Photoelectric conversion element and photoelectric conversion device

Abstract

Provided is a photoelectric conversion element having improved durability while achieving high initial photoelectric conversion efficiency. The photoelectric conversion element includes 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 an electrode area of the first electrode and an electrode area of the second electrode is S [cm2], S [cm2] is S [cm2] in a Nyquist map based on an impedance measurement result; the maximum value Rrecc [omega] among resistance values obtained by fitting an arc corresponding to a phase maximum value in a low-frequency range by a parallel circuit of the resistive element and the constant-phase element satisfies the following formula (E1): 1.0 * 104 lt; rrec* Slt; 1.0 * 107 (E1), and a maximum value Rct [Omega] and Rrecc [Omega] among resistance values obtained by fitting an arc corresponding to a phase maximum value in a high-frequency range by a parallel circuit of the resistive element and the constant-phase element satisfy the following equation (E2): Rrecc / Rct > = 25 (E2).

Description

Technical Field

[0001] This invention relates to photoelectric conversion elements and photoelectric conversion devices. Background Technology

[0002] To address the depletion of fossil fuels and the global environmental problems caused by their use, research has been actively conducted on renewable and clean alternative energy sources such as solar, wind, and hydropower. In particular, there is increasing interest in solar cells, which directly convert sunlight into electricity. As used herein, the term "solar cell" refers to a cell that generates current and voltage by utilizing the photovoltaic effect, in which light energy is absorbed from sunlight to produce electrons and holes.

[0003] Recently, NP diode-based silicon (Si) monocrystalline solar cells with a light conversion efficiency greater than 20% have become widely known and are already being used in solar power generation. However, solar cells require high-temperature processing steps, and the materials themselves are expensive, resulting in a high cost per unit of electricity. Furthermore, there are supply issues regarding silicon resources.

[0004] Meanwhile, solar cells using organic materials (hereinafter also referred to as "organic solar cells") do not require high-temperature processing steps and can be produced on sheet-like substrates in so-called roll-to-roll systems. Therefore, cost reduction is desirable. However, for the practical application of organic solar cells, further improvements in power generation efficiency and durability are expected. In particular, the development of perovskite solar cells, which include crystals with a perovskite structure as the photoelectric conversion layer, has been progressing towards practical application due to the excellent photoelectric conversion characteristics of this cell.

[0005] Patent document 1 describes a technique that includes introducing organic semiconductors and polymeric compounds with a glass transition temperature of 100°C or higher into the hole transport layer to improve its stripping from the electrode.

[0006] Patent document 2 describes a configuration in which a layer formed of quinacridone pigment is disposed between a perovskite layer and a hole transport layer, and the impedance measurement results of this configuration.

[0007] Non-Patent Document 1 describes a technique for an inverse layer charge transport layer that improves photoelectric conversion efficiency by doping PEDOT:PSS with nickel phthalocyanine having substituents.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2018-170382

[0011] Patent Document 2: U.S. Patent Application Publication No. 2022 / 0285642

[0012] Non-patent literature

[0013] Non-patent literature 1: X.-F. Zhang, J. Mater. Chem. A, 2018, 6, 12515-12522 Summary of the Invention

[0014] Technical issues

[0015] According to research conducted by the inventors of this invention, it has been found that each of the photoelectric conversion elements described in Patent Document 1, Patent Document 2 and Non-Patent Document 1 has room for improvement in terms of durability.

[0016] Therefore, the present invention aims to provide photoelectric conversion elements and photoelectric conversion devices in which the durability of each is improved.

[0017] Solution to the problem

[0018] The above-mentioned objective is achieved by the present invention described below. Specifically, the photoelectric conversion element according to the present invention comprises: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure.

[0019] Wherein, the smaller of the electrode areas of the first electrode and the second electrode is S[cm] 2 ]express,

[0020] And by applying a DC voltage component V to the photoelectric conversion element DC =0[V] and the root mean square V of the AC voltage component rms =50mV AC voltage, while its frequency is changed from 1.0×10 -2 [Hz] changed to 1.0×10 6 When measuring impedance using [Hz]

[0021] In a graph of impedance-based measurement results, where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg],

[0022] The phase of the impedance is at 1.0 × 10⁻⁶. -2 Less than 1.0 × 10 2 It has a maximum value in the low-frequency range of [Hz].

[0023] And the phase of the impedance is 1.0 × 10 2 Up to 1.0×10 6It has a maximum value in the high-frequency range of [Hz], and in the Nyquist plot based on impedance measurements, where the horizontal axis represents the real part of the impedance Z′ [Ω] and the vertical axis represents the imaginary part of the impedance Z″ [Ω],

[0024] The maximum value R of the resistance obtained by fitting the arc corresponding to the phase maxima in the low-frequency range with a parallel circuit of resistive elements and constant-phase elements. rec [Ω] satisfies the following equation (E1):

[0025] 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1)

[0026] Furthermore, the maximum resistance value R is obtained by fitting the arc corresponding to the phase maxima in the high-frequency range with a parallel circuit of resistive elements and constant-phase elements. ct [Ω], with R rec [Ω] satisfies the following equation (E2):

[0027] R rec / R ct ≥25 (E2).

[0028] Advantages of the present invention

[0029] According to the present invention, a photoelectric conversion element with improved durability and high initial photoelectric conversion efficiency can be provided. Attached Figure Description

[0030] [ Figure 1 The figure is obtained in Embodiment 4 of the present invention, where the horizontal axis of the impedance data represents the frequency [Hz] and the vertical axis represents the phase [deg].

[0031] [ Figure 2 [ ] is the Nyquist plot of the impedance data and fitted curve obtained in Embodiment 4 of the present invention.

[0032] [ Figure 3 Figures (a) and (b) are diagrams describing the meaning of the arcs corresponding to the maximum value of the phase in this invention.

[0033] [ Figure 4 [This is an example of an equivalent circuit used in impedance analysis fitting in embodiments of the present invention.]

[0034] [ Figure 5 [Illustrated cross-sectional view of the photoelectric conversion element in the thickness direction according to the first embodiment of the present invention.]

[0035] [ Figure 6[This is a perspective view schematically illustrating a movable body including a photoelectric conversion element according to one embodiment of the present invention.]

[0036] [ Figure 7 [This is a perspective view schematically illustrating a building material including a photoelectric conversion element according to one embodiment of the present invention.] Detailed Implementation

[0037] The photoelectric conversion element of the present invention comprises: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the layer comprising a crystal having a perovskite structure. The element is characterized in that:

[0038] When the smaller of the electrode areas of the first electrode and the second electrode is S[cm 2 ]express,

[0039] And by applying a DC voltage component V to the photoelectric conversion element DC =0[V] and the root mean square V of the AC voltage component rms =50mV AC voltage, while its frequency is changed from 1.0×10 -2 [Hz] changed to 1.0×10 6 When measuring impedance using [Hz]

[0040] In a graph of impedance-based measurement results, where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg],

[0041] The phase of the impedance is at 1.0 × 10⁻⁶. -2 Less than 1.0 × 10 2 It has a maximum value in the low-frequency range of [Hz].

[0042] And the phase of the impedance is 1.0 × 10 2 Up to 1.0×10 6 It has a maximum value in the high-frequency range of [Hz];

[0043] Furthermore, in the Nyquist plot based on impedance measurements, where the horizontal axis represents the real part of the impedance Z′ [Ω] and the vertical axis represents the imaginary part of the impedance Z″ [Ω],

[0044] The maximum value R of the resistance obtained by fitting the arc corresponding to the phase maxima in the low-frequency range with a parallel circuit of resistive elements and constant-phase elements. rec [Ω] satisfies the following equation (E1):

[0045] 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1)

[0046] Furthermore, the maximum resistance value R is obtained by fitting the arc corresponding to the phase maxima in the high-frequency range with a parallel circuit of resistive elements and constant-phase elements. ct [Ω], with R rec [Ω] satisfies the following equation (E2):

[0047] R rec / R ct ≥25 (E2).

