 is an alkyl group. R 2 represents a single bond, an alkylene group having 1 to 10 carbon atoms in the main chain which may be substituted or unsubstituted, or a phenylene group which may be substituted or unsubstituted The substituent of the substituted alkylene group is an alkyl group, an aryl group, a hydroxyl group or a halogen atom; the substituent of the substituted phenylene group is a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkyl group or a halogen-substituted alkyl group, R 12 represents a hydrogen atom or an alkyl group, Ar 2 represents a substituted or unsubstituted phenylene group, and the substituents of the substituted phenylene group are halogen atoms, nitro groups, hydroxyl groups, cyano groups, alkyl groups or haloalkyl groups. A 1 and A 2 represents any one of the groups represented by the above formulas (A-1) to (A-5), E 1 represents a divalent group represented by any one of the following formulas (E-1) to (E-3), o, p and q are each independently 0 or 1, and the sum of o, p and q is 1 to 3, The side where the arrow points is combined with R 3 ​ In formula (D), R 4 , R 5 , R 6 and R 7 each independently represents an alkylene group having 1 to 5 carbon atoms in the main chain, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with an alkyl group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with a benzyl group, an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 5 carbon atoms in the main chain and substituted with a phenyl group, and one of the carbon atoms in the main chain of the alkylene group may be replaced by O, S, NH or NR 15 , where R 15 is an alkyl group. Ar 1 and Ar 2 each independently represents a substituted or unsubstituted phenylene group, and the substituent of the substituted phenylene group is a halogen atom, nitro group, hydroxyl group, cyano group, alkyl group or haloalkyl group A 2 represents a group represented by any one of the above formulas (A-1) to (A-6), l, m, n, o, p and q are each independently 0 or 1, and the sum of l, m and n and the sum of o, p and q are 1 to 3, In formulas (E-1) to (E-3), R 101 to R 106 , R 201 to R 210 , and R 301 to R 304 each independently represents a single bond, a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a dialkylamino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and one or both of R 101 to R 106 , one or both of R 201 to R 210 , and one or both of R 301 to R 304 are single bonds, and the substituents of the substituted alkyl group are an alkyl group, an aryl group, a halogen atom, or a carbonyl group; the substituents of the substituted aryl group or the substituted heterocyclic group are a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkoxy group, or a carbonyl group.

2. The optoelectronic conversion element according to claim 1, wherein D 1 is a group having 10 to 15 atoms in the main chain.

3. The photoelectric conversion element according to claim 1, wherein R 4 , R 5 , R 6 and R 7 are each independently an alkylene group having 1 to 5 carbon atoms in the main chain, or an alkylene group having 1 to 5 carbon atoms in the main chain substituted with a methyl group or an ethyl group.

4. The photoelectric conversion element according to claim 1, wherein Ar 1 and Ar 2 are unsubstituted phenylene groups.

5. A photoelectric conversion module, comprising: A first photoelectric conversion element; and a second photoelectric conversion element, characterized in that at least one of the first photoelectric conversion element and the second photoelectric conversion element is the photoelectric conversion element according to any one of claims 1 to 4.

6. A photoelectric conversion device, characterized in that, It includes: The photoelectric conversion element according to any one of claims 1 to 4; and a power storage unit connected to the photoelectric conversion element.

7. A photoelectric conversion device, characterized in that, It includes: The photoelectric conversion element according to any one of claims 1 to 4; and an inverter connected to the photoelectric conversion element.

8. A moving body, characterized in that, It includes: the photoelectric conversion element according to any one of claims 1 to 4; and a main body frame provided with the photoelectric conversion element.

9. A building material, characterized in that, It includes: The photoelectric conversion element according to any one of claims 1 to 4; and a protection member or a heat dissipation member for protecting the photoelectric conversion element.

Images