Photoelectric conversion thin film element and method for manufacturing the same

Abstract

To provide a perovskite-type photoelectric conversion element that is capable of maintaining or improving photoelectric conversion efficiency (conversion efficiency) over a long period of time (exhibits high durability), and a method for manufacturing the same.SOLUTION: A photoelectric conversion element is manufactured. The photoelectric conversion element includes a perovskite layer containing a perovskite compound having a perovskite-type structure and a polysilane layer containing polysilane. The perovskite layer includes a first perovskite layer containing a first perovskite compound having methyl ammonium and a second perovskite layer that has monovalent cations having an ion diameter larger than that of methyl ammonium and that contains a second perovskite compound different from the first perovskite compound. The second perovskite layer is located between the first perovskite layer and the polysilane layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a photoelectric conversion element (or photoelectric conversion thin film element) having a perovskite layer containing a perovskite compound (or perovskite compound) having a perovskite structure, and a method for manufacturing the same. [Background technology]

[0002] Solar power generation, which can convert inexhaustible, clean sunlight into electricity, is attracting much attention as a renewable energy source that can replace fossil fuels and nuclear power. Perovskite solar cells are currently attracting worldwide attention because they have high power generation efficiency, can be made low-cost, lightweight, and flexible, and are compatible with the wavelengths of indoor light.

[0003] Japanese Patent Publication No. 2021-193722 (Patent Document 1), Japanese Patent Publication No. 2018-98276 (Patent Document 2), and Japanese Patent Publication No. 2019-68018 (Patent Document 3) describe the combination of polysilanes in photoelectric conversion elements including perovskite layers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-193722 [Patent Document 2] Japanese Patent Application Publication No. 2018-98276 [Patent Document 3] Japanese Patent Application Publication No. 2019-68018 [Non-patent literature]

[0005] [Non-Patent Document 1] Energy & Environmental Science, 2021, 14, 5161-5190 Summary of the Invention [Problem to be solved by the invention]

[0006] In perovskite solar cells, methylammonium ions (CH3NH3 + There are concerns about instability in device characteristics due to factors such as the desorption of cations. Due to this crystal instability, if heat treatment is performed in an air atmosphere or at an excessively high heat treatment temperature during the manufacturing process (the process of growing perovskite crystals), it will lead to a rapid decline in photoelectric conversion efficiency. Therefore, perovskite crystals (perovskite layers) are usually produced in an inert gas atmosphere at a low heat treatment temperature of around 100°C. This makes the manufacturing process complicated, making it difficult to sufficiently improve productivity, and also tends to result in low durability due to a decline in photoelectric conversion efficiency over time.

[0007] In the examples of Patent Document 2, the perovskite layer is formed by heat treatment at 100°C, and there is no mention of the gas atmosphere. Furthermore, Patent Document 2 describes that high photoelectric conversion efficiency (conversion efficiency or power generation efficiency) is exhibited, but there is no specific mention of durability.

[0008] Furthermore, in the examples of Patent Document 3, it is described that the perovskite layer was prepared by heat treatment in the air at 100° C. However, there is no specific description about improving durability.

[0009] On the other hand, Patent Document 1 discloses a perovskite-type photoelectric conversion element that can maintain or improve conversion efficiency over a long period of time and exhibits high durability even when a perovskite layer is formed by high-temperature heat treatment in the atmosphere, and the examples in this document describe that the perovskite layer was prepared by high-temperature heat treatment at 180 to 210°C in the atmosphere.

[0010] However, the devices prepared in these publications contain a hole-transport layer containing the hole-transport material 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (also known as Spiro-OMeTAD). Although Spiro-OMeTAD is widely used worldwide as an excellent hole-transport material, its price is extremely high, at approximately ¥30,000 / g, accounting for approximately one-quarter of the device material cost, posing an obstacle to practical application. Furthermore, Spiro-OMeTAD and its dopants (e.g., lithium salts such as lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI)) are known to be hygroscopic, and absorbed moisture can cause degradation of the perovskite layer and reduce durability. Furthermore, these devices have poor heat resistance, and it is known that the dopant volatilizes from Spiro-OMeTAD at 85°C, degrading device characteristics, and that the device performance deteriorates even more rapidly at 100°C [see, for example, Energy & Environmental Science, 2021, 14, 5161-5190 (Non-Patent Document 1)].

[0011] Therefore, an object of the present disclosure is to provide a perovskite-type photoelectric conversion element capable of maintaining or improving photoelectric conversion efficiency (conversion efficiency) over a long period of time (exhibiting high durability), and a method for manufacturing the same. [Means for solving the problem]

[0012] As a result of extensive research to achieve the above object, the present inventors have found that by laminating two specific perovskite layers and a polysilane layer in a specific positional relationship, it is possible to maintain or improve conversion efficiency over a long period of time, and have completed the present invention (or the present disclosure). That is, the present disclosure may include the following aspects.

[0013] Aspect [1]: A photoelectric conversion element comprising a perovskite layer containing a perovskite compound having a perovskite structure and a polysilane layer containing polysilane, the perovskite layer comprises a first perovskite compound having methylammonium; a second perovskite layer including a second perovskite compound having monovalent cations with a larger ionic diameter than methylammonium and different from the first perovskite compound; A photoelectric conversion element, wherein the second perovskite layer is located between the first perovskite layer and the polysilane layer.

[0014] Aspect [2]: The photoelectric conversion element according to aspect [1], further comprising an intermediate polysilane layer containing the same or different polysilane as the polysilane in the polysilane layer, and positioned between the first perovskite layer and the second perovskite layer.

[0015] Aspect [3]: The polysilane (the polysilane in the polysilane layer and / or the polysilane in the intermediate polysilane layer) is represented by the following formulas (2a) and (2b):

[0016] [ka]

[0017] (In the formula, R 1 ~R 3 independently represent a hydrogen atom, a hydroxyl group, an organic group, or a silyl group. The photoelectric conversion element according to embodiment [1] or [2], comprising at least one structural unit selected from the structural units represented by:

[0018] Aspect [4]: ​​In the formula (2a), R 1 and R 2 At least one of the groups is an aryl group-containing group, and in the formula (2b), R 3 The photoelectric conversion element according to embodiment [3], wherein is an aryl group-containing group.

[0019] Aspect [5]: The photoelectric conversion element according to aspect [3] or [4], wherein the proportion of the structural unit represented by the formula (2a) is 50 mol % or more relative to the entire polysilane.

[0020] Aspect [6]: The photoelectric conversion element according to any one of aspects [1] to [5], wherein the polysilane (the polysilane in the polysilane layer and / or the polysilane in the intermediate polysilane layer) is a cyclic polysilane.

[0021] Aspect [7]: The photoelectric conversion element according to any one of aspects [1] to [6], wherein the proportion of polysilane in the polysilane layer is 50 to 100% by mass with respect to the entire polysilane layer.

[0022] Aspect [8]: The photoelectric conversion element according to any one of aspects [2] to [7], wherein the proportion of polysilane in the intermediate polysilane layer is 50 to 100% by mass with respect to the entire intermediate polysilane layer.

[0023] Aspect [9]: The photoelectric conversion element according to any one of aspects [1] to [8], wherein the first perovskite compound has methylammonium in a proportion of 50 mol % or more (for example, 50 to 100 mol %) relative to all monovalent cations in the first perovskite compound.

[0024] Aspect

[10] : The photoelectric conversion element according to any one of aspects [1] to [9], wherein the second perovskite compound has, as a monovalent cation having an ionic diameter larger than that of methylammonium, at least one monovalent cation selected from amidinium, guanidinium, and organic ammonium having two or more carbon atoms.

[0025] Aspect

[11] : The photoelectric conversion element according to any one of aspects [1] to

[10] , wherein the second perovskite compound has 0.1 to 90 mol % of monovalent cations having a larger ionic diameter than methylammonium relative to all monovalent cations in the second perovskite compound.

[0026] Aspect

[12] : The photoelectric conversion element according to any one of aspects [1] to

[11] , which does not include a hole transport layer containing 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

[0027] Aspect

[13] : The photoelectric conversion element according to any one of aspects [1] to

[12] , which has a conversion efficiency of 5% or more 200 days after production.

[0028] Aspect

[14] : A pre-lamination step of forming a pre-laminate by directly or indirectly laminating, in this order, a film containing a first perovskite precursor for forming a first perovskite compound having methylammonium, a film containing a second perovskite precursor for forming a second perovskite compound having monovalent cations with an ion diameter larger than that of methylammonium and different from the first perovskite compound, and a polysilane layer containing polysilane; and a heat treatment step of heat treating the preliminary laminate to form a laminate including a first perovskite layer, a second perovskite layer, and a polysilane layer.

[0029] Aspect

[15] : The manufacturing method according to aspect

[14] , wherein the heat treatment temperature in the heat treatment step is 150 to 250°C.

[0030] Aspect

[16] : The manufacturing method according to aspect

[14] or

[15] , wherein the pre-lamination step and the heat treatment step are carried out in the atmosphere.

[0031] The present disclosure may also achieve the following secondary objectives (or solve secondary problems).

[0032] That is, another object of the present disclosure is to provide a perovskite-type photoelectric conversion element that exhibits high conversion efficiency without using Spiro-OMeTAD, which is an excellent hole transport material, and a method for producing the same.

[0033] Still another object of the present disclosure is to provide a perovskite-type photoelectric conversion element that can be manufactured with high productivity and exhibits high durability, and a method for manufacturing the same.

[0034] In this specification and claims, the number of carbon atoms in a substituent is defined as C1, C6, C 10 For example, an alkyl group with 1 carbon atom is called a "C1 alkyl," and an aryl group with 6 to 10 carbon atoms is called a "C 6-10 It is indicated as "aryl" etc.

[0035] In the present specification and claims, the term "independently" means that two or more components are independent components, for example, a group R 1 ~R 3 In the case of R 1 ~R 3 does not have to be the same hydrogen atom, hydroxyl group, organic group or silyl group, and may be different from each other.

[0036] In this specification and claims, a numerical range indicated as "X to Y" may include the numerical values ​​X and Y. [Effects of the Invention]

[0037] According to the present disclosure, it is possible to provide a perovskite photoelectric conversion element capable of maintaining or improving photoelectric conversion efficiency (conversion efficiency) over a long period of time (exhibiting high durability), and a method for manufacturing the same. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram showing an example of a photoelectric conversion element according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing another example of the photoelectric conversion element of the present disclosure. [Figure 3] FIG. 3 shows an X-ray diffraction pattern measured using the photoelectric conversion element produced in Example 1. [Figure 4]FIG. 4 is a graph showing the change over time in photoelectric conversion efficiency η of the photoelectric conversion element produced in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0039] [Configuration of photoelectric conversion element] The photoelectric conversion element of the present disclosure comprises a perovskite layer containing a perovskite compound (perovskite crystal or perovskite phase) having a perovskite structure, and a polysilane layer (or a first polysilane layer) containing polysilane; the perovskite layer contains a first perovskite compound (first perovskite crystal or MA-containing perovskite compound) having methylammonium (CH3NH3 or MA). and a second perovskite layer (or large-ion-containing perovskite layer) containing a second perovskite compound (second perovskite crystal or large-ion-containing perovskite compound) that has monovalent cations with a larger ion diameter than methylammonium and is different from the first perovskite compound; the second perovskite layer is disposed (laminated) directly or indirectly between the first perovskite layer and the polysilane layer.

[0040] The photoelectric conversion element may further include an intermediate polysilane layer (second polysilane layer) that contains a polysilane that is the same as or different from the polysilane in the polysilane layer (first polysilane layer) and is located between the first perovskite layer and the second perovskite layer.

[0041] The photoelectric conversion element may further include, for example, a first electrode (transparent electrode), an electron transport layer (ETL), a second electrode (metal or carbon electrode), etc. Typical structures include a planar heterojunction type (or planar type (normal structure)) in which the first electrode / electron transport layer (ETL) / first perovskite layer / second perovskite layer / polysilane layer / second electrode are stacked directly or indirectly in this order; an inverted structure (or planar (OPV) type (normal structure)) in which the order of the first electrode and the second electrode is reversed compared to the planar heterojunction type; and a nanostructure type (or mesoporous type (normal structure)) in which a porous portion containing a porous oxide is formed adjacent to the electron transport layer near the interface between the perovskite layer and the electron transport layer in the planar heterojunction type, and a porous layer in which the perovskite compound is infiltrated (or impregnated) in this porous portion. The photoelectric conversion element may have any structure, but a nanostructure (mesoporous type) is preferred from the viewpoint of having a large surface area and being able to easily improve properties such as conversion efficiency. Specific examples of the structure include a structure in which a first electrode 1, an electron transport layer 2, a first perovskite layer 3 (a porous layer 3a containing a porous portion and the first perovskite compound, and a non-porous layer 3b containing the first perovskite compound), a second perovskite layer 4, a polysilane layer (first polysilane layer) 5, and a second electrode 6 are stacked directly or indirectly in this order, as shown in FIG. 1; and a structure in which a first electrode 11, an electron transport layer 12, a first perovskite layer 13 (a porous layer 13a containing a porous portion and the first perovskite compound, and a non-porous layer 13b containing the first perovskite compound), an intermediate polysilane layer (second polysilane layer) 17, a second perovskite layer 14, a polysilane layer (first polysilane layer) 15, and a second electrode 16 are stacked directly or indirectly in this order, as shown in FIG. 2. The photoelectric conversion element may or may not further include a hole transport layer (HTL) and / or an electron blocking layer, as necessary.

[0042] (Perovskite layer) The perovskite layers (first and second perovskite layers) only need to contain at least a perovskite compound (perovskite crystal or perovskite phase), and the perovskite compound is preferably a compound having a perovskite structure represented by the following formula (1). That is, the first and second perovskite layers preferably contain different types of perovskite compounds (perovskite crystals) from the perovskite compounds represented by the following formula (1).

[0043] AMX3(1) [In the formula, A (or A site) represents a monovalent cation (monovalent cation) containing at least one selected from organic ammonium (organic ammonium ion), amidinium (amidinium ion), guanidinium (guanidinium ion), and alkali metal ion; M (M site or B site) represents a divalent cation (divalent metal ion) of at least one metal element selected from the group 14 elements of the periodic table and the group 2 elements of the periodic table; X (or X site) represents a halide ion (halogen anion).

[0044] In the formula (1), the monovalent cation represented by A may include at least one selected from organic ammonium, amidinium, guanidinium [also referred to as C(NH) or GA], and alkali metal ions, or may include a combination of two or more of them.

[0045] Examples of organic ammonium (organic ammonium ion) at the A site include alkylammonium, specifically, C ammonium such as methylammonium (also known as CH3NH3 or MA), ethylammonium, n-propylammonium, isopropylammonium, n-butylammonium, isobutylammonium, s-butylammonium, and t-butylammonium. 1-6 Alkylammonium; arylammonium, specifically, C such as anilinium 6-10Aryl ammonium; aralkyl ammonium, specifically benzyl ammonium, phenethyl ammonium, etc. 6-10 Aryl C 1-6 These organic ammonium salts may be contained alone or in combination of two or more kinds.

[0046] Examples of A-site amidinium (amidinium ion) include formamidinium [also known as HC(NH2)2 or FA], acetamidinium, and propionamidinium. 1-6 These amidiniums may be contained alone or in combination of two or more.

