Photoelectric conversion element, coating solution, and method for manufacturing a photoelectric conversion element

Abstract

To provide a photoelectric conversion element with improved leakage resistance and conversion efficiency by protecting defects in the perovskite crystal structure. [Solution] A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite structure crystal disposed between the first electrode and the second electrode, wherein the photoelectric conversion element has a first charge transport layer between the photoelectric conversion layer and the first electrode, and a second charge transport layer between the photoelectric conversion layer and the second electrode, and the photoelectric conversion element has a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and contacts the first charge transport layer but does not contact the second charge transport layer.

Description

[Technical Field]

[0001] This invention relates to a photoelectric conversion element, a coating solution, and a method for manufacturing a photoelectric conversion element. [Background technology]

[0002] In order to address the depletion of fossil fuels and the environmental problems caused by their use, research is actively being conducted on renewable and clean alternative energy sources such as solar, wind, and hydroelectric power. Among these, there is growing interest in solar cells, which directly convert sunlight into electrical energy. Here, a solar cell refers to a battery that absorbs light energy from sunlight and generates current and voltage using the photovoltaic effect, which generates electrons and holes.

[0003] Currently, np diode type silicon (Si) single-crystal based solar cells with light energy conversion efficiencies exceeding 20% ​​are widely known and actually used in photovoltaic power generation. However, these have the problem of high cost per unit of power due to the need for high-temperature processing and the high price of the material itself. Furthermore, there are supply issues from the perspective of silicon resources.

[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 so-called roll-to-roll method on sheet substrates, which is expected to reduce costs. However, further improvement in power generation efficiency is desired for the practical application of organic solar cells. In particular, perovskite solar cells, which have a perovskite structure crystal as the photoelectric conversion layer, have excellent photoelectric conversion properties and are therefore being developed towards the practical application of solar cells.

[0005] For example, Patent Document 1 describes how constructing a perovskite layer with dense crystals suppresses shunt liquefaction and improves conversion efficiency. Non-Patent Document 1 describes how including polymethyl methacrylate (PMMA) as a leak-preventing layer on top of the perovskite increases conversion efficiency due to the suppression of shunt liquefaction. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 7245527 [Non-patent literature]

[0007] [Non-Patent Document 1] F. Wang,et al,J.Phys.Chem.C,2017,121,1562 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The photoelectric conversion element described in Patent Document 1 utilizes a dense crystal structure to suppress the generation of pinholes and inhibit shunt liquefaction, thereby achieving high conversion efficiency. On the other hand, it is known that crystal grain boundaries have defects that trap carriers. Therefore, while densifying the crystal of the perovskite layer suppresses shunt liquefaction, it increases carrier trapping, which hinders the improvement of conversion efficiency. Thus, there have been challenges in achieving further improvements in conversion efficiency through densification. Furthermore, the photoelectric conversion element described in Non-Patent Document 1 required the addition of a leak prevention layer to suppress shunt liquefaction, which presented a productivity challenge.

[0009] Therefore, an object of the present invention is to provide a photoelectric conversion element with high productivity and improved leak resistance by protecting defects in the perovskite crystal structure with another perovskite crystal structure. Another object of the present invention is to provide a method for manufacturing a photoelectric conversion element with high productivity and improved leak resistance by protecting defects in the perovskite crystal structure with another perovskite crystal structure. [Means for solving the problem]

[0010] The above objective is achieved by the present invention as follows: That is, the present invention is The first electrode and The second electrode, A photoelectric conversion layer comprising a perovskite crystal is disposed between the first electrode and the second electrode. A photoelectric conversion element having, A first charge transport layer is provided between the photoelectric conversion layer and the first electrode. A second charge transport layer is provided between the photoelectric conversion layer and the second electrode. The photoelectric conversion element is characterized by having a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and is in contact with the first charge transport layer but not with the second charge transport layer. Furthermore, the present invention is A coating solution for forming the above-mentioned photoelectric conversion element, comprising a photoelectric conversion layer precursor, a solvent, and an additive, The photoelectric conversion layer precursor is A 1 X 1 Compounds represented by B 1 X 1 It includes at least one selected from the group consisting of compounds represented by 2, A 1 It is a monovalent cation comprising at least one selected from the group consisting of alkali metal cations and organic ammonium compounds. Applicable B 1 is a divalent cation comprising at least one selected from the group consisting of lead, tin, bismuth, and silver. The X1 It is a monovalent anion of a halide ion, The aforementioned solvent comprises multiple solvent species and has a boiling point of 190°C or lower. The aforementioned additive is methylammonium chloride, and the solution is a coating solution. Furthermore, the present invention is The process of forming the first electrode, The process of forming the second electrode, The process involves forming a photoelectric conversion layer between the first electrode and the second electrode, which includes a perovskite crystal structure. The process involves forming a first charge transport layer between the photoelectric conversion layer and the first electrode. Includes, The method for manufacturing a photoelectric conversion element is characterized in that the photoelectric conversion element has a crystal A that is in contact with the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, is in contact with the first charge transport layer, and is not in contact with the second charge transport layer. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a photoelectric conversion element that has high productivity and improved leakage resistance and conversion efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] This is an example of a schematic cross-sectional view in the thickness direction of one embodiment of the photoelectric conversion element of the present invention. [Figure 2] This is another example of a schematic cross-sectional view in the thickness direction of one embodiment of the photoelectric conversion element of the present invention. [Figure 3] This is an example of a schematic cross-sectional view in the thickness direction of one embodiment of the photoelectric conversion layer of the present invention. [Figure 4] This is another example of a schematic cross-sectional view in the thickness direction of one embodiment of the photoelectric conversion layer of the present invention. [Figure 5] This is a schematic side view illustrating a coating apparatus used in a coating method according to one embodiment of the photoelectric conversion layer of the present invention. [Modes for carrying out the invention]

[0013] <First Embodiment> The first embodiment relates to a photoelectric conversion element. The photoelectric conversion element of the present invention is The first electrode and The second electrode, A photoelectric conversion layer comprising a perovskite crystal is disposed between the first electrode and the second electrode. A photoelectric conversion element having, A first charge transport layer is provided between the photoelectric conversion layer and the first electrode. A second charge transport layer is provided between the photoelectric conversion layer and the second electrode. The photoelectric conversion element is characterized by having a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and is in contact with the first charge transport layer but not with the second charge transport layer.

[0014] As a result of their investigation, the inventors have found that by having the above-mentioned crystal A and crystal B, a photoelectric conversion element can be obtained that exhibits high productivity, leakage resistance, and excellent conversion efficiency. The reason why a photoelectric conversion element with high conversion efficiency can be obtained in this invention is not entirely clear, but it is thought to be as follows.

[0015] Our previous studies have suggested that by utilizing a dense crystal group of perovskite structures, we can suppress the generation of pinholes and inhibit shunt liquefaction, thereby achieving high conversion efficiency. However, while densifying the perovskite layer crystals suppresses shunt liquefaction, it increases carrier traps, which hinders the improvement of conversion efficiency. Therefore, it has been found that achieving further improvements in conversion efficiency through further densification is difficult. Furthermore, our investigations revealed that the photoelectric conversion element described in Non-Patent Document 1 requires the addition of a leak prevention layer to suppress shunt liquefaction, which presents a productivity challenge.

