Method for producing tin-based perovskite layers

Abstract

To suppress oxidation of Sn2+ to Sn4+ without requiring a new reductant agent, in a method of manufacturing a tin-based perovskite layer.SOLUTION: A method of manufacturing a tin-based perovskite layer includes: a first step of dissolving a tin-based perovskite compound in a solvent not containing dimethyl sulfoxide (DMSO) to prepare a first solution (L3); a third step of applying the first solution on a base material (S) after the first step; and a second step of mixing the DMSO (L2) to the first solution after the first step and at a predetermined time before the third step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a tin-based perovskite layer used in solar cells and the like. [Background technology]

[0002] Solar cells using tin (Sn)-based perovskite layers instead of lead (Pb)-based perovskite layers as light absorption layers have been proposed as environmentally friendly solar cells (see Patent Document 1). However, in tin-based perovskites, divalent tin ions (Sn2+) in the material are easily oxidized to tetravalent tin ions (Sn4+), which increases the hole density in the layer and reduces the photoelectric conversion efficiency of the solar cell. Therefore, Patent Document 1 describes a method for producing a tin-based perovskite layer, which includes a step of adding a reducing agent to a solution containing a tin heavy halide to obtain a tin-based perovskite precursor solution. The reducing agent reduces tin fluoride in the tin-based perovskite precursor solution to tin but does not reduce the tin heavy halide in the tin-based perovskite precursor solution to tin. This manufacturing method is said to prevent the incorporation of Sn4+ and the oxidation of Sn2+, thereby producing extremely good solar cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2020 / 175705 publication Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the method for producing a tin-based perovskite layer described in Patent Document 1 requires the production of a new reducing agent, and further requires the optimization of the amount of reducing agent added.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to suppress the oxidation of Sn2+ to Sn4+ in a method for producing a tin-based perovskite layer without requiring an additional reducing agent. [Means for solving the problem]

[0006] A first means for solving the above problems is a method for producing a tin-based perovskite layer, A first step of preparing a first solution by dissolving a tin-based perovskite compound in a solvent that does not contain dimethyl sulfoxide (DMSO); a third step of applying the first solution to a substrate after the first step; a second step of mixing DMSO into the first solution after the first step and a predetermined time before the third step; Includes.

[0007] According to the above process, in the first step, a first solution is prepared by dissolving a tin-based perovskite compound in a solvent that does not contain dimethyl sulfoxide (DMSO). In the third step, the first solution is applied to a substrate after the first step. Adding DMSO when producing a tin-based perovskite layer is effective for promoting crystallization of the tin-based perovskite layer. However, the present inventors have noticed that DMSO oxidizes divalent tin ions (Sn2+) to tetravalent tin ions (Sn4+), reducing the photoelectric conversion efficiency of the tin-based perovskite layer.

[0008] Therefore, in the second step, DMSO is mixed into the first solution after the first step and a predetermined time before the third step. Therefore, compared to when DMSO is mixed in the first step, the timing of mixing DMSO can be delayed, and the oxidation of Sn2+ to Sn4+ by DMSO can be suppressed. Therefore, no additional reducing agent is required, and the oxidation of Sn2+ to Sn4+ can be suppressed. Furthermore, since DMSO is mixed when producing the tin-based perovskite layer, the crystallization of the tin-based perovskite layer can be promoted.

[0009] In a second method, the predetermined time is shorter than 2 hours. In a third method, the predetermined time is shorter than 1 hour. In a fourth method, the predetermined time is shorter than 5 minutes. These steps can further delay the timing of mixing DMSO, thereby further suppressing the oxidation of Sn2+ by DMSO to Sn4+.

[0010] In the fifth method, in the second step, DMSO is mixed with the first solution immediately before the third step. This method can minimize the timing of mixing DMSO, and can further suppress the oxidation of Sn2+ to Sn4+ by DMSO.

[0011] Specifically, as in the sixth means, in the first step, a step can be adopted in which a tin-based perovskite compound is mixed with a solvent not containing DMSO, and the mixture is stirred to dissolve the compound, thereby preparing the first solution.

