Perovskite film evaluation method, perovskite film formation method, and perovskite film formation device

Abstract

To provide a perovskite film evaluation method that allows evaluation to be conducted in-line with high accuracy.SOLUTION: A perovskite film evaluating method includes: a step (A) of irradiating a perovskite film with excitation light having an energy greater than a band gap of perovskite crystal, and acquiring a peak intensity of an emission spectrum of photoluminescence emitted from the perovskite film; a step (B) of irradiating the perovskite film with light having an energy greater than the band gap of the perovskite crystal, and acquiring transmittance of the perovskite film; and a step (C) of evaluating a crystalline state of the perovskite film, on the basis of a combination of the peak intensity and transmittance acquired in the step (A) and step (B).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating a perovskite film used in a light absorption layer of a solar cell, a method for forming a perovskite film, and an apparatus for forming a perovskite film. [Background technology]

[0002] Perovskite solar cells, which use a perovskite film as a light-absorbing layer, can achieve photoelectric conversion efficiency equivalent to that of conventional silicon-based solar cells, even though they are thin. They can also be made in flexible forms, and have other advantages, such as being able to be manufactured by coating and formed inexpensively using a relatively low-temperature process.

[0003] A common method for forming a perovskite film involves applying a solution containing dissolved elements of the perovskite crystal onto a substrate, and then drying the applied film to form a crystallized perovskite film on the substrate.

[0004] However, with this method, the crystalline state of the perovskite film can change significantly even with slight differences in coating and drying conditions, making it difficult to form a uniform, high-quality perovskite film over a large area. Because the crystalline state of the perovskite film is directly linked to the photoelectric conversion efficiency of perovskite solar cells, a method for evaluating the crystalline state of the perovskite film is needed.

[0005] Patent Document 1 describes a method for predicting the power generation performance of a solar cell based on an image obtained by irradiating a perovskite solar cell with light and capturing the light that has passed through the solar cell. The image of the transmitted light appears as color unevenness that reflects the crystalline state of the light absorption layer (perovskite film), and therefore the film quality of the perovskite film can be evaluated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-5473 Summary of the Invention [Problem to be solved by the invention]

[0007] The evaluation method described in Patent Document 1 evaluates the film quality of the perovskite film based on color unevenness in an image captured using transmitted light, and therefore cannot determine the crystalline state, such as crystal size or grain boundaries. As a result, it is difficult to accurately predict the photoelectric conversion efficiency of a perovskite solar cell based on color unevenness in an image captured using transmitted light.

[0008] On the other hand, the crystalline state of perovskite films can be evaluated by observation with a scanning electron microscope or analysis using X-ray diffraction, but it is difficult to quickly evaluate the in-plane distribution of the crystalline state of perovskite films over a large area.

[0009] The present invention has been made in view of the above points, and its main object is to provide a perovskite film evaluation method, a perovskite film formation method, and a perovskite film formation apparatus that are capable of evaluating, in-line and with high accuracy, the crystalline state of a perovskite film that is caused by coating and drying conditions. [Means for solving the problem]

[0010] The method for evaluating a perovskite film according to the present invention is a method for evaluating a perovskite film used in a light absorption layer of a solar cell, and includes the steps of: (A) irradiating the perovskite film to be evaluated with excitation light having an energy greater than the band gap of the crystals constituting the perovskite film, and obtaining the peak intensity of the emission spectrum of photoluminescence emitted from the perovskite film; (B) irradiating the perovskite film to be evaluated with light having an energy greater than the band gap of the crystals constituting the perovskite film, and obtaining the transmittance of the perovskite film; and (C) evaluating the crystalline state of the perovskite film based on a combination of the peak intensity and transmittance obtained in steps (A) and (B).

[0011] The method for evaluating a perovskite film according to the present invention is a method for evaluating a perovskite film used in a light absorption layer of a solar cell, and includes the following steps: (A) irradiating the perovskite film to be evaluated with excitation light having an energy greater than the band gap of the crystals constituting the perovskite film, and obtaining the peak intensity of the emission spectrum of photoluminescence emitted from the perovskite film; (B) irradiating the perovskite film to be evaluated with light, and detecting the light reflected from the perovskite film, thereby obtaining the glossiness of the perovskite film; and (C) evaluating the crystalline state of the perovskite film based on a combination of the peak intensity and glossiness obtained in steps (A) and (B).

[0012] The method for forming a perovskite film according to the present invention is a method for forming a perovskite film used in the light absorption layer of a solar cell, and comprises the steps of applying a solution containing dissolved constituent elements of a perovskite crystal onto a substrate to form a coating film containing perovskite, and drying the coating film to form a crystallized perovskite film on the substrate. In the method for evaluating the perovskite film, the application conditions of the solution and / or the drying conditions of the coating film are adjusted based on the crystalline state of the perovskite film evaluated in step (C).

