Photoelectric conversion element and photoelectric conversion device

Abstract

Provided is a photoelectric conversion element that has improved durability while achieving high initial photoelectric conversion efficiency. The photoelectric conversion element comprises a first electrode, a second electrode, and a photoelectric conversion layer including a crystal of a perovskite structure, and is characterized in that: when the smaller one of the electrode area of the first electrode and the electrode area of the second electrode is S [cm2], in a Nyquist plot based on an impedance measurement result, a maximum value Rrec [Ω] among resistance values obtained by fitting an arc corresponding to a phase maximum value in a low frequency range by a parallel circuit of a resistance element and a constant phase element satisfies the following formula (E1) 1.0 × 104 < Rrec × S < 1.0 × 107 (E1), and a maximum value Rct [Ω] among resistance values obtained by fitting an arc corresponding to a phase maximum value in a high frequency range by a parallel circuit of a resistance element and a constant phase element and Rrec [Ω] satisfy the following formula (E2) Rrec / Rct ≥ 25 (E2).

Description

Photoelectric conversion element and photoelectric conversion device

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

[0002] In order to solve the problems of fossil energy depletion and the global environmental problems caused by the use of fossil energy, active research is being conducted on renewable and clean alternative energy sources such as solar energy, wind power, and hydropower. Among these, interest is growing in solar cells that directly convert sunlight into electrical energy. Here, a solar cell refers to a cell that generates current and voltage by utilizing the photovoltaic effect, in which light energy from sunlight is absorbed and electrons and holes are generated.

[0003] Currently, n-p diode-type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% are widely known and are actually used for solar power generation. However, these require high-temperature processing steps and the materials themselves are expensive, resulting in high costs per unit of power. Furthermore, there are also supply issues due to the limited silicon resources.

[0004] On the other hand, solar cells using organic materials (hereinafter referred to as "organic solar cells") do not require high-temperature processing and can be produced using a sheet-like substrate by a so-called roll-to-roll method, which is expected to reduce costs. However, further improvements in power generation efficiency and durability are desired for the practical use of organic solar cells. In particular, perovskite solar cells, which have crystals with a perovskite structure as a photoelectric conversion layer, have excellent photoelectric conversion characteristics, and development is underway toward the practical use of solar cells.

[0005] Patent Document 1 describes a technique for improving peeling from an electrode by including an organic semiconductor and a polymer compound having a glass transition temperature of 100° C. or higher in a hole transport layer.

[0006] Patent Document 2 describes a configuration in which a layer made of a quinacridone pigment is provided between a perovskite layer and a hole transport layer, and describes the results of impedance measurements of this configuration.

[0007] Non-Patent Document 1 describes a technique for a charge transport layer for a reverse layer in which PEDOT:PSS is doped with nickel phthalocyanine having a substituent group to improve photoelectric conversion efficiency.

[0008] JP 2018-170382 A U.S. Patent Application Publication No. 2022 / 0285642

[0009] X. -F. Zhang, J. Mater. Chem. A, 2018, 6, 12515-12522

[0010] According to the investigations of the present inventors, it has been found that the photoelectric conversion elements described in Patent Document 1, Patent Document 2, and Non-Patent Document 1 have room for improvement in durability.

[0011] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a photoelectric conversion element and a photoelectric conversion device with improved durability.

[0012] The above object can be achieved by the present invention as described below. That is, the photoelectric conversion element according to the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure disposed between the first electrode and the second electrode, wherein the smaller of the electrode areas of the first electrode and the second electrode is S [cm ２ ], and a DC voltage component V ＤＣ = 0 [V], root mean square of AC voltage component V ｒｍｓ = 50 [mV] AC voltage with a frequency of 1.0 × 10 －２ [Hz] ~1.0×10 ６ When the impedance is measured while changing the frequency between [Hz] and [Hz], the horizontal axis is frequency [Hz] and the vertical axis is phase [deg], and the impedance is measured. －２ [Hz] or more 1.0×10 ２ The phase of the impedance has a maximum value in a low frequency range of less than 1.0 × 10 ２ [Hz] or more 1.0×10 ６The phase of the impedance has a maximum value in a high frequency range of not more than [Hz], and in a Nyquist plot based on the measurement results of the impedance, the horizontal axis is the real part of the impedance Z' [Ω] and the vertical axis is the imaginary part of the impedance Z'' [Ω], the maximum value R among the resistance values ​​obtained by fitting an arc corresponding to the maximum value of the phase in the low frequency range with a parallel circuit of a resistive element and a constant phase element ｒｅｃ [Ω] satisfies the following formula (E1), and is 1.0 × 10 ４ ≦R ｒｅｃ × S ≦ 1.0 × 10 ７ (E1) The maximum value R among the resistance values ​​obtained by fitting the arc corresponding to the maximum value of the phase in the high frequency range with a parallel circuit of a resistance element and a constant phase element ｃｔ [Ω] and the R ｒｅｃ [Ω] satisfies the following formula (E2), ｒｅｃ / R ｃｔ ≧25 (E2).

[0013] According to the present invention, it is possible to provide a photoelectric conversion element having high initial photoelectric conversion efficiency and improved durability.

[0014] 1 is a plot of impedance data obtained in Example 4 of the present invention, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg]. FIG. 2 is a Nyquist plot of impedance data and fitting curves obtained in Example 4 of the present invention. FIG. 3 is a diagram explaining the meaning of an arc corresponding to a maximum value of the phase in the present invention. FIG. 4 is an equivalent circuit used in fitting in impedance analysis in the Examples of the present invention. FIG. 5 is a schematic cross-sectional view in the thickness direction of a first embodiment of a photoelectric conversion element of the present invention. FIG. 6 is a perspective view schematically showing an embodiment of a mobile body equipped with a photoelectric conversion element of the present invention. FIG. 7 is a perspective view schematically showing an embodiment of a building material equipped with a photoelectric conversion element of the present invention.

[0015] The photoelectric conversion element of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal of a perovskite structure disposed between the first electrode and the second electrode, wherein the smaller of the electrode areas of the first electrode and the second electrode is defined as S [cm ２], and a DC voltage component V ＤＣ = 0 [V], root mean square of AC voltage component V ｒｍｓ = 50 [mV] AC voltage with a frequency of 1.0 × 10 －２ [Hz] ~1.0×10 ６ When the impedance is measured by applying a voltage varying between 1.0 × 10 and 2.0 × 10, the horizontal axis is frequency [Hz] and the vertical axis is phase [deg] based on the impedance measurement results. －２ [Hz] or more 1.0×10 ２ The phase of the impedance has a maximum value in a low frequency range of less than 1.0 × 10 ２ [Hz] or more 1.0×10 ６ The phase of the impedance has a maximum value in a high frequency range of not more than [Hz], and in a Nyquist plot based on the measurement results of the impedance, the horizontal axis is the real part of the impedance Z' [Ω] and the vertical axis is the imaginary part of the impedance Z'' [Ω], the maximum value R among the resistance values ​​obtained by fitting an arc corresponding to the maximum value of the phase in the low frequency range with a parallel circuit of a resistive element and a constant phase element. ｒｅｃ [Ω] satisfies the following formula (E1), and is 1.0 × 10 ４ ≦R ｒｅｃ × S ≦ 1.0 × 10 ７ (E1) The maximum value R among the resistance values ​​obtained by fitting the arc corresponding to the maximum value of the phase in the high frequency range with a parallel circuit of a resistance element and a constant phase element ｃｔ [Ω] and the R ｒｅｃ [Ω] satisfies the following formula (E2), ｒｅｃ / R ｃｔ ≧25 (E2).