[0012] In the seventh method, in the first step, a tin-based perovskite compound is mixed with a solvent not containing DMSO and stirred for 10 hours or more to dissolve the compound, thereby preparing the first solution. This step makes it possible to make the first solution, in which a tin-based perovskite compound is dissolved in a solvent not containing DMSO, closer to homogeneity.

[0013] In the eighth method, in the first step, a tin-based perovskite compound is mixed with a solvent not containing DMSO and stirred for 24 hours or more to dissolve the compound, thereby preparing the first solution. This step makes it possible to make the first solution, in which a tin-based perovskite compound is dissolved in a solvent not containing DMSO, even more homogeneous.

[0014] In the ninth method, in the second step, the first solution is stirred after DMSO is mixed into the first solution. This step makes it possible to prevent uneven distribution of DMSO in the first solution.

[0015] Specifically, as in the tenth means, a process can be adopted in which the general formula of the tin-based perovskite layer is represented by ASnX3, A is at least one of an alkali metal ion, a rubidium ion, a methylammonium ion, an ethylammonium ion, a formamidium ion, a guanidium ion, and an alkylammonium ion, and X is at least one of Group VII elements, fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0016] Specifically, as in the eleventh means, a process can be adopted in which the first solution contains iodine ions (I-), fluorine ions (F-), methylammonium ions (MA+), and dimethylformamide (DMF), and the first solution contains SnI2, SnF2, and MAI as solutes and DMF as a solvent.

[0017] In a twelfth means, the first solution further contains FAI as the solute, such as formamidium ions (FA+). According to this process, the properties of the tin-based perovskite layer can be further improved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing a manufacturing apparatus for a tin-based perovskite layer. [Figure 2] 10 is a graph showing the relationship between the stirring time and the hole density in a comparative example in which only DMSO was used as a solvent. [Figure 3] 10 is a graph showing the relationship between output voltage and current density for stirring times of 1 hour and 24 hours in a comparative example. [Figure 4] 10 is a graph showing the relationship between external quantum efficiency and short-circuit current density with respect to wavelength for stirring times of 1 hour and 24 hours in a comparative example. [Figure 5] 10 is a graph showing the relationship between stirring time and hole density in a comparative example in which DMF:DMSO=4:1 was used as a solvent. [Figure 6] FIG. 10 is a schematic diagram showing a modified example of the apparatus for producing a tin-based perovskite layer. [Figure 7] FIG. 10 is a schematic diagram showing another modified example of the apparatus for producing a tin-based perovskite layer. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention realized in a manufacturing apparatus for a tin-based perovskite layer used in a tin-based perovskite solar cell will be described with reference to the drawings.

[0020] As shown in FIG. 1, the manufacturing apparatus 100 includes a first container 11, a first pump 13, a first solenoid valve 15, a second container 21, a second pump 23, a second solenoid valve 25, a stirring tank 30, a third pump 33, a third solenoid valve 35, a buffer tank 40, a fourth pump 42, an inkjet printer 44, etc.

[0021] The first container 11 stores a first raw material liquid L1 (first solution). The first raw material liquid L1 contains dimethylformamide (DMF), tin ions (Sn), iodine ions (I), fluorine ions (F), and methylammonium ions (MA), and does not contain dimethyl sulfoxide (DMSO). Before being stored in the first container 11, the first raw material liquid L1 is stirred for 24 hours (10 hours or more, 24 hours or more).

[0022] SnI2, SnF2, and MAI correspond to raw materials for the tin-based perovskite compound. The tin-based perovskite compound can be represented by the general formula ASnX3. The first raw material liquid L1 can be made of raw materials for the perovskite compound represented by the general formulas AX and SnX2. Here, A is at least one of an alkali metal ion, a rubidium ion, a methylammonium ion, an ethylammonium ion, a formamidium ion, a guanidium ion, and an alkylammonium ion. X is at least one of the Group VII elements fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0023] In the first raw material liquid L1, the molar ratio of AX to SnX2 is adjusted depending on the desired properties of the perovskite layer. When forming a perovskite compound as a light absorber, the molar ratio of AX to SnX2 is preferably 1:10 to 10:1.