[0048] As a result of research conducted by the inventors of this invention, it has been discovered that by satisfying the above-described configuration, the degradation of the photoelectric conversion element during its long-term use due to defects in the photoelectric conversion layer can be suppressed. In related technologies, when the resistance of the photoelectric conversion element is increased to suppress its degradation, the movement of charges generated in the photoelectric conversion layer is hindered, and its initial photoelectric conversion efficiency deteriorates. Conversely, when the resistance is decreased to improve the initial photoelectric conversion efficiency, the degradation suppression effect becomes insufficient.

[0049] In view of the above, the inventors of this invention have discovered that, under the condition that the impedance at low frequencies satisfies the following equation (E1), when the ratio of the impedance at low frequencies to the impedance at high frequencies satisfies R... rec / R ct At a value of ≥25, both initial photoelectric conversion efficiency and degradation suppression can be achieved.

[0050] 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1).

[0051] The inventors of this invention speculate on the reasons mentioned above as follows.

[0052] On the one hand, the impedance R at low frequencies rec [Ω] refers to the recombination resistance, which is related to the difficulty of recombination of electrons and holes generated in the photoelectric conversion layer. When the value exceeds a certain threshold, durability degradation is suppressed. However, when the value is too large, the initial photoelectric conversion efficiency deteriorates. The following equation (E1) needs to be satisfied to achieve a balance between suppression and efficiency:

[0053] 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1).

[0054] On the other hand, the impedance R at high frequencies ct[Ω] refers to the charge transfer resistance, which is related to the ease of charge movement when the photoelectric conversion element performs photoelectric conversion, and the initial photoelectric conversion efficiency improves as the value becomes smaller. Therefore, in addition to equation (E1), the following equation (E2) also needs to be satisfied to achieve both initial photoelectric conversion efficiency and suppression of degradation:

[0055] R rec / R ct ≥25 (E2).

[0056] As stated above, by providing conditions for the correlation between impedance characteristic values ​​in different frequency ranges as given in Equation (E2), rather than providing conditions for the range of a single impedance characteristic value or the range of each of multiple impedance characteristic values ​​as given in Equation (E1), the related technical difficulties of achieving initial photoelectric conversion efficiency and suppressing degradation can be largely solved.

[0057] The effects of the present invention can be achieved when the components work synergistically with each other in the mechanism described above.

[0058] The present invention will now be described in detail by way of preferred embodiments. The present invention is not limited to the following embodiments, and the following embodiments, with appropriate changes and modifications based on common knowledge of those skilled in the art without departing from the spirit of the invention, are also included within the scope of the present invention.

[0059] [Impedance characteristics of the present invention]

[0060] The photoelectric conversion element of the present invention comprises: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the layer comprising a crystal having a perovskite structure. The element is characterized in that:

[0061] When the smaller of the electrode areas of the first electrode and the second electrode is S[cm 2 ]express,

[0062] And by applying a DC voltage component V to the photoelectric conversion element DC =0[V] and the root mean square V of the AC voltage component rms =50mV AC voltage, while its frequency is changed from 1.0×10 -2 [Hz] changed to 1.0×10 6 When measuring impedance using [Hz]

[0063] In a graph of impedance-based measurement results, where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg],

[0064] The phase of the impedance is at 1.0 × 10⁻⁶. -2 Less than 1.0 × 102 It has a maximum value in the low-frequency range of [Hz].

[0065] And the phase of the impedance is 1.0 × 10 2 Up to 1.0×10 6 It has a maximum value in the high-frequency range of [Hz]; and

[0066] In the Nyquist plot based on impedance measurements, where the horizontal axis represents the real part of the impedance Z′ [Ω] and the vertical axis represents the imaginary part of the impedance Z″ [Ω],

[0067] The maximum value R of the resistance obtained by fitting the arc corresponding to the phase maxima in the low-frequency range with a parallel circuit of resistive elements and constant-phase elements. rec [Ω] satisfies the following equation (E1):

[0068] 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1)

[0069] Furthermore, the maximum resistance value R is obtained by fitting the arc corresponding to the phase maxima in the high-frequency range with a parallel circuit of resistive elements and constant-phase elements. ct [Ω], with R rec [Ω] satisfies the following equation (E2):

[0070] R rec / R ct ≥25 (E2).

[0071] In this article, a graph is used where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg], as shown below. Figure 1 The figure shown is a graph in which the frequency value of the AC voltage in the impedance measurement is correlated with the angle “arctan(Z″ / Z′)” formed by the real part Z′ and the imaginary part Z″ of the impedance obtained when the frequency is applied to the complex plane.

[0072] Furthermore, the Nyquist plot, in which the horizontal axis represents the real part of the impedance Z′[Ω] and the vertical axis represents the imaginary part of the impedance Z″[Ω], corresponds to... Figure 2 The diagram shown is plotted on the complex plane of the real part Z′ and the imaginary part Z″ of the impedance.

[0073] However, in this invention, -Z″ is used as the vertical axis for both positive and negative signs. Correspondingly, in this invention, the - (negative) direction is also used as the vertical axis for phase [deg]. Therefore, the maximum value of phase in the low-frequency or high-frequency range in this invention refers to the extreme value of phase increase in the - direction.

[0074] The issues concerning positive and negative signs depend on the definition of complex impedance Z[Ω], and are not fundamental issues.

[0075] This describes the meaning of the arc corresponding to the phase maxima in the low-frequency or high-frequency range. For example... Figure 3 As shown in (a), when the maximum value in the low frequency range is determined by θ low When represented, θ low Corresponding to in Figure 3 In the Nyquist plot of (b), the slope is determined when a tangent passing through the origin is drawn to an arc that exists in the low-frequency range. Therefore, the arc corresponding to the phase maxima precisely refers to the arc to which such a tangent is drawn.

[0076] The constant phase element of the present invention is described. For example... Figure 4 As shown in the example, constant-phase elements are used in the equivalent circuit to fit impedance data, and are generated by elements appearing in... Figure 4 In the R-CPE parallel circuit, "CPE(1 to 3)" indicates the capacitor element. A constant-phase element is one in which the capacitive element (capacitor element) is mathematically distorted for fitting purposes. The complex impedance of the capacitive element is expressed by the following equation (E7):

[0077] ZC = 1 / (i²πfC) (E7)

[0078] (The conditions are that "i" represents the imaginary unit, π represents the ratio of the circumference of a circle to its diameter, "f" represents the frequency [Hz], and C represents the capacitance [F]).

[0079] The complex impedance of a constant phase element is represented by the following equation (E8).

[0080] ZCPE=1 / [(i2πf)PT] (E8)

[0081] When P=1 is satisfied (in this case, T=C is satisfied), Equation (E8) is consistent with Equation (E7), so the constant phase element is of course a mathematical transformation of the capacitor element.

[0082] The exponent P of the constant-phase element, as expressed by equation (E8), corresponds to the degree of collapse of the arc in the Nyquist plot. When the arc is a perfect semicircle, P=1, but when the arc is a semicircle sunk into the fourth quadrant of the Nyquist plot, P<1. This implies that impedance dispersion is greater when P is less than 1, because the degree of collapse of the arc in the Nyquist plot is related to impedance dispersion.

[0083] To enhance the effectiveness of the present invention, a more preferred method is to multiply by "R". rec ×S”[Ω·cm 2 It satisfies the following equation (E5):

[0084] 1.0×105 <R rec ×S<1.0×10 6 (E5).

[0085] Furthermore, it is preferred to use a material that is more than "R" rec / R ct "It satisfies the following formula (E6):"

[0086] R rec / R ct ≥50 (E6).

[0087] Furthermore, in order to more effectively suppress degradation, it is preferable to obtain R... rec The constant-phase element obtained by fitting [Ω] is the exponent P. rec The following equation (E3) must be satisfied:

[0088] P rec ≥0.80 (E3).

[0089] When equation (E3) is satisfied, the impedance dispersion corresponding to the recombination resistance at low frequencies is sufficiently small. Therefore, since the recombination resistance, which helps to hide defects in the photoelectric conversion layer, becomes uniform relative to the planar direction of the photoelectric conversion layer, the probability of hiding defects in the photoelectric conversion layer is improved.

[0090] Furthermore, in order to effectively maintain a high initial photoelectric conversion efficiency, it is preferable to obtain R... ct The constant-phase element obtained by fitting [Ω] is the exponent P. ct The following equation (E4) must be satisfied:

[0091] P ct ≤0.95 (E4).