[0016] As a result of investigations, the inventors have found that by satisfying the above-mentioned configuration, it is possible to suppress deterioration of a photoelectric conversion element during durable use, which is caused by defects in the photoelectric conversion layer. Conventionally, when the resistance of a photoelectric conversion element is increased to suppress deterioration, the movement of charges generated in the photoelectric conversion layer is hindered, resulting in a deterioration in initial photoelectric conversion efficiency. In contrast, when the resistance is reduced to improve the initial photoelectric conversion efficiency, the effect of suppressing deterioration is insufficient.

[0017] Therefore, the inventors have determined that the impedance on the low frequency side is expressed by the following formula (E1): 1.0×10 ４ ≦R ｒｅｃ × S ≦ 1.0 × 10 ７ (E1) is satisfied, the ratio of the impedance on the low frequency side to the impedance on the high frequency side is R ｒｅｃ / R ｃｔ It has been found that both high initial photoelectric conversion efficiency and suppression of degradation can be achieved if the condition of .gtoreq.25 is satisfied. The present inventors speculate that the reason for this is as follows.

[0018] On the other hand, the impedance R ｒｅｃ [Ω] means the recombination resistance, which correlates with the difficulty of recombining electrons and holes generated in the photoelectric conversion layer. If this value is equal to or greater than a certain value, durability degradation is suppressed. However, if this value is too large, the initial photoelectric conversion efficiency deteriorates. In order to balance these two, the following formula (E1) 1.0 × 10 ４ ≦R ｒｅｃ × S ≦ 1.0 × 10 ７ (E1) must be satisfied.

[0019] On the other hand, the impedance R ｃｔ [Ω] means the charge transfer resistance which correlates with the ease of charge transfer when the photoelectric conversion element performs photoelectric conversion, and the smaller this value, the better the initial photoelectric conversion efficiency. Therefore, in order to achieve both the initial photoelectric conversion efficiency and the suppression of deterioration, in addition to the above formula (E1), the following formula (E2) R ｒｅｃ / R ｃｔ ≧25 (E2) must be satisfied.

[0020] As described above, by establishing a condition that provides a correlation between impedance characteristic values ​​in different frequency ranges, such as in formula (E2), rather than a range condition for a single impedance characteristic value, such as in formula (E1), or a range condition for each of a plurality of impedance characteristic values, it is possible to essentially solve the conventional difficulty of achieving both high initial photoelectric conversion efficiency and suppression of degradation.

[0021] As explained above, the effects of the present invention can be achieved by the synergistic effects of the various components.

[0022] The present invention will be described in detail below with reference to preferred embodiments. The present invention is not limited to the following embodiments, and any modifications or improvements to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0023] [Impedance characteristics of the present invention] The photoelectric conversion element of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal of a perovskite structure disposed between the first electrode and the second electrode, wherein the smaller of the electrode area of ​​the first electrode and the electrode area of ​​the second electrode is defined as S [cm ２ ], and a DC voltage component V ＤＣ = 0 [V], root mean square of AC voltage component V ｒｍｓ = 50 [mV] AC voltage with a frequency of 1.0 × 10 －２ [Hz] ~1.0×10 ６ When the impedance is measured while changing the frequency between [Hz] and [Hz], the horizontal axis is frequency [Hz] and the vertical axis is phase [deg], and the impedance is measured. －２ [Hz] or more 1.0×10 ２ The phase of the impedance has a maximum value in a low frequency range of less than 1.0 × 10 ２ [Hz] or more 1.0×10 ６ The phase of the impedance has a maximum value in a high frequency range of not more than [Hz], and in a Nyquist plot based on the measurement results of the impedance, the horizontal axis is the real part of the impedance Z' [Ω] and the vertical axis is the imaginary part of the impedance Z'' [Ω], the maximum value R among the resistance values ​​obtained by fitting an arc corresponding to the maximum value of the phase in the low frequency range with a parallel circuit of a resistive element and a constant phase element. ｒｅｃ [Ω] satisfies the following formula (E1): 1.0 × 10 ４ ≦Rrec×S≦1.0×10 ７ (E1) The maximum value R among the resistance values ​​obtained by fitting the arc corresponding to the maximum value of the phase in the high frequency range with a parallel circuit of a resistance element and a constant phase element ｃｔ[Ω] and the R ｒｅｃ [Ω] satisfies the following formula (E2), ｒｅｃ / R ｃｔ ≧25 (E2).

[0024] Here, the plot with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg] is a graph that correlates the value of the frequency of the AC voltage in the impedance measurement with the angle formed on the complex plane by the real part Z' and imaginary part Z'' of the impedance obtained when that frequency is applied: arctan (Z'' / Z'), as shown in FIG.

[0025] Furthermore, a Nyquist plot with the horizontal axis representing the real part of impedance Z' [Ω] and the vertical axis representing the imaginary part of impedance Z'' [Ω] corresponds to a graph in which the real part Z' and imaginary part Z'' of the impedance described above are plotted on a complex plane, as shown in FIG. 2.

[0026] However, in the present invention, the vertical axis represents the positive and negative signs, with -Z'' representing the positive and negative. Accordingly, in the present invention, the vertical axis represents the negative (minus) direction of the phase [deg]. Therefore, the maximum value of the phase in the low frequency range or high frequency range in the present invention means the extreme value where the phase increases in the negative direction. The issue of these positive and negative signs depends on the definition of the complex impedance Z [Ω] and is not an essential issue.

[0027] The following explains what is meant by an arc corresponding to a maximum value of the phase in the low-frequency range or the high-frequency range. As shown in FIG. 3A, if the maximum value in the low-frequency range is θlow, then this θlow corresponds to the slope of a tangent line passing through the origin to an arc present in the low-frequency range in the Nyquist plot of FIG. 3B. Therefore, the arc corresponding to the maximum value of the phase is exactly the arc to which such a tangent line is drawn.

[0028] The constant phase element of the present invention will now be described. The constant phase element is used in the equivalent circuit when fitting impedance data shown as an example in FIG. 4, and is indicated by "CPE (1-3)" that appears in the R-CPE parallel circuit in FIG. 4. The constant phase element is an element obtained by mathematically transforming a capacitive element (capacitor element) for fitting. The complex impedance of a capacitive element is expressed by the following formula (E7): ZC = 1 / (i2πfC) (E7) (where i is the imaginary unit, π is the ratio of the circumference of a circle to its diameter, f is frequency [Hz], and C is capacitance [F]). The complex impedance of a constant phase element is expressed by the following formula (E8): ZCPE = 1 / [(i2πf)PT] (E8)

[0029] If P = 1, the above equation (E8) coincides with equation (E7) (where T = C), and therefore the constant phase element is indeed a mathematical transformation of a capacitive element. The exponent P of the constant phase element expressed by equation (E8) corresponds to the degree of compression of the arc on the Nyquist plot; if the arc is a perfect semicircle, P = 1, but if the semicircle sinks into the fourth quadrant on the Nyquist plot, P < 1. The degree of compression of the arc on the Nyquist plot correlates with the variance of the impedance, so the smaller P is than 1, the greater the variance of the impedance.

[0030] In order to enhance the effect of the present invention, R ｒｅｃ × S [Ω cm ２ ] is expressed by the following formula (E5): 1.0 × 10 ５ <R ｒｅｃ × S < 1.0 × 10 ６ (E5) is more preferable.

[0031] Also, R ｒｅｃ / R ｃｔ is the following formula (E6): ｒｅｃ / R ｃｔ It is preferable that the relationship is ≧50 (E6).

[0032] In order to suppress deterioration more effectively, the R ｒｅｃ The exponent P of the constant phase element obtained by fitting to obtain [Ω] ｒｅｃ is represented by the following formula (E3):ｒｅｃ ≧0.80 (E3). When the above formula (E3) is satisfied, the variance of the impedance on the low frequency side corresponding to the recombination resistance is sufficiently small. Therefore, the recombination resistance that contributes to concealing defects in the photoelectric conversion layer becomes uniform in the surface direction of the photoelectric conversion layer, thereby improving the probability of concealing defects in the photoelectric conversion layer.