[0024] DMF corresponds to a solvent that does not contain DMSO. The DMSO-free solvent is not particularly limited as long as it can dissolve the AX and SnX2, but polar solvents are preferred. Specific examples include γ-butyrolactone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, isopropanol, sulfolane, propylene carbonate, ethyl cyanoacetate, acetylacetone, cyclopentanone, cyclohexanone, cycloheptane, aniline, piperidine, pyridine, cyclooctanone, tetrahydrofurfuryl acetate, cyclohexyl acetate, cyclopentyl methyl ether, phenylethylamine, ethylenediamine, triethylamine, diisopropylethylamine, and hydrazine.

[0025] A first pump 13 is connected to the first container 11 via a flow path 12. A stirring tank 30 is connected to the first pump 13 via a flow path 14. A first solenoid valve 15 is provided in the flow path 14. The first pump 13 discharges the first raw material liquid L1 sucked from the first container 11 to the first solenoid valve 15. The first solenoid valve 15 supplies and cuts off the first raw material liquid L1 discharged by the first pump 13 to the stirring tank 30. The first pump 13 and the first solenoid valve 15 are controlled by a control unit 50.

[0026] The second container 21 stores a second raw material liquid L2. The second raw material liquid L2 is made of DMSO. A second pump 23 is connected to the second container 21 via a flow path 22. The second pump 23 is connected to a stirring tank 30 via a flow path 24. A second solenoid valve 25 is provided in the flow path 24. The second pump 23 discharges the second raw material liquid L2 sucked from the second container 21 to the second solenoid valve 25. The second solenoid valve 25 supplies and blocks the second raw material liquid L2 discharged by the second pump 23 to the stirring tank 30. The second pump 23 and the second solenoid valve 25 are controlled by a control unit 50.

[0027] The stirring tank 30 stores the first raw material liquid L1 supplied via the first solenoid valve 15 and the second raw material liquid L2 supplied via the second solenoid valve 25, and stirs the stored raw material liquids. That is, the stirring tank 30 functions as a tank for storing the raw material liquids. The stirring tank 30 also functions as an agitator for stirring the stored raw material liquids. By stirring the raw material liquids in the stirring tank 30, a precursor solution L3 (solution) in which a tin-based perovskite compound is dissolved in a solvent is prepared. The stirring tank 30 is controlled by the control unit 50.

[0028] A third pump 33 is connected to the stirring tank 30 via a flow path 32. A buffer tank 40 is connected to the third pump 33 via a flow path 34. A third solenoid valve 35 is provided in the flow path 34. The third pump 33 discharges the precursor solution L3 drawn in from the stirring tank 30 to the third solenoid valve 35. The third solenoid valve 35 supplies and blocks the precursor solution L3 discharged by the third pump 33 to the buffer tank 40. The third pump 33 and the third solenoid valve 35 are controlled by a control unit 50.

[0029] The buffer tank 40 stores the precursor solution L3 supplied via the third solenoid valve 35. The capacity of the buffer tank 40 is set to a capacity that allows the precursor solution L4 to be stably supplied to the inkjet printer 44, which ejects the precursor solution L4 continuously for a certain period of time.

[0030] A fourth pump 42 is connected to the buffer tank 40 via a flow path 41. An inkjet printer 44 is connected to the fourth pump 42 via a flow path 43. The fourth pump 42 ejects the precursor solution L4 sucked from the buffer tank 40 to the inkjet printer 44. The fourth pump 42 is controlled by a control unit 50.

[0031] The inkjet printer 44 (discharge unit) discharges the precursor solution L4 supplied from the buffer tank 40 onto the substrate S. That is, the inkjet printer 44 applies the precursor solution L4 to the substrate S. The inkjet printer 44 is controlled by the control unit 50. The substrate S is formed, for example, by laminating a transparent conductive film, an electron transport layer, or a hole transport layer on a substrate (such as a glass substrate or a flexible substrate) from the substrate side. The inkjet printer 44 can also be replaced with a slot die, a spin coater, a roll coater, or the like.

[0032] Then, after chlorobenzene as a poor solvent is dropped into the precursor solution L4 applied to the substrate S, the applied precursor solution L4 is heated and dried (annealing step, heating step) to form a perovskite layer. The heating temperature is 20 to 300°C, preferably 50 to 170°C. When the applied precursor solution L4 is heated, a three-dimensional structure crystal (perovskite structure) begins to form. In this embodiment, the three-dimensional structure crystal is MASnI3 (CH3NH3SnI3).