[0092] When equation (E4) is satisfied, the impedance dispersion corresponding to the charge transfer resistor at high frequencies is sufficiently large. Therefore, because low-resistance paths for the movement of photocharge generated in the photoconversion layer are sufficiently present, high-resistance composite resistor elements that help hide global defects relative to the planar direction of the photoconversion layer and low-resistance charge transfer resistor elements that help local charge transfer paths of the photoconversion element can further coexist.

[0093] The photoelectric conversion element of the present invention and the structure of its layers are described in detail below with reference to preferred embodiments. Several examples of obtaining the above-mentioned [impedance characteristics of the present invention] are described below. Therefore, the present invention is not limited to the following embodiments, and the following embodiments, which are appropriately modified and altered based on common sense of those skilled in the art without departing from the spirit of the present invention, are also included within the scope of the present invention.

[0094] As used herein, the term "layer" refers not only to a layer with clearly defined boundaries or a flat, thin film-like structure, but also to a layer with a concentration gradient in which the concentration of elements gradually changes, or a layer that can form a complex, interwoven structure with other layers. Furthermore, elemental analysis of layers can be performed, for example, by measuring and observing the elemental distribution of specific elements through TOF-SIMS / FE-TEM / EDS line analysis of a cross-section of a photoelectric conversion element. Analysis of individual layers can be performed by peeling and removing layers from a completed photoelectric conversion element to expose the layer to be analyzed. For quantitative volume ratios, the area ratio of the exposed surface or cross-section can also be used as the volume ratio of the layers.

[0095] Figure 5 This is a schematic cross-sectional view illustrating the configuration of a photoelectric conversion element according to an embodiment of the present invention. The photoelectric conversion element 1 includes a substrate 2, and a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 disposed thereon. One of the first electrode 7 and the second electrode 3 is an anode, and the other electrode is a cathode. Current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0096] The photoelectric conversion layer 5 is excited by light entering the layer through the substrate 2, the second electrode 3, and the electron transport layer 4, or the first electrode 7 and the charge transport layer 6, to generate 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 in some cases may not be formed. Multiple electron transport layers 4 and photoelectric conversion layers 5 can be stacked. This type of arrangement can also be called a "tandem structure." The individual components are described below. Furthermore, photoelectric conversion elements can be manufactured 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.

[0097] Photoelectric conversion element

[0098] The photoelectric conversion element of the present invention is characterized by comprising: a first electrode; a second electrode; a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure; and a charge transport layer between the photoelectric conversion layer and the first electrode. Furthermore, to improve photoelectric conversion efficiency, a series configuration in which the photoelectric conversion elements are stacked can be employed. The type of stacked photoelectric conversion element is not limited, and for example, in addition to perovskite solar cells using perovskite crystals in their photoelectric conversion layers, silicon solar cells or CIGS solar cells can also be used.

[0099] Methods for forming the photoelectric conversion layer and charge transport layer of the photoelectric conversion element of the present invention include, for example, coating methods or 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 rod coating. Coating methods include preparing coating solutions for the layers described below, applying the liquids in a desired layer sequence, and drying the liquids. A desired method can be selected as such a formation method depending on the layers.

[0100] The following describes each layer.

[0101] [Substrate]

[0102] The photoelectric conversion element 1 of the present invention may include a substrate 2, and examples of such substrates include a transparent glass substrate, a ceramic substrate, and a transparent plastic substrate made of soda-lime glass or alkali-free glass. When light is incident from the side of the first electrode 7, an opaque material may be used as the substrate 2, and when light is incident from the side of the second electrode 3, the substrate 2 is formed of a transparent material.

[0103] [electrode]

[0104] The photoelectric conversion element of the present invention includes a first electrode and a second electrode. The material of the first electrode 7 or the second electrode 3 is not particularly limited, and materials known to date can be used. Examples include: metals such as gold, silver, titanium, and copper; sodium; sodium-potassium alloys; lithium; magnesium; carbon; carbon nanotubes; aluminum; magnesium-silver mixtures; magnesium-indium mixtures; aluminum-lithium alloys; Al / Al2O3 mixtures; and Al / LiF mixtures. Examples of transparent electrode materials include: conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, zinc aluminum oxide (AZO), indium zinc oxide (IZO), zinc gallium oxide (GZO), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide (ATO); and conductive transparent polymers. These materials can be used alone or in combination. At least one of the first electrode 7 or the second electrode 3 on the light incident side is a transparent electrode, and the other electrode can be a transparent electrode or may be used as a reflective layer formed of a light-reflective material, or may be a transparent electrode including a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 and the substrate 2 can be a transparent electrode and a reflective layer, respectively. The electrodes can be patterned electrodes.

[0105] [Photoelectric conversion layer]

[0106] The photoelectric conversion layer 5 comprises a crystal having a perovskite structure. The perovskite structure crystal used in the present invention is preferably represented by the following general formula [1].

[0107] ABX3 [1]

[0108] In general formula [1], A represents a monovalent cation of an organic molecule or metal atom, B represents a divalent metal cation, and X represents a monovalent halide anion.

[0109] In the case of, for example, organic molecules, A in general formula [1] preferably represents C. p N q H r ("p", "q", and "r" each represent a positive integer). Specific examples include methylammonium and formamidinium.

[0110] Furthermore, there are no particular restrictions on inorganic atoms, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms can be used alone or in combination.

[0111] When the contained cation A is too large to fit a crystal with a three-dimensional perovskite structure, a crystal with a two-dimensional perovskite structure, a 2.5-dimensional perovskite structure with properties of both two-dimensional and three-dimensional perovskite structures, a bilayer crystal with three-dimensional and two-dimensional perovskite structures, or a crystal with a mixed three-dimensional / two-dimensional perovskite structure is formed, and any of these structures serves as a photoelectric conversion layer. A bilayer crystal with a three-dimensional and two-dimensional perovskite structure refers to a crystal in which crystals with three-dimensional and two-dimensional perovskite structures are stacked as independent and separate layers. A crystal with a mixed three-dimensional / two-dimensional perovskite structure refers to a crystal with a structure in which regions or domains of crystals with two-dimensional or 2.5-dimensional layered structures and three-dimensional perovskite structures are mixed.

[0112] Preferably, crystals having a two-dimensional perovskite or 2.5-dimensional perovskite structure are represented by each of the following general formulas [2] to [4] ("n" represents a positive integer).

[0113] R′2A n-1 B n X 3n+1 [2]

[0114] R″A n-1 B n X 3n+1 [3]

[0115] [4]

[0116] General formulas [2], [3] and [4] form Ruddlesden-Popper (RP), Dion-Jacobson (DJ) and interlayer alternating cation (ACI) perovskite structures, respectively.

[0117] R′, R″ and in general formulas [2] to [4] Each represents an organic molecule or metal cation that may have substituents. Specifically, ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexammonium diammonium, isobutylammonium, 3-(nonafluoro-tert-butyloxy)propylamine, 1,3-propane diammonium, 1,5-pentamethylenediamine, octyl diammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidinium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidineonium, cyclohexylammonium, 4- Fluorophenylethylammonium, 4-fluorophenylethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenylethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidinium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophene dimethylammonium, phenylpropylammonium, 1,4-phenylene dimethylamine, 3-phenyl-2-propen-1-ammonium, phenylbutylammonium, 4-tert-butylbenzylammonium, 3-(aminomethyl)piperidinium, and 4-(aminomethyl)piperidinium are preferred.

[0118] In each of the general formulas [1] to [4], B represents a metal atom, and examples of such metals include lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of electron orbital overlap. These metal atoms may be used alone or in combination.

[0119] In each of the general formulas [1] to [4], X represents a halogen atom, and examples include chlorine, bromine, and iodine. These halogen atoms can be used alone or in combination. Halogen atoms are preferred because when halogen atoms are introduced into the structure, the crystals with the perovskite structure described above readily become soluble in organic solvents, thus enabling their application in inexpensive printing methods, etc. Furthermore, iodine is more preferred because crystals with the perovskite structure have a narrow band gap.