[0033] In order to effectively maintain a high initial photoelectric conversion efficiency, the R ｃｔ The exponent P of the constant phase element obtained by fitting to obtain [Ω] ｃｔ is represented by the following formula (E4): ｃｔ It is preferable to satisfy the following relation: ≦0.95 (E4). When the above formula (E4) is satisfied, the variance of the impedance on the high frequency side corresponding to the charge transfer resistance is sufficiently large. Therefore, since there are sufficient low-resistance paths for the transfer of photocharges generated in the photoelectric conversion layer, a high-resistance recombination resistance element that contributes to global defect concealment in the surface direction of the photoelectric conversion layer and a low-resistance charge transfer resistance element that contributes to local charge transfer paths in the photoelectric conversion element are further achieved.

[0034] Hereinafter, the photoelectric conversion element of the present invention and the configuration of each layer thereof will be described in detail with reference to preferred embodiments. The following are some examples for obtaining the above-mentioned [impedance characteristics of the present invention]. Therefore, the present invention is not limited to the following embodiments, and appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of a person skilled in the art are also included within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

[0035] In this specification, the term "layer" refers not only to a layer with clear boundaries or a flat, thin-film layer, but also to a layer with a concentration gradient in which the contained elements gradually change, or to a layer that can form a complex, intricate structure together with other layers. Elemental analysis of a layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis of a cross section of a photoelectric conversion element to confirm the element distribution of a specific element. Analysis of each layer may be performed by peeling and removing the layer from a completed photoelectric conversion element to expose the layer to be analyzed. The volume ratio can also be quantified by using the area ratio of the exposed surface or cross section as the volume ratio of that layer.

[0036] 5 is a cross-sectional view schematically illustrating the configuration of one embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion element has a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 on a substrate 2. One of the first electrode 7 and the second electrode 3 is an anode and the other is a cathode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0037] The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or through the first electrode 7 and the charge transport layer 6, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and the two electrodes 3 and 7, and may not be formed in some cases. A structure in which multiple electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a structure may also be called a tandem structure. Each component will be described below. Alternatively, a photoelectric conversion element may be fabricated on the substrate 2 in the order of the first electrode 7, the charge transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3.

[0038] [Photoelectric Conversion Element] The photoelectric conversion element of the present invention is characterized by having a first electrode, a second electrode, a photoelectric conversion layer containing a crystal of a perovskite structure disposed between the first electrode and the second electrode, and a charge transport layer between the photoelectric conversion layer and the first electrode. Furthermore, in order to improve photoelectric conversion efficiency, the photoelectric conversion elements may be stacked in a tandem configuration. The photoelectric conversion elements to be stacked are not limited to a specific type of photoelectric conversion element, and may include, in addition to perovskite solar cells that use perovskite crystals in the photoelectric conversion layer, silicon solar cells, CIGS solar cells, and the like.

[0039] Methods for forming each layer, including the photoelectric conversion layer and the charge transport layer, of the photoelectric conversion element of the present invention include coating methods and vapor deposition methods. Examples of coating methods include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method involves preparing a coating solution for each layer described below, applying the solution in the desired layer order, and drying the solution. A desired method can be selected from these film formation methods depending on the layer. Each layer will be described below.

[0040] [Substrate] The photoelectric conversion element 1 of the present invention may include a substrate 2, examples of which include a transparent glass substrate such as soda-lime glass or alkali-free glass, a ceramic substrate, a transparent plastic substrate, etc. When light is taken in from the first electrode 7 side, an opaque material can be used for the substrate 2, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0041] [Electrodes] The photoelectric conversion element of the present invention has a first electrode and a second electrode. The materials for the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, carbon, carbon nanotubes, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, and Al / Al ２ O ３Examples of transparent electrode materials include CuI, ITO (indium tin oxide), and SnO. ２ Examples of the conductive transparent material include AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimony-doped tin oxide), as well as conductive transparent polymers. These materials may be used alone or in combination of two or more. The first electrode 7 and the second electrode 3 are configured such that at least one electrode on the light incident side is a transparent electrode, and the other electrode may be a transparent electrode or may double as a reflective layer formed of a light-reflective material, or may be a transparent electrode with a reflective layer on the side opposite the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The electrodes may be patterned electrodes.

[0042] [Photoelectric Conversion Layer] The photoelectric conversion layer 5 has a crystal with a perovskite structure. The crystal with a perovskite structure used in the present invention is preferably represented by the following general formula [1]: ABX ３ [1] In the above general formula [1], A is a monovalent cation of an organic molecule or a metal atom, B is a divalent metal cation, and X is a monovalent halide anion.

[0043] As A in the general formula [1], for example, in the case of an organic molecule, it is preferable that it is represented by CpNqHr (p, q, and r are all positive integers). Specific examples include methylammonium and formamidium.

[0044] The inorganic atom is not particularly limited, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms may be used alone or in combination of two or more.

[0045] If the constituent cation A is too large to fit within a crystal with a three-dimensional perovskite structure, the resulting crystal will be a two-dimensional perovskite structure, a 2.5-dimensional perovskite structure crystal having both two-dimensional and three-dimensional properties, a bilayer crystal of a three-dimensional and two-dimensional perovskite structure, or a crystal with a mixed three-dimensional and two-dimensional perovskite structure, all of which function as a photoelectric conversion layer. A bilayer crystal of a three-dimensional and two-dimensional perovskite structure refers to a crystal in which crystals with a three-dimensional and two-dimensional perovskite structure are stacked as independent, separate layers, while a mixed three-dimensional and two-dimensional perovskite refers to a crystal with a structure in which regions or domains of both two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed.

[0046] The crystal of the two-dimensional perovskite or 2.5-dimensional perovskite structure is preferably represented by the following general formulas [2] to [4]: ​​(n is a positive integer) R' ２ A ｎ－１ B ｎ X ３ｎ＋１ [2] R''A ｎ－１ BnX ３ｎ＋１ [3] R'''A ｎ BnX ３ｎ＋１ [4] In the above general formulas, [2] forms an RP (Ruddlesden-Popper) type perovskite structure, [3] forms a DJ (Dion-Jacobson) type perovskite structure, and [4] forms an ACI (Alternating cations in the interlayer) type perovskite structure.

[0047] R', R'', and R''' in the above general formulas [2] to [4] are organic molecules or metal cations which may have a substituent, and specific examples thereof include ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexadiammonium, isobutylammonium, 3-(nonafluoro-tert-butyloxy)propylamine, 1,3-propanediammonium, 1,5-pentamethylenediamine, octyldiammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium ... Cylammonium, 4-fluorophenethylammonium, 4-fluorophenethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophenedimethylammonium, phenylpropylammonium, 1,4-phenylenedimethanamine, 3-phenyl-2-propene-1-ammonium, phenylbutylammonium, 4-tert-butyl - benzylammonium, 3- (aminomethyl) piperidinium, 4- (aminomethyl) piperidinium is preferred.

[0048] In the above general formulas [1] to [4], B is a metal atom, such as lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of electron orbital overlap. These metal atoms may be used alone or in combination of two or more.

[0049] X in the above general formulas [1] to [4] is a halogen atom, such as chlorine, bromine, or iodine. These halogen atoms may be used alone or in combination of two or more. Among these, halogen atoms are preferred because the inclusion of halogen in the structure makes the perovskite structure crystal more soluble in organic solvents, enabling application to inexpensive printing methods, etc. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite structure crystal.