[0033] The thickness of the perovskite layer is preferably 10 to 5000 nm, more preferably 100 to 1000 nm, from the viewpoint of easily improving photoelectric conversion efficiency even in low-temperature treatment (200°C or less).A hole transport layer or electron transport layer and an electrode are further laminated on the perovskite layer.

[0034] The control unit 50 is configured by, for example, a microcomputer equipped with a CPU, ROM, RAM, an input / output interface, etc. The control unit 50 controls the first pump 13, the first solenoid valve 15, the second pump 23, the second solenoid valve 25, the stirring tank 30, the third pump 33, the third solenoid valve 35, the fourth pump 42, and the inkjet printer 44.

[0035] Next, a method for producing a tin-based perovskite layer will be described.

[0036] First, the first raw material liquid L1 is stirred for 24 hours (10 hours or more, 24 hours or more) using a stirring device (not shown) (first step). The stirring device may be controlled by the control unit 50, another control device, or may be manually operated by an operator. Then, the stirred first raw material liquid L1 is supplied to the first container 11.

[0037] Subsequently, the control unit 50 causes the first pump 13 to discharge the first raw material liquid L1 to the first electromagnetic valve 15, and causes the first electromagnetic valve 15 to supply the first raw material liquid L1 to the stirring tank 30.

[0038] Subsequently, the control unit 50 causes the second pump 23 to discharge the second raw material liquid L2 to the second electromagnetic valve 25, and causes the second electromagnetic valve 25 to supply the second raw material liquid L2 to the stirring tank 30. That is, after causing the first electromagnetic valve 15 to supply the first raw material liquid L1, which has been stirred in advance, to the stirring tank 30, the control unit 50 causes the second electromagnetic valve 25 to supply the second raw material liquid L2 to the stirring tank 30 (second step).

[0039] Next, the control unit 50 causes the first raw material liquid L1 and the second raw material liquid L2 stored in the stirring tank 30 to be stirred (quickly) for, for example, one minute, thereby preparing the precursor solution L3.

[0040] Subsequently, the control unit 50 causes the third pump 33 to discharge the precursor solution L3 to the third electromagnetic valve 35, and causes the third electromagnetic valve 35 to supply the precursor solution L3 to the buffer tank 40. That is, after the first raw material liquid L1 and the second raw material liquid L2 stored in the stirring tank 30 are stirred, the control unit 50 causes the third electromagnetic valve 35 to supply the precursor solution L3 to the buffer tank 40.

[0041] Next, the control unit 50 controls the fourth pump 42 to eject the precursor solution L4 stored in the buffer tank 40 into the inkjet printer 44.

[0042] Next, the control unit 50 causes the inkjet printer 44 to eject the precursor solution L4 supplied from the buffer tank 40 onto the substrate S (third step). Here, the control unit 50 causes the second solenoid valve 25 to supply the second raw material liquid L2 to the stirring tank 30 after the first raw material liquid L1 has been stirred in advance and a predetermined time before the inkjet printer 44 ejects the precursor solution L4 supplied from the buffer tank 40 onto the substrate S. The predetermined time is shorter than two hours, preferably shorter than one hour, and more preferably shorter than five minutes.

[0043] FIG. 2 is a graph showing the relationship between the stirring time and the hole density in a comparative example in which only DMSO was used as the solvent.

[0044] In a tin-based perovskite layer fabricated using only DMSO as a solvent for dissolving the tin-based perovskite compound, the hole density increases the longer the raw material solution consisting of DMSO, SnI2, SnF2, and MAI is stirred. This is because DMSO oxidizes divalent tin ions (Sn2+) to tetravalent tin ions (Sn4+). As the hole density of the tin-based perovskite layer increases, the photoelectric conversion efficiency of the tin-based perovskite layer decreases.

[0045] 3 is a graph showing the relationship between output voltage [V] and current density [mA / cm2] for the comparative example where the stirring time is 1 hour and 24 hours. When the stirring time is 24 hours, the current density is lower than when the stirring time is 1 hour.