[0120] Specifically, MAPbI3, FAPbCl3, FAPbI3, and MAPbI are three-dimensional perovskites, two-dimensional perovskites, and mixed three-dimensional / two-dimensional perovskites. α Br 3-α MAPbI α Cl 3-α Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3、{Cs β1 (FAβ 2MA 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 (FAPbI3) 0.95 (MAPbBr3) 0.05 (FAPbI3) 0.85 (MAPbBr3) 0.15 CsPbI3, CsPbBr3, Cs β (MA) 1-β PbI3, Cs β (FA) 1-β PbI3, MA β (FA) 1-β PbI3, MA 0.17 FA 0.83 Pb(I 0.83 Br 0.17 3. Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 (PEA)2(MA)2Pb3I 10 (PTA)2(MA)4Pb5I 16 (PEA)2(MA)4Pb5I 16 (ThMA)2(MA)2Pb3I 10 (3BBA)2(MA)2Pb3I 10 (ThMA)2(FA)4Pb5I 16 (4FPEA)2 (FA 0.3 MA 0.7 4Pb5I 16 (PDMA)FA2Pb3I 10 (3AMPY)(MA)3Pb4I 13 (PDMA)MA5Pb6I 19 (PDMA)MA3Pb4I13 (TTDMA)MA3Pb4I 13 (TTDMA)MA4Pb5I 16 、(BA 0.9 PEA 0.1 )2MA4Pb5I 16 、(BA 0.9 PEA 0.1 )2MA3Pb4I 13 (4FPEA)2MA3Pb4I 13 (4FPEA)2MA4Pb5I 16 (BA)2MA2Pb3I 10 (BA)2MA3Pb4I 13 (TEA)2MA2Pb3I 10 (BA)2MA4Pb5I 16 (BA)2MA3Pb4I 13 CsSnBr3, CsSnI3, FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I3, FAMASnGeI3, FAMASnBr3, FAMASnI3, MA2Sn3I8, MASnBr3, MASnGeI3, and MASnI3 are preferred. The A, B, or X positions of each general formula can be adjusted to be insufficient or excessive depending on the purpose, and the combination of β1 to β3 and γ1 and γ2 can be changed according to the purpose. Examples of the combinations of β1 to β3 and γ1 and γ2 are shown in Table 1. 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. Furthermore, the ranges of α and β are 0 < α < 3 and 0 < β < 1, respectively. MACl can be introduced as a material for forming perovskite crystals.

[0121] [Table 1]

[0122] Table 1

[0123]

[0124] In the specific examples above, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenylethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylene dimethylammonium, "TTDMA" represents thieno[3,2-b]thiophene-2,5-dimethylammonium, "4FPEA" represents 4-fluorophenylethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiopheneethylammonium.

[0125] The aforementioned perovskite-structured crystals preferably have a cubic structure, wherein metal atoms B, organic molecules A, and halogen atoms X are respectively disposed at the body-center, vertex, and face-center positions. Details are unclear, but it is speculated that when such a structure exists, the orientation of the octahedrons in the lattice can be easily changed, thus increasing the electron mobility in the perovskite-structured crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0126] The organic-inorganic perovskite compound used in this invention is preferably a crystalline semiconductor. The term "crystalline semiconductor" refers to a semiconductor capable of measuring the X-ray scattering intensity distribution to detect scattering peaks. When the organic-inorganic perovskite compound is a crystalline semiconductor, the electron mobility in the organic-inorganic perovskite compound increases, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

[0127] The thickness of the photoelectric conversion layer according to the present invention is preferably from 5 nm to 2,000 nm. When the thickness is 5 nm or more, light can be sufficiently absorbed, and when the thickness is less than 2,000 nm, the generated charge can be transported to the corresponding electrode. More preferably, the lower limit is 50 nm or more, more preferably, the upper limit is 1,200 nm, even more preferably, the lower limit is 100 nm, and even more preferably, the upper limit is 1,000 nm.

[0128] [charge transport layer]

[0129] In this invention, the photoelectric conversion element includes a charge transport layer between the photoelectric conversion layer and the first electrode, and preferably, the charge transport layer comprises a charge transport material and an insulating resin on the surface of the photoelectric conversion layer. When the charge transport layer is a mixture of the charge transport material and the insulating resin, it becomes easier to achieve both a locally low-resistance charge transfer resistive element that contributes to initial photoelectric conversion efficiency and a globally high-resistance element that helps suppress degradation. From this viewpoint, it is preferable that the volume resistivity of the insulating resin is 10. 8 Ω·cm or higher.

[0130] The inventors of this invention speculate that a preferred configuration of the charge transport layer is a means of realizing the configuration of the present invention as described above, and the reasons will be described below.

[0131] On the one hand, the impedance R at low frequencies rec [Ω] corresponds to the interface resistance between the photoelectric conversion layer and the charge transport layer, as impedance refers to the recombination resistance related to the difficulty of recombination of electrons and holes generated in the photoelectric conversion layer. To set the value above a certain level and suppress durability degradation, defects in the photoelectric conversion element only need to be sufficiently hidden by the insulating resin of the charge transport layer. However, when the value is too large, charge transfer at the interface is hindered, and the initial photoelectric conversion efficiency deteriorates. As mentioned above, the following equation (E1) needs to be satisfied to achieve a balance between suppression and efficiency.

[0132] 1.0×10 4 <R rec ×S<1.0×10 7 (E1)

[0133] On the other hand, the impedance R at high frequencies ct [Ω] refers to the charge transfer resistance, which is related to the ease of charge movement when the photoelectric conversion element performs photoelectric conversion, and the impedance corresponds to the bulk resistance of the charge transport layer. The charge transport material of the charge transport layer is effective in setting this value small to facilitate charge movement in the photoelectric conversion element and improve the initial photoelectric conversion efficiency.

[0134] Based on the above, when the charge transport layer is helpful in increasing R rec Insulating resin and helps reduce R ct When a mixed system of charge transport materials is used, it becomes easier to obtain a photoelectric conversion element that satisfies the following formula (E2) of the present invention and achieves both initial photoelectric conversion efficiency and suppression of degradation.

[0135] R rec / R ct ≥25 (E2)

[0136] Furthermore, in this invention, the charge transport material is preferably charge transport particles. When the charge transport material is particles, the impedance dispersion at high frequencies corresponding to the bulk resistance becomes larger, and it becomes easier to satisfy the following equation (E4).

[0137] P ct ≤0.95 (E4)

[0138] As described above, when equation (E4) is satisfied, the impedance dispersion corresponding to the charge transfer resistor at high frequencies becomes sufficiently large, and the low-resistance path for the movement of photocharge generated in the photoelectric conversion layer is sufficiently present in the charge transport layer. As a result, the coexistence of high-resistance composite resistor elements that help hide global defects relative to the planar direction of the photoelectric conversion layer and low-resistance charge transfer resistor elements that help local charge transfer paths of the photoelectric conversion element becomes even easier.

[0139] Furthermore, the charge-transporting material is more preferably a pigment with a particle size of 10 nm to 500 nm. Within this range, a charge distribution capable of suppressing migration is easily formed. Specific examples of pigments include phthalocyanine pigments, azo pigments, lake pigments, quinacridone pigments, dioxazine pigments, perylene pigments, and isoindolinone pigments.

[0140] The volume ratio of the charge transport material to the insulating resin is preferably 5 to 30 times. When the volume ratio falls within this range, it becomes easier to satisfy the following formula (E3).

[0141] P rec ≥0.80 (E3)

[0142] As described above, when equation (E3) is satisfied, the impedance dispersion corresponding to the recombination resistance at low frequencies becomes sufficiently small, and the recombination resistance, which helps to hide defects in the photoelectric conversion layer, becomes uniform relative to the planar direction of the photoelectric conversion layer. Therefore, the probability of hiding defects in the photoelectric conversion layer is increased, and it becomes easier to achieve both initial photoelectric conversion efficiency and suppression of degradation. The ratio between the volume of the insulating resin and the volume of the charge transport material can be determined, for example, by the area ratio of the cross-sections determined by FETEM / EDS as described above.

[0143] The charge transport material is more preferably a phthalocyanine compound, and even more preferably has a structure represented by the following formula (Pc-2). The charge transport material makes it easier to increase impedance dispersion at high frequencies corresponding to bulk resistance, and makes it easier to achieve both initial photoelectric conversion efficiency and suppression of degradation.