[0016] Therefore, in this invention, by having crystal A having a perovskite structure and crystal B having a perovskite structure that covers the gap between adjacent crystals A, it is not necessary to add a new leak prevention layer, thus improving productivity, suppressing carrier trapping and shunt liquefaction, and contributing to an increase in conversion efficiency.

[0017] As described above, the effects of the present invention can be achieved through the synergistic effects of each component constituting the present invention.

[0018] 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 the scope of the present invention also includes modifications, improvements, etc., to the following embodiments based on the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention.

[0019] In this specification, the term "layer" refers not only to layers with clear boundaries or flat, thin films, but also to layers with gradually changing elemental concentrations and layers that can form complex, interwoven structures with other layers. Elemental analysis of a layer can be performed, for example, by conducting TOF-SIMS / FE-TEM / EDS line analysis measurements of a cross-section of a photoelectric conversion element to confirm the elemental distribution of specific elements.

[0020] The photoelectric conversion element of the present invention comprises a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite crystal disposed between the first electrode and the second electrode. Figure 1 shows a schematic cross-sectional view illustrating the configuration of one embodiment of the photoelectric conversion element of the present invention. The substrate 2 has a second electrode 3, a second charge transport layer 4, a photoelectric conversion layer 5, a first charge transport layer 6, and a first electrode 7. One of the first electrode 7 and the second electrode 3 is a positive electrode and the other is a negative electrode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit. One of the first charge transport layer 6 and the second charge transport layer 4 is a hole transport layer and the other is an electron transport layer. The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3 and the second charge transport layer 4, or the first electrode 7 and the first charge transport layer 6, generating electrons or holes. In other words, the photoelectric conversion layer 5 generates an electric current between the first electrode 7 and the second electrode 3.

[0021] The second charge transport layer 4 is a layer placed between the photoelectric conversion layer 5 and the two electrodes 3 and 7. Multiple layers of the second charge transport layer 4 and the photoelectric conversion layer 5 may be stacked. This configuration can also be called a tandem structure. Alternatively, the photoelectric conversion element may be fabricated on the substrate 2 in the following order: first electrode 7, first charge transport layer 6, photoelectric conversion layer 5, second charge transport layer 4, and second electrode 3.

[0022] The following describes the components that make up the photoelectric conversion element of the present invention. [Photoelectric conversion element] The photoelectric conversion element of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite structure crystal disposed between the first electrode and the second electrode, characterized in that it has a first charge transport layer between the photoelectric conversion layer and the first electrode. Furthermore, in order to improve the photoelectric conversion efficiency, a tandem type in which photoelectric conversion elements are stacked may be used. The type of photoelectric conversion element to be stacked is not limited to perovskite type solar cells that use a perovskite structure crystal as the photoelectric conversion layer, but is also silicon type solar cells, CIGS type solar cells, etc.

[0023] Methods for forming the photoelectric conversion layer and charge transport layer of the photoelectric conversion element of the present invention include coating methods and vapor deposition methods. Examples of coating methods include immersion coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method involves preparing the coating solution for each layer, which will be described later, applying it in the desired order, and drying it. These film formation methods can be selected according to the requirements of each layer. The following explains each layer.

[0024] 〔substrate〕 The photoelectric conversion element 1 of the present invention may include a substrate 2, such as a transparent glass substrate made of soda-lime glass or alkali-free glass, a ceramic substrate, or a transparent plastic substrate. When light is taken in from the first electrode 7 side, the substrate 2 can be made of an opaque material, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0025] 〔electrode〕 The photoelectric conversion element of the present invention has a first electrode and a second electrode. The materials of the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. Examples include metals such as gold, silver, titanium, and copper; sodium, sodium-potassium alloys; lithium, magnesium, carbon, carbon nanotubes; aluminum, magnesium-silver mixtures; magnesium-indium mixtures; aluminum-lithium alloys; Al / Al2O3 mixtures; and Al / LiF mixtures. Examples of transparent electrode materials include conductive transparent materials and conductive transparent polymers such as CuI, ITO (indium tin oxide), SnO2, AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimond-doped tin oxide).

[0026] These materials may be used individually or in combination of two or more. The first electrode 7 and the second electrode 3 may have at least one electrode on the light incidence side that is transparent, while the other electrode may be transparent or also serve as a reflective layer made of a light-reflective material, or it may be a transparent electrode with a reflective layer on the side opposite to the light incidence side. When the first electrode 7 is on the light incidence side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The transparent electrode may also be a patterned electrode.

[0027] [Photoelectric conversion layer] The photoelectric conversion element of the present invention has a photoelectric conversion layer containing a perovskite crystal disposed between a first electrode and a second electrode, wherein the photoelectric conversion element has crystal A that contacts the second charge transport layer, and crystal B that covers the gap between adjacent crystals A, contacts the first charge transport layer, and does not contact the second charge transport layer. Here, crystals A and B are parts of the photoelectric conversion layer, and have basically the same composition as the other parts of the photoelectric conversion layer, and are crystallized from those parts.

[0028] Figure 3 is a schematic cross-sectional view showing an example of the configuration of one embodiment of the photoelectric conversion layer of the present invention. In one example of the embodiment of the photoelectric conversion layer, perovskite crystal A5A is a crystal adjacent to the first charge transport layer and the second charge transport layer, and perovskite crystal B5B is a crystal adjacent to the first charge transport layer, and the void between adjacent crystals A5A is a sealing void 8 covered by crystal B5B. Here, the first charge transport layer 6 is a hole transport layer, and the second charge transport layer 4 is an electron transport layer.

[0029] Figure 4 is a schematic cross-sectional view showing another example of the configuration of one embodiment of the photoelectric conversion layer of the present invention. As in the case of Figure 4, the positions of the first charge transport layer and the second charge transport layer may be reversed compared to the case of Figure 3.

[0030] In the photoelectric conversion element of the present invention, the surface area of ​​the crystal A in the direction intersecting the layer thickness direction of the photoelectric conversion element is 0.05 μm². 2It is preferably as described above, and the thickness of crystal B in the layer thickness direction of the photoelectric conversion element is preferably less than the thickness of the first charge transport layer and less than 300 nm. In the photoelectric conversion element of the present invention, the width of crystal B in the direction intersecting the layer thickness direction of the photoelectric conversion element is preferably larger than the thickness of crystal B in the layer thickness direction of the photoelectric conversion element. By doing so, the photoelectric conversion element of the present invention can achieve higher productivity, better leakage resistance, and improved conversion efficiency. In the present invention, the sizes of crystal A and crystal B can be confirmed by transmission electron microscope (TEM) observation.