[0046] 4 is a graph showing the relationship between the external quantum efficiency (EQE) and the short-circuit current density (Jsc) versus wavelength for the stirring times of 1 hour and 24 hours in the comparative example. When the stirring time is 24 hours, the external quantum efficiency (EQE) and the short-circuit current density (Jsc) are lower than when the stirring time is 1 hour.

[0047] FIG. 5 is a graph showing the relationship between the stirring time and the hole density in a comparative example in which DMF:DMSO=4:1 was used as the solvent.

[0048] In a tin-based perovskite layer fabricated using a DMF:DMSO=4:1 ratio as a solvent for dissolving the tin-based perovskite compound, the hole density increased the longer the raw material solution consisting of DMF, DMSO, SnI2, SnF2, and MAI was stirred. In this case, too, DMSO oxidized divalent tin ions (Sn2+) to tetravalent tin ions (Sn4+).

[0049] However, mixing DMSO when producing a Sn-based perovskite layer is effective in promoting crystallization of the Sn-based perovskite layer. Therefore, in the above-described method for producing a Sn-based perovskite layer, in order to prevent Sn2+ from being oxidized to Sn4+, the first solenoid valve 15 supplies the pre-stirred first raw material liquid L1 to the stirring tank 30, and then the second solenoid valve 25 supplies the second raw material liquid L2 to the stirring tank 30. Furthermore, after the first raw material liquid L1 has been pre-stirred and a predetermined time before the precursor solution L4 supplied from the buffer tank 40 is ejected onto the substrate S by the inkjet printer 44, the second solenoid valve 25 supplies the second raw material liquid L2 to the stirring tank 30.

[0050] The photoelectric conversion efficiency of the tin-based perovskite layer of the comparative example, in which the first raw material liquid L1 and the second raw material liquid L2 were simultaneously supplied to the stirring tank 30 and stirred in the stirring tank 30 for 24 hours, was 2.9%. In contrast, the photoelectric conversion efficiency of the tin-based perovskite layer of the present embodiment, in which the first raw material liquid L1 that had been stirred for 24 hours in advance was supplied to the stirring tank 30, and then the second raw material liquid L2 was supplied to the stirring tank 30 and stirred (quickly) for 1 minute in the stirring tank 30, was 6.4%. Therefore, by shortening the time from adding DMSO after stirring the first raw material liquid L1 to discharging the precursor solution L4 using the inkjet printer 44, it is possible to suppress the oxidation of Sn2+ to Sn4+.

[0051] The present embodiment described above in detail has the following advantages.

[0052] In the second step, DMSO is mixed into the precursor solution L3 after the first step and a predetermined time before the third step. Specifically, the control unit 50 controls the second solenoid valve 25 to supply the second raw material liquid L2 to the stirring tank 30 after the first solenoid valve 15 has supplied the pre-mixed first raw material liquid L1 to the stirring tank 30 and a predetermined time before the inkjet printer 44 ejects the precursor solution L4 supplied from the buffer tank 40 onto the substrate S. This delays the timing of mixing DMSO compared to mixing DMSO in the first step, thereby preventing Sn2+ from being oxidized to Sn4+ by DMSO. Therefore, no additional reducing agent is required, and oxidation of Sn2+ to Sn4+ can be prevented. Furthermore, since DMSO is mixed when producing the tin-based perovskite layer, crystallization of the tin-based perovskite layer can be promoted.

[0053] The predetermined time is shorter than 2 hours. Preferably, the predetermined time is shorter than 1 hour. More preferably, the predetermined time is shorter than 5 minutes. These steps can further delay the timing of mixing DMSO, thereby further suppressing the oxidation of Sn2+ to Sn4+ by DMSO.

[0054] In the first step, a tin-based perovskite compound is mixed with a DMSO-free solvent and stirred for 24 hours (10 hours or more, 24 hours or more) to dissolve the compound, thereby preparing the first raw material liquid L1. This process makes it possible to make the first raw material liquid L1, in which the tin-based perovskite compound is dissolved in a DMSO-free solvent, nearly homogeneous.

[0055] In the second step, DMSO is mixed with the first raw material liquid L1, and then the first raw material liquid L1 is stirred. Specifically, the control unit 50 controls the second solenoid valve 25 to supply the second raw material liquid L2 to the stirring tank 30, and after stirring the first raw material liquid L1 and the second raw material liquid L2 stored in the stirring tank 30, controls the third solenoid valve 35 to supply the precursor solution L3. This step makes it possible to prevent DMSO from being unevenly distributed in the precursor solution L3.