[0144] [Chemical Formula 1]

[0145]

[0146] In formula (Pc-2), M represents H2 or a metal atom that may have ligands. In this invention, the structure of the chemical substance can be determined by nuclear magnetic resonance (NMR).

[0147] In particular, when M in equation (Pc-2) represents H2, equation (Pc-2) is represented by the following equation (Pc-1).

[0148] [Chemical Formula 2]

[0149]

[0150] Specific examples of insulating resins include polyacetal resins, acrylic resins, polyaryl compound resins, polycarbonate resins, polyvinyl acetate resins, polyester resins, polyamide resins, polyurethane resins, and polystyrene resins.

[0151] The glass transition temperature of the insulating resin is more preferably below 95°C. When the glass transition temperature falls within this range, the insulating resin readily comes into close contact with the charge transport material, and the coexistence of locally low-resistance elements that contribute to initial photoelectric conversion efficiency and globally high-resistance elements that help suppress degradation can be achieved more effectively. Therefore, the impedance parameters of the present invention become easier to obtain. The glass transition temperature can be determined by differential scanning calorimetry (DSC).

[0152] The insulating resin is more preferably polyvinyl acetal resin or polyvinyl butyral resin. When an insulating resin is used, it can easily come into close contact with the charge transport material, and the impedance parameters of the present invention can be obtained more effectively.

[0153] The charge transport layer more preferably comprises an aromatic ring compound having hydroxyl groups, which is different from the charge transport material and the insulating resin. When the charge transport layer comprises an aromatic ring compound having hydroxyl groups, the charge transport material and the insulating resin can come into contact with each other more easily, and the impedance parameters of the present invention can be obtained more effectively.

[0154] The photoelectric conversion element may include a second charge transport layer between the first electrode and the charge transport layer. When the photoelectric conversion element includes a second charge transport layer, it can facilitate the transfer of charge carriers to the electrode.

[0155] The thickness of the charge transport layer is preferably from 1 nm to 1,000 nm, more preferably from 5 nm to 500 nm, and particularly preferably from 10 nm to 200 nm.

[0156] The charge transport layer can be formed by preparing a coating solution containing the above-described materials and solvents, forming a liquid coating film on the photoelectric conversion layer, and drying the coating film. Examples of solvents used for 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 or aromatic hydrocarbon-based solvents are preferred.

[0157] [Second charge transport layer]

[0158] In this invention, from the viewpoint of the compatibility of the charge transport layer 6 film, the photoelectric conversion element 1 may further include a second charge transport layer between the charge transport layer 6 and the first electrode 7.

[0159] The material of the second charge transport layer is not particularly limited, and examples include spirofluorene compounds, triphenylamine compounds, phenylene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds. From the viewpoint of membrane interface compatibility, the compound is particularly preferably having an aromatic ring, and Spiro-OMeTAD, PTAA, or phthalocyanine compounds are preferred.

[0160] Furthermore, the second charge transport layer may contain dopants as additives to improve its charge transport capability. Examples of substances that can be used as dopants include lithium compounds such as lithium bis(trifluoromethanesulfonyl)imide, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris(bis(trifluoromethanesulfonyl)imide)], boron compounds such as tetra(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds each having a tetracyanoquinone dimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinone dimethane, and organic compounds each having a pyridine skeleton such as 4-tert-butylpyridine.

[0161] [Control of charge transport particle size]

[0162] The particle size of the charge transport layer can be altered by dispersing it with a coating liquid using a paint mixer, and the particle size can be reduced by increasing the dispersion time. Furthermore, the particle size can be further reduced by subjecting the charge transport layer to a centrifuge.

[0163] [Electron transport layer]

[0164] In the photoelectric conversion element of the present invention, the electron transport layer 4 can be disposed between the second electrode 3 and the photoelectric conversion layer 5, such as... Figure 5 As shown.

[0165] The material of electron transport layer 4 is not particularly limited, and examples 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, and surfactants. Specific examples include cyano-containing polyphenylene vinylidenes, boron-containing polymers, bath copper compounds, bath phenanthroline, aluminum hydroxyquinoline, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluorine-containing phthalocyanines, titanium dioxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide. Specifically, tin oxide can be obtained by reacting tin(II), tin(IV), tin(II) dihydrate, or tin(IV) pentahydrate with oxygen.

[0166] The preferred lower limit of the thickness of the electron transport layer 4 is 1 nm, and its preferred upper limit is 2,000 nm. When the thickness is above 1 nm, holes can be sufficiently blocked, and when the thickness is below 2,000 nm, the electron transport layer 4 is less likely to act as a resistor during electron transport, thus improving the photoelectric conversion efficiency. A more preferred lower limit of the thickness is 3 nm, its more preferred upper limit is 1,000 nm, even more preferred lower limit is 5 nm, and its more preferred upper limit is 500 nm.

[0167] Photoelectric conversion equipment

[0168] Photoelectric conversion devices can be formed using multiple photoelectric conversion elements of the present invention. When multiple photoelectric conversion elements are connected, such photoelectric conversion devices can also be called "photoelectric conversion units" or "photoelectric conversion modules". In the photoelectric conversion elements, elements with different absorption wavelengths can be stacked to increase the output voltage. Furthermore, the photoelectric conversion device includes the photoelectric conversion elements of the present invention and an inverter. The inverter can be a converter that converts DC voltage to AC voltage. The photoelectric conversion device can include an energy storage section connected to the photoelectric conversion elements. The energy storage section is not limited, as long as it can store electricity. Examples include secondary batteries using lithium ions, all-solid-state batteries, and double-layer capacitors. To impart functions such as maintaining or increasing the amount of incident light, a surface layer in which water or dirt is difficult to adhere can be added, or the function of collecting or guiding light can be added.

[0169] [Moving Object]

[0170] Figure 6This is a schematic perspective view of a moving body including a photoelectric conversion element according to one embodiment of the present invention. The moving body 30 includes the photoelectric conversion element 31 of the present invention and a body 32 including the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position on the body 32 where it can receive ambient light. When the moving body 30 is a vehicle, the photoelectric conversion element 31 may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 can be used as the power source for the moving body 30 or for any other electrical equipment. The electrical energy generated by the power source of the moving body 30 can be used to power the photoelectric conversion element 31. When the moving body 30 is a vehicle, the frictional energy generated by the brakes can be converted into electrical energy for controlling the photoelectric conversion element 31.

[0171] The mobile body 30 can be, for example, a car, motorcycle, railway vehicle, ship, or aircraft including satellites, airplanes, and drones. The structure of the body 32 of the mobile body 30 is not particularly limited, but it is preferably formed of a high-strength material.

[0172] [Building Materials]

[0173] Figure 7 This is a schematic perspective view of a building material including a photoelectric conversion element according to one embodiment of the present invention. The building material 40 may be the roof of a building. The building material 40 of this embodiment includes the photoelectric conversion element 41 of the present invention, a protective member 42 protecting the photoelectric conversion element 41, a heat dissipation member 43, and external fittings 44a and 44b.

[0174] The building material 40 of the present invention may include a heat dissipation member 43 with a thermal conductivity higher than that of the photoelectric conversion element 41. When the building material 40 is used in the roof, etc., the temperature of the photoelectric conversion element 41 may rise due to sunlight, and therefore the photoelectric conversion efficiency may decrease. By using the heat dissipation member 43, the decrease in photoelectric conversion efficiency can be suppressed. Examples of heat dissipation members 43 include metals, alloys, liquid metals, and liquid resins.

[0175] Furthermore, the building material 40 of the present invention may include exterior panels 44a and 44b. Exterior panels 44a and 44b may display different colors or the same color. Exterior panels 44a and 44b may be formed from the same components or from different components. Coatings or transparent substrates may be used for each exterior panel. Exterior panels with low light absorption and high thermal insulation are preferred.

[0176] In addition to the above-mentioned application examples, the following application examples can be given: portable devices, such as calculators, sensors, and small solar panels; wearable devices, such as glasses-type terminals, watch-type terminals, and portable medical devices; sheet structures supported by multiple frames, such as tents, plastic houses, and truck loading platforms; and structures used by fixing, such as road panels, floating panels, building materials utilizing the flexibility of substrates, wall-type building materials, glass-type building materials, and large solar panels.