[0047] Examples of the alkali metal ions at the A site include lithium ions, sodium ions, potassium ions, rubidium ions, and cesium ions, and these alkali metal ions may be contained alone or in combination of two or more.

[0048] Examples of elements corresponding to the divalent cation represented by M include elements of Group 14 of the periodic table, such as lead (Pb), tin (Sn), and germanium (Ge), and elements of Group 2 of the periodic table (or alkaline earth metals), such as radium (Ra), barium (Ba), strontium (Sr), calcium (Ca), and magnesium (Mg). M may contain these divalent cations alone or in combination.

[0049] Examples of halogen elements corresponding to the halide ions (halogen anions) represented by X include iodine (I), bromine (Br), and chlorine (Cl). X may contain these halide ions alone or in combination of two or more.

[0050] First perovskite layer (MA-containing perovskite layer) The first (MA-containing) perovskite layer contains a first (MA-containing) perovskite compound (crystal) that has at least methylammonium (CH3NH3 or MA) at the A site. Perovskite compounds containing MA at the A site are known to have an unstable crystal structure due to MA cleavage, resulting in low durability. However, in the photoelectric conversion element of the present disclosure, the first perovskite layer is combined with a second perovskite layer and a polysilane layer, and these are stacked in a specific positional relationship. This effectively suppresses cleavage even when MA is present at the A site, significantly improving durability. In other words, the first perovskite compound is preferably a compound represented by the following formula (1-1):

[0051] A 1 M 1 X 1 3(1-1) [In the formula, A 1 (or the first A site) represents a monovalent cation (monovalent cation) containing at least MA; M 1 (the first M site or the first B site) represents a divalent cation (divalent metal ion) of at least one metal element selected from the group 14 elements of the periodic table and the group 2 elements of the periodic table, X 1 (or the first X site) represents a halide ion (halogen anion)].

[0052] In the formula (1-1), A 1 It is sufficient that the compound contains at least MA, and if necessary, it may contain other monovalent cations different from MA. Examples of other monovalent cations include the organic ammoniums exemplified as A in formula (1) above (excluding MA), amidinium, guanidinium, and alkali metal ions. These other monovalent cations may be used alone or in combination of two or more.

[0053] First perovskite compound A 1 The proportion of MA at (the first A site) is A 1The proportion of MA relative to the total (first A site, monovalent cations in the first perovskite compound) is, for example, about 10 to 100 mol %, preferably in steps of 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %. When the proportion of MA is within an appropriate range that is not too small, it tends to facilitate the formation of a perovskite structure and facilitate the absorption and effective use of high-energy, short-wavelength light.

[0054] In the formula (1-1), M 1 Examples of elements corresponding to the divalent cation represented by the formula (1) include the elements of Group 14 of the periodic table and the elements of Group 2 of the periodic table, which are exemplified as elements corresponding to M in the formula (1). 1 may contain divalent cations of these elements either alone or in combination. 1 Examples of the divalent cation include elements of Group 14 of the periodic table such as Pb, Sn, and Ge, elements of Group 2 of the periodic table such as Ba, Sr, Ca, and Mg, more preferably elements of Group 14 of the periodic table such as Pb and Sn, and particularly preferably divalent cations of Pb.

[0055] The first perovskite compound M 1 The proportion of divalent cations of group 14 elements (especially Pb ions) in the first M site is M 1 It is, for example, about 10 to 100 mol % relative to the total, preferably in the following stepwise manner: 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %.

[0056] In the formula (1-1), X 1 Examples of the halide ion represented by the formula (1) include anions of the halogen elements exemplified as the halogen element corresponding to X in the formula (1). 1 may contain these halide ions alone or in combination of two or more. 1 is the iodide ion.

[0057] X of the first perovskite compound 1 The proportion of iodide ions in the first X site is X 1 The proportion of iodide ions is, for example, about 10 to 100 mol % relative to the total, preferably in the following stepwise manner: 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %. When the proportion of iodide ions is within a moderate range that is not too small, perovskite crystals tend to be formed more easily.

[0058] Representative examples of the first perovskite compound represented by the formula (1-1) include: 1 MA is A 1 Contains 30 mol% or more of the total, M 1 contains at least a divalent cation of a group 14 element of the periodic table, such as Pb ion, and X 1 and compounds containing at least an iodide ion;

[0059] Preferably A 1 MA is A 1 Contains 50 mol % or more of the total, M 1 Pb ions are transported by M 1 Contains 50 mol% or more of the total, and X 1 X iodide ions 1 a compound containing the compound in a proportion of 50 mol % or more relative to the total;

[0060] More preferably, A 1 MA is A 1 Contains 70 mol % or more of the total, M 1 Pb ions are transported by M 1 Contains 70 mol% or more of the total, and X 1 X iodide ions 1 a compound containing the compound in an amount of 70 mol % or more relative to the total;

[0061] Particularly preferably A 1 MA is A 1 Contains 90 mol % or more of the total, M 1 Pb ions are transported by M 1Contains 90 mol % or more of the total, and X 1 X iodide ions 1 a compound containing 90 mol% or more of the compound;

[0062] Most preferred is MAPbI3.

[0063] The proportion of the first perovskite compound represented by formula (1-1) is, for example, about 10 to 100 mass% of the entire first perovskite layer, preferably in the following stepwise manner: 30 mass% or more, 50 mass% or more, 70 mass% or more, 90 mass% or more, 95 mass% or more, and more preferably substantially 100 mass%.

[0064] When the photoelectric conversion element is of the nanostructure type (mesoporous type), the perovskite layer (particularly, the first perovskite layer) may include a porous portion containing a porous oxide adjacent to the electron transport layer, a porous layer formed of a perovskite compound (particularly, the first perovskite compound) that has infiltrated (or impregnated) the voids of this porous portion, and a non-porous layer formed of a perovskite compound (particularly, the first perovskite compound) that is stacked on (continuous with) this porous layer. That is, the perovskite layer (particularly, the first perovskite layer) may be formed of a porous layer stacked adjacent to the electron transport layer and a non-porous layer stacked on this porous layer.

[0065] Representative porous oxides constituting the porous portion of the porous layer include metal oxides such as titanium(IV) oxide, zinc(II) oxide, tin(IV) oxide, aluminum oxide, and zirconium(IV) oxide. These metal oxides may be contained alone or in combination of two or more. Among these metal oxides, metal oxides having photoactivity (involved in charge transport), such as titanium(IV) oxide, zinc(II) oxide, and tin(IV) oxide, are preferred, with titanium(IV) oxide being particularly preferred. The porous oxide may be different from the electron transport material constituting the electron transport layer described below, but is usually the same.

[0066] The average thickness of the porous layer is, for example, about 100 to 1000 nm, preferably 150 to 980 nm, 200 to 950 nm, and 300 to 900 nm in the following stepwise manner. When the average thickness of the porous layer (or porous portion) is within an appropriate range that is not too large, a decrease in production efficiency tends to be easily suppressed, and when it is within an appropriate range that is not too small, a decrease in conversion efficiency tends to be easily suppressed.

[0067] In the present specification and claims, the average thickness of each layer may be measured using a transmission electron microscope (TEM) or an atomic force microscope (AFM).

[0068] The non-porous layer does not include a porous portion and includes a perovskite compound (particularly, a first perovskite compound). The type of the perovskite compound in the non-porous layer may be the same as or different from the type of the perovskite compound in the porous layer, and is preferably the same.

[0069] The average thickness of the non-porous layer (the average thickness of the first perovskite layer when the photoelectric conversion element is of a planar heterojunction type or an inverted structure type and does not include a porous layer) is, for example, about 5 to 1000 nm, preferably in the following stepwise manner: 10 to 500 nm, 30 to 300 nm, and 50 to 200 nm. If the average thickness of the non-porous layer is within an appropriate range that is not too large, it tends to be possible to suppress decreases in production efficiency and conversion efficiency.

[0070] Second perovskite layer (large ion-containing perovskite layer) The second (large ion-containing) perovskite layer contains a second (large ion-containing) perovskite compound (crystal) that has at least a monovalent cation (large ion) with an ionic diameter (ionic radius or ionic size) larger than methylammonium (MA) at the A site (second A site) and has a different composition from the first perovskite compound (crystal). Monovalent cations (large ions) with an ionic diameter larger than MA are known to stabilize the perovskite crystal structure by improving (or bringing closer to 1) the tolerance factor (an empirical index that estimates the stability of the perovskite structure), and tend to improve durability. For example, JP 2021-193722 (Patent Document 1) also describes the introduction of large cations in combination with MA into a single perovskite layer. The present inventors have found that by providing two different perovskite layers (an MA-containing perovskite layer and a large ion-containing perovskite layer) instead of a single layer, and arranging or stacking them so that the large ion-containing perovskite layer is above the MA-containing perovskite layer (upper in the stacking direction in the manufacturing method described below), and further combining and arranging a polysilane layer (first polysilane layer) on top, durability can be effectively improved and high conversion efficiency can be achieved. That is, the second perovskite compound is preferably a compound represented by the following formula (1-2):

[0071] A 2 M 2 X 2 3(1-2) [In the formula, A 2 (or the second A site) represents a monovalent cation (monovalent cation) containing a monovalent cation (large ion) having an ionic diameter larger than that of at least MA; M 2 (the second M site or the second B site) represents a divalent cation (divalent metal ion) of at least one metal element selected from the group consisting of elements of Group 14 of the periodic table and elements of Group 2 of the periodic table; X 2 (or the second X site) represents a halide ion (halogen anion)].

[0072] In the formula (1-2), A 2 Examples of monovalent cations (large ions) having a larger ionic diameter than MA contained in the (second A site, A site in the second perovskite compound) include organic ammoniums having two or more carbon atoms, amidiniums, and guanidiniums.

[0073] Examples of organic ammonium having two or more carbon atoms include the same organic ammonium as exemplified as A in the formula (1), that is, alkylammonium (excluding MA), specifically, C alkylammonium such as ethylammonium (EA), n-propylammonium, isopropylammonium, n-butylammonium, isobutylammonium, s-butylammonium, and t-butylammonium. 2-6 Alkylammonium; arylammonium, specifically, C such as anilinium 6-10 Aryl ammonium; aralkyl ammonium, specifically benzyl ammonium, phenethyl ammonium, etc. 6-10 Aryl C 1-6 Alkyl ammonium and the like.

[0074] Examples of the amidinium include the same amidiniums as those exemplified as A in the formula (1), and preferably C 1-4 amidinium, more preferably C 1-3 amidinium, more preferably C 1-2 Amidinium is preferred, and formamidinium (FA) is particularly preferred.

[0075] A 2 These large ions may be contained alone or in combination of two or more. Preferred large ions are amidinium, guanidinium (GA), and alkylammonium having two or more carbon atoms (particularly amidinium and / or guanidinium), and more preferably C 1-4 Amidinium, guanidinium, C 2-4 Alkylammonium, more preferably C 1-3Amidinium, guanidinium (GA), C 2-3 Alkylammonium, especially C 1-2 Amidinium and guanidinium, particularly formamidinium (FA), guanidinium (GA), and ethylammonium (EA) [particularly FA and / or GA] are preferred, with guanidinium (GA) being the most preferred since it easily achieves a good balance between high durability, high conversion efficiency, and high productivity.

[0076] In addition, A 2 In addition to the large ions, A may or may not contain MA and / or alkali metal ions (e.g., alkali metal ions exemplified as A in the formula (1) above) as needed. 2 Furthermore, when MA is contained, the formation of photoinactive phases (or non-perovskite phases) such as the δ phase and the one-dimensional phase is effectively suppressed, and the perovskite structure is easily formed. 2 Preferably, includes at least large ions and MAs.

[0077] A of the second perovskite compound 2 The proportion of large ions (preferably organic ammonium having two or more carbon atoms such as EA, amidinium and / or GA, more preferably amidinium and / or GA such as FA, particularly GA) in the (A site) is A 2 The proportion of large ions relative to the total (second A site, total monovalent cations in the second perovskite compound) may be, for example, about 0.01 mol% or more (e.g., about 0.1 to 90 mol%), and preferably ranges in the following stepwise manner: 0.3 to 50 mol%, 0.5 to 40 mol%, 1 to 30 mol%, 3 to 25 mol%, 5 to 20 mol%, 8 to 18 mol%, 10 to 15 mol%, 11 to 14 mol%, and 12 to 13 mol%. When the proportion of large ions is within a moderate range, not too low, durability and conversion efficiency tend to be easily improved, while when the proportion is within a moderate range, not too high, the formation of photoinactive phases (or non-perovskite phases) such as the δ phase and one-dimensional phase tends to be easily suppressed.

[0078] A of the second perovskite compound 2The ratio of the total amount of large ions (preferably organic ammoniums having two or more carbon atoms such as EA, amidinium and / or GA, more preferably amidinium and / or GA such as FA, especially GA) and MA in the (second A site) is A 2 The proportion of the large ions and MA is preferably in the range of 10 to 100 mol %, more preferably 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %. When the proportion of the total amount of large ions and MA is in a moderate range that is not too small, the conversion efficiency tends to be improved.

[0079] A of the second perovskite compound 2 In the (second A site), the ratio of large ions (preferably organic ammonium having two or more carbon atoms such as EA, amidinium and / or GA, more preferably amidinium and / or GA such as FA, especially GA) to MA is, for example, the former / latter (molar ratio) = 0.01 / 99.99 to 99 / 1 (e.g., 0.1 / 99.9 to 90 / 10), preferably in the following stepwise manner: 0.3 / 99.7 to 50 / 50, 0.5 / 99.5 to 40 / 60, 1 / 99 to 30 / 70, 3 / 97 to 25 / 75, 5 / 95 to 20 / 80, 8 / 92 to 18 / 82, 10 / 90 to 15 / 85, 11 / 89 to 14 / 86, 12 / 88 to 13 / 87. When the proportion of large ions is within a moderate range that is not too small, durability and conversion efficiency tend to be improved, and when the proportion of MA is within a moderate range that is not too small, the formation of photoinactive phases (or non-perovskite phases) such as the δ phase and one-dimensional phase tends to be effectively suppressed.

[0080] In the formula (1-2), M 2 Examples of elements corresponding to the divalent cation represented by the formula (1) include the elements of Group 14 of the periodic table and the elements of Group 2 of the periodic table, which are exemplified as elements corresponding to M in the formula (1). 2 may contain divalent cations of these elements either alone or in combination. 2Examples of the divalent cation include elements of Group 14 of the periodic table such as Pb, Sn, and Ge, elements of Group 2 of the periodic table such as Ba, Sr, Ca, and Mg, more preferably elements of Group 14 of the periodic table such as Pb and Sn, and particularly preferably divalent cations of Pb.

[0081] M of the second perovskite compound 2 The proportion of divalent cations of group 14 elements (especially Pb ions) at the (second M site) is M 2 It is, for example, about 10 to 100 mol % relative to the total, preferably in the following stepwise manner: 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %.

[0082] In the formula (1-2), X 2 Examples of the halide ion represented by the formula (1) include anions of the halogen elements exemplified as the halogen element corresponding to X in the formula (1). 2 may contain these halide ions alone or in combination of two or more. 2 is the iodide ion.