[0056] The first solenoid valve 15 supplies and cuts off the first raw material liquid L1, which is a mixture of a tin-based perovskite compound and a solvent that does not contain DMSO. The first solenoid valve 15 can supply the first raw material liquid L1 that has been stirred in advance.

[0057] The second solenoid valve 25 supplies and blocks DMSO as the second raw material liquid L2. The stirring tank 30 stores the first raw material liquid L1 supplied via the first solenoid valve 15 and the second raw material liquid L2 supplied via the second solenoid valve 25, and stirs the stored raw material liquids. The control unit 50 controls the first solenoid valve 15, the second solenoid valve 25, and the stirring tank 30. Therefore, the control unit 50 controls the first solenoid valve 15 and the second solenoid valve 25 to supply the first raw material liquid L1 and the second raw material liquid L2 to the stirring tank 30, and controls the stirring tank 30 to stir the stored raw material liquids.

[0058] By controlling the first solenoid valve 15 and the second solenoid valve 25 using the control unit 50, it is possible to control the timing of supplying the first raw material liquid L1 to the stirring tank 30 and the timing of supplying the second raw material liquid L2 to the stirring tank 30. Therefore, the timing of supplying the second raw material liquid L2 to the stirring tank 30 can be delayed relative to the timing of supplying the first raw material liquid L1 to the stirring tank 30. Thereafter, the stirring tank 30 can be controlled to stir the stored first raw material liquid L1 and second raw material liquid L2. Therefore, no additional reducing agent is required, and oxidation of Sn2+ to Sn4+ can be suppressed. Moreover, since DMSO is mixed when producing the Sn-based perovskite layer, crystallization of the Sn-based perovskite layer can be promoted. The precursor solution L3 supplied from the stirring tank 30 can then be supplied to the buffer tank 40 via the third solenoid valve 35.

[0059] The buffer tank 40 stores the precursor solution L3 supplied via the third solenoid valve 35. Therefore, the precursor solution L3 supplied via the third solenoid valve 35 can be temporarily stored in the buffer tank 40, and the precursor solution L3 can be stably supplied to the inkjet printer 44. The control unit 50 then controls the inkjet printer 44 to eject the precursor solution L4 supplied from the buffer tank 40 onto the substrate S.

[0060] The control unit 50 causes the first pump 13 to discharge the first raw material liquid L1 to the first solenoid valve 15, and then causes the first solenoid valve 15 to supply the first raw material liquid L1 to the stirring tank 30, and then causes the second pump 23 to discharge the second raw material liquid L2 to the second solenoid valve 25, and then causes the second solenoid valve 25 to supply the second raw material liquid L2 to the stirring tank 30. With this configuration, the timing at which the second raw material liquid L2 is supplied to the stirring tank 30 can be delayed from the timing at which the first raw material liquid L1 is supplied to the stirring tank 30.

[0061] The first raw material liquid L1, which has been stirred in advance, can be supplied to the stirring tank 30, and then the second raw material liquid L2 can be supplied to the stirring tank 30. This allows the tin-based perovskite compound to be dissolved in a DMSO-free solvent beforehand, and then the second raw material (DMSO) can be added. This further prevents Sn2+ from being oxidized to Sn4+.

[0062] After the first raw material liquid L1 and the second raw material liquid L2 stored in the stirring tank 30 are stirred, the precursor solution L3 can be supplied to the third solenoid valve 35. This makes it easier to dissolve the tin-based perovskite compound in the DMSO added later.

[0063] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0064] The first raw material liquid L1 (precursor solution L3) may further contain FAI as a solute, such as formamidium ions (FA+). In this case, the first raw material liquid L1 and the second raw material liquid L2 were simultaneously supplied to the stirring tank 30 and stirred in the stirring tank 30 for 24 hours to produce a tin-based perovskite layer in a comparative example. The photoelectric conversion efficiency of the tin-based perovskite layer was 4.6%. In contrast, the photoelectric conversion efficiency of the tin-based perovskite layer in this embodiment was 9.5%. Therefore, even when the first raw material liquid L1 contains FAI, the oxidation of Sn2+ to Sn4+ can be suppressed by shortening the time from adding DMSO after stirring the first raw material liquid L1 to discharging the precursor solution L4 using the inkjet printer 44.