[0177] Methods for manufacturing photoelectric conversion elements

[0178] The method for producing 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 comprising a crystal having a perovskite structure between the first electrode and the second electrode.

[0179] The following describes the steps of the production method.

[0180] [Steps for forming the first electrode and steps for forming the second electrode]

[0181] The method for producing the photoelectric conversion element of the present invention includes the steps of: forming a first electrode; and forming a second electrode. In the steps of forming the first electrode and forming the second electrode, appropriate methods can be selected according to the materials of the first electrode and the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering, vacuum evaporation, chemical vapor deposition (CVD), and spray pyrolysis deposition (SPD). The materials of the first electrode and the second electrode are as described above. When one or both of the first electrode and the second electrode are transparent electrodes, the thickness of each transparent electrode is preferably from 0.03 μm to 3 μm.

[0182] When manufacturing solar cells, cutting processes can be performed to form circuits between steps. Examples of cutting processes include mechanical patterning and laser patterning.

[0183] [Modularization Steps]

[0184] Elements formed to electrodes can be sealed. Sealing methods include, for example, sealing with resin or sealing with a membrane. Examples of materials used for sealing include silazane, silicone rubber, resins each having a siloxane backbone, and glass.

[0185] Furthermore, from the viewpoint of suppressing adhesion between components that occurs during winding in a roll-to-roll system, a hairline treatment can be applied to the surface of the sealing element.

[0186] [Steps for forming a photoelectric conversion layer]

[0187] The steps of forming the photoelectric conversion layer may include applying a liquid containing a material comprising the photoelectric conversion layer as described above. Examples of application methods include spin coating, blade coating, slot die coating, screen printing, bar coating, casting, printing transfer, immersion, inkjet printing, spraying, and vacuum evaporation. The method is appropriately selected based on the characteristics of the produced photoelectric conversion layer, such as thickness control and orientation control.

[0188] Annealing can be performed under reduced pressure or in an inert atmosphere (nitrogen or argon) to remove the solvent or dispersion medium from the liquid containing the applied photoelectric conversion layer. The annealing temperature is preferably from 40°C to 300°C, more preferably from 50°C to 150°C. Annealing is preferred because the materials forming the layers can permeate each other at the interfaces between the stacked layers to increase the contact area, thereby increasing the short-circuit current.

[0189] [Steps for forming a charge transport layer]

[0190] The method of producing the photoelectric conversion element of the present invention may include the step of forming a charge transport layer between the photoelectric conversion layer and the first electrode.

[0191] The step of forming the charge transport layer is preferably achieved by applying a resin solution in which an insulating resin is dissolved. Therefore, when gaps exist between perovskite grains, the insulating resin preferentially and easily penetrates.

[0192] Additionally, examples of steps for forming a charge transport layer include: a method comprising disposing charge transport particles on the surface of a photoelectric conversion layer and then applying a resin solution in which an insulating resin is dissolved; a method comprising applying a resin solution in which an insulating resin is dissolved on the surface of a photoelectric conversion layer and then disposing charge transport particles thereon; and a method comprising applying a solution obtained by dispersing charge transport particles in a resin solution in which an insulating resin is dissolved on the surface of a photoelectric conversion layer.

[0193] [Impedance Measurement and Analysis]

[0194] Impedance measurement is performed by connecting the first and second electrodes of the photoelectric conversion element to an impedance analyzer via appropriate probes; and applying a DC voltage component V to the photoelectric conversion element. DC =0[V] and the root mean square V of the AC voltage component rms =50mV AC voltage, while its frequency is changed from 1.0×10 -2 [Hz] changed to 1.0×10 6 [Hz].

[0195] Various impedance analyzers can be used for measurements, and for example, the ModuLab XM MTS (manufactured by Solartron Analytical) can be used. Alternatively, the SI1287 electrochemical interface (manufactured by Toyo Corporation) can be used as a power source, the dielectric interface Solartron 1296 (manufactured by Toyo Corporation) can be used as a current amplifier, the impedance / gain phase analyzer Solartron SI1260 (manufactured by Toyo Corporation) can be used as a galvanometer, and Solartron Materials Research and Testing Software version 3.0.1 (manufactured by Solartron Analytical) can be used as measurement software.

[0196] Various analysis software programs can be used to analyze the acquired data, and an example is the Zview 4 analysis software (manufactured by Scribner Associates, Inc.).

[0197] In this invention, we analyze a plot (a phase plot of a Bode plot) where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg] based on impedance measurements, and a Nyquist plot where the horizontal axis represents the real part of impedance Z′ [Ω] and the vertical axis represents the imaginary part of impedance Z″ [Ω]. Specifically, regarding the analysis of the Nyquist plot, when creating a biaxial plot containing the real component Z′ and the imaginary component Z″ of impedance Z, and represented by coordinates (Z′, Z″), we fit the results using an appropriate equivalent circuit. At this time, when using an equivalent circuit where at least two “resistive element-constant phase element parallel circuits (RCPE parallel circuits)” are connected in series, we obtain a low-frequency range (1.0 × 10⁻⁶). -2 Less than 1.0 × 10 2 [Hz]) and high frequency range (1.0×10 2 Up to 1.0×10 6 When analyzing the resistance (R) and the index of the constant phase element (CPE) for each element in the [Hz], it is easy to perform the analysis. An example is as follows: Figure 4 The equivalent circuit shown is formed by connecting one series resistor (R1), one series inductor (L1), and three parallel circuits of "resistive element-constant phase element" ("R4-CPE3", "R2-CPE1", and "R3-CPE2") in series. In Embodiment 4 of the present invention, the photoelectric conversion element 4 according to the present invention is used... Figure 4 The equivalent circuit fitting results are derived from Figure 2The Nyquist diagram in [reference] is shown, but the impedance analysis of the present invention is not limited to using an equivalent circuit. In addition, the impedance parameters of the present invention can be obtained by other analysis methods without using an equivalent circuit, such as a method including extracting only the required circular arc on the Nyquist diagram and fitting it with a parallel circuit of a resistance element - constant phase element.

[0198] In the present invention, ModuLab XM MTS (manufactured by Solartron Analytical) is used for impedance measurement. The measurement conditions are as described below.

[0199] <Measurement conditions of ModuLab XM MTS>

[0200] Experiment type: Sample & Reference

[0201] Instrument configuration: Mat + Femtoammeter

[0202] Grounding: Internal

[0203] DC: 0 V

[0204] AC: 0.05 V rms

[0205] Frequency: 1 MHz to 0.01 Hz

[0206] Number of measurement points: 6 points / octave

[0207] Examples

[0208] The present invention will be described in more detail below with reference to examples and comparative examples. Without departing from the gist thereof, the present invention is in no way limited to the following examples. In the description of the following examples, unless otherwise specified, the term "part" is by mass.

[0209] <Production of Particle 1>

[0210] Step (1)

[0211] Under a nitrogen gas flow atmosphere, 5.46 parts of phthalonitrile and 45 parts of α-chloronaphthalene were charged into a reaction kettle. Thereafter, the mixture was heated to raise its temperature to 30 °C and then maintained at that temperature. Next,

[0212] Step (2)

[0213] 4.65 parts of gallium chlorophthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and the solution was added dropwise to 620 parts of ice water with stirring, causing the particles to recrystallize. The solution was then filtered under reduced pressure using a filter press. A No. 5C filter (manufactured by Advantec Toyo Kaisha, Ltd.) was used as the filter. The resulting wet filter cake (filter residue) was dispersed and washed with 2% ammonia for 30 minutes, and then filtered using a filter press. Next, the resulting wet filter cake (filter residue) was dispersed and washed with deionized water, and then filtered using a filter press, repeated three times. Finally, the filter residue was freeze-dried to provide hydroxy gallium phthalocyanine particles (hydrated hydroxy gallium phthalocyanine particles) with a solid content of 23% by mass, yielding 71%. The hydroxy gallium phthalocyanine particles were dried using an ultra-dryer (product name: HD-06R, frequency (oscillation frequency): 2,455MHz±15MHz, manufactured by Biocon (Japan) Ltd.). Therefore, hydroxy gallium phthalocyanine (HOGaPc) particles (crystals) with a water content of less than 1.0% by mass were obtained.