[0050] Specifically, 3D perovskite, 2D perovskite, and mixed 3D / 2D perovskite are MAPbI ３ and FAPbCl ３ , FAPbI ３ , MAPbIαBr ３ -α, MAPbIαCl ３ -α, Cs ０．０５ (MA ０．１７ FA ０．８３ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ , {Cs β１ (FA β２ MA １－β２ ) １－β１} γ１ Pb(I β３ Br １－β３ ) γ２ , Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ , (FAPbI ３ ) ０．９５ (MAPbBr ３ )０．０５ 、(FAPbI ３ ) ０．８５ (MAPbBr ３ ) ０．１５ 、CsPbI ３ 、CsPbBr ３ 、Cs β (MA) １－β PbI ３ 、Cs β (FA) １－β PbI ３ 、MA β (FA) １－β PbI ３ 、MA ０．１７ FA ０．８３ Pb(I ０．８３ Br ０．１７ ) ３ 、Cs ０．１５ FA ０．８５ PbI ２．５５ Br ０．４５ 、Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ 、Cs ０．１５ FA ０．８５ PbI ２．５５ Br ０．４５ 、(PEA) ２ (MA) ２ Pb ３ I １０ 、(PTA) ２ (MA) ４ Pb ５ I １６ 、(PEA) ２ (MA) ４ Pb ５ I １６ 、(ThMA) ２ (MA) ２ Pb ３ I １０ 、(3BBA) ２ (MA) ２ Pb ３ I １０ 、(ThMA) ２ (FA) ４ Pb ５ I １６ ,(4FPEA) ２ (FA ０．３ MA ０．７ ) ４Pb ５ I １６ 、(PDMA)FA ２ Pb ３ I １０ 、(3AMPY)(MA) ３ Pb ４ I １３ 、(PDMA)MA ５ Pb ６ I １９ 、(PDMA)MA ３ Pb ４ I １３ 、(TTDMA)MA ３ Pb ４ I １３ ,(TTDMA)MA ４ Pb ５ I １６ 、(BA ０．９ PEA ０．１ ) ２ MA ４ Pb ５ I １６ 、(BA ０．９ PEA ０．１ ) ２ MA ３ Pb ４ I １３ 、(4FPEA) ２ MA ３ Pb ４ I １３ 、(4FPEA) ２ MA ４ Pb ５ I １６ 、(BA) ２ MA ２ Pb ３ I １ 0、(BA) ２ MA ３ Pb ４ I １３ 、(TEA) ２ MA ２ Pb ３ I １０ 、(BA) ２ MA ４ Pb ５ I １６ 、(BA) ２ MA ３ Pb ４ I １３ 、CsSnBr ３ 、CsSnI ３, F.A. ０．７５ MA ０．２５ Sn ０．９５ Ge ０．０５ I ３ , FAMASnGeI ３ , FASnBr ３ , FASnI ３ , M.A. ２ Sn ３ I ８ , MASnBr ３ , MASnGeI ３ , MASnI ３ is preferred. Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be insufficient or excessive, and the combinations of β1 to β3 and γ1 to γ2 may be changed depending on the purpose. Table 1 shows, for example, combinations of β1 to β3 and γ1 to γ2. Particularly preferred ranges are 0.03≦β1≦0.10, 0.80≦β2≦0.96, 0.80≦β3≦0.96, 0.95≦γ1≦1.05, and 2.95≦γ2≦3.05. The ranges of α and β are 0<α<3 and 0<β<1, respectively. MACl may be included as a material for forming perovskite crystals.

[0051] In the above specific examples, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylenedimethaneammonium, "TTDMA" represents thieno[3,2-b]thiophene-2.5-diyldimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0052] The perovskite crystal preferably has a cubic structure in which a metal atom B is located at the body center, an organic molecule A at each vertex, and a halogen atom X at the face center. Although the details are not clear, it is presumed that such a structure allows the orientation of the octahedra in the crystal lattice to be easily changed, thereby increasing the mobility of electrons in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0053] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor refers to a semiconductor from which a scattering peak can be detected by measuring an X-ray scattering intensity distribution. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound increases, improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0054] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. A thickness of 5 nm or more allows sufficient absorption of light, and a thickness of 2000 nm or less allows generated charges to be transported to each electrode. A more preferred lower limit is 50 nm or more, a more preferred upper limit is 1200 nm, an even more preferred lower limit is 100 nm, and an even more preferred upper limit is 1000 nm.

[0055] [Charge Transport Layer] In the present invention, the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, and the charge transport layer preferably contains a charge transport material and an insulating resin on the surface of the photoelectric conversion layer. When the charge transport layer is a mixed system of a charge transport material and an insulating resin, it becomes easy to achieve both a local low-resistance charge transfer resistance element that contributes to the initial photoelectric conversion efficiency and a global high-resistance element that contributes to the suppression of deterioration. From this viewpoint, the insulating resin has a volume resistivity of 10 ８ It is preferably Ω·cm or more.

[0056] The present inventors speculate that the preferable structure of the charge transport layer as a means for achieving the above-described structure of the present invention and the reason for this are as follows.

[0057] On the other hand, the impedance R ｒｅｃ[Ω] means the recombination resistance that correlates with the difficulty of recombining electrons and holes generated in the photoelectric conversion layer, and therefore corresponds to the interface resistance between the photoelectric conversion layer and the charge transport layer. In order to set this value to a certain value or more and suppress durability degradation, defects in the photoelectric conversion element can be sufficiently concealed by the insulating resin of the charge transport layer. However, if this value is too large, charge transfer at the interface is hindered, and the initial photoelectric conversion efficiency deteriorates. In order to balance these two, as described above, the following formula (E1) 1.0 × 10 ４ <R ｒｅｃ × S < 1.0 × 10 ７ (E1) had to be satisfied.

[0058] On the other hand, the impedance R ｃｔ [Ω] means the charge transfer resistance, which correlates with the ease of charge transfer when the photoelectric conversion element performs photoelectric conversion, and corresponds to the bulk resistance of the charge transport layer. To reduce this value to smooth the charge transfer in the photoelectric conversion element and improve the initial photoelectric conversion efficiency, the charge transport material of the charge transport layer is effective.

[0059] From the above, the charge transport layer is ｒｅｃ and an insulating resin that contributes to increasing R ｃｔ By using a mixed system of charge transport materials that contribute to reducing the ｒｅｃ / R ｃｔ ≧25 (E2) and thus it becomes easier to obtain a photoelectric conversion element that satisfies both the initial photoelectric conversion efficiency and the suppression of deterioration.

[0060] In the present invention, the charge transport material is preferably a charge transport particle. When the charge transport material is a particle, the dispersion of the impedance on the high frequency side corresponding to the bulk resistance becomes large, and the following formula (E4) P ｃｔ≦0.95 (E4) is more likely to be satisfied. As described above, by satisfying the above formula (E4), the dispersion of the impedance on the high frequency side corresponding to the charge transfer resistance becomes sufficiently large, and a sufficient number of low-resistance paths for the transfer of photocharges generated in the photoelectric conversion layer are present in the charge transport layer. As a result, it becomes easier to achieve both a high-resistance recombination resistance element that contributes to global defect concealment in the surface direction of the photoelectric conversion layer and a low-resistance charge transfer resistance element that contributes to local charge transfer paths in the photoelectric conversion element.

[0061] Furthermore, it is more preferable that the charge transport material is a pigment having a particle size of 10 nm to 500 nm. This range facilitates the formation of a charge distribution that can suppress migration. Specific examples of pigments include phthalocyanine pigments, azo pigments, lake pigments, quinacridone pigments, dioxazine pigments, perylene pigments, and isoindolinone pigments.

[0062] The volume ratio of the charge transport material to the insulating resin is preferably 5 times or more and 30 times or less. ｒｅｃ ≧0.80 (E3). As described above, when the above formula (E3) is satisfied, the variance of the impedance on the low frequency side corresponding to the recombination resistance becomes sufficiently small, and the recombination resistance that contributes to concealing defects in the photoelectric conversion layer becomes uniform in the plane direction of the photoelectric conversion layer, thereby improving the probability of concealing defects in the photoelectric conversion layer and making it easier to achieve both initial photoelectric conversion efficiency and suppression of deterioration. The ratio of the volume of the insulating resin to the volume of the charge transport material can be measured, for example, from the area ratio of the cross section determined by FETEM / EDS, as described above.