[0031] When the sum of the area of the surface of crystal A in the direction intersecting the layer thickness direction of the photoelectric conversion element, the area of the surface of crystal B in the direction intersecting the layer thickness direction of the photoelectric conversion element, the area of the surface of the void in the direction intersecting the layer thickness direction of the photoelectric conversion element, and the area of the surface of the portion where the first charge transport layer and the second charge transport layer are short-circuited in the direction intersecting the layer thickness direction of the photoelectric conversion element is defined as the total area, the ratio of the area of the void in the direction intersecting the layer thickness direction of the photoelectric conversion element to the total area (defect rate in Table 1) is preferably 0.01% or less. By doing so, the photoelectric conversion element of the present invention can achieve higher productivity, better leakage resistance, and improved conversion efficiency.

[0032] The ratio of the sum of the area of the surface of crystal A in the direction intersecting the layer thickness direction of the photoelectric conversion element and the area of the surface of crystal B in the direction intersecting the layer thickness direction of the photoelectric conversion element to the area of the surface of the photoelectric conversion layer in the direction intersecting the layer thickness direction of the photoelectric conversion element is preferably 97% or more. By doing so, the photoelectric conversion element of the present invention can achieve higher productivity, better leakage resistance, and improved conversion efficiency.

[0033] The photoelectric conversion layer 5 has a perovskite-structured crystal. The photoelectric conversion layer forms a planar heterojunction with the first charge transport layer or the second charge transport layer, and the perovskite-structured crystal used in the present invention is preferably represented by the following general formula [1]. A o Bp X q [1]

[0034] In the above general formula [1], A is the first cation, B is the second cation, and X is the halide anion. o, p, and q satisfy 0 ≤ o ≤ 10, 0 ≤ p ≤ 10, and 0 ≤ q ≤ 20, respectively, and A, B, and X may be composed of a single material or two or more types may be used in combination. Additives may be added within the range that the above general formula holds true. Preferably, the first cation is an organic cation, and preferably the second cation is a metal cation. In the present invention, the perovskite crystal structure can be confirmed, for example, by X-ray photoelectron spectroscopy (XPS).

[0035] The above general formula generally forms a three-dimensional perovskite crystal. However, if the constituent cation A is large enough to fit within the three-dimensional perovskite crystal, it can form a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal possessing properties of both two and three dimensions, a two-layer crystal with three-dimensional and two-dimensional perovskite structures, or a mixed three-dimensional / two-dimensional perovskite crystal, all of which function as photoelectric conversion layers.

[0036] A two-layer crystal of 3D and 2D perovskite refers to a crystal in which 3D and 2D perovskite crystals are stacked as independent, separate layers, while a mixed 3D-2D perovskite refers to a crystal in which regions or domains of both 2D or 2.5D layered and 3D perovskite crystals are mixed. The 2D perovskite or 2.5D perovskite crystal may form RP (Ruddlesden-Popper), DJ (Dion-Jacobson), or ACI (Alternating cations in the interlayer) type perovskite structures.

[0037] The A cation in the above general formula [1] is not particularly limited. The A cation may or may not have substituents, and the following structural formulas are examples of this. [ka] [ka]

[0038] Furthermore, while the inorganic atoms are not particularly limited, lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms may be used individually, or two or more may be used in combination.

[0039] In the general formula [1] above, B is a cation atom, and examples include lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, bismuth, and silver are preferred from the viewpoint of the stability of the perovskite crystal structure. These atoms may be used individually or in combination of two or more.

[0040] In the general formula [1] above, X is a halogen or chalcogen atom, such as chlorine, bromine, iodine, oxygen, sulfur, selenium, tellurium, and polonium. These halogen or chalcogen atoms may be used individually or in combination of two or more. Among these, halogen atoms are preferred because the inclusion of a halogen in the structure makes the perovskite crystal more soluble in organic solvents, enabling its application to inexpensive printing methods and the like. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite crystal.

[0041] Specifically, 3D perovskites, 2D perovskites, and mixed 3D-2D perovskites are MAPbI3, FAPbCl3, FAPbI3, and MAPbI x Br 3-x MAPbI x Cl 3-x , Cs 0.05 (MA 0.17 FA 0.83 ) 0.95Pb(I 0.83 Br 0.17 )3、{Cs x1 (FA x2 MA 1-x2 ) 1-x1} x3 Pb(I x4 Br 1-x4 ) x5 、Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 、(FAPbI3) 0.95 (MAPbBr3) 0.05 、(FAPbI3) 0.85 (MAPbBr3) 0.15 、CsPbI3、CsPbBr3、Cs x (MA) 1-x PbI3、Csx(FA) 1-x PbI3、MA x (FA) 1-x PbI3、MA 0.17 FA 0.83 Pb(I 0.83 Br 0.17 )3、Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 、Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 、Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 、(AND)2(MA)2Pb3I 10 、(PTA)2(MA)4Pb5I 16 、(AND)2(MA)4Pb5I 16 、(ThMA)2(MA)2Pb3I 10 、(3BBA)2(MA)2Pb3I 10 、(ThMA)2(FA)4Pb5I 16 、(pF-AND)2(FA 0.3 MA 0.7 )4Pb5I 16 、(PDMA)FA2Pb3I 10 、(3AMPY)(MA)3Pb4I 13(PDMA)MA5Pb6I 19 (PDMA)MA3Pb4I 13 , (BA 0.9 PEA 0.1 )2MA4Pb5I 16 (BA)2MA4Pb5I 16 (BA)2MA3Pb4I 13 , CsSnBr3, CsSnI3, FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I3, FAMASnGeI3, FASnBr3, FASnI3, MA2Sn3I8, MASnBr3, MASnGeI3, and MASnI3 are preferred.

[0042] Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be too little or too much, and the combinations of x1 to x5 may be changed according to the purpose. Examples of x1 to x5 combinations are shown in Table 1. Particularly preferred ranges for the x1 to x5 combinations are 0.03≦x1≦0.10, 0.80≦x2≦0.96, 0.95≦x3≦1.05, 0.80≦x4≦0.96, and 2.95≦x5≦3.05. MACl may also be included as the material for forming the perovskite crystal.

[0043] [Table 1]

[0044] The perovskite crystal described above preferably has a cubic crystal structure in which a metal atom B is located at the body center, organic molecules A are located at each vertex, and halogen atoms X are located at the face centers. Although the details are not clear, it is presumed that having such a structure allows the orientation of octahedra within the crystal lattice to change easily, thereby increasing the electron mobility in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0045] The perovskite crystal used in this invention is preferably a crystalline semiconductor. A crystalline semiconductor is a semiconductor in which the X-ray scattering intensity distribution can be measured and a scattering peak can be detected. Because the perovskite crystal is a crystalline semiconductor, the electron mobility within the perovskite crystal is increased, improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0046] The thickness of the photoelectric conversion layer according to the present invention is preferably 200 nm or more and 1000 nm or less. If the thickness is 200 nm or more, light can be sufficiently absorbed, and if it is 1000 nm or less, the generated charge can be transported to each electrode.