[0083] X of the second perovskite compound 2 The proportion of iodide ions at the second X site is X 2 The proportion of iodide ions is, for example, about 10 to 100 mol % relative to the total, preferably in the following stepwise manner: 30 mol % or more, 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably substantially 100 mol %. When the proportion of iodide ions is within a moderate range that is not too small, perovskite crystals tend to be formed more easily.

[0084] Representative second perovskite compounds represented by the formula (1-2) include, for example, 2 contains at least one large ion selected from amidinium, guanidinium (GA) and organic ammonium having two or more carbon atoms, and M 2 contains at least a divalent cation of a group 14 element of the periodic table, such as Pb ion, and X 2and compounds containing at least an iodide ion;

[0085] Preferably A 2 Amidinium, GA and C 2-6 It contains at least one large ion selected from alkyl ammonium having two or more carbon atoms, such as alkyl ammonium, and MA, and M 2 contains at least Pb ions, and X 2 is a compound containing at least an iodide ion;

[0086] More preferably, A 2 At least one large ion selected from amidinium and GA and MA, the total amount of which is A 2 The content is 50 mol % or more of the total, and M 2 Pb ions are transported by M 2 Contains 50 mol% or more of the total, and X 2 X iodide ions 2 a compound containing the compound in a proportion of 50 mol % or more relative to the total;

[0087] More preferably, A 2 C 1-4 At least one large ion selected from amidinium such as amidinium and GA and MA, the total amount of which is A 2 The content is 70 mol % or more of the total, and M 2 Pb ions are transported by M 2 Contains 70 mol% or more of the total, and X 2 X iodide ions 2 a compound containing the compound in an amount of 70 mol % or more relative to the total;

[0088] Particularly preferably A 2 C 1-3 Amidinium such as Amidinium (e.g. C 1-2 amidinium, especially FA) and at least one large ion (especially GA) selected from GA and MA in a total amount of A 2 The content is 90 mol % or more of the total, and M 2 Pb ions are transported by M2 Contains 90 mol % or more of the total, and X 2 X iodide ions 2 a compound containing 90 mol% or more of the compound;

[0089] Most preferably MA 1-a1 FA a1 PbI3, MA 1-a2 GA a2 PbI3 (especially MA 1-a2 GA a2 PbI3). Also, MA 1-a1 FA a1 PbI3, MA 1-a2 GA a2 PbI3, MA 1-a3 EA a3 PbI3 is also preferred. Note that the coefficients a1, a2, and a3 in the formula are each greater than 0 and less than 1.

[0090] The proportion of the second perovskite compound represented by formula (1-2) is, for example, about 10 to 100 mass% of the entire second perovskite layer, preferably in the following stepwise manner: 30 mass% or more, 50 mass% or more, 70 mass% or more, 90 mass% or more, 95 mass% or more, and more preferably substantially 100 mass%.

[0091] The second perovskite layer may be disposed (laminated) directly or indirectly between the first perovskite layer and the polysilane layer (first polysilane layer). From the viewpoint of facilitating improved productivity, it is preferable that the second perovskite layer be laminated to the first perovskite layer without an intermediate polysilane layer (second polysilane layer). From the viewpoint of facilitating improved durability and conversion efficiency, it is preferable that the second perovskite layer be laminated indirectly to the first perovskite layer via an intermediate polysilane layer (second polysilane layer).

[0092] The average thickness of the second perovskite layer is, for example, about 5 to 1000 nm, for example, 10 to 500 nm (for example, 100 to 450 nm), preferably 30 to 400 nm (for example, 150 to 350 nm), and more preferably 50 to 300 nm (for example, 200 to 300 nm). If the average thickness of the second perovskite layer is within an appropriate range that is not too large, there is a tendency to be able to suppress decreases in production efficiency and conversion efficiency.

[0093] (Polysilane layer) The polysilane layer is a layer containing at least polysilane.

[0094] In the photoelectric conversion element of the present disclosure, a polysilane layer (first polysilane layer) is stacked on a first (MA-containing) perovskite layer in combination with a second (large ion-containing) perovskite layer. This significantly improves durability even if the first perovskite layer contains unstable (or easily desorbed) ions such as MA, and allows the conversion efficiency to be maintained or improved over a long period of time without significant degradation.

[0095] Furthermore, if Spiro-OMeTAD is not contained, the conversion efficiency usually drops significantly and the element often ceases to function as a photoelectric conversion element. However, in the photoelectric conversion element of the present disclosure, the conversion efficiency appears to be easily improved even without Spiro-OMeTAD, or even without dopants (dopant-free), possibly because the polysilane layer and the second (large ion-containing) perovskite layer are combined.

[0096] In addition to the first polysilane layer, the photoelectric conversion element may optionally further include an intermediate polysilane layer (second polysilane layer) containing polysilane between the first (MA-containing) perovskite layer and the second (large ion-containing) perovskite layer. By interposing the intermediate polysilane layer between the first and second perovskite layers, it appears that the conversion efficiency can be effectively improved even when the size of the large ions in the second perovskite layer is somewhat small.

[0097] The types of polysilane in the polysilane layer (first polysilane layer) and the intermediate polysilane layer (second polysilane layer) may be different from each other, but are preferably the same.

[0098] The polysilane is a compound having a shape or structure that is linear, cyclic, branched, reticulated (or network-like), or a combination thereof, and has an Si-Si bond, and preferably has at least one structural unit selected from the structural units represented by the following formulas (2a) and (2b).

[0099] [ka]

[0100] (In the formula, R 1 ~R 3 independently represent a hydrogen atom, a hydroxyl group, an organic group, or a silyl group).

[0101] In the formulas (2a) and (2b), the group (or side chain) R 1 ~R 3 Examples of the organic group represented by the formula (I) include hydrocarbon groups such as alkyl groups, alkenyl groups, cycloalkyl groups, cycloalkenyl groups, aryl groups, and aralkyl groups; and groups corresponding to these hydrocarbon groups linked through an ether bond, such as alkoxy groups, cycloalkyloxy groups, aryloxy groups, and aralkyloxy groups.

[0102] Examples of the alkyl group include C groups such as methyl, ethyl, propyl, isopropyl, n-butyl, i-butyl, s-butyl, t-butyl, pentyl, and hexyl. 1-14 alkyl group, and preferably C 1-10 alkyl group, more preferably C 1-6 It is an alkyl group.

[0103] Examples of the alkoxy group include C alkoxy groups such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, and pentyloxy groups. 1-14 Examples thereof include an alkoxy group.

[0104] Examples of the alkenyl group include C 1 groups such as vinyl, allyl, butenyl, and pentenyl groups. 2-14 Examples include alkenyl groups.

[0105] Examples of the cycloalkyl group include a C cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, and the like. 5-14 Examples include a cycloalkyl group.

[0106] Examples of the cycloalkyloxy group include a C cyclopentyloxy group, a cyclohexyloxy group, and the like. 5-14 Examples thereof include a cycloalkyloxy group.

[0107] Examples of the cycloalkenyl group include a C cyclopentenyl group, a cyclohexenyl group, and the like. 5-14 Examples include a cycloalkenyl group.

[0108] Examples of the aryl group include C phenyl, methylphenyl (tolyl), dimethylphenyl (xylyl), and naphthyl groups. 6-20 aryl groups, and preferably C 6-14 Aryl groups, more preferably C 6-12 C such as an aryl group, more preferably a phenyl group 6-10 It is an aryl group.

[0109] Examples of the aryloxy group include C aryloxy groups such as phenoxy and naphthyloxy groups. 6-20 Examples thereof include an aryloxy group.

[0110] Examples of the aralkyl group include C aryl groups such as benzyl, phenethyl, and phenylpropyl groups. 6-20 Aryl-C1-6 Examples include alkyl groups.

[0111] Examples of the aralkyloxy group include C aryloxy groups such as benzyloxy groups, phenethyloxy groups, and phenylpropyloxy groups. 6-20 Aryl-C 1-6 Examples thereof include an alkyloxy group.

[0112] These organic groups may be used alone or in combination of two or more. Among these organic groups, hydrocarbon groups such as alkyl groups, alkenyl groups, cycloalkyl groups, aryl groups, and aralkyl groups are preferred.

[0113] base R 1 ~R 3 Examples of the silyl group represented by the formula include a silyl group, a disilanyl group, a trisilanyl group, and the like. 1-10 silanyl groups, and preferably Si 1-6 It is a silanyl group.

[0114] In addition, R 1 ~R 3 In the above, the organic group (such as an alkyl group or an aryl group) or the silyl group may have a substituent (or a functional group). Examples of such a substituent (or functional group) include the same groups as those exemplified above, such as a hydroxyl group, an alkyl group, an aryl group, and an alkoxy group, and the number of substituents (or functional groups) is not particularly limited.

[0115] In addition, in the formula (2a), R 1 and R 2 The types may be different from each other, but are preferably the same.

[0116] These R 1 ~R 3 Among these, alkyl groups, such as methyl groups, 1-4 alkyl groups and aryl-containing groups such as aryl groups, e.g., C groups such as phenyl groups; 6-20Preferably, R is an aryl group, and more preferably, R contains at least an aryl group-containing group from the viewpoint of easily improving hole transport efficiency after charge separation. 1 and R 2 At least one of R is preferably an aryl group-containing group, 1 and R 2 It is more preferable that both of R are aryl group-containing groups. 3 is preferably an aryl group-containing group.

[0117] Examples of the aryl group-containing group include the same groups as the aryl group, aralkyl group, aryloxy group, and aralkyloxy group exemplified above as the organic group. Preferred aryl group-containing groups include C groups such as phenyl group, naphthyl group, and biphenylyl group. 6-12 Aryl group, C 6-12 Aryl-C 1-6 Alkyl group, C 6-12 Aryloxy group, C 6-12 Aryl-C 1-6 An alkoxy group is preferred, and C 6-10 Aryl group, C 6-10 Aryl-C 1-4 Alkyl group, C 6-10 Aryloxy group, C 6-10 Aryl-C 1-4 Among these aryl-containing groups, C 6-10 Aryl groups such as aryl groups are preferred, with phenyl groups being particularly preferred.

[0118] Preferred structural units include those represented by the formula (2a) above, 1 and R 2 a structural unit in which one of the structural units is an aryl group-containing group and the other is an alkyl group; R 1 and R 2 and R 3 is an aryl group-containing group.

[0119] In the formula (2a), R 1 and R 2 Among these, examples of structural units in which one is an aryl group-containing group and the other is an alkyl group include alkyl-aryl-silane units, and specifically, C 1-6 Alkyl-C 6-10 Examples include aryl-silane units.

[0120] In the formula (2a), R 1 and R 2 Examples of structural units in which both are aryl group-containing groups include diaryl-silane units, and specifically, di-C such as diphenyl-silane units. 6-10 Examples include aryl-silane units.

[0121] In the formula (2b), R 3 Examples of structural units in which is an aryl group-containing group include an aryl-silane unit, and specifically, C such as a phenyl-silane unit. 6-10 Examples include aryl-silane units.

[0122] These structural units may be used alone or in combination of two or more. Among these structural units, R 1 and R 2 Structural units in which both are aryl-containing groups are preferred, and diaryl-silane units such as diphenyl-silane units are particularly preferred.

[0123] The proportion of aryl-containing groups in the side chains of the polysilane is determined by the proportion of the aryl-containing groups in the entire side chains of the polysilane (e.g., R 1 ~R 3The proportion of the aryl group-containing group (total amount) is, for example, about 10 mol% or more, preferably in the following stepwise manner: 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, and preferably substantially 100 mol%. The proportion may be selected, for example, from a range of about 30 to 100 mol%, for example, 60 to 99.9 mol%, preferably 80 to 99 mol%, and more preferably 90 to 95 mol%. When the proportion of the aryl group-containing group is in an appropriate range that is not too small, the photoelectric conversion efficiency tends to be easily improved.

[0124] In addition, when the polysilane has an acyclic structure such as a linear, branched, or network structure, the terminals are often substituted with hydrogen atoms, hydroxyl groups, alkoxy groups, silyl groups, or the like. The terminals may be capped or not. In polysilanes whose terminals are not capped, the terminal silicon atoms usually have, in addition to the organic groups such as methyl groups and phenyl groups, hydrogen atoms, hydroxyl groups, halogen atoms such as chlorine atoms, or the like, and in particular, hydroxyl groups. Furthermore, the polysilane may contain, or may not substantially contain, reactive groups such as radically polymerizable groups.

[0125] Representative polysilanes include, for example, linear or cyclic polysilanes having a structural unit represented by the formula (2a), polysilanes (network polysilanes) having a structural unit represented by the formula (2b), and polysilanes (branched or network polysilanes) having a combination of structural units represented by the formulas (2a) and (2b). In these polysilanes, the structural units represented by the formulas (2a) and (2b) may be used alone or in combination of two or more. The branched or network polysilanes may further contain a structural unit represented by the following formula (2c):

[0126] [ka]

[0127] The shape of the polysilane may be any of linear, cyclic, branched, network, or a combination of two or more of these, but linear, cyclic, or network is preferred, and linear or cyclic, especially cyclic, is likely to improve the conversion efficiency. Therefore, it is preferred that the polysilane contains at least the structural unit represented by the formula (2a) among the structural units represented by the formulas (2a) and (2b).

[0128] When the polysilane contains a structural unit represented by formula (2a), the proportion of the structural unit represented by formula (2a) relative to the total structural units of the polysilane is, for example, about 10 mol% or more, preferably 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and more preferably substantially 100 mol%. The proportion may be, for example, about 30 to 100 mol%, for example, 60 to 99 mol%, preferably 80 to 97 mol%. When the proportion of the structural unit represented by formula (2a) is within a moderate range that is not too small, photoelectric conversion efficiency tends to be improved.

[0129] Specific examples of linear or cyclic polysilanes having a structural unit represented by the formula (2a) include poly(dialkylsilanes) such as poly(dimethylsilane), poly(methyl-propyl-silane), poly(methyl-butyl-silane), poly(methyl-pentyl-silane), poly(dibutylsilane), poly(dihexylsilane), and (dimethylsilane)-(methyl-hexyl-silane) copolymers; and poly(alkylsilanes) such as poly(methyl-phenyl-silane) and (methyl-phenyl-silane)-(phenyl-hexyl-silane) copolymers. poly(diarylsilanes) such as poly(diphenylsilane); (dialkylsilane)-(alkyl-aryl-silane) copolymers such as (dimethylsilane)-(methyl-phenyl-silane) copolymer, (dimethylsilane)-(phenyl-hexyl-silane) copolymer, and (dimethylsilane)-(methyl-naphthyl-silane) copolymer; and (alkyl-aryl-silane)-(diarylsilane) copolymers such as (methyl-phenyl-silane)-(diphenylsilane) copolymer.

[0130] Examples of network polysilanes having a structural unit represented by the formula (2b) include poly(alkylsilanes) such as poly(methylsilane), poly(propylsilane), poly(butylsilane), and poly(hexylsilane); and poly(arylsilanes) such as poly(phenylsilane).