[0063] The charge transport material is more preferably a phthalocyanine compound, and more preferably has a structure represented by the following formula (Pc-2): This charge transport material tends to increase the dispersion of impedance on the high frequency side corresponding to bulk resistance, making it easier to achieve both high initial photoelectric conversion efficiency and suppression of degradation. M in the above formula (Pc-2) represents H2 or a metal atom which may have a ligand. In the present invention, the structure of the chemical substance can be determined by nuclear magnetic resonance (NMR). In particular, when M in the above formula (Pc-2) is H2, the above formula (Pc-2) is represented by the following formula (Pc-1):

[0064] Specific examples of insulating resins include polyacetal resin, acrylic resin, polyarylate resin, polycarbonate resin, polyvinyl acetate resin, polyester resin, polyamide resin, polyurethane resin, and polystyrene resin.

[0065] It is more preferable that the glass transition temperature of the insulating resin is 95° C. or lower. Within this range, the insulating resin is likely to come into close contact with the charge transport material, and it is possible to more effectively achieve both a local low resistance element that contributes to the initial photoelectric conversion efficiency and a global high resistance element that contributes to the suppression of degradation, thereby facilitating the determination of the impedance parameters of the present invention. The glass transition temperature can be determined by a differential scanning calorimeter (DSC).

[0066] The insulating resin is preferably a polyvinyl acetal resin or a polyvinyl butyral resin, which can easily come into close contact with the charge transport material and more effectively obtain the impedance parameter of the present invention.

[0067] It is more preferable that the charge transport layer contains an aromatic ring compound having a hydroxyl group different from the charge transport material and the insulating resin, since the aromatic ring compound having a hydroxyl group makes it easier for the charge transport material and the insulating resin to come into contact with each other, thereby more effectively obtaining the impedance parameter of the present invention.

[0068] The photoelectric conversion element may have a second charge transport layer between the first electrode and the charge transport layer. The presence of the second charge transport layer may facilitate the transfer of carriers to the electrode.

[0069] The thickness of the charge transport layer is preferably from 1 nm to 1000 nm, more preferably from 5 nm to 500 nm, and particularly preferably from 10 nm to 200 nm.

[0070] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming this coating film on the photoelectric conversion layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0071] [Second Charge Transport Layer] In the present invention, a second charge transport layer may be further provided between the charge transport layer 6 and the first electrode 7 from the viewpoint of film compatibility of the charge transport layer 6 .

[0072] The material for the second charge transport layer is not particularly limited, and examples thereof include spirofluorene compounds, triphenylamine compounds, chrysene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds. In particular, from the viewpoint of compatibility at the film interface, those having an aromatic ring are preferred, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred. Furthermore, the second charge transport layer may contain a dopant as an additive to improve charge transport capability. Examples of substances that can be used as dopants include lithium compounds such as bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)], boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, and organic compounds having a pyridine skeleton such as 4-tert-butylpyridine.

[0073] [Control of particle size of charge transport particles] The particle size of the charge transport particles can be changed by dispersing the coating liquid for the charge transport layer using a paint shaker, and the particle size can be reduced by extending the dispersion time. Furthermore, the particle size can be reduced by centrifuging the coating liquid for the charge transport layer. [Electron transport layer] In the photoelectric conversion element of the present invention, an electron transport layer 4 may be disposed between the second electrode 3 and the photoelectric conversion layer 5, as shown in FIG. 5 .

[0074] The material for the electron transport layer 4 is not particularly limited, and examples thereof include N-type conductive polymers, N-type low-molecular-weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc. Specific examples thereof include cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc. In particular, tin oxide may be obtained by reacting tin(2) chloride, tin(4) chloride, tin(2) chloride dihydrate, or tin(4) chloride pentahydrate.

[0075] The thickness of the electron transport layer 4 is preferably 1 nm or more at the lower limit and 2000 nm or more at the upper limit. A thickness of 1 nm or more sufficiently blocks holes, while a thickness of 2000 nm or less prevents electron transport and increases photoelectric conversion efficiency. The thickness is more preferably 3 nm or less at the lower limit and 1000 nm or less at the upper limit, and even more preferably 5 nm or less at the lower limit and 500 nm or less at the upper limit.

[0076] [Photoelectric Conversion Device] A photoelectric conversion device can be constructed by using multiple photoelectric conversion elements of the present invention. When multiple photoelectric conversion elements are connected, such a photoelectric conversion device can also be called a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion elements may be stacked with elements having different absorption wavelengths to increase the output voltage. The photoelectric conversion device may also include the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current to alternating current. The photoelectric conversion device may also include a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited as long as it can store electricity. Examples of the power storage unit include secondary batteries using lithium ions, all-solid-state batteries, and electric double-layer capacitors. To impart functionality such as maintaining or increasing the amount of incident light, a surface layer that is resistant to water and dirt, or a function to collect or guide light, may be added.

[0077] [Mobile object] Fig. 6 is a perspective view schematically showing one embodiment of a mobile object equipped with a photoelectric conversion element of the present invention. The mobile object 30 has a photoelectric conversion element 31 of the present invention and a body 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed in a position on the body 32 where it can receive external light. If the mobile object 30 is an automobile, it may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 may power the mobile object 30 or may power other electrical equipment. Electrical energy generated from the power of the mobile object 30 may be used to power the photoelectric conversion element 31. If the mobile object 30 is an automobile, frictional energy generated by braking may be converted into electrical energy and used to control the photoelectric conversion element 31.

[0078] The mobile object 30 may be, for example, an automobile, a motorcycle, a railroad vehicle, a ship, an artificial satellite, an airplane, or a flying object including a drone. The configuration of the body 32 of the mobile object 30 is not particularly limited, but it is preferably made of a high-strength material.

[0079] 7 is a perspective view schematically showing one embodiment of a building material including a photoelectric conversion element of the present invention. The building material 40 may be the roof of a building. The building material 40 of this embodiment has a photoelectric conversion element 41 of the present invention, a protective member 42 that protects the photoelectric conversion element 41, a heat dissipation member 43, and exterior coverings 44a and 44b.

[0080] The building material 40 of the present invention may have a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, sunlight may increase the temperature of the photoelectric conversion element 41, potentially reducing the photoelectric conversion efficiency. The use of the heat dissipation member 43 can reduce the reduction in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include a metal, an alloy, a liquid metal, and a liquid resin.

[0081] The building material 40 of the present invention may also have exterior coatings 44a and 44b. The exterior coatings 44a and 44b may emit different colors or may be the same. 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior coating. A material with low light absorption and high heat insulation properties is preferred.

[0082] In addition to the above application examples, the following can be mentioned: Portable devices include calculators, sensors, and small solar panels. Wearable devices include eyeglass-type terminals, wristwatch-type terminals, and portable medical equipment. Sheet structures supported by multiple frames include tents, greenhouses, and truck beds. Fixed structures include road panels, floating panels, building materials that take advantage of the flexibility of the substrate, wall-type building materials, glass-type building materials, and mega solar panels.

[0083] [Method for manufacturing photoelectric conversion element] The method for manufacturing the photoelectric conversion element of the present invention includes the steps of forming a first electrode, forming a second electrode, and forming a photoelectric conversion layer containing crystals with a perovskite structure between the first electrode and the second electrode. Each step of the manufacturing method will be described below.