[0214] Step (3)

[0215] Five parts of hydroxygallium phthalocyanine particles were mixed with five parts of N-methylformamide solvent, and the mixture was dispersed for six hours using a sand mill containing five parts of glass beads (TSG-1 / 4G-4U, manufactured by Igarashi Machine Production Co., Ltd. (now AIMEX Co., Ltd.), with a disc diameter of 70 mm and a number of discs of 5). The mixture was then filtered and dried to provide particle 1 (specific gravity: 1.6).

[0216] <Production of Resin Solution 1>

[0217] 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity: 1.6) was dissolved in 19 g of 2-propanol by stirring for 24 hours to provide resin solution 1.

[0218] (Production of photoelectric conversion components)

[0219] (Production of photoelectric conversion element 1)

[0220] [Formation of the electron transport layer]

[0221] The glass substrate containing ITO was washed and a 5-fold diluted tin(II) colloidal solution (15% aqueous dispersion, manufactured by Alfa Aesar) was applied onto it by spin coating. The substrate was then heated at 150°C for 30 minutes to form a thin-film electron transport layer with a thickness of 16 nm.

[0222] [Formation of the photoelectric conversion layer]

[0223] 0.487 g of lead bromide, 1.034 g of formamidinium 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 stirred for 1 hour (solution 1). Additionally, 0.100 g of cesium iodide was dissolved in 0.285 g of dimethyl sulfoxide, and the solution was stirred for 1 hour (solution 2). The cesium iodide solution (solution 2) was then added to solution 1 to prepare a coating solution for the photoelectric conversion layer. The coating solution was applied to the electron transport layer by spin coating to form a Cs... 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 )3 A photoelectric conversion layer with a thickness of 600 nm was formed.

[0224] [Formation of the charge transport layer]

[0225] 0.1 g of particle 1 and 0.01 g of calixarene compound (Japanese Patent Application Publication No. 2003-207913) were mixed with 10.6 g of 2-propanol, and 11 g of beads (zirconia beads, Torayceram (trademark) zirconia beads, 0.3 mm) were added to the mixture. The mixture was then dispersed in a paint stirrer (manufactured by Toyo Seiki Co., Ltd.) for 3 hours. Afterwards, 0.2 g of resin solution 1 was added, and the mixture was dispersed again in a paint stirrer for 4 hours to prepare a coating solution for the charge transport layer. The charge transport layer coating solution was spin-coated onto the photoelectric conversion layer to form a charge transport layer with a thickness of 180 nm.

[0226] [Formation of the second charge transport layer]

[0227] 0.15 g of Spiro-OMeTAD, used as the material for the second charge transport layer, was dissolved in 2.2 g of chlorobenzene. 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile and 60 μL of 4-tert-butylpyridine (TBP) were added to the chlorobenzene solution, and the contents 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(III)tris(bis(trifluoromethanesulfonyl)imide)] in 0.3 g of acetonitrile was mixed in to prepare a coating solution for the second charge transport layer. The coating solution for the charge transport layer was applied onto the above charge transport layer by spin coating to form a second charge transport layer with a thickness of 100 nm.

[0228] [Formation of the first electrode]

[0229] A layer with a thickness of 80 nm and an area of ​​0.09 cm² was formed on the second charge transport layer using vacuum evaporation. 2 The gold electrode is thus used to obtain the photoelectric conversion element 1. In various embodiments according to the present invention, a small electrode is used as the first electrode.

[0230] [Analysis of compound amount]

[0231] The electrode surfaces of the photoelectric conversion element are peeled off to expose the surface of the charge transport layer. The surface of the charge transport layer is then wiped with a solvent (such as a cotton swab) and dissolved in deuterated sulfuric acid, followed by... 1 H-NMR measurements (equipment: AVANCE 3-500 manufactured by BRUKER). Furthermore, elemental analysis of the stripped charge transport layer components was performed to confirm the presence of compounds, including GPC and MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX.

[0232] In addition, after the photoelectric conversion element was cut and the sample was fixed on the tilted sample stage, the thickness was observed using a cross-sectional SEM (equipment: SmartSEM manufactured by Carl Zeiss Co., Ltd.).

[0233] [Particle size analysis of charge transport materials]

[0234] The particle size of a charge transport material is the number-average particle size within its particle size distribution. In this invention, the particle size of the charge transport material is derived using an imaging method involving TEM (Transient Electron Microscopy).

[0235] Specifically, firstly, using image processing software Photoshop (manufactured by Adobe Inc.), N particles (N representing 1,000 or more) were extracted from a TEM image of the cross-section of the charge transport layer. Next, the area S of each particle was measured, and the diameter of a circle with the same area (=2×(S / π)) was used. 1 / 2 ) is used as the particle size, and the average value of the central 80% of the N particles is taken.

[0236] Table 2 shows the device configuration of photoelectric conversion element 1.

[0237] (Production of photoelectric conversion elements 2 to 7 and 21)

[0238] Except for changing the volume ratio of charge transport material to insulating resin to the values ​​shown in Table 2, photoelectric conversion elements 2 to 7 and 21 are obtained in the same manner as in photoelectric conversion element 1.

[0239] (Production of photoelectric conversion element 8)

[0240] In addition to the formation of the charge transport layer, the charge transport layer obtained by dispersion by paint agitator is further centrifuged with coating liquid (at 15,000 rpm for 6 minutes) to reduce the particle size in the dispersion. Then the volume ratio of charge transport material to insulating resin is adjusted to more than 10 times to obtain photoelectric conversion element 8 in the same manner as in photoelectric conversion element 1.

[0241] (Production of photoelectric conversion element 9)

[0242] Except for changing polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd.) to polyvinyl butyral (product name: BX-1, manufactured by Sekisui Chemical Co., Ltd.), the photoelectric conversion element 9 is obtained in the same manner as in the photoelectric conversion element 1.

[0243] (Production of photoelectric conversion element 10)

[0244] Except for changing the calixarene compound to 2-naphthol, the photoelectric conversion element 10 is obtained in the same manner as in the photoelectric conversion element 1.

[0245] (Production of photoelectric conversion element 11)

[0246] Except for changing particle 1 to nickel phthalocyanine particles, the photoelectric conversion element 11 is obtained in the same manner as in the photoelectric conversion element 1.

[0247] (Production of photoelectric conversion element 12)

[0248] Except for not providing a second charge transport layer, the photoelectric conversion element 12 is obtained in the same manner as in the photoelectric conversion element 1.

[0249] (Production of photoelectric conversion element 13)

[0250] The photoelectric conversion element 13 is obtained in the same manner as in the photoelectric conversion element 1, except that calixarene compounds are not used.

[0251] (Production of photoelectric conversion element 14)

[0252] Except for changing polyvinyl butyral to polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich Co. LLC, glass transition temperature: 70°C), the photoelectric conversion element 14 is obtained in the same manner as in the photoelectric conversion element 1.

[0253] (Production of photoelectric conversion element 15)

[0254] Except for changing polyvinyl butyral to polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich Co. LLC, glass transition temperature: 100°C), the photoelectric conversion element 15 is obtained in the same manner as in the photoelectric conversion element 1.

[0255] (Production of photoelectric conversion element 16)

[0256] Except that particle 1 is changed to particles containing a compound represented by the following formula (Pc-3), photoelectric conversion element 16 is obtained in the same manner as in photoelectric conversion element 1.

[0257] [Chemical Formula 3]

[0258]

[0259] (Production of photoelectric conversion element 17)

[0260] Except for changing particle 1 to quinacridone particles, photoelectric conversion element 17 is obtained in the same manner as in photoelectric conversion element 1.

[0261] (Production of photoelectric conversion element 18)

[0262] Except for changing the composition of the photoelectric conversion layer to MAPbI3, the photoelectric conversion element 18 is obtained in the same manner as in Example 1.

[0263] (Production of photoelectric conversion element 19)

[0264] In addition to forming a layer similar to the second charge transport layer formed in the photoelectric conversion element 1 as the charge transport layer of the photoelectric conversion element 19, and without providing a second charge transport layer on the charge transport layer, the photoelectric conversion element 19 is obtained in the same manner as in the photoelectric conversion element 1.

[0265] (Production of photoelectric conversion element 20)

[0266] The photoelectric conversion element 20 is obtained in the same manner as in the photoelectric conversion element 1, except that particle 1 is not used.