[0131] These polysilanes may be used alone or in combination of two or more in the polysilane layer (first polysilane layer) and the intermediate polysilane layer (second polysilane layer). Among these polysilanes, linear or cyclic poly(alkyl-aryl-silane), specifically linear or cyclic poly(C) such as poly(methyl-phenyl-silane), is preferred. 1-6 Alkyl-C 6-12 Aryl-silanes; linear or cyclic poly(diarylsilanes), specifically linear or cyclic poly(diC), such as poly(diphenylsilane); 6-12Arylsilanes; linear or cyclic (C arylsilanes) such as linear or cyclic (alkyl-aryl-silane)-(diarylsilane) copolymers, in particular linear or cyclic (methyl-phenyl-silane)-(diphenylsilane) copolymers. 1-6 Alkyl-C 6-12 Aryl-silane)-(diC 6-12 network poly(arylsilane) copolymers; network poly(arylsilane), specifically network poly(C) such as network poly(phenylsilane); 6-12 Among them, linear or cyclic poly(diarylsilane) [particularly, cyclic poly(diarylsilane)] is preferred, and linear or cyclic poly(diC) such as poly(diphenylsilane) is preferred. 6-10 Cyclic poly(di-C) such as decaphenylcyclopentasilane is more preferred because of its excellent heat resistance and light resistance. 6-10 Arylsilanes are particularly preferred.

[0132] The weight-average molecular weight Mw of the polysilane, as measured by GPC (polystyrene equivalent), is, for example, about 300 or more, preferably in the following stepwise order: 300 to 50,000, 300 to 25,000, 350 to 20,000, 400 to 14,000, 450 to 10,000, 500 to 3,000, 500 to 1,000, and 700 to 1,000. When the weight-average molecular weight is within a suitable range that is not too small, deterioration of the photoelectric conversion element tends to be effectively suppressed, while when the weight-average molecular weight is within a suitable range that is not too large, difficulty in fabricating the photoelectric conversion element due to a decrease in solubility (or dispersibility) in the solvent tends to be suppressed.

[0133] The average degree of polymerization of the polysilane is, for example, about 3 to 500 in terms of silicon atoms (that is, the average number of silicon atoms per molecule), preferably 3 to 100, 3 to 50, 4 to 10, 5 to 7, 5 to 6, and more preferably 5 in the following stepwise order.

[0134] The polysilane may be in a liquid state or a solid state at room temperature, for example, about 20°C.

[0135] Polysilanes can be produced by conventional methods, such as a method of dehalogenating condensation polymerization of halosilanes using magnesium as a reducing agent (the "magnesium reduction method," WO98 / 29476, etc.), a method of dehalogenating condensation polymerization of halosilanes in the presence of an alkali metal (the "Kipping method," J. Am. Chem. Soc., 110, 124 (1988), Macromolecules, 23, 3423 (1990), etc.), or a method of dehalogenating condensation polymerization of halosilanes by electrode reduction. (J. Chem. Soc., Chem. Commun., 1161 (1990), J. Chem. Soc., Chem. Commun., 897 (1992), etc.), a method of dehydrogenative condensation polymerization of hydrosilanes in the presence of a metal catalyst (JP-A No. 4-334551, etc.), a method of anionic polymerization of disilene crosslinked with biphenyl or the like (Macromolecules, 23, 4494 (1990), etc.), a method of ring-opening polymerization of cyclic silanes, etc.

[0136] The proportion of polysilane in the first polysilane layer is, for example, about 20% by mass or more, preferably in the following stepwise manner: 30 to 100% by mass, 50 to 100% by mass, 70 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, and more preferably substantially 100% by mass. When the proportion of polysilane is within a moderate range that is not too small, it tends to be easy to suppress the desorption of unstable ions such as MA, and to easily effectively improve durability.

[0137] The average thickness of the first polysilane layer is, for example, about 1 to 100 nm, preferably in the following stepwise order: 2 to 70 nm, 3 to 40 nm, 5 to 20 nm, and 5 to 15 nm. When the average thickness of the first polysilane layer is within a suitable range that is not too thin, it is possible to suppress the desorption of unstable ions such as MA, and durability tends to be easily effectively improved. When the average thickness is within a suitable range that is not too thick, it is easy to suppress a decrease in manufacturing efficiency and also easy to effectively suppress a decrease in conversion efficiency due to an increase in electrical resistance.

[0138] The proportion of polysilane in the entire intermediate polysilane layer (second polysilane layer) is, for example, about 20% by mass or more, preferably in the following stepwise manner: 30 to 100% by mass, 50 to 100% by mass, 70 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, and more preferably substantially 100% by mass. When the proportion of polysilane is within an appropriate range that is not too small, conversion efficiency tends to be easily and effectively improved.

[0139] The average thickness of the intermediate polysilane layer (second polysilane layer) is, for example, about 1 to 100 nm, preferably 2 to 70 nm, 3 to 40 nm, 5 to 20 nm, and 5 to 15 nm in the following stepwise order. When the average thickness of the intermediate polysilane layer (second polysilane layer) is within a suitable range that is not too thin, conversion efficiency tends to be effectively improved, and when it is within a suitable range that is not too thick, reductions in manufacturing efficiency tend to be easily suppressed, and reductions in conversion efficiency due to increased electrical resistance tend to be effectively suppressed.

[0140] (Hole Transport Layer (HTL)) The photoelectric conversion element of the present disclosure may or may not further include a hole transport layer as necessary. The hole transport layer is a layer containing a hole transport material (excluding polysilane), and the hole transport layer may be laminated on a polysilane layer (e.g., a first polysilane layer) to improve conversion efficiency.

[0141] As the hole transport material, any conventional hole transport material can be used, and they can be roughly divided into inorganic compounds and organic compounds.

[0142] Examples of inorganic compounds include metal salts such as copper(I) thiocyanate; metal oxides such as nickel(II) oxide, vanadium(V) oxide, and copper aluminum oxide (CuAlO2); metal iodides such as copper(I) iodide and cesium tin iodide (CsSnI3); and carbon materials such as graphene oxide.

[0143] Organic compounds can be further classified into low molecular weight compounds and high molecular weight compounds. Examples of low molecular weight compounds include phthalocyanines such as phthalocyanine, naphthalocyanine, and subphthalocyanine; carbazoles such as 1,3,5-tris[2,7-(N,N-(p-methoxyphenyl)amino)-9H-carbazol-9-yl]benzene (SGT405); thiophenes such as 2,5-bis[4-(N,N-bis(p-methoxyphenyl)amino)phenyl]-3,4-ethylenedioxythiophene (H101) and 2,3,4,5-tetrakis[4-(N,N-bis(p-methoxyphenyl)amino)phenyl]thiophene (H111); triptycenes such as 2,6,14-tris[5'-(4-(N,N-bis(p-methoxyphenyl)amino)phenyl)-thiophen-2'-yl]triptycene (T103); and spirobifluorenes such as the compound represented by formula (3) described below.

[0144] Examples of the polymer compound include poly(3-hexylthiophene-2,5-diyl) (P3HT), poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT), poly[N-9'-heptadecanyl-2,7-carbazole-alt-3,6-bis(thiophen-5-yl)-2,5-dioctyl-2,5-dihydropyrrolo[3,4]pyrrole-1,4-dione] (PCBTDPP), poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2, Examples of suitable polythiophenes include poly[bis(phenyl-4-yl)-(2,4,6-trimethylphenyl)amine] (PTAA) and poly[bis(phenyl-4-yl)-(4-butylphenyl)amine] (PolyTPD), and polyfluorenes such as poly[9,9-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine] (PFB).

[0145] These hole transport materials may be used alone or in combination.

[0146] Examples of the spirobifluorenes include compounds represented by the following formula (3).

[0147] [ka]

[0148] (In the formula, Z 1 ~Z 8 each independently represents an arene ring, and R 4a ~R 4h each independently represents an alkoxy group, and k1 to k8 each independently represents an integer of 0 or more).

[0149] In the formula (3), Z 1 ~Z 8 Examples of aromatic hydrocarbon rings (arene rings) represented by the formula (I) include monocyclic aromatic hydrocarbon rings (monocyclic arene rings) such as a benzene ring, and polycyclic aromatic hydrocarbon rings (polycyclic arene rings). Examples of polycyclic aromatic hydrocarbon rings include fused polycyclic aromatic hydrocarbon rings (fused polycyclic arene rings) and ring-assembled aromatic hydrocarbon rings (ring-assembled arene rings).

[0150] Examples of the fused polycyclic arene ring include fused bicyclic arene rings, fused tricyclic arene rings, and other fused bicyclic to tetracyclic arene rings. Examples of the fused bicyclic arene ring include fused bicyclic C rings such as a naphthalene ring. 10-16 Examples of the fused tricyclic arene ring include an anthracene ring and a phenanthrene ring. Preferred fused polycyclic arene rings include fused polycyclic C arenes such as a naphthalene ring and an anthracene ring. 10-16 arene rings, and more preferably fused polycyclic C 10-14 An arene ring is exemplified, and a naphthalene ring is particularly preferred.

[0151] Examples of the ring-assembled arene ring include biarene rings and terarene rings. Examples of the biarene ring include biphenyl rings, binaphthyl rings, phenylnaphthalene rings, and other biarene rings. 6-12 Examples of the phenylnaphthalene ring include a 1-phenylnaphthalene ring and a 2-phenylnaphthalene ring. Examples of the terarene ring include a terphenylene ring. 6-12 A preferred ring-assembly arene ring is a biC 6-10 An arene ring is exemplified, and a biphenyl ring is particularly preferred.

[0152] These rings Z 1 ~Z 8 Among them, C rings such as benzene ring, naphthalene ring, and biphenyl ring 6-12 An arene ring is preferred, and a C ring such as a benzene ring is preferred. 6-10 An arene ring is more preferred, and a benzene ring is particularly preferred. 1 ~Z 8 The types of rings Z may be different from each other, but are preferably the same. 1 ~Z 8 The bonding position to the nitrogen atom in may be any position.

[0153] In the formula (3), R 4a ~R 4h Examples of the alkoxy group (linear or branched alkoxy group) represented by the formula (I) include C alkoxy groups such as methoxy group, ethoxy group, propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, and t-butoxy group. 1-6 Alkoxy groups are preferred. 1-4 C such as an alkoxy group, more preferably a methoxy group 1-2 It is an alkoxy group.

[0154] base R 4a ~R 4h The substitution numbers k1 to k8 of the ring Z 1 ~Z 8can be appropriately selected depending on the type of group, and may be, for example, an integer of about 0 to 7, preferably an integer of 0 to 6, an integer of 0 to 4, an integer of 0 to 2, more preferably 0 or 1, and particularly preferably 1. k1 to k8 may be different from each other, but are preferably the same. When k1 to k8 are 2 or more, the corresponding 2 or more groups R 4a ~R 4h The types may be the same or different from each other.

[0155] base R 4a ~R 4h The substitution position of 1 ~Z 8 There are no particular limitations on the position of the ring Z, as long as it is at a position other than the position where the ring Z is bonded to the nitrogen atom. 1 ~Z 8 is a benzene ring, and k1 to k8 are 1, the group R 4a ~R 4h The substitution position of 1 ~Z 8 The bond may be in any of the o-, m-, or p-position relative to the bonding position to the nitrogen atom, preferably the m- or p-position, and more preferably the p-position.

[0156] In the formula (3), the positions at which the four nitrogen atoms are bonded to the four benzene rings forming the spirobifluorene skeleton are not particularly limited. For example, the four nitrogen atoms may be bonded to any one of the 2- to 4-positions, any one of the 5- to 7-positions, any one of the 2'- to 4'-positions, and any one of the 5'- to 7'-positions of the spirobifluorene ring, and it is preferable that the four nitrogen atoms are bonded to the 2, 2', 7, and 7'-positions of the spirobifluorene ring.

[0157] Representative compounds represented by the formula (3) include, for example, ring Z 1 ~Z 8is a benzene ring, and k1 to k8 are 1, for example, tetrakis[bis(alkoxyphenyl)amino]-9,9'-spirobifluorenes such as 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis[N-(4-methoxyphenyl)-N-(3-methoxyphenyl)-amino]-9,9'-spirobifluorene, 2,2',7,7'-tetrakis[N-(4-methoxyphenyl)-N-(2-methoxyphenyl)-amino]-9,9'-spirobifluorene, and 2,2',7,7'-tetrakis[N,N-bis(4-ethoxyphenyl)amino]-9,9'-spirobifluorene. 1-4 alkoxyphenyl)amino]-9,9'-spirobifluorene, and the like.

[0158] These compounds represented by the formula (3) can be used alone or in combination of two or more kinds.

[0159] In addition, Spiro-OMeTAD, an excellent hole transport material, is widely used worldwide in conventional photoelectric conversion elements. These compounds represented by formula (3) (especially Spiro-OMeTAD) may be commercially available, but they are very expensive and do not effectively improve the productivity of photoelectric conversion elements. Furthermore, their durability is easily reduced by moisture (or hygroscopicity) and heat, making it difficult to effectively promote the widespread use of perovskite solar cells. The photoelectric conversion element of the present disclosure tends to improve conversion efficiency even without Spiro-OMeTAD, possibly due to the combination of a polysilane layer and a second (large ion-containing) perovskite layer. Therefore, it is preferable not to include a hole transport layer containing a compound represented by formula (3) such as Spiro-OMeTAD.

[0160] Therefore, when a hole transport layer is provided, the proportion of the compound represented by formula (3) (particularly, Spiro-OMeTAD) relative to the total amount of the hole transport material in the hole transport layer is, for example, about 50% by mass or less, preferably 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, and 1% by mass or less, and more preferably substantially no compound (0% by mass) is contained.

[0161] When a hole transport layer is provided, the hole transport layer does not necessarily contain an additive in addition to the hole transport material, but may further contain a conventional additive such as a dopant, if necessary. Examples of the dopant (or p-type dopant) include metal compounds and non-metal compounds such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane. Examples of metal compounds include metal salts such as lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI); metal complexes such as tris(p-bromophenyl)ammonium hexachloroantimonate, tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) tris[bis(trifluoromethylsulfonyl)imide] and molybdenum tris[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene]; metal chlorides such as tin(IV) chloride, antimony(V) chloride and iron(III) chloride; and metal oxides such as tungsten(VI) oxide.

[0162] When a hole transport layer is provided, the proportion of additives such as dopants is, for example, 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, and more preferably 5 to 15 parts by weight, per 100 parts by weight of the total amount of hole transport material. Conventional photoelectric conversion elements often utilize dopants (e.g., metal salts such as Li-TFSI). However, the inclusion of such dopants, which have high hygroscopicity and / or low heat resistance, prevents effective improvement of durability. Therefore, the proportion of additives such as dopants is, for example, 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 1 part by weight or less, per 100 parts by weight of the total amount of hole transport material. It is particularly preferable that additives such as dopants are substantially absent (0 parts by weight). The photoelectric conversion element of the present disclosure appears to be able to easily improve conversion efficiency without dopants (dopant-free), possibly due to the combination of a polysilane layer and a second (large ion-containing) perovskite layer.

[0163] When a hole transport layer is provided, the thickness (average thickness) of the hole transport layer is, for example, about 5 to 300 nm, preferably 10 to 200 nm, 20 to 100 nm, and 30 to 50 nm in the following stepwise manner. When the average thickness of the hole transport layer is in an appropriate range that is not too thin, holes can be efficiently transported and a decrease in conversion efficiency tends to be easily suppressed, and when the average thickness is in an appropriate range that is not too thick, a decrease in conversion efficiency due to an increase in electrical resistance tends to be easily suppressed.