[0084] [Step of Forming a First Electrode and Step of Forming a Second Electrode] The method for manufacturing a photoelectric conversion element of the present invention includes a step of forming a first electrode and a step of forming a second electrode. For the step of forming the first electrode and the step of forming the second electrode, appropriate methods can be selected depending on the materials of the first electrode and the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering, vacuum deposition, CVD (chemical vapor deposition), and SPD (spray pyrolysis deposition). The materials for the first electrode and the second electrode are as described above. When either or both of the first electrode and the second electrode are transparent electrodes, the thickness of the transparent electrode is preferably 0.03 μm or more and 3 μm or less. When manufacturing a solar cell, cutting may be performed between each step to form a circuit. Examples of cutting include mechanical patterning and laser patterning.

[0085] [Modularization Process] The elements having electrodes formed thereon may be sealed. Examples of sealing methods include sealing with a resin or sealing with a film. Examples of materials used for sealing include silazane, silicone rubber, resins having a siloxane skeleton, and glass. In addition, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll-to-roll manner, the surfaces of the sealed elements may be subjected to a hairline treatment.

[0086] [Step of Forming Photoelectric Conversion Layer] The step of forming the photoelectric conversion layer may include a step of applying a liquid containing the above-mentioned photoelectric conversion layer material. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, molding, print transfer, immersion and lifting, inkjet printing, spraying, and vacuum deposition. Among these, an appropriate method is selected depending on the characteristics of the photoelectric conversion layer to be produced, such as thickness control and orientation control. Annealing may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere) to remove the solvent or dispersion medium from the applied liquid containing the photoelectric conversion layer material. The temperature of the annealing treatment is preferably 40°C or higher and 300°C or lower, and more preferably 50°C or higher and 150°C or lower. Annealing is preferable because it may increase the contact area at the interface between the stacked layers due to the penetration of the materials constituting each layer into each other, thereby increasing the short-circuit current.

[0087] [Step of Forming Charge Transport Layer] The method for producing the photoelectric conversion element of the present invention may include a step of forming a charge transport layer between the photoelectric conversion layer and the first electrode. The step of forming the charge transport layer is preferably a method of applying a resin solution in which an insulating resin is dissolved. This allows the insulating resin to preferentially penetrate into gaps between perovskite crystal grains. Examples of the step of forming the charge transport layer include the following: a method of disposing charge transport particles on the surface of the photoelectric conversion layer and then applying a resin solution in which an insulating resin is dissolved. Alternatively, a method of disposing charge transport particles on the surface of the photoelectric conversion layer and then applying a resin solution in which an insulating resin is dissolved. Alternatively, a method of disposing charge transport particles in a resin solution in which an insulating resin is dissolved. Alternatively, a method of applying a solution in which charge transport particles are dispersed in a resin solution in which an insulating resin is dissolved onto the surface of the photoelectric conversion layer.

[0088] [Impedance Measurement and Analysis] The impedance was measured by connecting the first and second electrodes of the photoelectric conversion element to an impedance analyzer through appropriate probes, and applying a DC voltage component V ＤＣ = 0 [V], root mean square of AC voltage component V ｒｍｓ = 50 [mV] AC voltage with a frequency of 1.0 × 10 －２ [Hz] ~1.0×10 ６ The frequency is varied between [Hz] and [Hz].

[0089] Various impedance analyzers can be used for the measurement, such as ModuLab XM MTS (manufactured by Solartron Corporation). Alternatively, an SI1287 electrochemical interface (manufactured by Toyo Corporation) can be used as the power supply, a DIELECTRIC INTERFACE solartron 1296 (manufactured by Toyo Corporation) as the current amplifier, an IMPEDANCE / GAINPHASE ANALYZER solartron SI1260 (manufactured by Toyo Corporation) as the ammeter, and Solartron Material Research and Test software Ver. 3.0.1 (manufactured by Solartron Analytical Corporation) can also be used as the measurement software.

[0090] The obtained data can be analyzed using various analytical software, such as the analytical software Zview Ver. 4 (manufactured by Scribner Associates).

[0091] In the present invention, analysis is performed on plots based on impedance measurement results, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg] (phase graph of a Bode diagram), and Nyquist plots with the horizontal axis being the real part of impedance Z' [Ω] and the vertical axis being the imaginary part of impedance Z'' [Ω]. In particular, for the analysis of Nyquist plots, specifically, a two-axis graph consisting of the real component Z' and the imaginary component Z'' of impedance Z is created, and when it is expressed in coordinates (Z', Z''), this is fitted using an appropriate equivalent circuit. In this case, in the low frequency range (1.0 x 10 －２ [Hz] or more 1.0×10 ２ [Hz]) and high frequency range (less than 1.0 × 10 ２ [Hz] or more 1.0×10 ６ In order to obtain the resistance (R) and constant phase element (CPE) indices for each frequency band (Hz or less), analysis is facilitated by using an equivalent circuit in which at least two "resistance element-constant phase element parallel circuits (RCPE parallel circuits)" are connected in series. For example, as shown in FIG. 4, there is an equivalent circuit in which one series resistance (R1), one series inductance (L1), and three "resistance element-constant phase element parallel circuits" ("R4-CPE3," "R2-CPE1," and "R3-CPE2") are connected in series. FIG. 2 shows the Nyquist plot of the results of fitting the photoelectric conversion element 4 according to the present invention to the equivalent circuit of FIG. 4, as implemented in Example 4 of the present invention. However, the impedance analysis of the present invention is not limited to the use of this equivalent circuit. Alternatively, the impedance parameters of the present invention may be obtained by using another analysis method that does not use an equivalent circuit, for example, by extracting only the necessary arcs on the Nyquist plot and fitting them to one resistance element-constant phase element parallel circuit.

[0092] In the present invention, ModuLab XM MTS (manufactured by Solartron) was used for impedance measurement. The measurement conditions are as follows: <Measurement conditions for ModuLab XM MTS> Experiment type: Sample & Reference Instrument configuration: Mat + Femto Ammometer Ground: Internal DC: 0 V AC: 0.05 V ｒｍｓ Frequency: 1MHz to 0.01Hz Number of measurement points: 6 points / decade

[0093] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0094] <Preparation of Particles 1> Step (1) Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were added to a reaction vessel, which was then heated to 30°C and maintained at that temperature. Next, 3.75 parts of gallium trichloride was added at this temperature (30°C). The water concentration of the mixed solution at the time of addition was 150 ppm. The temperature was then increased to 200°C. Next, under a nitrogen flow atmosphere, the mixture was reacted at 200°C for 4.5 hours, cooled, and when the temperature reached 150°C, the product was filtered. The resulting filtrate was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, followed by filtration. The resulting filtrate was washed with methanol and dried to obtain chlorogallium phthalocyanine particles in a yield of 71%.

[0095] Step (2) 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at a temperature of 10°C, and the solution was dropped into 620 parts of ice water under stirring to reprecipitate, followed by vacuum filtration using a filter press. No. 5C (manufactured by Advantec Co., Ltd.) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press. Next, the obtained wet cake (filtrate) was dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solids content of 23% by mass in a yield of 71%. The hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (product name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) to obtain hydroxygallium phthalocyanine (HOGaPc) particles (crystals) with a water content of 1.0 mass % or less.

[0096] Step (3) Five parts of the hydroxygallium phthalocyanine particles were mixed with five parts of an N-methylformamide solvent, and the mixture was dispersed for six hours using a sand mill (TSG-1 / 4G-4U, manufactured by Igarashi Machinery Manufacturing Co., Ltd. (now Imex Co., Ltd.), disk diameter 70 mm, number of disks 5) containing five parts of glass beads, filtered, and dried to obtain particles 1 (specific gravity 1.6).

[0097] <Preparation of Resin Solution 1> Resin solution 1 was obtained by dissolving 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity 1.6) in 19 g of 2-propanol with stirring for 24 hours.

[0098] (Fabrication of Photoelectric Conversion Element) (Fabrication of Photoelectric Conversion Element 1) [Formation of Electron Transport Layer] A glass substrate with ITO was cleaned, and a 5-fold diluted tin oxide (2) colloidal solution (15% aqueous dispersion, manufactured by Alfa Aesar) was applied thereon by spin coating, followed by heating at 150°C for 30 minutes to form a thin-film electron transport layer with a thickness of 16 nm.