[0267] (Production of photoelectric conversion element 22)

[0268] Except for changing particle 1 to Spiro-OMeTAD; setting the volume ratio of charge transport material to insulating resin to 1; setting the thickness of charge transport layer to 100 nm; not using calixarene compounds; and not setting a second charge transport layer on the charge transport layer, the photoelectric conversion element 22 is obtained in the same manner as in the photoelectric conversion element 15.

[0269] (Production of photoelectric conversion element 23)

[0270] Except that the thickness of the charge transport layer is set to 180 nm, the photoelectric conversion element 23 is obtained in the same manner as in the photoelectric conversion element 22.

[0271] (Production of photoelectric conversion element 24)

[0272] Except that the thickness of the charge transport layer is set to 300 nm, the photoelectric conversion element 24 is obtained in the same manner as in the photoelectric conversion element 22.

[0273] (Production of photoelectric conversion element 25)

[0274] Except for changing particle 1 to Spiro-OMeTAD; setting the thickness of the charge transport layer to 180 nm; and not setting a second charge transport layer on the charge transport layer, the photoelectric conversion element 25 is obtained in the same manner as in the photoelectric conversion element 15.

[0275] (Production of photoelectric conversion element 26)

[0276] Except for changing particle 1 to nickel(II) phthalocyanine tetrasodium salt particles and changing the insulating resin to PEDOT:PSS, photoelectric conversion element 26 is obtained in the same manner as in photoelectric conversion element 1.

[0277] (Production of photoelectric conversion element 27)

[0278] Except for changing particle 1 to particles containing a compound represented by the following formula (Pc-4) and changing the insulating resin to P3HT, the photoelectric conversion element 27 is obtained in the same manner as in the photoelectric conversion element 1.

[0279] [Chemical Formula 4]

[0280]

[0281] (Example 1)

[0282] [evaluate]

[0283] Impedance measurements were performed on photoelectric conversion element 1, which was manufactured in this section (production of photoelectric conversion elements). A ModuLab XM MTS (manufactured by Solartron Analytical) was used for the measurement. Figure 2 As shown in the example ( Figure 2 (This is an example of photoelectric conversion element 4), using... Figure 4 The equivalent circuit shown fits the obtained impedance data and determines R. rec ×S[Ω·cm 2 ]、R rec / R ct P rec and P ct The values ​​are shown in Table 3.

[0284] Next, a power supply (model 236, manufactured by Keithley Instruments) was connected between the electrodes of photoelectric conversion element 1, and its initial photoelectric conversion efficiency was measured by using an intensity of 110 mW / cm². 2 A solar simulator (manufactured by Yamashita Denso Corporation) was used to illuminate the elements with constant light; and the resulting current and voltage were measured. Furthermore, measurements were taken of each of the ten electrodes of each element, and the average of the measurements was used as a representative value for the element. The results are shown in Table 3. Subsequently, 10,000 Lx of light was continuously applied to the elements using a white LED, and their photoelectric conversion efficiency was measured after 50 days. The retention rate of the photoelectric conversion efficiency after 50 days relative to the initial photoelectric conversion efficiency was then evaluated. The results are shown in Table 3.

[0285] In Table 3, the photoelectric conversion efficiency in Example 1 is set to 100%, and the ratio of each component to its conversion efficiency is shown.

[0286] The initial photoelectric conversion efficiency and the maintenance rate of photoelectric conversion efficiency of the photoelectric conversion elements of Examples 2 to 18 and Comparative Examples 1 to 9 were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0287] In Comparative Example 2, the initial photoelectric conversion efficiency was not measured, so the maintenance rate of photoelectric conversion could not be evaluated.

[0288] [Table 2]

[0289] Table 2

[0290]

[0291] [Table 3]

[0292] Table 3

[0293]

[0294] This invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. The appended claims are intended to disclose the scope of the invention.

[0295] This application claims based on Japanese Patent Application No. 2023-184761, No. 2023-184756, No. 2023-184750, filed on October 27, 2023; and Japanese Patent Application No. 2023-216294, No. 2023-216296, filed on December 21, 2023. The prior art to Japanese Patent Application No. 2023-216299, filed on December 21, 2024; 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, is hereby incorporated herein by reference in its entirety.

[0296] Explanation of reference numerals in the attached figures

[0297] 1. Photoelectric conversion element

[0298] 2 substrate

[0299] 3 Second electrode

[0300] 4. Electron transport layer

[0301] 5 Photoelectric conversion layer

[0302] 6. Charge transport layer

[0303] 7 First Electrode

[0304] 30 moving bodies

[0305] 31, 41 Photoelectric conversion elements

[0306] 32 bodies

[0307] 40 Building Materials

[0308] 42 Protective components

[0309] 43 Heat dissipation components

[0310] 44a, 44b exterior

Claims

1. A photoelectric conversion element, comprising: First electrode; Second electrode; and A photoelectric conversion layer is disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising crystals having a perovskite structure. Wherein, when the smaller of the electrode areas of the first electrode and the second electrode is S[cm 2 This indicates that, and by applying a DC voltage component V to the photoelectric conversion element... DC =0[V] and the root mean square V of the AC voltage component rms =50mV AC voltage, while its frequency is changed from 1.0×10 -2 [Hz] changed to 1.0×10 6 When measuring impedance using [Hz], in a graph based on the measurement results of said impedance, where the horizontal axis represents frequency [Hz] and the vertical axis represents phase [deg], the phase of said impedance is within 1.0 × 10⁻⁶. -2 Less than 1.0 × 10 2 The impedance has a maximum value in the low-frequency range of [Hz], and the phase of the impedance is within 1.0 × 10⁻⁶. 2 Up to 1.0×10 6 It has a maximum value in the high-frequency range of [Hz], and In the Nyquist plot based on the impedance measurement results, where the horizontal axis represents the real part of the impedance Z′ [Ω] and the vertical axis represents the imaginary part of the impedance Z″ [Ω], the maximum value R of the resistance obtained by fitting the arc corresponding to the phase maxima in the low-frequency range with a parallel circuit of resistive elements and constant-phase elements is obtained. rec [Ω] satisfies the following equation (E1): 1.0×10 4 ≤R rec ×S≤1.0×10 7 (E1) Furthermore, the maximum resistance value R obtained by fitting the arc corresponding to the maximum phase value in the high-frequency range with a parallel circuit of the resistive element and the constant phase element is obtained. ct [Ω], with R rec [Ω] satisfies the following equation (E2): R rec / R ct ≥25 (E2)。 2. The photoelectric conversion element according to claim 1, wherein by obtaining the R rec The constant phase element's exponent P obtained by fitting [Ω] is... rec The following equation (E3) must be satisfied: P rec ≥0.80 (E3)。 3. The photoelectric conversion element according to claim 1 or 2, wherein by obtaining the R ct The index P of the constant phase element obtained by fitting [Ω] ct The following equation (E4) must be satisfied: P ct ≤0.95 (E4)。 4. The photoelectric conversion element according to any one of claims 1 to 3, wherein R rec [Ω] satisfies the following equation (E5): 1.0×10 5 <R rec ×S<1.0×10 6 (E5) 5. The photoelectric conversion element according to any one of claims 1 to 4, wherein the R ct [Ω] and the R rec [Ω] satisfies the following equation (E6): R rec / R ct ≥50 (E6)。 6. The photoelectric conversion element according to any one of claims 1 to 5, The photoelectric conversion element further includes a charge transport layer between the photoelectric conversion layer and the first electrode, and The charge transport layer comprises 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 charge transport particles.

8. The photoelectric conversion element according to claim 7, wherein the average particle size of the charge transport particles is from 10 nm to 500 nm.

9. The photoelectric conversion element according to claim 6, wherein the volume ratio of the charge transport material to the insulating resin is 5 to 30 times.

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): [Chemical Formula 1] In the formula (Pc-2), M represents H2 or a metal atom that may have ligands.

12. The photoelectric conversion element according to claim 6, wherein the glass transition temperature of the insulating resin is below 95°C.

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

14. The photoelectric conversion element of claim 6, wherein the charge transport layer comprises an aromatic ring compound having hydroxyl groups, the aromatic ring compound being different from the charge transport material and the insulating resin.

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

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

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