[0065] In step 2, DMSO can be mixed into precursor solution L3 immediately before step 3. This allows the timing of mixing DMSO to be delayed as much as possible, further preventing Sn2+ from being oxidized to Sn4+ by DMSO.

[0066] 6, the buffer tank 40 and the fourth pump 42 can be omitted from the manufacturing apparatus 100 for a tin-based perovskite layer. In this case, it is desirable to set the capacity of the stirring tank 30 to be equal to or greater than the capacity of the buffer tank 40.

[0067] As shown in Fig. 7, in the manufacturing apparatus 100 for a tin-based perovskite layer, the first pump 13, the second pump 23, and the third pump 33 may be further omitted from the configuration of Fig. 6. In this case, the first raw material liquid L1 stored in the first container 11, the second raw material liquid L2 stored in the second container 21, and the precursor solution L3 stored in the stirring tank 30 may be supplied by utilizing their potential energies.

[0068] The above modifications may be combined and implemented. [Explanation of symbols]

[0069] 11...first container, 21...second container, 30...mixing tank, 40...buffer tank, 44...inkjet printer (discharge unit), 50...control unit, 100...manufacturing apparatus.

Claims

1. A method for producing a tin-based perovskite layer, comprising: A first step of preparing a first solution by dissolving a tin-based perovskite compound in a solvent that does not contain dimethyl sulfoxide (DMSO); a third step of applying the first solution to a substrate after the first step; a second step of mixing DMSO into the first solution after the first step and a predetermined time before the third step; Including, In the second step, DMSO is mixed into the first solution immediately before the third step.

2. A method for producing a tin-based perovskite layer, comprising: A first step of preparing a first solution by dissolving a tin-based perovskite compound in a solvent that does not contain dimethyl sulfoxide (DMSO); a third step of applying the first solution to a substrate after the first step; a second step of mixing DMSO into the first solution after the first step and a predetermined time before the third step; Including, The method for producing a tin-based perovskite layer, wherein the predetermined time is shorter than 2 hours.

3. The method for producing a tin-based perovskite layer according to claim 2 , wherein the predetermined time is shorter than one hour.

4. The method for producing a tin-based perovskite layer according to claim 2 or 3, wherein the predetermined time is shorter than 5 minutes.

5. 5. The method for producing a tin-based perovskite layer according to claim 1, wherein in the first step, a tin-based perovskite compound is mixed with a solvent not containing DMSO, and the mixture is stirred to dissolve the compound, thereby preparing the first solution.

6. 6. The method for producing a tin-based perovskite layer according to claim 1, wherein in the first step, a tin-based perovskite compound is mixed with a solvent not containing DMSO and stirred for 10 hours or more to dissolve the compound, thereby preparing the first solution.

7. 7. The method for producing a tin-based perovskite layer according to claim 1, wherein in the first step, a tin-based perovskite compound is mixed with a solvent not containing DMSO and stirred for 24 hours or more to dissolve the compound, thereby preparing the first solution.

8. The method for producing a tin-based perovskite layer according to any one of claims 5 to 7, wherein in the second step, the first solution is mixed with DMSO and then stirred.

9. The general formula of the tin-based perovskite layer is represented by ASnX3, A is at least one of an alkali metal ion, a rubidium ion, a methylammonium ion, an ethylammonium ion, a formamidium ion, a guanidium ion, and an alkylammonium ion; The method for producing a tin-based perovskite layer according to any one of claims 1 to 8, wherein X is at least one of Group VII elements fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

10. Iodine ion (I-), fluorine ion (F-), methylammonium ion (MA+), dimethylformamide (DMF), 10. The method for producing a tin-based perovskite layer according to claim 1, wherein the first solution is a solution containing SnI2, SnF2, and MAI as solutes and DMF as a solvent.

11. As formamidium ion (FA+), The method for producing a tin-based perovskite layer according to claim 10 , wherein the first solution further contains FAI as the solute.

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