[0047] [First charge transport layer] The photoelectric conversion element of the present invention has a first charge transport layer between the photoelectric conversion layer and the first electrode. In the photoelectric conversion element of the present invention, it is preferable that the first charge transport layer is a hole transport compound. In the present invention, the material of the first charge transport layer 6 is not particularly limited, and examples include spirofluorene compounds, triphenylamine compounds, chrysene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds. In particular, it is preferable that it has an aromatic ring from the viewpoint of compatibility at the film interface, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred.

[0048] Furthermore, the first charge transport layer 6 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 bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazole-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.

[0049] The preferred thickness of the first charge transport layer 6 is 200 nm at the lower limit and 1000 nm at the upper limit. If the thickness of the first charge transport layer 6 is 200 nm or more, it can sufficiently block electrons, and if it is 1000 nm or less, it will not become a resistance during hole transport, and the photoelectric conversion efficiency will be high.

[0050] [Second charge transport layer] As shown in Figures 1 and 2, the photoelectric conversion element of the present invention has a second charge transport layer 4 between the second electrode 3 and the photoelectric conversion layer 5. That is, the photoelectric conversion element of the present invention may have a configuration in which the positions of the first charge transport layer and the second charge transport layer are swapped, as shown in the configuration of Figure 2 compared to the configuration of Figure 1.

[0051] In the photoelectric conversion element of the present invention, it is preferable that the second charge transport layer is an electron transport compound. The material of the second charge 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, surfactants, and more specifically, cyano group-containing polyphenylene vinylene, boron-containing polymers, vasocuproin, vasophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, fullerene compounds, perylene compounds, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium dioxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide.

[0052] The thickness of the second charge transport layer 4 is preferably between 1 nm (lower limit) and 2000 nm (upper limit). If the thickness is 1 nm or more, holes can be sufficiently blocked, and if it is 2000 nm or less, it will not become a resistance during electron transport, resulting in higher photoelectric conversion efficiency.

[0053] <Application Examples> [Photoelectric converter] The photoelectric conversion device of the present invention has a photoelectric conversion element of the present invention. A photoelectric conversion device can be constructed by using multiple photoelectric conversion elements of the present invention. When multiple photoelectric conversion elements are connected together, 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 in order to increase the output voltage. Furthermore, the photoelectric conversion device has the photoelectric conversion element of the present invention and an inverter.

[0054] The inverter may be a converter that converts direct current into alternating current. The photoelectric conversion device may have a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited as long as it can store electricity. For example, a secondary battery using lithium ions, an all-solid-state battery, and an electric double layer capacitor can be mentioned. In order to impart functions such as maintaining or increasing the amount of incident light, a surface layer that is difficult to attach water or dirt, or a function of condensing or guiding light may be added.

[0055] <Second Embodiment> The second embodiment is about the coating liquid. The coating liquid of the present invention is a coating liquid for forming a photoelectric conversion element of the present invention, comprising a photoelectric conversion layer precursor, a solvent, and an additive, the photoelectric conversion layer precursor contains at least one selected from the group consisting of a compound represented by A 1 X 1 and a compound represented by B 1 X 1 2, the A 1 is a monovalent cation containing at least one selected from the group consisting of an alkali metal cation and an organic ammonium, the B 1 is a divalent cation containing at least one selected from the group consisting of lead, tin, bismuth, and silver, the X 1 is a monovalent anion of a halide ion, the solvent contains a plurality of solvent species and has a boiling point of 190°C or lower, the additive is methylammonium chloride.

[0056] X 1 、A 1 、B 1 which are components of the precursor, are each prepared as the precursor of X, A, and B in the above formula [1]. X 1 、A 1 、B 1 may be anything as long as it can be the precursor of X, A, and B in the above formula [1].

[0057] 〔solvent〕 In the drying process for generating perovskite crystals, using only low-boiling-point solvents results in a rapid drying rate of the solvent, easily leading to a supersaturated state and the generation of many crystal nuclei. However, the rapid drying rate of the solvent prevents sufficient nucleus growth, resulting in smaller perovskite crystals. Perovskite layers composed of small crystals have many crystal interfaces, increasing the opportunities for charge recombination at these interfaces, which in turn reduces photoelectric conversion efficiency.

[0058] On the other hand, when only high-boiling-point solvents are used, solvent drying is suppressed compared to low-boiling-point solvents, which sustains the saturated concentration state that contributes to crystal growth, resulting in large crystal growth. However, the supersaturated state that generates crystal nuclei is reduced, decreasing the number of crystal nuclei. In perovskite layers composed of a small number of large perovskite crystals, spaces are more likely to form between the perovskite crystals, causing a short circuit between the first and second charge transport layers, resulting in a decrease in photoelectric conversion efficiency.

[0059] Based on the above, the solvent used in the drying process for producing perovskite crystals is preferably a combination of a low-boiling point solvent to obtain sufficient crystal nuclei and a high-boiling point solvent to grow the crystal nuclei. In particular, the low-boiling point solvent is preferably DMF (N,N-dimethylformamide, boiling point 153°C), and the high-boiling point solvent is preferably DMSO (dimethyl sulfoxide, boiling point 189°C).

[0060] [Additives] To obtain even higher photoelectric conversion efficiency, it is desirable to have large crystals with minimal perovskite crystal interfaces while suppressing the appearance of unwanted spaces between crystals. To obtain such crystals, it is necessary to generate and grow a number of crystal nuclei commensurate with the space available for crystal growth. Therefore, in the drying process, it is necessary to optimize the generation of crystal nuclei by mitigating the supersaturation state and to increase the crystal growth time by suppressing the drying of the solvent.

[0061] The drying process that generates perovskite crystals using the boiling point of the solvent contributes to some extent to the relaxation of the supersaturation state and an increase in crystal growth time. However, because the solvent volatilizes quickly overall, too many crystal nuclei are generated, leading to the formation of unwanted crystal interfaces. Furthermore, the insufficient growth time makes it difficult to obtain large crystals.

[0062] Therefore, additives that suppress the rate of solvent evaporation become useful. MACl is preferred as an additive that suppresses the rate of solvent evaporation. It is presumed that MACl has the effect of suppressing the rate of solvent evaporation by coordinating chloride ions with solvent molecules. Specific examples of MACl are as described above.

[0063] <Third Embodiment> The third embodiment relates to a method for manufacturing a photoelectric conversion element. The method for manufacturing the photoelectric conversion element of the present invention is as follows: The process of forming the first electrode, The process of forming the second electrode, The process involves forming a photoelectric conversion layer between the first electrode and the second electrode, which includes a perovskite crystal structure. The process involves forming a first charge transport layer between the photoelectric conversion layer and the first electrode, The process involves forming a second charge transport layer between the photoelectric conversion layer and the second electrode. Includes, The photoelectric conversion element is characterized by having a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and is in contact with the first charge transport layer but not with the second charge transport layer. The following describes each step of the manufacturing process.