[0099] [Formation of Photoelectric Conversion Layer] 0.487 g of lead bromide, 1.034 g of formamidium iodide, 2.903 g of lead iodide, and 0.139 g of methylammonium bromide were dissolved in 4.25 g of N,N-dimethylformamide and 1.216 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 1). Furthermore, 0.100 g of cesium iodide was dissolved in 0.285 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 2). The dissolved cesium iodide solution (Solution 2) was then added to Solution 1 to prepare a coating solution for the photoelectric conversion layer. This coating solution was spin-coated on the electron transport layer, thereby forming a Cs ０．０５ (FA ０．８３ MA ０．１７ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ A photoelectric conversion layer having a thickness of 600 nm was formed.

[0100] [Formation of Charge Transport Layer] 0.1 g of the particles 1 and 0.01 g of a calixarene compound (JP 2003-207913 A) were mixed with 10.6 g of 2-propanol. 11 g of beads (zirconia beads, Treceram (registered trademark) zirconia beads, 0.3 mm) were encapsulated in this mixture, and the mixture was dispersed in a paint shaker (manufactured by Toyo Seiki Seisaku-sho). 0.2 g of resin solution 1 was then added, and the mixture was dispersed again in a paint shaker for 4 hours to prepare a coating liquid for the charge transport layer. This coating liquid for the charge transport layer was spin-coated on the photoelectric conversion layer to form a charge transport layer with a thickness of 180 nm.

[0101] [Introduction of Second Charge Transport Layer] 0.15 g of Spiro-OMeTAD, a material for the second charge transport layer, was dissolved in 2.2 g of chlorobenzene. To this chlorobenzene solution, 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile was added, and 60 μL of 4-tert-butylpyridine (TBP) were mixed. Furthermore, 58 μL of an acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile was added to prepare a coating solution for the second charge transport layer. This solution was applied to the charge transport layer by spin coating to form a second charge transport layer with a thickness of 100 nm.

[0102] [Formation of First Electrode] A first electrode having a thickness of 80 nm and an area of ​​0.09 cm was formed on the second charge transport layer. ２ The gold electrode was formed by vacuum deposition to obtain a photoelectric conversion element 1. In the example according to the present invention, the first electrode was a small electrode.

[0103] [Analysis of Compound Amount] The electrode surface of the photoelectric conversion element was peeled off to expose the charge transport layer surface. This charge transport layer surface was wiped with a cotton swab or the like soaked in a solvent, dissolved in heavy water sulfuric acid, and subjected to 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER). The peeled charge transport layer components were subjected to mass and structural analysis using elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of the compound. The film thickness was also confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then using a cross-sectional SEM (apparatus: SmartSEM, manufactured by Carl Zeiss K.K.).

[0104] [Analysis of particle size of charge transport material] The particle size of the charge transport material is the number-average particle size in the particle size distribution. In the present invention, the particle size of the charge transport material was determined by an image imaging method using a TEM. Specifically, first, using the obtained TEM image of the cross section of the charge transport layer, N particles (N is 1,000 or more) were extracted using image processing software Photoshop (manufactured by Adobe). Next, the area S of each particle was determined, and the diameter of a circle with the same area (= 2 × (S / π) 1 / 2) was used as the particle size, and the average value of the median 80% of the N particles was taken. The element configuration of photoelectric conversion element 1 is shown in Table 2.

[0105] (Preparation of Photoelectric Conversion Elements 2 to 7 and 21) Photoelectric conversion elements 2 to 7 and 21 are obtained in the same manner as in the preparation of photoelectric conversion element 1, except that the volume ratio of the charge transport material to the insulating resin is changed to the value shown in Table 2.

[0106] (Preparation of photoelectric conversion element 8) In forming the charge transport layer, the coating liquid for the charge transport layer obtained by paint shaker dispersion is further centrifuged (at 15,000 rpm for 6 minutes) to reduce the particle size in the dispersion, and then the volume ratio of the charge transport material to the insulating resin is adjusted to be 10 times, and photoelectric conversion element 8 is obtained in the same manner as photoelectric conversion element 1.

[0107] (Preparation of Photoelectric Conversion Element 9) Photoelectric conversion element 9 is obtained in the same manner as photoelectric conversion element 1, except that the polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd.) is replaced with polyvinyl butyral (product name: BX-1, manufactured by Sekisui Chemical Co., Ltd.).

[0108] (Preparation of Photoelectric Conversion Element 10) Photoelectric conversion element 10 is obtained in the same manner as photoelectric conversion element 1, except that the calixarene compound is changed to 2-naphthol.

[0109] (Preparation of Photoelectric Conversion Element 11) Photoelectric conversion element 11 is obtained in the same manner as photoelectric conversion element 1, except that the particles 1 are nickel phthalocyanine particles.

[0110] (Fabrication of Photoelectric Conversion Element 12) Photoelectric conversion element 12 is obtained in the same manner as photoelectric conversion element 1, except that the second charge transport layer is not provided.

[0111] (Preparation of Photoelectric Conversion Element 13) Photoelectric conversion element 13 is obtained in the same manner as photoelectric conversion element 1, except that the calixarene compound is not used.

[0112] (Preparation of Photoelectric Conversion Element 14) Photoelectric conversion element 14 is obtained in the same manner as photoelectric conversion element 1, except that polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 70°C) is used instead of the polyvinyl butyral.

[0113] (Preparation of Photoelectric Conversion Element 15) Photoelectric conversion element 15 is obtained in the same manner as photoelectric conversion element 1, except that polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 100°C) is used instead of the polyvinyl butyral.

[0114] (Preparation of Photoelectric Conversion Element 16) Photoelectric conversion element 16 is obtained in the same manner as photoelectric conversion element 1, except that particles 1 are particles containing the compound represented by (Pc-3).

[0115] (Preparation of Photoelectric Conversion Element 17) Photoelectric conversion element 17 is obtained in the same manner as photoelectric conversion element 1, except that particles 1 are replaced with quinacridone particles.

[0116] (Fabrication of Photoelectric Conversion Element 18) A photoelectric conversion element 18 is obtained in the same manner as in Example 1, except that the composition of the photoelectric conversion layer is changed to MAPbI3.

[0117] (Preparation of photoelectric conversion element 19) Photoelectric conversion element 19 is obtained in the same manner as photoelectric conversion element 1, except that a layer similar to the second charge transport layer formed in photoelectric conversion element 1 is formed as the charge transport layer of photoelectric conversion element 19, and the second charge transport layer is not provided on the charge transport layer.

[0118] (Preparation of Photoelectric Conversion Element 20) Photoelectric conversion element 20 is obtained in the same manner as photoelectric conversion element 1, except that the particles 1 are not used.

[0119] (Preparation of photoelectric conversion element 22) Photoelectric conversion element 22 is obtained in the same manner as photoelectric conversion element 15, except that the particles 1 are Spiro-OMeTAD, the volume ratio of the charge transport material to the insulating resin is 1, the film thickness of the charge transport layer is 100 nm, no calixarene compound is used, and no second charge transport layer is provided on the charge transport layer.

[0120] (Fabrication of Photoelectric Conversion Element 23) Photoelectric conversion element 23 is obtained in the same manner as photoelectric conversion element 22, except that the thickness of the charge transport layer is set to 180 nm.

[0121] (Fabrication of Photoelectric Conversion Element 24) The photoelectric conversion element 24 is obtained in the same manner as the photoelectric conversion element 22, except that the thickness of the charge transport layer is set to 300 nm.