[0164] In addition, since the photoelectric conversion element of the present disclosure easily improves conversion efficiency due to the combination of the polysilane layer and the second (large ion-containing) perovskite layer, it is preferable not to include a hole transport layer in order to improve productivity.

[0165] (electron blocking layer) The photoelectric conversion element of the present disclosure may or may not further include an electron blocking layer, as necessary. The electron blocking layer may be a layer containing a p-type semiconductor formed (directly or indirectly stacked) between the perovskite layer and the polysilane layer, and may be formed on at least a portion of one surface of the perovskite layer (the surface on the adjacent polysilane layer side), or may be formed over the entire surface (particularly, very thinly and uniformly). The electron blocking layer restricts the movement of electrons generated in the perovskite layer toward the polysilane layer, suppressing their recombination with holes, depending on the energy gap and the maximum energy position of the valence band of the p-type semiconductor. Therefore, the presence of an electron blocking layer may effectively improve conversion efficiency over a long period of time.

[0166] The electron blocking layer need only contain a p-type semiconductor, and may contain a conventional p-type semiconductor such as a hole transport material described below, but preferably contains at least a compound represented by the following formula (1b):

[0167] MX2(1b) (wherein M and X are the same as those in the formula (1) above, including preferred embodiments).

[0168] Representative compounds represented by formula (1b) include, for example, compounds in which M is Pb in formula (1b), such as PbI2, PbBr2, and PbCl2. These compounds represented by formula (1b) may be contained alone or in combination of two or more. Among these compounds, PbI2, which has an energy gap of about 2.5 eV, is preferred.

[0169] The proportion of the compound represented by formula (1b) is, for example, 50% by mass or more, preferably 90% by mass or more, and even more preferably substantially 100% by mass, based on the total mass of the p-type semiconductor in the electron blocking layer. In other words, it is more preferable that the electron blocking layer is formed solely of the compound represented by formula (1b).

[0170] The electron blocking layer may be formed as a thin layer, and its average thickness may be, for example, about 1 to 10 nm. If the average thickness is within a moderate range, not too thick, it tends to be easy to suppress a decrease in conversion efficiency due to an increase in electrical resistance, and if it is within a moderate range, not too thin, it tends to be easy to effectively improve conversion efficiency or durability.

[0171] (first electrode) The first electrode is a transparent electrode formed by coating at least a portion of one surface of a transparent substrate, such as an inorganic material such as glass or a transparent resin such as a methacrylic resin or a polycarbonate resin, with a transparent conductive metal oxide such as FTO (fluorine-doped tin oxide), ITO (indium tin oxide), or ZnO (zinc oxide). The coating method is not particularly limited, and examples include vapor deposition such as vacuum deposition and coating. Among the metal oxides, FTO is preferred from the viewpoint of heat resistance.

[0172] The metal oxide may be formed into a desired pattern by etching or the like. Furthermore, a functional layer such as an anti-reflection layer or a hard coat layer may be formed on the other surface of the transparent substrate. The first electrode may be an anode, but is usually a cathode.

[0173] The average thickness of the transparent conductive metal oxide coating film in the first electrode is, for example, about 5 to 2000 nm, preferably 100 to 1500 nm, 500 to 1200 nm, and 800 to 1000 nm in the following stepwise order. If the average thickness is within a moderate range (not too thick), the weight of the photoelectric conversion element tends to be reduced, while if the average thickness is within a moderate range (not too thin), the deterioration of durability tends to be suppressed. The average thickness of the transparent substrate in the first electrode can be selected depending on the material, and is, for example, 0.1 to 3 mm, preferably 1 to 2 mm.

[0174] (Electron transport layer (ETL)) The electron transport layer efficiently transports electrons, improving properties such as conversion efficiency and preventing short circuits caused by contact with the cathode between the first perovskite layer, second perovskite layer, first polysilane layer, second polysilane layer, etc. The electron transport layer is usually formed by densely depositing (not porous) electron transport material on the metal oxide-coated surface of the first electrode (or on one surface of the second electrode in the case of an inverted structure).

[0175] Examples of the electron transport material include metal oxides such as titanium(IV) oxide, zinc(II) oxide, and tin(IV) oxide, and fullerenes such as phenyl-C61-butylic acid methyl ester (

[60] PCBM). These electron transport materials may be used alone or in combination. Among these electron transport materials, metal oxides are preferred, with titanium(IV) oxide and zinc(II) oxide being more preferred, and titanium(IV) oxide being particularly preferred.

[0176] The electron transport layer may be doped with other atoms. When the electron transport material is a metal oxide, it may be doped with an atom having a valence greater than that of the metal atom in the metal oxide. For example, titanium (IV) oxide may be doped with a pentavalent atom such as vanadium (V), niobium (Nb), or tantalum (Ta), and zinc (II) oxide may be doped with a trivalent atom such as aluminum (Al), gallium (Ga), or indium (In).

[0177] The average thickness of the electron transport layer is, for example, about 5 to 100 nm, preferably 10 to 80 nm, 20 to 60 nm, and 30 to 50 nm in the following stepwise manner. If the average thickness is within a moderate range that is not too thick, an increase in electrical resistance tends to be easily suppressed, and if the average thickness is within a moderate range that is not too thin, electrons tend to be easily transported efficiently.

[0178] (Second electrode) The second electrode is usually a metal or carbon electrode formed of a conductor with a work function of 5.2 eV or less, such as gold (Au), silver (Ag), copper (Cu), or aluminum (Al), or carbon (C), adjacent to the first polysilane layer (if a hole transport layer is provided, or adjacent to the electron transport layer if an inverted structure is used). These conductors (or electrode-forming materials) may be used alone or in combination. Among these conductors (or electrode-forming materials), Au is preferred. The second electrode may be a cathode corresponding to the first electrode, but is usually an anode.

[0179] The average thickness of the second electrode is, for example, about 100 to 500 nm, preferably 120 to 300 nm, 150 to 250 nm, and 180 to 220 nm in the following stepwise manner. If the average thickness is within a moderate range that is not too thick, a decrease in production efficiency tends to be easily suppressed, and if the average thickness is within a moderate range that is not too thin, current collection tends to be easy to achieve.

[0180] [Method of manufacturing photoelectric conversion element and characteristics] The photoelectric conversion element of the present disclosure includes a preliminary lamination step (primary lamination step) of forming a preliminary laminate (primary laminate) by directly or indirectly laminating, in this order, a film (or a first perovskite precursor layer) containing a first perovskite precursor for forming a first perovskite compound having MA, a film (or a second perovskite precursor layer) containing a second perovskite precursor for forming a second perovskite compound having monovalent cations with an ion diameter larger than that of MA and different from the first perovskite compound, and a polysilane layer (first polysilane layer) containing polysilane; The pre-laminate obtained in the pre-lamination step is heat-treated to form a laminate (secondary laminate or laminate structure) including a first perovskite layer, a second perovskite layer, and a polysilane layer (first polysilane layer), as a heat treatment step (or perovskite crystal growth step).

[0181] (Pre-lamination process (primary lamination process)) The preliminary lamination process (primary lamination process) includes at least a first perovskite precursor film (layer) formation process for forming a film containing a first perovskite precursor (first perovskite precursor layer), a second perovskite precursor film (layer) formation process for forming a film containing a second perovskite precursor (second perovskite precursor layer), and a polysilane layer (first polysilane layer) formation process for forming a polysilane layer (first polysilane layer).

[0182] Perovskite precursor film (layer) formation process The method for forming the first and second perovskite precursor films (layers) is not particularly limited as long as it forms films (or perovskite precursor layers) containing the respective perovskite precursors for forming compounds having the respective perovskite structures. Conventional methods such as immersion or vapor deposition may be used, and preferably a method of forming the films by coating with a perovskite layer precursor solution (or dispersion) containing a perovskite precursor (perovskite precursor compound) and a solvent (or dispersion medium).

[0183] In the first perovskite precursor layer formation process, the first perovskite precursor layer is typically deposited by coating a first perovskite layer precursor solution (or dispersion) onto the electron transport layer formed in the electron transport layer formation process described below, or onto the porous portion formed in the porous portion formation process; in the second perovskite precursor layer formation process, the second perovskite layer precursor solution (or dispersion) is typically coated onto the first perovskite precursor layer, or onto the intermediate polysilane layer (second polysilane layer) formed in the intermediate polysilane layer (second polysilane layer) formation process described below, to deposit the second perovskite precursor layer.

[0184] The perovskite precursors contained in the perovskite layer precursor solutions may be, for example, precursors corresponding to the perovskite compounds represented by formula (1) [formula (1-1) or (1-2)], i.e., compounds represented by the following formulas (1a) and (1b).

[0185] AX (1a) MX2(1b) (wherein A, M and X are the same as in formula (1) above).

[0186] The first perovskite precursor is a compound represented by the formula (1a) and (1b), wherein A is A 1 , M is M 1 , and X is X 1 The second perovskite precursor is the same as the formula (1-1) including preferred embodiments corresponding thereto; 2 , M is M 2 , and X is X 2 The formula (1-2) is the same as the formula (1-2) above, including preferred embodiments corresponding to each of the above. Note that, in each perovskite precursor layer formation process, the perovskite precursor layers can be formed in the same manner except that the type of perovskite precursor used and the layering position differ depending on the type of perovskite precursor layer. Therefore, for convenience, each perovskite precursor layer formation process will be described below using the formulas (1), (1a), and (1b).

[0187] Representative compounds represented by the formula (1a) correspond to the perovskite compounds targeted in each perovskite layer, and include, for example, CH3NH3I (or MAI), CH3NH3Br (or MABr), CH3NH3Cl (or MACl), CH3CH2NH3I (or EAI), CH3CH2NH3Br (or EABr), etc., where A in formula (1a) is C. 1-6 Alkylammonium compounds; HC(NH2)2I (or FAI), HC(NH2)2Br (or FABr), etc., in which A is C 1-6 and compounds where A is guanidinium, such as C(NH2)3I (or GAI). Of these compounds, iodides such as MAI, EAI, FAI, and GAI are preferred, with MAI being preferred as the first perovskite precursor and iodides such as MAI, EAI, FAI, and GAI being preferred as the second perovskite precursor.

[0188] Representative compounds represented by the formula (1b) include compounds in which M is Pb in the formula (1b), such as PbI2, PbBr2, and PbCl2. Among these compounds, PbI2 and PbCl2 are preferred, and PbCl2 is more preferred.

[0189] The compounds represented by the formulas (1a) and (1b) can be used alone or in combination of two or more depending on the type of perovskite compound desired in each perovskite layer. Therefore, by combining the compounds represented by the formulas (1a) and (1b) in the desired ratios, each perovskite compound described in the section for each perovskite layer above can be prepared stoichiometrically (according to the charging ratio).

[0190] The ratio of the compound represented by formula (1a) to the compound represented by formula (1b) may be, for example, a former / latter (molar ratio) of 1 / 0.9 to 1 / 1.1, or substantially equimolar (1 / 1). However, when growing perovskite crystals by heat treatment at high temperature in the heat treatment step described below, the former / latter (molar ratio) is substantially about 3 / 1, for example, about 3 / 0.9 to 3 / 1.1, preferably 3 / 0.95 to 3 / 1.05, and more preferably 3 / 1 to 3 / 1.03. When heat treatment is performed at high temperature, it is preferable to use a compound (MCl) in which X is chlorine (Cl), such as PbCl, as the compound represented by formula (1b). That is, when heat treatment is performed at high temperature, the perovskite compound (AMX) represented by formula (1) is prepared according to the following reaction formula (4).

[0191] 3AX + MCl2→ AMX3+ 2ACl↑ (4) (wherein A, X and M are the same as defined above).

[0192] As is clear from formula (4) above, by appropriately selecting the types and proportions of the compounds AX and MCl2 (or the ions represented by A, X, and M) on the left side of the formula in accordance with the target perovskite compound (AMX3), it is possible to prepare the perovskite compounds described above in the section on each perovskite layer in accordance with stoichiometry.

[0193] In addition, in the right side of the formula (4), the monovalent cation A constituting the gaseous compound (2ACl) is preferably methylammonium (MA). That is, it is preferable to use at least 2 moles of the compound (MAX) where A is MA relative to a total of 3 moles of the compound (AX) represented by the formula (1a) [preferably, 2 moles of MAX where A is MA and 1 mole (total) of the compound where A corresponds to A in AMX3 on the right side of the formula (1a) are used out of the total 3 moles of the compound (AX)]. In this way, 2ACl (particularly 2MACl) vaporizes and escapes out of the reaction system, making it difficult for air and the like to enter the reaction system, which appears to effectively inhibit the degradation of the generated perovskite compound and the like due to reaction with air and the like.

[0194] Examples of the solvent (or dispersion medium) for dissolving or dispersing the perovskite precursor (perovskite precursor compound) include lactones and amides. Examples of lactones include C lactones such as γ-butyrolactone, δ-valerolactone, and ε-caprolactone. 3-7 Examples of the amides include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP).

[0195] These solvents may be used alone or in combination of two or more. Among these solvents, amides such as DMF are preferred.

[0196] The proportion of the solvent is, for example, 10 to 1000 parts by mass, preferably 50 to 500 parts by mass, and more preferably 100 to 200 parts by mass, relative to 100 parts by mass of the total amount of the compounds represented by formulas (1a) and (1b).

[0197] The compound represented by formula (1a), the compound represented by formula (1b), and the solvent may be mixed while being heated to a temperature below the boiling point of the solvent, and the heating temperature is, for example, 40 to 80°C, preferably 50 to 70°C. The mixing time is, for example, 1 to 48 hours, preferably 12 to 36 hours. Each perovskite layer precursor solution prepared in this manner may be applied or coated while being heated to a temperature below the boiling point of the solvent, and the heating temperature is, for example, 50 to 90°C, preferably 60 to 80°C.

[0198] The perovskite layer precursor solution can be coated using a conventional coating method, for example, a coating or printing method such as spin coating, doctor blade method, or screen printing method, or a vapor deposition method such as vacuum deposition method, and preferably, spin coating method.

[0199] When forming a film containing a perovskite precursor by spin coating, it is preferable to use an air-blowing method, in which a high-temperature air current is blown during spin coating to generate crystal nuclei, from the viewpoint of improving productivity. As will be described later, when the perovskite layer precursor solution is coated multiple times, the air-blowing method may be performed multiple times (for each coating). The temperature of the air current blown in the air-blowing method may be selected from the range of, for example, about 50 to 140°C, and preferably in the following stepwise order: 70 to 120°C, 80 to 100°C, and 85 to 95°C.

[0200] The number of times each perovskite layer precursor solution is coated may be once, but it is preferable to coat it multiple times, for example, 1 to 5 times, preferably 2 to 4 times, and more preferably 2 to 3 times. Coating may be performed once, but coating it multiple times tends to facilitate efficient impregnation or immersion, for example, when coating a porous portion. If the number of coatings is within an appropriate range and not too many, productivity tends to be easily improved and a decrease in conversion efficiency tends to be easily suppressed.