[0064] [Steps for forming the first electrode and steps for forming the second electrode] The present invention relates to a method for manufacturing a photoelectric conversion element, comprising 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 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 (vapor deposition), and SPD (spray pyrolysis deposition). The materials of the first electrode and the second electrode are as described above. When either or both of the first and second electrodes are transparent electrodes, the thickness of the transparent electrode is preferably 0.03 μm or more and 3 μm or less.

[0065] When manufacturing solar cells, cutting processes may be performed between each manufacturing step to form circuits. Examples of cutting processes include mechanical patterning and laser patterning.

[0066] [Process for forming the photoelectric conversion layer] The present invention relates to a method for manufacturing a photoelectric conversion element, which includes the step of forming a photoelectric conversion layer containing a perovskite crystal between a first electrode and a second electrode. The photoelectric conversion layer formation step may include the step of applying a liquid containing the above-mentioned photoelectric conversion layer material. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, mold making, print transfer, immersion pulling, inkjet, spray, and vacuum deposition. These can be appropriately selected according to the characteristics of the photoelectric conversion layer to be manufactured, such as thickness control and orientation control.

[0067] Annealing may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere) to remove the material of the applied photoelectric conversion layer from the liquid or the dispersion medium. The temperature of the annealing treatment is preferably 40°C to 300°C, and more preferably 50°C to 150°C. Annealing is preferable because it can increase the contact area at the interface between the stacked layers, as the materials constituting each layer penetrate each other, thereby increasing the short-circuit current.

[0068] In the method for manufacturing a photoelectric conversion element of the present invention, the photoelectric conversion element has a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, contacts the first charge transport layer, and does not contact the second charge transport layer. As described above, the explanation of crystals A and B is omitted.

[0069] [Steps for forming the first charge transport layer and steps for forming the second charge transport layer] The present invention provides a method for manufacturing a photoelectric conversion element, comprising the steps of forming a first charge transport layer between a photoelectric conversion layer and a first electrode, and forming a second charge transport layer between a photoelectric conversion layer and a second electrode. The steps for forming the first and second charge transport layers are preferably performed by applying a liquid containing the material for the first charge transport layer and a liquid containing the material for the second charge transport layer, respectively. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, mold making, print transfer, immersion and pull-up, inkjet, spray, and vacuum deposition.

[0070] [Modularization Process] The element with electrodes formed may be sealed. Examples of sealing methods include sealing with resin or sealing with film. Examples of materials used for sealing include silazane, silicone rubber, resin having a siloxane skeleton, and glass. Furthermore, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll-to-roll manner, the surface of the sealed elements may be given a hairline finish.

[0071] [Die coating process] In the method for manufacturing the photoelectric conversion element of the present invention, it is preferable that the step of forming the photoelectric conversion layer includes a die coating step. The die coating step preferably includes the steps of discharging a coating solution containing a photoelectric conversion layer precursor, a solvent, and an additive from a slit nozzle toward a heated and held object to be coated in a humidity-controlled environment, thereby coating the object with the coating solution, and after forming a coating film from the coating solution, annealing the coating film together with the object to be coated.

[0072] The coating process preferably includes the steps of moving the object to be coated and the slit nozzle relative to each other, and supplying gas from a gas blow nozzle toward the surface of the coating liquid applied to the object to be coated, and it is preferable that the direction of gas supply is aligned with the relative movement direction of the object to be coated.

[0073] Figure 5 shows the die coating process 101. The die coating process includes discharging a coating solution 53 containing the photoelectric conversion layer precursor, which will become the photoelectric conversion layer, the solvent, and the additives from a slit nozzle 52 toward the heated and held object to be coated 50 in a humidity-controlled environment, thereby coating the object to be coated 50 with the coating solution 53.

[0074] The step of applying the coating liquid 53 to the object to be coated 50 includes a step of moving the object to be coated 50 and the slit nozzle 52 relative to each other, and supplying gas 56 from the gas blow nozzle 55 toward the coating liquid 53 applied to the object to be coated 50.

[0075] The direction of supply of the gas 56 is aligned with the relative movement direction of the object to be coated 50, and the process includes forming a coating film 54 from the coating liquid 53, and then annealing the coating film 54 together with the object to be coated 50 using the heater plate 58.

[0076] In the method for manufacturing a photoelectric element of the present invention, it is preferable that the concentration of the additive in the coating solution is 35 mol / L or more and 45 mol / L or less. In the present invention, the concentration of the additive can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS). Furthermore, it is preferable that the solvent is composed of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide), and that the ratio (molar ratio) of DMF to DMSO is 3:1 in the coating solution. In the present invention, the ratio of DMF to DMSO can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS). In the method for manufacturing a photoelectric element of the present invention, it is preferable that the humidity-controlled environment has a humidity of 10% or less. The coating solution supply unit 51 supplies the coating solution toward the slit nozzle 52.

[0077] The temperature at which the heater plate 58 heats and maintains the object to be coated 50, which is placed on the support plate 57, is preferably 30°C to 60°C. The distance L1 between the coating liquid discharge portion of the slit nozzle 52 and the object to be coated 50 is 100 μm. In the method for manufacturing the photoelectric conversion element of the present invention, the relative movement speed is preferably 5 m / s in the relative movement step.

[0078] In the method for manufacturing the photoelectric conversion element of the present invention, in the step of supplying gas, the wind velocity of the gas 56 on the upper surface of the coated film 54 (surface of the coating liquid) is preferably 50 m / s or more and 70 m / s or less, and the temperature of the gas 56 is preferably 20°C or more and 40°C or less. The gas preferably contains at least one selected from the group consisting of nitrogen, helium, neon, argon, and air.

[0079] The distance L1 between the coating liquid discharge portion of the slit nozzle 52 and the object to be coated 50 is preferably 100 μm, the distance L2 between the gas supply port end of the gas blow nozzle 55 and the object to be coated 50 is preferably 10 mm, the horizontal distance L3 between the coating liquid discharge port end of the slit nozzle 52 and the gas supply port end is preferably 42 mm, and the angle θ between the gas supply port end of the gas blow nozzle 55 and the object to be coated is preferably 35.5°.

[0080] In the method for manufacturing the photoelectric conversion element of the present invention, it is preferable that the annealing of the coated film 54 is performed at 100°C for 10 minutes, followed by 150°C for 5 minutes. By doing so, the photoelectric conversion element of the present invention can achieve higher productivity and improved leakage resistance and conversion efficiency. [Examples]

[0081] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples, unless it exceeds the scope of its essence.

[0082] (Example 1) [Formation of the second charge transport layer] The ITO-coated glass substrate was cleaned, and tin(2) oxide adjusted to 3% by mass was applied thereon by spin coating. Then, it was heated at 150°C for 30 minutes to form a second charge transport layer in the form of a thin film with a thickness of 15 nm.

[0083] [Formation of the photoelectric conversion layer] 67 mg of methylammonium chloride and 397 mg of methylammonium iodide. 1152 mg of lead iodide was dissolved in 1396 mg of N,N-dimethylformamide and 493 mg of dimethyl sulfoxide, and the mixture was stirred for 1 hour to prepare a photoelectric conversion layer coating solution. By die-coating this coating solution onto the electron transport layer, a photoelectric conversion layer made of MAPbI3 was formed.