[0122] (Preparation of Photoelectric Conversion Element 25) Photoelectric conversion element 25 is obtained in the same manner as photoelectric conversion element 15, except that the particles 1 are Spiro-OMeTAD, the film thickness of the charge transport layer is 180 nm, and a second charge transport layer is not provided on the charge transport layer.

[0123] (Preparation of Photoelectric Conversion Element 26) Photoelectric conversion element 26 is obtained in the same manner as photoelectric conversion element 1, except that the particles 1 are changed to nickel (II) phthalocyanine-tetrasulfonic acid tetrasodium salt particles and the insulating resin is changed to PEDOT:PSS.

[0124] (Preparation of photoelectric conversion element 27) Photoelectric conversion element 27 is obtained in the same manner as photoelectric conversion element 1, except that particle 1 is made into a particle having a compound represented by the following formula (Pc-4) and further made into the insulating resin P3HT.

[0125] (Example 1) [Evaluation] The impedance of the photoelectric conversion element 1 fabricated in (Fabrication of photoelectric conversion element) was measured. A ModuLab XM MTS (manufactured by Solartron) was used for the measurement. The obtained impedance data was fitted using the equivalent circuit shown in FIG. 4 as shown in the example of FIG. 2 (FIG. 2 is an example of a photoelectric conversion element 4), and R ｒｅｃ × S [Ω cm ２ ], R ｒｅｃ / R ｃｔ , Pｒｅｃ , P ｃｔ The results are shown in Table 3.

[0126] Next, a power supply (KEITHLEY, Model 236) was connected between the electrodes of the photoelectric conversion element 1, and an intensity of 110 mW / cm ２ The initial photoelectric conversion efficiency was measured by irradiating the device with a constant amount of light using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and measuring the generated current and voltage. Measurements were also made at 10 electrodes for each device, and the average value was used as the representative value for that device. The results are shown in Table 3. After that, the device was continuously irradiated with 10,000 Lx of light from a white LED, and the photoelectric conversion efficiency after 50 days was measured. The maintenance rate of the photoelectric conversion efficiency after 50 days relative to the initial photoelectric conversion efficiency was evaluated. The results are shown in Table 3. In Table 3, the photoelectric conversion efficiency in Example 1 was set to 100%, and the conversion efficiency of each device was expressed as a percentage of this efficiency.

[0127] The initial photoelectric conversion efficiency and the maintenance rate of photoelectric conversion efficiency were evaluated for Examples 2 to 18 and Comparative Examples 1 to 9 in the same manner as in Example 1. The results are shown in Table 3. For Comparative Example 2, the initial photoelectric conversion was not measured, and the maintenance rate of photoelectric conversion could not be evaluated.

[0128]

[0129]

[0130] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0131] This application is related to Japanese Patent Application No. 2023-184761 filed on October 27, 2023, Japanese Patent Application No. 2023-184756 filed on October 27, 2023, Japanese Patent Application No. 2023-184750 filed on October 27, 2023, Japanese Patent Application No. 2023-216294 filed on December 21, 2023, Japanese Patent Application No. 2023-216296 filed on December 21, 2023, and Japanese Patent Application No. 2023-216297 filed on December 21, 2023. Priority is claimed based on Japanese Patent Application No. 2023-216299, Japanese Patent Application No. 2024-022244 filed on February 16, 2024, Japanese Patent Application No. 2024-022251 filed on February 16, 2024, Japanese Patent Application No. 2024-022246 filed on February 16, 2024, and Japanese Patent Application No. 2024-085998 filed on May 28, 2024, the entire contents of which are incorporated herein by reference.

[0132] REFERENCE SIGNS LIST 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode 30 Mobile body 31, 41 Photoelectric conversion element 32 Airframe 40 Building material 42 Protective member 43 Heat dissipation member 44a, 44b Exterior

Claims

1. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal of a perovskite structure disposed between the first electrode and the second electrode, wherein the smaller of the electrode areas of the first electrode and the second electrode is S [cm ２ ], and a DC voltage component V ＤＣ = 0 [V], the root mean square of the AC voltage component V ｒｍｓ = 50 [mV] AC voltage with frequency 1.0 x 10 －２ [Hz] ~1.0×10 ６ When the impedance was measured while changing the frequency between 1.0×10 and 2.0×10, the impedance was measured by plotting the frequency (Hz) on the horizontal axis and the phase (deg) on ​​the vertical axis. －２ [Hz] or more 1.0×10 ２ The phase of the impedance has a maximum value in a low frequency range of less than 1.0 × 10 ２ [Hz] or more 1.0×10 ６ The phase of the impedance has a maximum value in a high frequency range of not more than 1000 Hz, and in a Nyquist plot based on the measurement results of the impedance, with the horizontal axis being the real part of the impedance Z' [Ω] and the vertical axis being the imaginary part of the impedance Z'' [Ω], the maximum value R among the resistance values ​​obtained by fitting an arc corresponding to the maximum value of the phase in the low frequency range with a parallel circuit of a resistor element and a constant phase element is ｒｅｃ [Ω] satisfies the following formula (E1): 1.0×10 ４ ≦R ｒｅｃ × S ≦ 1.0 × 10 ７ (E1) The maximum value R among the resistance values ​​obtained by fitting the arc corresponding to the maximum value of the phase in the high frequency range with a parallel circuit of a resistance element and a constant phase element ｃｔ [Ω] and the R ｒｅｃ [Ω] satisfies the following formula (E2); ｒｅｃ / R ｃｔ ≧25 (E2).

2. The above R ｒｅｃ The exponent P of the constant phase element obtained by fitting to obtain [Ω] ｒｅｃ The photoelectric conversion element according to claim 1 , wherein P satisfies the following formula (E3): ｒｅｃ ≧0.80 (E3) 3. The above R ｃｔ The exponent P of the constant phase element obtained by fitting to obtain [Ω] ｃｔ The photoelectric conversion element according to claim 1 or 2, wherein P satisfies the following formula (E4): ｃｔ ≦0.95 (E4) 4. The above R ｒｅｃ The photoelectric conversion element according to any one of claims 1 to 3, wherein [Ω] satisfies the following formula (E5): ５ <R ｒｅｃ ×S<1.0×10 ６ (E5) 5. The above R ｃｔ [Ω] and the R ｒｅｃ The photoelectric conversion element according to any one of claims 1 to 4, wherein [Ω] satisfies the following formula (E6): ｒｅｃ / R ｃｔ ≧50 (E6) 6. The photoelectric conversion element according to any one of claims 1 to 5, wherein the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, and the charge transport layer contains a charge transport material and an insulating resin on the surface of the photoelectric conversion layer.

7. The photoelectric conversion element according to claim 6, wherein the charge transport material is a charge transport particle.

8. The photoelectric conversion element according to claim 7, wherein the charge transporting particles have an average particle size of 10 nm or more and 500 nm or less.

9. The photoelectric conversion element according to claim 6, wherein a volume ratio of said charge transport material to said insulating resin is 5 times or more and 30 times or less.

10. The photoelectric conversion element according to claim 6, wherein the charge transport material is a phthalocyanine compound.

11. The photoelectric conversion element according to claim 10, wherein the phthalocyanine compound has a structure represented by the following formula (Pc-2): (In the above formula (Pc-2), M represents H2 or a metal atom which may have a ligand.) 12. The photoelectric conversion element according to claim 6, wherein the glass transition temperature of the insulating resin is 95° C. or lower.

13. The photoelectric conversion element according to claim 6, wherein the insulating resin is a polyvinyl acetal resin or a polyvinyl butyral resin.

14. The photoelectric conversion element according to claim 6, wherein the charge transport layer contains an aromatic ring compound having a hydroxyl group different from those of the charge transport material and the insulating resin.

15. The photoelectric conversion element according to claim 6, further comprising a second charge transport layer between the first electrode and the charge transport layer.

16. A photoelectric conversion device comprising the photoelectric conversion element according to any one of claims 1 to 15.

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