[0201] The formation of each perovskite precursor film may be carried out in an inert gas atmosphere such as nitrogen gas, as in the conventional method. However, in the present disclosure, even if the perovskite precursor film formation process is carried out in an air atmosphere, the conversion efficiency can be maintained high or improved over a long period of time, thereby effectively improving productivity.

[0202] Each perovskite precursor layer thus formed may partially contain, in addition to the perovskite precursors represented by the formulas (1a) and (1b), a perovskite compound (AMX3) corresponding to the precursor, for example, a perovskite compound partially produced by the air-blowing method.

[0203] Polysilane layer (first polysilane layer) formation process In the polysilane layer (first polysilane layer) formation process, a polysilane layer (first polysilane layer) containing polysilane is laminated on one side of the film containing the second perovskite precursor to form a preliminary laminate (primary laminate). The polysilane layer (first polysilane layer) may be formed by a conventional method such as immersion or vapor deposition, but a method of coating with a polysilane layer (first polysilane layer) formation solution (or dispersion) containing polysilane and a solvent (or dispersion medium) is preferred.

[0204] Examples of solvents (or dispersion media) for dissolving or dispersing polysilane include hydrocarbons, halogenated hydrocarbons, alcohols, ethers, glycol ethers, glycol ether acetates, ketones, esters, carbonates, carboxylic acids, nitriles, amides, sulfoxides, water, and mixed solvents thereof.

[0205] Examples of hydrocarbons include aliphatic hydrocarbons such as hexane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as toluene and xylene.

[0206] Examples of halogenated hydrocarbons include chlorinated hydrocarbons, such as chlorinated aliphatic hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane, and chlorinated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene.

[0207] Examples of alcohols include C 12 alcohols such as methanol, ethanol, 2-propanol, n-butanol, and t-butanol. 1-6 C such as alkane monools and ethylene glycol 2-4 Alkanediols and the like.

[0208] Examples of the ethers include chain ethers such as diisopropyl ether, and cyclic ethers such as tetrahydrofuran.

[0209] Examples of glycol ethers include cellosolves such as methyl cellosolve, carbitols such as methyl carbitol, (poly)C ethers such as triethylene glycol monomethyl ether and propylene glycol monomethyl ether. 2-4 Alkylene glycol mono C 1-4 Alkyl ethers; (poly)C such as ethylene glycol dimethyl ether and dipropylene glycol dimethyl ether 2-4 Alkylene glycol di C 1-4Alkyl ethers and the like.

[0210] Examples of glycol ether acetates include (poly)C such as cellosolve acetates, carbitol acetates, propylene glycol monomethyl ether acetate, and dipropylene glycol monobutyl ether acetate. 2-4 Alkylene glycol mono C 1-4 Examples of cellosolve acetates include C methyl cellosolve acetate. 1-4 Examples of carbitol acetates include C carbitol acetates such as methyl carbitol acetate. 1-4 Alkyl carbitol acetate and the like.

[0211] Examples of ketones include chain ketones such as acetone and methyl ethyl ketone, and cyclic ketones such as cyclohexanone.

[0212] Examples of esters include acetate esters such as ethyl acetate, and lactate esters such as methyl lactate.

[0213] Examples of carbonates include chain carbonates such as dimethyl carbonate, and cyclic carbonates such as ethylene carbonate and propylene carbonate.

[0214] Examples of carboxylic acids include acetic acid and propionic acid.

[0215] Examples of nitriles include acetonitrile and propionitrile.

[0216] Examples of amides include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

[0217] The sulfoxides include, for example, dimethyl sulfoxide.

[0218] These solvents can be used alone or in combination. Among these solvents, halogenated hydrocarbons such as chlorobenzene are preferred. The concentration of polysilane in the polysilane layer (first polysilane layer) forming solution is, for example, 5 to 50 mg / mL, preferably 10 to 30 mg / mL, and more preferably 15 to 25 mg / mL.

[0219] The coating method for the polysilane layer (first polysilane layer) forming solution can be, for example, any of the conventional coating methods exemplified as the coating method for the perovskite layer precursor solution, with spin coating being preferred. Spin coating of the polysilane layer (first polysilane layer) forming solution may be performed by dripping the second perovskite layer precursor solution when forming a film containing the second perovskite precursor by spin coating (or during the final spin coating if spin coating is performed multiple times), and then dripping the polysilane forming solution after a predetermined time, for example, 30 to 60 seconds, has elapsed. Therefore, it is preferable to spin coat the polysilane layer forming solution using the air blow method described above.

[0220] The polysilane layer formation process may be performed in an inert gas atmosphere such as nitrogen gas, but in the present disclosure, even if it is performed in an air atmosphere, the conversion efficiency can be maintained high or improved over a long period of time, thereby effectively improving productivity.

[0221] Intermediate polysilane layer (second polysilane layer) formation process The preliminary lamination step (primary lamination step) may further include an intermediate polysilane layer (second polysilane layer) formation step between the first perovskite precursor layer formation step and the second perovskite precursor layer formation step. The intermediate polysilane layer formation step is not particularly limited as long as it can form an intermediate polysilane layer between the first perovskite precursor layer and the second perovskite precursor layer, and examples thereof include methods similar to the polysilane layer (first polysilane layer) formation step. That is, the method is similar to the polysilane layer (first polysilane layer) formation step, including preferred aspects, except for the lamination position. For example, the intermediate polysilane layer (second polysilane layer) can be formed by coating an intermediate polysilane layer (second polysilane layer) formation solution (or dispersion) containing polysilane (the polysilane contained in the intermediate polysilane layer) and a solvent (or dispersion medium).

[0222] When forming an intermediate polysilane layer (second polysilane layer) by spin coating an intermediate polysilane layer-forming solution, the first perovskite layer precursor solution may be dropped when forming a film containing the first perovskite precursor by spin coating (or at the final spin coating if spin coating is performed multiple times), and then the intermediate polysilane forming solution may be dropped after a predetermined time, for example, 30 to 60 seconds, has elapsed. Therefore, it is preferable to spin coat the intermediate polysilane layer-forming solution using the air blow method described above.

[0223] In this way, a preliminary laminate (primary laminate) may be formed which includes, in this order, a first perovskite precursor layer, an intermediate polysilane layer (second polysilane layer), a second perovskite precursor layer, and a polysilane layer (first polysilane layer).

[0224] (Heat treatment process (or crystal growth process)) In the heat treatment step for growing perovskite crystals, the preliminary laminate (primary laminate) obtained in the preliminary lamination step (primary lamination step) is heat treated to form a laminate (secondary laminate or laminate structure) including at least a first perovskite layer, a second perovskite layer, and a polysilane layer (first polysilane layer) in this order. Note that when the preliminary laminate (primary laminate) includes an intermediate polysilane layer, a laminate (secondary laminate or laminate structure) including at least a first perovskite layer, an intermediate polysilane layer (second polysilane layer), a second perovskite layer, and a polysilane layer (first polysilane layer) in this order can be formed.

[0225] Specifically, first and second perovskite crystals (first and second perovskite compounds) are grown in the first and second perovskite precursor layers, respectively, by heat treatment, particularly heat treatment at high temperatures, to form first and second perovskite layers.

[0226] During the heat treatment, a trace amount of compound MX2, which is a p-type semiconductor, may be produced from the perovskite layer precursor in a layer-like form in a very thin region on the surface of the perovskite precursor layer (the interface with the polysilane layer, for example, the interface between the second perovskite layer and the polysilane layer (for example, the first polysilane layer)), thereby forming an electron blocking layer.

[0227] The heat treatment temperature for growing perovskite crystals may be approximately 80 to 100°C, as in conventional methods. However, in the present disclosure, the high heat resistance of each polysilane layer effectively improves durability even when heat treated at high temperatures. Therefore, the heat treatment temperature may be selected from a range of approximately 140 to 250°C, for example, and preferably in the following stepwise order: 150 to 250°C, 150 to 240°C, 160 to 230°C, 170 to 220°C, 175 to 210°C, and 180 to 200°C. A heat treatment temperature within a moderate range (not too low) tends to sufficiently improve durability, while a heat treatment temperature within a moderate range (not too high) tends to prevent decomposition of each perovskite crystal and suppress declines in productivity. The heat treatment time may be, for example, approximately 1 to 60 minutes, preferably 2 to 30 minutes, and more preferably 3 to 10 minutes.

[0228] The heat treatment may be carried out in an inert gas atmosphere such as nitrogen gas as in the conventional case; however, in the present disclosure, even if the heat treatment step is carried out in an air atmosphere, the conversion efficiency can be maintained high or improved over a long period of time, thereby effectively improving productivity.

[0229] (Hole transport layer forming step) The manufacturing method of the present disclosure may further include, if necessary, a hole transport layer forming step of laminating a hole transport layer on the polysilane layer (first polysilane layer), but preferably does not include this step.

[0230] In the hole transport layer formation process, a hole transport layer is formed by coating the polysilane layer (first polysilane layer) of the laminate (secondary laminate) formed in the heat treatment process with a hole transport layer formation solution (or dispersion liquid) containing the hole transport material and a solvent (or dispersion medium).

[0231] Examples of the solvent (or dispersion medium) include the solvents exemplified in the polysilane layer (first polysilane layer) formation process. These solvents may be used alone or in combination. Among these solvents, halogenated hydrocarbons such as chlorobenzene are preferred. The proportion of the solvent is, for example, 500 to 2000 parts by mass, preferably 1000 to 1500 parts by mass, per 100 parts by mass of the total amount of the hole transport material.

[0232] The hole transport layer-forming solution may contain, as necessary, additives such as dopants exemplified in the section on the hole transport layer, and the proportions of these additives may be the same as those described in the section on the hole transport layer, including preferred embodiments. Additives such as dopants may be added after being dissolved or dispersed in the same solvent as the hole transport material, for example, nitriles such as acetonitrile.

[0233] Furthermore, the hole transport layer forming solution may contain amines such as heterocyclic amines and tertiary amines as needed, from the viewpoint of improving the open circuit voltage by changing the quasi-Fermi level. Examples of heterocyclic amines include C amines such as 4-t-butylpyridine. 1-6 Examples of tertiary amines include tri C such as triethylamine. 1-6 Tri-C such as alkylamines and triethanolamine 1-6 Examples of suitable amines include alkanolamines. These amines may be used alone or in combination of two or more. Among these amines, heterocyclic amines such as 4-t-butylpyridine are preferred. The ratio of the amines is, for example, 0.1 to 10 parts by volume, preferably 1 to 5 parts by volume, relative to 100 parts by volume of the solvent. The volume in the above ratio may be the volume at 1 atmosphere and room temperature of about 25°C.

[0234] The hole transport layer forming solution may be prepared while being heated, and the heating temperature is, for example, 50 to 100° C., preferably 60 to 80° C. The hole transport layer forming solution does not need to be heat-treated after coating, from the viewpoint of suppressing decomposition of the hole transport material.

[0235] The hole transport layer forming solution can be coated by any of the conventional coating methods exemplified above as the coating method for the perovskite layer precursor solution, with spin coating being preferred.

[0236] The hole transport layer forming step may be carried out in an inert gas atmosphere such as nitrogen gas as in the conventional method, or in an air atmosphere.

[0237] The method for producing a photoelectric conversion element according to the present disclosure may further include other steps such as an electron transport layer forming step, a porous portion forming step, and a second electrode forming step.

[0238] (Electron transport layer formation process) In the electron transport layer forming step, an electron transport layer precursor solution (or dispersion) containing the electron transport material or its precursor and a solvent (or dispersion medium) is applied to form an electron transport layer. Note that the coating may be applied to the conductive metal oxide-coated surface of the first electrode if the photoelectric conversion element is of a nanostructure type or a planar heterojunction type, or to the second electrode if the photoelectric conversion element is of an inverted structure type.

[0239] The electrode to be coated, preferably the first electrode, may be subjected to a cleaning treatment before being coated with the electron transport layer precursor solution. The cleaning method is not particularly limited, and examples thereof include a method of immersing the electrode in a ketone such as acetone or an alcohol such as methanol, followed by ultrasonic cleaning, and then drying under an inert gas such as nitrogen gas or a rare gas; a method of UV-ozone treatment; and a combination of these methods.

[0240] Precursors of the electron transport material include compounds corresponding to the electron transport materials exemplified in the section on the electron transport layer, such as titanium(IV) oxide precursors and zinc(II) oxide precursors. Examples of titanium(IV) oxide precursors include titanium complexes such as titanium diisopropoxide bis(acetylacetonate) and alkyl titanates such as tetraisopropoxytitanium(IV). Examples of zinc(II) oxide precursors include zinc carbonate.

[0241] Examples of the solvent (or dispersion medium) include the solvents exemplified in the polysilane layer (first polysilane layer) formation process. These solvents may be used alone or in combination of two or more. Among these solvents, C 10 solvents such as n-butanol are preferred. 1-5 Alkane monools and the like are preferred.

[0242] The concentration of the electron transport material or its precursor in the electron transport layer precursor solution is, for example, 0.01 to 1 M, and preferably 0.1 to 0.4 M. In order to form an electron transport layer that is in close contact with an electrode such as the first electrode and is dense, two or more solutions with different concentrations may be prepared and coated in order of increasing solution concentration.

[0243] The electron transport layer precursor solution can be coated by any of the conventional coating methods exemplified above as the perovskite layer precursor solution coating method, with spin coating being preferred.

[0244] After coating, a heat treatment may be carried out to remove the solvent, and the heating temperature is, for example, 80 to 200° C., preferably 100 to 150° C. Furthermore, in order to form a metal oxide from the precursor, a heat treatment may be carried out at a higher temperature, and the heating temperature can be selected depending on the type of the precursor, and is, for example, 300 to 800° C., preferably 400 to 600° C.

[0245] (Porous part formation process) When the photoelectric conversion element is a nanostructure type, the porous portion (porous portion of the first perovskite layer) for contacting the first perovskite compound over a wide surface area may be formed on the electron transport layer before coating with the first perovskite layer precursor solution. The porous portion is formed by coating with a porous portion-forming solution containing a metal oxide, a polymer compound, water, an organic compound, and a surfactant, followed by heat treatment.

[0246] Examples of the metal oxide include the same metal oxides as those exemplified as the porous oxide in the section on the first perovskite layer, including preferred embodiments thereof. The metal oxide may be in a powder form.

[0247] Examples of polymer compounds include water-soluble polymer compounds, specifically polyethylene glycol, polyvinyl alcohol, poly(meth)acrylic acid derivatives, and cellulose derivatives. Examples of poly(meth)acrylic acid derivatives include poly(meth)acrylic acid or its salts, and poly(meth)acrylamide. Examples of cellulose derivatives include carboxymethyl cellulose or its salts, and cellulose ethers such as hydroxypropyl cellulose. The number-average molecular weight or weight-average molecular weight of the polymer compound is, for example, 10,000 to 30,000, and preferably 15,000 to 25,000. The proportion of the polymer compound is, for example, 1 to 30 parts by mass, and preferably 5 to 15 parts by mass, per 100 parts by mass of the metal oxide.

[0248] The water is preferably ultrapure water. The proportion of water is, for example, 100 to 1000 parts by mass, preferably 300 to 700 parts by mass, per 100 parts by mass of the metal oxide.