[0084] The concentration of the additive in the coating solution is 40 mol / L, the solvent is composed of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide), the ratio (molar ratio) of DMF to DMSO is 3:1, the humidity environment is 6%, and the coating solution supply unit 51 supplies the coating solution toward the slit nozzle 52.

[0085] The heater plate 58 heated and maintained the workpiece 50 placed on the support plate 57 at a temperature of 56°C, the distance L1 between the coating liquid discharge portion of the slit nozzle 52 and the workpiece 50 was 100 μm, the relative moving speed was 5 m / s, the air velocity of the gas 56 on the upper surface of the coating film 54 was 53 m / s, the temperature of the gas 56 was 25°C, the distance L2 between the gas supply port end of the gas blow nozzle 55 and the workpiece 50 was 10 mm, the horizontal distance L3 between the coating liquid discharge port end of the slit nozzle 52 and the gas supply port end was 42 mm, the angle θ between the gas supply port end of the gas blow nozzle 55 and the workpiece was 35.5°, and the coating film 54 was annealed at 100°C for 10 minutes followed by 150°C for 5 minutes to form a photoelectric conversion layer with a thickness of 220 nm.

[0086] [Formation of the first charge transport layer] 0.15 g of Spiro-OMeTAD, used as the material for the first 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 and 60 μL of 4-tert-butylpyridine (TBP) were added and mixed.

[0087] Furthermore, 58 μL of acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile was mixed to prepare the material solution for the first charge transport layer. This solution was then applied to the above photoelectric conversion layer by spin coating to form a hole transport layer that would become the first charge transport layer with a thickness of 285 nm.

[0088] [Formation of the first electrode] On the aforementioned first charge transport layer, a layer with a thickness of 80 nm and an area of ​​0.09 cm² 2 Gold electrodes were formed by vacuum deposition to obtain a photoelectric conversion element.

[0089] (Example 2) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the thickness of the photoelectric conversion layer was set to 984 nm.

[0090] (Example 3) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the MACl concentration was set to 45 mol / L.

[0091] (Example 4) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the gas temperature was set to 20°C.

[0092] (Example 5) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the gas temperature was set to 40°C.

[0093] (Example 6) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the gas wind speed was set to 66 m / s.

[0094] (Example 7) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the temperature of the coated body was set to 32°C.

[0095] (Example 8) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the first charge transport layer was an electron transport layer and the second charge transport layer was a hole transport layer.

[0096] (Comparative Example 1) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the gas wind speed was set to 40 m / s.

[0097] (Comparative Example 2) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the gas wind speed was set to 76 m / s.

[0098] (Comparative Example 3) A photoelectric conversion element was obtained in the same manner as in Example 1, except that the solvent consisted of DMF and NMP (N-methyl-2-pyrrolidone), and the coating solution had a molar ratio of 9:11 between DMF and NMP.

[0099] [evaluation] The following evaluations were performed on the photoelectric conversion elements obtained in each example and each comparative example. [Common evaluation criteria] The photoelectric conversion element was cut in half and fixed to an inclined sample stage, then examined by cross-sectional observation using a SEM (SmartSEM, Carl Zeiss Co., Ltd.). During observation, the photoelectric conversion layer and other layers were distinguished by differences in contrast of the observed image and compositional analysis using the SEM-EDX function, and images were processed at a magnification of 50,000x.

[0100] [Presence or absence of crystals A and B] Image processing obtained from the above evaluation common items identified crystals A and B in the photoelectric conversion layer. Five locations were randomly photographed, and the presence or absence of crystals A and B was determined. The results are shown in Table 2.

[0101] [Presence or absence of crystal B covering the gap between crystals A] Image processing obtained from the above common evaluation criteria identified crystals A and B in the photoelectric conversion layer. Five locations were randomly photographed, and the presence or absence of crystal B covering the gaps between crystals A was determined. The results are shown in Table 2.

[0102] [Crystal area of ​​crystal A] The crystal area of ​​crystal A in the photoelectric conversion layer was measured using image processing obtained from the common evaluation criteria described above. Five random locations were photographed, and the average of these five points was used as the crystal area of ​​crystal A in the photoelectric conversion layer. The results are shown in Table 2.

[0103] [Measurement of the thickness and width of crystal B] The thickness and width of crystal B in the photoelectric conversion layer portion were measured by the image processing obtained from the above-described common evaluation items. Five locations were randomly photographed, and the average of the five average values was taken as the thickness and width of crystal B in the photoelectric conversion layer portion. The results are shown in Table 2.

[0104] [Measurement of average film thickness] The average values of the film thicknesses of the charge transport layer and the photoelectric conversion layer portion were measured by the image processing obtained from the above-described common evaluation items. Five locations were randomly photographed, and the average of the five average values was taken as the average film thickness of the charge transport layer and the photoelectric conversion layer. The results are shown in Table 2.

[0105] [Defect rate of photoelectric conversion layer] The area of crystal A, the area of crystal B, the area of the void sealed by crystal B, and the area of the void where the first charge transport layer and the second charge transport layer are short-circuited in the photoelectric conversion layer were measured by the image processing obtained from the above-described common evaluation items. Five locations were randomly photographed, and the average of the five average values was taken as each average area.

[0106] The sum of the average of crystal A, the average area of crystal B, and the average void area sealed by crystal B was taken as the total area, and the ratio of the average void area to the total area was taken as the defect rate. The results are shown in Table 2.

[0107] [Abundance ratio of crystal A and crystal B in photoelectric conversion layer] The crystal area, the area of crystal A, and the area of crystal B constituting the photoelectric conversion layer were measured by the image processing obtained from the above-described common evaluation items. Five locations were randomly photographed, and the average of the five average values was taken as each average area. The ratio of the sum of the average area of crystal A and the average area of crystal B to the average crystal area was taken as the abundance ratio of crystal A and crystal B. The results are shown in Table 2.

[0108] [Power generation efficiency evaluation] In Example 1, a power supply (model 236, manufactured by KEITHLEY) was connected between the electrodes of the photoelectric conversion element, and the intensity was 100 mW / cm 2The photoelectric conversion efficiency was evaluated by irradiating a constant amount of light using a solar simulator (manufactured by Yamashita Densou Co., Ltd.) and measuring the generated current and voltage. The series resistance was approximated by calculating the reciprocal of the slope near Voc of the obtained current-voltage curve, and the shunt resistance was approximated by calculating the reciprocal of the slope near Jsc of the obtained current-voltage curve.

[0109] Examples 2-6 and Comparative Examples 1-3 were evaluated in the same manner as Example 1, and the photoelectric conversion efficiency was determined. The results are shown as relative values ​​with the result of Example 1 set to 1. A relative value of 0.80 or higher was considered good. The results are shown in Table 2.

[0110] [Table 2]

[0111] This embodiment includes the following configurations and methods. (Composition 1) The first electrode and The second electrode, A photoelectric conversion layer comprising a perovskite crystal is disposed between the first electrode and the second electrode. A photoelectric conversion element having, A first charge transport layer is provided between the photoelectric conversion layer and the first electrode. A second charge transport layer is provided between the photoelectric conversion layer and the second electrode. The photoelectric conversion element is characterized by having a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and is in contact with the first charge transport layer but not with the second charge transport layer. (Configuration 2) The area of ​​the surface of crystal A in the direction intersecting the layer thickness direction of the photoelectric conversion element is 0.05 μm². 2 The above describes the photoelectric conversion element as described in Configuration 1. (Composition 3) The photoelectric conversion element according to configuration 1 or 2, wherein the thickness of the crystal B in the layer thickness direction of the photoelectric conversion element is smaller than the thickness of the first charge transport layer, and is less than 300 nm. (Composition 4) The photoelectric conversion element according to any one of configurations 1 to 3, wherein the width of the crystal B in the direction intersecting the layer thickness direction of the photoelectric conversion element is greater than the thickness of the crystal B in the layer thickness direction of the photoelectric conversion element. (Composition 5) The photoelectric conversion element according to any one of configurations 1 to 4, wherein the thickness of the photoelectric conversion layer is 200 nm or more and 1000 nm or less. (Composition 6) When the total area is the sum of the area of ​​the surface of crystal A in a direction intersecting the thickness direction of the photoelectric conversion element, the area of ​​the surface of crystal B in a direction intersecting the thickness direction of the photoelectric conversion element, the area of ​​the surface of the void in a direction intersecting the thickness direction of the photoelectric conversion element, and the area of ​​the portion where the first charge transport layer and the second charge transport layer are short-circuited in a direction intersecting the thickness direction of the photoelectric conversion element, The ratio of the area of ​​the void in a direction intersecting the thickness direction of the photoelectric conversion element to the total area is 0.01% or less. A photoelectric conversion element according to any one of configurations 1 to 5, wherein the ratio of the area of ​​the surface of the photoelectric conversion layer in a direction intersecting the thickness direction of the photoelectric conversion element to the area of ​​the surface of the crystal A in a direction intersecting the thickness direction of the photoelectric conversion element and the area of ​​the surface of the crystal B in a direction intersecting the thickness direction of the photoelectric conversion element is 97% or more. (Composition 7) The photoelectric conversion layer forms a planar heterojunction with the first charge transport layer or the second charge transport layer. The aforementioned photoelectric conversion layer is, General formula A o B p X q It is represented as, (Here, A is the first cation, B is the second cation, X is a halide anion, and o, p, and q are 0≦o≦10, 0≦p≦10, and 0≦q≦20, respectively.) The first cation is an organic cation, A photoelectric conversion element according to any one of configurations 1 to 6, wherein the second cation is a metal cation. (Composition 8) A coating solution for forming a photoelectric conversion element according to any one of claims 1 to 7, comprising a photoelectric conversion layer precursor, a solvent, and an additive, The photoelectric conversion layer precursor is A 1 X 1 Compounds represented by B 1 X 1 It includes at least one selected from the group consisting of compounds represented by 2, A 1 It is a monovalent cation comprising at least one selected from the group consisting of alkali metal cations and organic ammonium compounds. Applicable B 1 is a divalent cation comprising at least one selected from the group consisting of lead, tin, bismuth, and silver. The X 1 It is a monovalent anion of a halide ion, The aforementioned solvent comprises multiple solvent species and has a boiling point of 190°C or lower. The aforementioned additive is methylammonium chloride in the coating solution. (Method 1) The process of forming the first electrode, The process of forming the second electrode, The process involves forming a photoelectric conversion layer between the first electrode and the second electrode, which includes a perovskite crystal structure. The process involves forming a first charge transport layer between the photoelectric conversion layer and the first electrode, The process involves forming a second charge transport layer between the photoelectric conversion layer and the second electrode. Includes, A method for manufacturing a photoelectric conversion element, characterized in that the photoelectric conversion element has a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and contacts the first charge transport layer but does not contact the second charge transport layer. (Method 2) The process of forming the photoelectric conversion layer includes a die-coating process, The die coating process involves discharging a coating solution containing a photoelectric conversion layer precursor, a solvent, and additives from a slit nozzle towards a heated and held object to be coated, in a humidity-controlled environment, thereby coating the object with the coating solution. A method for producing a photoelectric conversion element according to Method 1, comprising the steps of forming a coating film from the coating liquid and then annealing the coating film together with the object to be coated. (Method 3) The coating step includes the steps of moving the object to be coated and the slit nozzle relative to each other, and supplying gas from a gas blow nozzle toward the surface of the coating liquid applied to the object to be coated, The method for manufacturing a photoelectric conversion element according to Method 2, wherein the direction of supply of the gas is aligned with the relative movement direction of the object to be coated. (Method 4) A method for manufacturing a photoelectric conversion element according to method 2 or 3, wherein the concentration of the additive in the coating solution is 35 mol / L or more and 45 mol / L or less. (Method 5) A method for manufacturing a photoelectric conversion element according to any one of methods 2 to 4, wherein the solvent is composed of DMF and DMSO, and the ratio (molar ratio) of DMF to DMSO is 3:1. (Method 6) The humidity-controlled environment has a humidity of 10% or less. A method for manufacturing a photoelectric conversion element according to any one of methods 2 to 5, wherein the temperature at which the heating and holding takes place is 30°C or higher and 60°C or lower. (Method 7) The method for manufacturing a photoelectric conversion element according to Method 3, wherein in the step of relative movement, the speed of movement is 5 m / s. (Method 8) A method for manufacturing a photoelectric conversion element according to method 3 or 7, wherein in the step of supplying the gas, the air velocity of the gas on the surface of the coating liquid is 50 m / s or more and 70 m / s or less. (Method 9) A method for manufacturing a photoelectric conversion element according to method 3, 7, or 8, wherein in the step of supplying the gas, the temperature of the gas is 20°C or higher and 40°C or lower. (Method 10) The distance L1 between the coating liquid discharge portion of the slit nozzle and the object to be coated is 100 μm. The distance L2 between the gas supply port end of the gas blow nozzle and the object to be coated is 10 mm. The horizontal distance L3 between the coating liquid discharge end and the gas supply end of the slit nozzle is 42 mm. The method for manufacturing a photoelectric conversion element according to method 3, 7, 8, or 9, wherein the angle θ between the gas supply port end of the gas blow nozzle and the object to be coated is 35.5°. (Method 11) A method for manufacturing a photoelectric conversion element according to any one of methods 2 to 10, wherein the annealing step is performed at 100°C for 10 minutes, followed by 150°C for 5 minutes. (Method 12) A method for manufacturing a photoelectric element according to method 3, 7, 8, 9, or 10, wherein the gas comprises at least one selected from the group consisting of nitrogen, helium, neon, argon, and air. [Explanation of symbols]

[0112] 1. Photoelectric conversion element 2 circuit boards 3. Second electrode 4. Second charge transport layer 5 Photoelectric conversion layer 5A Crystal A 5B Crystal B 6. First charge transport layer 7. First electrode 8 Sealed air gap 50 Object to be coated 51 Coating liquid supply unit 52 Slit Nozzle 53. Application solution 54 Coating film 55 Gas blow nozzle 56 Gas 57 Support plate 58 Heater Plate

Claims

1. The first electrode and The second electrode, A photoelectric conversion layer comprising a perovskite crystal is disposed between the first electrode and the second electrode. A photoelectric conversion element having, A first charge transport layer is provided between the photoelectric conversion layer and the first electrode. A second charge transport layer is provided between the photoelectric conversion layer and the second electrode. The photoelectric conversion element is characterized by having a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and is in contact with the first charge transport layer but not with the second charge transport layer.