[0249] Examples of organic compounds include complex-forming organic compounds such as acetylacetone. The ratio of the organic compound is, for example, 0.1 to 10 parts by volume, preferably 1 to 5 parts by volume, per 100 parts by volume of water. The volume in the above ratio may be the volume at 1 atmosphere and room temperature of about 25°C.

[0250] Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, and nonionic surfactants are preferred. Examples of nonionic surfactants include polyoxyethylene (C ) surfactants such as polyethylene glycol-(t-octylphenyl) ether. 6-20 The surfactant may be present in an amount of, for example, 0.05 to 5 parts by volume, and preferably 0.1 to 3 parts by volume, relative to 100 parts by volume of water. The volume in the above ratio may be the volume at 1 atmosphere and room temperature of about 25°C.

[0251] The porous portion-forming solution may be prepared by mixing a metal oxide, a polymer compound, and water, stirring the mixture, and then adding an organic compound and a surfactant to the resulting mixture and stirring the mixture. Alternatively, the solution may be left to stand for 1 hour to 2 days, preferably 12 hours to 1 day, after preparation to remove air bubbles.

[0252] The porous portion forming solution can be coated by any of the conventional coating methods exemplified above as the coating method for the perovskite layer precursor solution, with spin coating being preferred.

[0253] The heat treatment temperature after coating with the porous portion-forming solution is, for example, 300 to 800° C., preferably 400 to 600° C. The porous portion thus obtained can be coated (or impregnated) with the first perovskite layer precursor solution in the first perovskite precursor film-forming treatment to form a film containing the first perovskite precursor.

[0254] (Second electrode forming process) In the second electrode forming step, a conductor such as a metal or carbon exemplified in the second electrode section is deposited, for example, by vacuum deposition, to form the second electrode. If the photoelectric conversion element is a nanostructure type or a planar heterojunction type, deposition may be performed on the polysilane layer (first polysilane layer) or the hole transport layer, or if the photoelectric conversion element is an inverted structure type, deposition may be performed on the electron transport layer formed in the electron transport layer forming step.

[0255] After laminating the layers, wiring may be connected or a cover may be attached as necessary to complete the photoelectric conversion element.

[0256] (Photoelectric conversion element characteristics) The photoelectric conversion element of the present disclosure exhibits high durability, allowing the conversion efficiency to be maintained at a high level or improved over a long period of time, even when used or stored in the atmosphere. Therefore, the conversion efficiency η of the photoelectric conversion element at the initial stage of fabrication is, for example, about 4% or more, preferably in the following stepwise order: 4.5 to 15%, 5 to 10%, 5.5 to 8%. Furthermore, the conversion efficiency η after a long period of time in the atmosphere (e.g., after 200 days, preferably after 250 days from fabrication) is, for example, about 5% or more, preferably in the following stepwise order: 6 to 15%, 6.5 to 14%, 7.5 to 13%, 8 to 12%, 8.5 to 11%, 9 to 10%.

[0257] Short-circuit current density J at the initial stage of photoelectric conversion element fabrication sc is, for example, 5 mA cm -2 At least about 10-30 mA cm, preferably in stages -2 , 15 to 25 mA·cm -2 , 17~21mA·cm -2 , 18~20mA·cm -2 The short-circuit current density J after a long period of time in the atmosphere (for example, after 200 days, preferably after 250 days from the time of manufacture) sc is, for example, 5 mA cm -2 At least about 10-30 mA cm, preferably in stages -2 , 16~25mA·cm -2 , 18~22mA·cm -2 , 19~21mA·cm -2 is.

[0258] Open-circuit voltage V at the initial stage of photoelectric conversion element fabrication oc is, for example, about 0.4 to 1.2 V, preferably in the following stepwise manner: 0.5 to 1 V, 0.55 to 0.8 V, 0.6 to 0.75 V, and 0.63 to 0.72 V. The open-circuit voltage V oc is, for example, about 0.5 to 1.2 V, preferably in the following stepwise manner: 0.6 to 1 V, 0.65 to 0.85 V, 0.7 to 0.8 V, and 0.73 to 0.75 V.

[0259] In the photoelectric conversion element of the present disclosure, the conversion efficiency η and short-circuit current density J sc , open circuit voltage V oc Even if the resistance is low, the properties may gradually improve because the properties are stable over a long period of time.

[0260] In this specification and claims, the conversion efficiency η, short-circuit current density J sc , open circuit voltage V oc is an illuminance of 100mWcm -2 , AM (air mass) 1.5, irradiation area 0.04cm 2 The measurement can be performed at room temperature (about 25°C), and in detail, by the method described in the Examples.

[0261] Carrier trap density N of photoelectric conversion element t For example, 10.5 x 10 15 cm -3 Less than about (e.g., 0.1 × 10 15 ~10×10 15 cm -3 ), preferably 9.5 × 10 15 cm -3 or less (e.g., 1×10 15 ~9×10 15 cm -3 ), more preferably 8.5 × 10 15 cm -3 Less than (e.g., 3×10 15 ~8×10 15 cm -3 ), more preferably 7.5 × 10 15 cm -3 Less than (e.g., 4×10 15 ~7×10 15 cm -3 ), especially 6.5 × 10 15 cm -3 Less than (e.g., 5 × 10 15 ~6×10 15 cm -3 ) where the carrier trap density N t may be a value at an early stage after the device is fabricated, or preferably a value 150 days after fabrication.

[0262] In this specification and claims, the carrier trap density can be measured by the method described in the examples below. [Example]

[0263] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples. The preparation methods of the raw materials used are also shown below.

[0264] [Preparation of raw materials] (FTO substrate (first electrode)) A glass substrate coated with fluorine-doped tin oxide (FTO) (thickness: 1.8 mm, thickness of FTO coating: approximately 900 nm) was ultrasonically cleaned in acetone and then in methanol. The substrate was then dried under nitrogen gas and subjected to UV-ozone treatment for 20 minutes.

[0265] (Electron transport layer precursor solution (0.15M)) The solution was prepared by mixing 0.055 mL of titanium diisopropoxide bis(acetyl acetonate) [manufactured by Sigma-Aldrich] and 1 mL of 1-butanol (manufactured by Nacalai Tesque, Inc., purity 99%) and stirring.

[0266] (Electron transport layer precursor solution (0.30M)) This solution was prepared by mixing 0.11 mL of titanium diisopropoxide bis(acetylacetonate) and 1 mL of 1-butanol and stirring.

[0267] (Porous part forming solution) 100 mg of TiO powder (AEROXIDE TiO P25, manufactured by Nippon Aerosil Co., Ltd.) and 10 mg of polyethylene glycol (PEG (#20000), manufactured by Nacalai Tesque, Inc.) were mixed with 0.5 mL of ultrapure water and stirred. 10.0 μL of acetylacetone (Fujifilm Wako Pure Chemical Industries, Ltd., purity 99%) and 5.0 μL of 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Sigma-Aldrich Triton-X-100) were added and stirred for 30 minutes, then allowed to stand for half a day.

[0268] (Perovskite layer precursor solution 1 (MA layer precursor solution)) 190.8 mg of CH3NH3I (monomethylamine hydroiodide or MAI, manufactured by Tokyo Chemical Industry Co., Ltd., purity 99.0%), 111.2 mg of PbCl2 (lead(II) chloride, manufactured by Sigma-Aldrich, purity 99.999%), and 0.5 mL of N,N-dimethylformamide (DMF, manufactured by Sigma-Aldrich) were mixed, heated to 60°C, and stirred for half a day.

[0269] (Perovskite layer precursor solution 2 (GA layer precursor solution)) 182.8 mg of CH3NH3I (monomethylamine hydroiodide or MAI, manufactured by Tokyo Chemical Industry Co., Ltd., purity 99.0%), 9.3 mg of CH6IN3 (guanidinium iodide or GAI, manufactured by Sigma-Aldrich, purity 99.0%), 111.2 mg of PbCl2 (lead(II) chloride, manufactured by Sigma-Aldrich, purity 99.999%), and 0.5 mL of N,N-dimethylformamide (DMF, manufactured by Sigma-Aldrich) were mixed, heated to 60°C, and stirred for half a day.

[0270] (Perovskite layer precursor solution 3 (FA layer precursor solution)) 182.8 mg of CH3NH3I (monomethylamine hydroiodide or MAI, manufactured by Tokyo Chemical Industry Co., Ltd., purity 99.0%), 8.6 mg of CH5IN2 (formamidinium iodide or FAI, manufactured by Sigma-Aldrich), 111.2 mg of PbCl2 (lead(II) chloride, manufactured by Sigma-Aldrich, purity 99.999%), and 0.5 mL of N,N-dimethylformamide (DMF, manufactured by Sigma-Aldrich) were mixed, heated to 60°C, and stirred for half a day.

[0271] (Perovskite layer precursor solution 4 (EA layer precursor solution)) 182.8 mg of CH3NH3I (monomethylamine hydroiodide or MAI, manufactured by Tokyo Chemical Industry Co., Ltd., purity 99.0%), 8.7 mg of CH3CH2NH3I (ethylammonium iodide or EAI, manufactured by Tokyo Chemical Industry Co., Ltd.), 111.2 mg of PbCl2 (lead(II) chloride, manufactured by Sigma-Aldrich, purity 99.999%), and 0.5 mL of N,N-dimethylformamide (DMF, manufactured by Sigma-Aldrich) were mixed, heated to 60°C, and stirred for half a day.

[0272] (Polysilane layer forming solution) 10 mg of decaphenylcyclopentasilane (OGSOL SI-30-15, manufactured by Osaka Gas Chemicals Co., Ltd., hereafter referred to simply as DPPS) as polysilane was mixed with 0.5 mL of chlorobenzene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred at room temperature (approximately 25°C) for one day to prepare a polysilane layer-forming solution.

[0273] [Fabrication of photoelectric conversion element] (Production Example 1) An electron transport layer precursor solution (0.15 M) was dropped onto an FTO substrate and spin-coated (3000 rpm, 30 seconds) using a spin coater (MS-A100, manufactured by Mikasa Corporation), followed by heat treatment (125°C, 5 minutes) on a hot plate (ND-1, manufactured by AS ONE Corporation). Next, an electron transport layer precursor solution (0.30 M) was dropped onto the FTO substrate and spin-coated (3000 rpm, 30 seconds). This electron transport layer precursor solution (0.30 M) was spin-coated twice, followed by heat treatment (125°C, 5 minutes) on a hot plate. Further heat treatment (550°C, 30 minutes) was performed in an electric furnace (SMF-2, manufactured by AS ONE Corporation) to form an electron transport layer (dense TiO layer) with a thickness of approximately 40 nm.

[0274] The porous portion-forming solution was dropped onto this electron transport layer and spin-coated (5000 rpm, 30 seconds), followed by heat treatment in an electric furnace (550°C, 30 minutes) to form a porous portion (porous TiO2 portion) with a thickness of approximately 300 to 900 nm, producing a laminate in which the FTO substrate / electron transport layer / porous portion were directly stacked in this order. Note that the film formation up to the electron transport layer and porous portion described above was all carried out in the atmosphere.

[0275] (Reference example 1) Perovskite layer precursor solution 1 (MA layer precursor solution) heated to 60°C was dropped and allowed to penetrate into the porous portion (or voids) of the laminate (FTO substrate / electron transport layer / porous portion) obtained in Preparation Example 1, and spin coating (1000 rpm for 5 seconds, then 2000 rpm for a further 60 seconds) was performed three times while a 90°C airflow was blown toward the substrate using a heat gun (Hakko Corporation's "HEATING GUN 882") for 5 seconds (while generating crystal nuclei by air-blowing), to form a film containing the first perovskite precursor (MA layer precursor).

[0276] The resulting mixture was then heat-treated at 190°C for 10 minutes on a hot plate to grow perovskite crystals, forming an MA layer containing MAPbI3 as the first perovskite compound (i.e., a first perovskite layer consisting of a porous layer in which the first perovskite compound has impregnated or infiltrated into the voids of the porous portion (approximately 300 to 900 nm thick) and a film of the first perovskite compound (a non-porous layer approximately 100 nm thick) formed continuously on top of the porous layer).The MA layer (first perovskite layer) was formed entirely in air.

[0277] Then, gold (Au) was deposited (or film-formed) on the resulting MA layer (first perovskite layer) using a vacuum deposition system (SVC-700TMSG / 7PS800E, manufactured by Sanyu Electronics Co., Ltd.) to form a second electrode (metal electrode) with a thickness of approximately 200 nm. In this way, a photoelectric conversion element was fabricated, comprising a first electrode / electron transport layer / MA layer (first perovskite layer) / second electrode (excluding the second perovskite layer and polysilane layer).

[0278] (Reference example 2) A photoelectric conversion element was fabricated in the same manner as in Reference Example 1, except that perovskite layer precursor solution 2 (GA layer precursor solution) was spin-coated (at 1000 rpm for 5 seconds, then at 2000 rpm for 60 seconds) onto the film containing the first perovskite precursor (MA layer precursor) while generating crystal nuclei using an air-blowing method, a total of two times, to form a film containing a second perovskite precursor (GA layer precursor) before subjecting it to heat treatment.

[0279] That is, on the MA layer (first perovskite layer) similar to that in Reference Example 1, MA as the second perovskite compound was formed. 0.875 GA 0.125A GA layer containing PbI3 (second perovskite layer with a thickness of approximately 200-300 nm) was formed, and a photoelectric conversion element (not including a polysilane layer) was fabricated, which included a first electrode, an electron transport layer, an MA layer (first perovskite layer), a GA layer (second perovskite layer), and a second electrode. The deposition of the electron transport layer to the GA layer (second perovskite layer) was all carried out in the atmosphere.

[0280] (Reference example 3) A photoelectric conversion element was fabricated in the same manner as in Reference Example 1, except that in the third spin coating when forming a film containing the first perovskite precursor (MA layer precursor), the polysilane layer forming solution was dropped 45 seconds after the start of the spin coating, and a heat gun (Hakko Corporation's "HEATING GUN 882") was immediately used to blow a 90°C airflow toward the substrate for 5 seconds, thereby laminating a thin-film polysilane layer on the film containing the first perovskite precursor, and then the substrate was subjected to heat treatment.

[0281] That is, a photoelectric conversion element comprising a first electrode / electron transport layer / MA layer (first perovskite layer) / polysilane layer / second electrode (not including a second perovskite layer) was fabricated by forming a polysilane layer with a thickness of approximately 10 nm on an MA layer (first perovskite layer) similar to that in Reference Example 1. The deposition of the electron transport layer to the polysilane layer was all carried out in the atmosphere.

[0282] (Reference example 4) A photoelectric conversion element was fabricated in the same manner as in Reference Example 3, except that when forming a film containing the first perovskite precursor, perovskite layer precursor solution 2 (GA layer precursor solution) was used instead of perovskite layer precursor solution 1 (MA layer precursor solution), the number of spin coatings was changed from three to five, and the polysilane layer forming solution was dropped during the fifth spin coating, and the resulting laminate (a laminate in which a thin-film polysilane layer was laminated on a film containing a perovskite precursor (GA layer precursor)) was subjected to heat treatment.