2. The area of ​​the surface of crystal A in the direction intersecting the layer thickness direction of the photoelectric conversion element is 0.05 μm². ２ The photoelectric conversion element described in claim 1 is as described above.

3. The photoelectric conversion element according to claim 1, wherein the thickness of the crystal B in the layer thickness direction of the photoelectric conversion element is less than the thickness of the first charge transport layer, and is less than 300 nm.

4. The photoelectric conversion element according to claim 1, wherein the width of the crystal B in the direction intersecting the layer thickness direction of the photoelectric conversion element is greater than the thickness of the crystal B in the layer thickness direction of the photoelectric conversion element.

5. The photoelectric conversion element according to claim 1, wherein the thickness of the photoelectric conversion layer is 200 nm or more and 1000 nm or less.

6. When the total area is the sum of the area of ​​the surface of crystal A in a direction intersecting the thickness direction of the photoelectric conversion element, the area of ​​the surface of crystal B in a direction intersecting the thickness direction of the photoelectric conversion element, the area of ​​the surface of the void in a direction intersecting the thickness direction of the photoelectric conversion element, and the area of ​​the portion where the first charge transport layer and the second charge transport layer are short-circuited in a direction intersecting the thickness direction of the photoelectric conversion element, The ratio of the area of ​​the void in a direction intersecting the thickness direction of the photoelectric conversion element to the total area is 0.01% or less. The photoelectric conversion element according to claim 1, wherein the ratio of the area of ​​the surface of the photoelectric conversion layer in a direction intersecting the thickness direction of the photoelectric conversion element to the area of ​​the surface of the crystal A in a direction intersecting the thickness direction of the photoelectric conversion element and the area of ​​the surface of the crystal B in a direction intersecting the thickness direction of the photoelectric conversion element is 97% or more.

7. The photoelectric conversion layer forms a planar heterojunction with the first charge transport layer or the second charge transport layer. The aforementioned photoelectric conversion layer is, in general form, A ｏ B ｐ X ｑ It is represented as, (Here, A is the first cation, B is the second cation, X is a halide anion, and o, p, and q are 0 ≤ o ≤ 10, 0 ≤ p ≤ 10, and 0 ≤ q ≤ 20, respectively.) The first cation is an organic cation, The photoelectric conversion element according to claim 1, wherein the second cation is a metal cation.

8. A coating solution for forming a photoelectric conversion element according to any one of claims 1 to 7, comprising a photoelectric conversion layer precursor, a solvent, and an additive, The photoelectric conversion layer precursor contains at least one selected from the group consisting of a compound represented by A １ X １ and a compound represented by B １ X １ ２ ​ A １ It is a monovalent cation comprising at least one selected from the group consisting of alkali metal cations and organic ammonium compounds. Said B １ is a divalent cation comprising at least one selected from the group consisting of lead, tin, bismuth, and silver. The X １ It is a monovalent anion of a halide ion, The aforementioned solvent comprises multiple solvent species and has a boiling point of 190°C or lower. The aforementioned additive is methylammonium chloride in the coating solution.

9. The process of forming the first electrode, The process of forming the second electrode, The process involves forming a photoelectric conversion layer between the first electrode and the second electrode, which includes a perovskite crystal structure. The process involves forming a first charge transport layer between the photoelectric conversion layer and the first electrode, The process involves forming a second charge transport layer between the photoelectric conversion layer and the second electrode. Includes, A method for manufacturing a photoelectric conversion element, characterized in that the photoelectric conversion element has a crystal A that contacts the second charge transport layer, and a crystal B that covers the gap between adjacent crystals A, and contacts the first charge transport layer but does not contact the second charge transport layer.

10. The process of forming the photoelectric conversion layer includes a die-coating process, The die coating process involves discharging a coating solution containing a photoelectric conversion layer precursor, a solvent, and additives from a slit nozzle towards a heated and held object to be coated, in a humidity-controlled environment, thereby coating the object with the coating solution. A method for manufacturing a photoelectric element according to claim 9, comprising the steps of forming a coating film from the coating liquid and then annealing the coating film together with the object to be coated.

11. The coating step includes the steps of moving the object to be coated and the slit nozzle relative to each other, and supplying gas from a gas blow nozzle toward the surface of the coating liquid applied to the object to be coated, The method for manufacturing a photoelectric conversion element according to claim 10, wherein the direction of supply of the gas is aligned with the relative movement direction of the object to be coated.

12. The method for manufacturing a photoelectric element according to claim 10, wherein the concentration of the additive in the coating solution is 35 mol / L or more and 45 mol / L or less.

13. The method for manufacturing a photoelectric element according to claim 10, wherein the solvent is composed of DMF and DMSO, and the ratio (molar ratio) of DMF to DMSO is 3:

1.

14. The humidity-controlled environment described above has a humidity of 10% or less. The method for manufacturing a photoelectric conversion element according to claim 10, wherein the temperature at which the heating and holding takes place is 30°C or higher and 60°C or lower.

15. The method for manufacturing a photoelectric conversion element according to claim 11, wherein in the step of moving the element relative to the element, the speed of movement is 5 m / s.

16. The method for manufacturing a photoelectric conversion element according to claim 11, wherein in the step of supplying the gas, the air velocity of the gas on the surface of the coating liquid is 50 m / s or more and 70 m / s or less.

17. The method for manufacturing a photoelectric conversion element according to claim 11, wherein in the step of supplying the gas, the temperature of the gas is 20°C or more and 40°C or less.

18. The distance L1 between the coating liquid discharge portion of the slit nozzle and the object to be coated is 100 μm. The distance L2 between the gas supply port end of the gas blow nozzle and the object to be coated is 10 mm. The horizontal distance L3 between the coating liquid discharge end and the gas supply end of the slit nozzle is 42 mm. The method for manufacturing a photoelectric conversion element according to claim 11, wherein the angle θ between the gas supply port end of the gas blow nozzle and the object to be coated is 35.5°.

19. The method for manufacturing a photoelectric conversion element according to claim 10, wherein the annealing step is performed at 100°C for 10 minutes, followed by 150°C for 5 minutes.

20. The method for manufacturing a photoelectric element according to claim 11, wherein the gas comprises at least one selected from the group consisting of nitrogen, helium, neon, argon, and air.

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