[0283] That is, MA as a perovskite compound 0.875 GA 0.125A PbI3-containing GA layer (a perovskite layer consisting of a porous layer (approximately 300-900 nm thick) impregnated or infiltrated with a perovskite compound in the voids of the porous portion) and a continuous perovskite compound film (approximately 100-200 nm thick non-porous layer) formed on the porous layer) was then formed. A polysilane layer (approximately 10 nm thick) was then formed on the GA layer to produce a photoelectric conversion element comprising a first electrode, an electron transport layer, a GA layer, a polysilane layer, and a second electrode. The deposition of the electron transport layer, the polysilane layer, and the second electrode was all carried out in air.

[0284] Example 1 A photoelectric conversion element was fabricated in the same manner as in Reference Example 2, except that in the second spin coating to form a film containing a second perovskite precursor (GA layer precursor), the polysilane layer forming solution was dropped 45 seconds after the start of the spin coating, and a heat gun (Hakko Corporation's "HEATING GUN 882") was immediately used to blow a 90°C airflow toward the substrate for 5 seconds, thereby laminating a thin-film polysilane layer on the film containing the second perovskite precursor, and then the substrate was subjected to heat treatment.

[0285] That is, a photoelectric conversion element comprising a first electrode / electron transport layer / MA layer (first perovskite layer) / GA layer (second perovskite layer) / polysilane layer / second electrode was fabricated by forming a polysilane layer with a thickness of approximately 10 nm on the same MA layer (first perovskite layer) and GA layer (second perovskite layer) as in Reference Example 2. The deposition of the electron transport layer to the polysilane layer was all carried out in the atmosphere.

[0286] Example 2 A photoelectric conversion element was fabricated in the same manner as in Example 1, except that perovskite layer precursor solution 3 (FA layer precursor solution) was used instead of perovskite layer precursor solution 2 (GA layer precursor solution) to form a second perovskite layer.

[0287] That is, on the MA layer (first perovskite layer) similar to that in Reference Example 1, MA as the second perovskite compound was formed. 0.875 FA 0.125An FA layer (second perovskite layer with a thickness of approximately 300 nm) containing PbI3 was formed, and a polysilane layer similar to that in Example 1 was formed on the FA layer to produce a photoelectric conversion element having a first electrode / electron transport layer / MA layer (first perovskite layer) / FA layer (second perovskite layer) / polysilane layer / second electrode. Note that the deposition of the electron transport layer to the polysilane layer was all carried out in the atmosphere.

[0288] Example 3 A photoelectric conversion element was fabricated in the same manner as in Example 1, except that perovskite layer precursor solution 4 (EA layer precursor solution) was used instead of perovskite layer precursor solution 2 (GA layer precursor solution) to form a second perovskite layer.

[0289] That is, on the MA layer (first perovskite layer) similar to that in Reference Example 1, MA as the second perovskite compound was formed. 0.875 EA 0.125 A PbI3-containing EA layer (second perovskite layer with a thickness of approximately 300 nm) and a polysilane layer similar to that in Example 1 were formed on the EA layer to produce a photoelectric conversion element having a first electrode / electron transport layer / MA layer (first perovskite layer) / EA layer (second perovskite layer) / polysilane layer / second electrode. The deposition of the electron transport layer to the polysilane layer was all carried out in the atmosphere.

[0290] Example 4 In the third spin coating for forming a film containing the first perovskite precursor (MA layer precursor), 45 seconds after the start of the spin coating, polysilane layer formation solution was dropped, and a heat gun (Hakko Corporation, "HEATING GUN 882") was immediately used to blow a 90°C airflow toward the substrate for 5 seconds, depositing a thin intermediate polysilane layer on the film containing the first perovskite precursor; on this intermediate polysilane layer, perovskite layer precursor solution 2 (GA layer precursor solution) was spin coated (at 1000 rpm for 5 seconds, then at 2000 rpm for 60 seconds) while generating crystal nuclei by air-blowing, a total of three times, to form a film containing the second perovskite precursor (GA layer precursor); in the third spin coating for forming this film containing the second perovskite precursor, polysilane layer formation solution was dropped, and a heat gun (Hakko Corporation, "HEATING GUN 882") was immediately used to spray a 90°C airflow toward the substrate for 5 seconds, depositing a thin intermediate polysilane layer on the film containing the first perovskite precursor; on this intermediate polysilane layer, perovskite layer precursor solution 2 (GA layer precursor solution) was spin coated (at 1000 rpm for 5 seconds, then at 2000 rpm for 60 seconds) while generating crystal nuclei by air-blowing, a total of three times, to form a film containing the second perovskite precursor (GA layer precursor); A photoelectric conversion element was produced in the same manner as in Reference Example 1, except that an airflow at 90°C was blown toward the substrate for 5 seconds using a 90°C airflow control device (Evaporator 882) to laminate a thin-film polysilane layer on the film containing the second perovskite precursor before the heat treatment.

[0291] That is, on the MA layer (first perovskite layer) similar to that in Reference Example 1, an intermediate polysilane layer having a thickness of about 10 nm and MA as the second perovskite compound were formed. 0.875 GA 0.125 A PbI3-containing GA layer (second perovskite layer, approximately 300 nm thick) and a 10 nm thick polysilane layer were formed to fabricate a photoelectric conversion element comprising a first electrode, an electron transport layer, an MA layer (first perovskite layer), an intermediate polysilane layer, a GA layer (second perovskite layer), a polysilane layer, and a second electrode. The deposition of the electron transport layer, the polysilane layer, and the second electrode was all carried out in the atmosphere.

[0292] Example 5 A photoelectric conversion element was prepared in the same manner as in Example 4, except that perovskite layer precursor solution 3 (FA layer precursor solution) was used instead of perovskite layer precursor solution 2 (GA layer precursor solution) to form the second perovskite layer.

[0293] That is, MA as the second perovskite compound was deposited on the MA layer (first perovskite layer) and the intermediate polysilane layer similar to those in Example 4. 0.875 FA 0.125 A PbI3-containing FA layer (second perovskite layer with a thickness of approximately 300 nm) was formed on the FA layer, and a polysilane layer similar to that in Example 4 was formed on the FA layer to produce a photoelectric conversion element comprising a first electrode / electron transport layer / MA layer (first perovskite layer) / intermediate polysilane layer / FA layer (second perovskite layer) / polysilane layer / second electrode. Note that the deposition of the electron transport layer to the polysilane layer was all carried out in the atmosphere.

[0294] [XRD (X-ray diffraction) measurement] X-ray diffraction (XRD) was measured for the photoelectric conversion elements fabricated in the examples and reference examples using an X-ray diffractometer (Bruker AXS "D2 PHASER"). Figure 3 shows, as a representative example, the X-ray diffraction patterns of the device of Example 1 at an early stage (0 days) and 200 days after fabrication.

[0295] As is clear from Figure 3, the photoelectric conversion element of Example 1 showed no significant change in diffraction pattern even after 200 days from production, compared to the initial stage (day 0). Similarly, for the other Examples, no significant change in diffraction pattern was observed even after a predetermined number of days had passed. Therefore, the photoelectric conversion elements of the Examples were stable and had excellent durability.

[0296] [Evaluation of photoelectric conversion element characteristics] (Short-circuit current density J SC , open circuit voltage V OC , photoelectric conversion efficiency η) Optical property measurement device (Precision source / measure unit, KEYSIGHT "B2901A"), solar simulator (Minae Electric Mfg. Co., Ltd. "XES-301S", light source: xenon lamp, illuminance: 100mWcm -2 ) with an AM (air mass) of 1.5 and an irradiation area of ​​0.04 cm 2The current density-voltage curves of the photoelectric conversion elements obtained in the examples and reference examples were measured under room temperature (approximately 25°C). Light was irradiated through the FTO substrate side of the photoelectric conversion element. The measurement results are shown in Table 1.

[0297] In the layer structure column in Table 1, "MA layer" refers to a layer containing methylammonium (MA or CH3NH3) as the A site, "GA layer" refers to a layer containing guanidinium (GA or C(NH2)3) as the A site, and "FA layer" refers to a layer containing formamidinium (FA or HC(NH2)2) as the A site. Also, "days elapsed" refers to the number of days that have passed since the device was fabricated. The photoelectric conversion efficiency η indicates the highest value for reverse scanning (scanning in the direction of decreasing voltage).

[0298] [Table 1]

[0299] As is clear from the results in Table 1, in comparison with the reference example, the examples showed high conversion efficiency η immediately after device fabrication, and even after a long period of time, η did not decrease, but rather improved.

[0300] In particular, Reference Examples 2 and 3 differ from Reference Example 1 in that they each have a second perovskite layer (Reference Example 2) or a polysilane layer (Reference Example 3), and all of them have improved η compared to Reference Example 1. However, in Example 1, which includes both the second perovskite layer and the polysilane layer, η improved to a degree that could not be predicted from the degree of improvement in Reference Examples 2 and 3. The reason for this is unclear, but as shown in Table 2 below, by introducing both the second perovskite layer and the polysilane layer in combination, the carrier trap density N t This is presumably because the

[0301] On the other hand, Reference Example 4 is an example in which only one perovskite layer containing both MA and GA (large ions) was formed and combined with a polysilane layer, without dividing the MA layer and GA layer into two layers as in Example 1, but the η was lower than in Example 1.

[0302] Furthermore, comparing Example 1 (GA layer) and Example 2 (FA layer), Example 1, which contains GA with a larger ionic diameter, had a higher η even after 200 days, exceeding 9% despite not containing Spiro-OMeTAD. On the other hand, Example 4 (GA layer) and Example 5 (FA layer), which contain an intermediate polysilane layer, showed no significant difference in η after 200 or 250 days. In other words, Example 5, even though it uses FA with a slightly smaller ionic diameter than GA, exhibits an η comparable to that of Examples 1 and 4, which use GA, by combining it with an intermediate polysilane layer.

[0303] Furthermore, since the examples can exhibit a high η even without containing Spiro-OMeTAD, they are advantageous not only in terms of durability but also in terms of cost, and can effectively improve productivity.

[0304] (Carrier trap density N t ) Using an optical property measurement device (Keysight Precision Source / Measure Unit, B2901A), current-voltage measurements were performed with light completely blocked (dark current measurements) to determine the carrier trap density N t [The number of carrier traps per unit volume in the semiconductor that inhibit the movement of carriers (electrons or holes) due to defects in the perovskite layer (or desorption of MA)] was calculated.

[0305] The results are shown in the following Table 2. In Table 2, "days elapsed" indicates the number of days elapsed since the device was fabricated.

[0306] [Table 2]

[0307] Carrier trap density N t The smaller the J, the easier it is for the current to flow. SC Improvements in N and η are expected, but the results of Reference Example 1 show that N t It can be seen that, compared to Reference Example 1, in Reference Example 2 having the second perovskite layer and Reference Example 3 having the polysilane layer, N t In the example having both the second perovskite layer and the polysilane layer in combination, N is slightly reduced compared to Reference Examples 2 and 3. t It was suggested that this significantly reduced the η. [Industrial Applicability]

[0308] The present disclosure can be effectively used as a perovskite-type photoelectric conversion element (perovskite compound photoelectric conversion thin film device or perovskite-type solar cell). Furthermore, compared to currently widely used Si-based solar cells, the photoelectric conversion element of the present disclosure uses a direct transition semiconductor, and therefore has high external quantum efficiency at visible light wavelengths, and has potential applications in IoT devices that require small, lightweight, and flexible properties for indoor and outdoor use (e.g., indoors), the wall surfaces of buildings or structures (e.g., buildings) that require light weight, and the roofs of vehicles (e.g., automobiles) that require curved surfaces. [Explanation of symbols]

[0309] 1, 11...first electrode 2,12...Electron transport layer (ETL) 3, 13...First perovskite layer (MA-containing perovskite layer) 3a, 13a...Porous portion and porous layer containing first perovskite compound 3b, 13b...Non-porous layer containing a first perovskite compound 4,14...Second perovskite layer (large ion-containing perovskite layer) 5, 15...Polysilane layer (first polysilane layer) 6,16...Second electrode 17...Intermediate polysilane layer (second polysilane layer)

Claims

1. A photoelectric conversion element comprising a perovskite layer containing a perovskite compound having a perovskite structure and a polysilane layer containing polysilane, the perovskite layer comprising a first perovskite compound having methylammonium; a second perovskite layer including a second perovskite compound having monovalent cations with a larger ion diameter than methylammonium and different from the first perovskite compound; The photoelectric conversion element, wherein the second perovskite layer is located between the first perovskite layer and the polysilane layer.

2. 2. The photoelectric conversion element according to claim 1, further comprising an intermediate polysilane layer containing the same or different polysilane as that in the polysilane layer and positioned between the first perovskite layer and the second perovskite layer.

3. The polysilane is represented by the following formulas (2a) and (2b): 【Chemical 1】 (In the formula, R １ ~R ３ independently represent a hydrogen atom, a hydroxyl group, an organic group, or a silyl group.

3. The photoelectric conversion element according to claim 1, comprising at least one structural unit selected from the structural units represented by the following formula:

4. In the formula (2a), R １ and R ２ At least one of the groups is an aryl group-containing group, and in the formula (2b), R ３ The photoelectric conversion element according to claim 3, wherein is an aryl group-containing group.

5. 4. The photoelectric conversion element according to claim 3, wherein the proportion of the structural unit represented by formula (2a) is 50 mol % or more based on the entire polysilane.

6. 3. The photoelectric conversion element according to claim 1, wherein the polysilane is a cyclic polysilane.

7. 3. The photoelectric conversion element according to claim 1, wherein the proportion of polysilane in said polysilane layer is 50 to 100% by mass based on the total mass of said polysilane layer.

8. 3. The photoelectric conversion element according to claim 2, wherein the proportion of polysilane in said intermediate polysilane layer is 50 to 100% by mass based on the entire intermediate polysilane layer.

9. 3. The photoelectric conversion element according to claim 1, wherein the first perovskite compound contains methylammonium at a ratio of 50 mol % or more relative to all monovalent cations in the first perovskite compound.

10. 3. The photoelectric conversion element according to claim 1, wherein the second perovskite compound has, as the monovalent cation having a larger ion diameter than methylammonium, at least one monovalent cation selected from amidinium, guanidinium, and organic ammonium having two or more carbon atoms.

11. 3. The photoelectric conversion element according to claim 1, wherein the second perovskite compound has 0.1 to 90 mol % of monovalent cations having a larger ion diameter than methylammonium relative to all monovalent cations in the second perovskite compound.

12. 3. The photoelectric conversion element according to claim 1, which does not include a hole transport layer containing 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

13. 3. The photoelectric conversion element according to claim 1, which has a conversion efficiency of 5% or more 200 days after production.

14. a pre-lamination step of forming a pre-laminate by directly or indirectly laminating, in this order, a film containing a first perovskite precursor for forming a first perovskite compound having methylammonium, a film containing a second perovskite precursor for forming a second perovskite compound having monovalent cations with an ion diameter larger than that of methylammonium and different from the first perovskite compound, and a polysilane layer containing polysilane; The method for producing a photoelectric conversion element according to claim 1 or 2, further comprising a heat treatment step of heat treating the preliminary laminate to form a laminate including the first perovskite layer, the second perovskite layer and the polysilane layer.

15. The method according to claim 14, wherein the heat treatment temperature in the heat treatment step is 150 to 250°C.

16. The manufacturing method according to claim 14 or 15, wherein the pre-laminating step and the heat treatment step are carried out in the atmosphere.

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