[0013] The perovskite film forming apparatus according to the present invention is an apparatus for forming a perovskite film used in the light absorption layer of a solar cell, and comprises a coating section that applies a solution in which perovskite crystals are dissolved onto a substrate to form a coating film containing perovskite, a drying section that dries the coating film to form a crystallized perovskite film on the substrate, and an evaluation section that evaluates the crystalline state of the perovskite film, and the evaluation section adjusts the application conditions of the solution in the coating section and / or the drying conditions of the coating film in the drying section based on the crystalline state of the perovskite film evaluated in step (C) in the perovskite film evaluation method described above. [Effects of the Invention]

[0014] The present invention provides a perovskite film evaluation method, a perovskite film formation method, and a perovskite film formation apparatus that can accurately evaluate the crystalline state of a perovskite film caused by coating and drying conditions in-line. [Brief explanation of the drawings]

[0015] [Figure 1] 1(A) to 1(C) are diagrams showing a method for forming a perovskite film on a substrate. [Figure 2] FIG. 2 is a diagram showing a schematic diagram of the state of crystal nucleation in the coating film after drying under reduced pressure and the state of crystal growth in the perovskite film after drying under heat. [Figure 3] FIG. 3 is a graph qualitatively showing the relationship between crystal size and conversion efficiency. [Figure 4] FIG. 4 is a graph qualitatively showing the relationship between the crystal gap and the conversion efficiency. [Figure 5] 5(A) to 5(D) are diagrams showing the crystalline state of the perovskite film as shown in FIG. [Figure 6] FIG. 6 is a flowchart showing a method for evaluating a perovskite film in this embodiment. [Figure 7] FIG. 7 shows a method for measuring the PL intensity of the emission spectrum. [Figure 8] FIG. 8 is a diagram showing a method for measuring the transmittance of a perovskite film. [Figure 9] FIG. 9 is a diagram showing a method for evaluating the in-plane distribution of the crystalline state of a perovskite film. [Figure 10] FIG. 10 is a diagram showing an example of the in-plane distribution of PL intensity on the plane of a perovskite film. [Figure 11] FIG. 11 is a diagram showing an example of the in-plane distribution of transmittance on the plane of a perovskite film. [Figure 12] FIG. 12 is a diagram showing the in-plane distribution of PL intensity and transmittance superimposed on each other. [Figure 13]FIG. 13 is a diagram illustrating the magnitude of the values ​​when the PL intensity and the transmittance are combined. [Figure 14] FIG. 14 is a diagram showing a schematic diagram of different crystalline states of a perovskite film. [Figure 15] FIG. 15 is a flowchart showing a method for evaluating a perovskite film in a modified example. [Figure 16] FIG. 16 is a diagram showing a method for measuring the glossiness of a perovskite film. [Figure 17] Figures 17(A) and 17(B) show an example of the in-plane distribution of PL intensity and glossiness on the plane of a perovskite film, and Figure 17(C) shows the in-plane distribution of PL intensity and glossiness superimposed on each other. [Figure 18] FIG. 18 is a flowchart showing a method for forming a perovskite film in this embodiment. [Figure 19] FIG. 19 is a graph comparing the in-plane distribution of PL intensity and transmittance when perovskite films are formed under different drying conditions. [Figure 20] FIG. 20 is a block diagram showing a perovskite film forming apparatus according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Before describing the embodiments of the present invention, the circumstances by which the inventors of the present invention came up with the idea will be described.

[0017] 1(A) to 1(C) are diagrams showing a general method for forming a perovskite film on a substrate. Note that in an actual perovskite solar cell (hereinafter simply referred to as a "solar cell"), a transparent electrode and a hole transport layer or an electron transport layer are laminated on a transparent support such as quartz glass, and a perovskite film is formed thereon; however, in the following explanation, the transparent support on which the transparent electrode and the hole transport layer or the electron transport layer are laminated will be referred to as a "substrate."

[0018] As shown in Figure 1(A), a substrate W is placed on a stage 10, and a slit nozzle 11 is moved relative to the substrate W held on the stage 10, while a solution (coating liquid) in which the constituent elements of a perovskite crystal accumulated in a manifold 12 are dissolved is ejected (applied) from an outlet 14 of a slit 13 toward the substrate W, thereby forming a coating film M on the substrate W.

[0019] An air knife 20 is attached to the slit nozzle 11, and immediately after the coating liquid discharged from the slit nozzle 11 lands on the substrate W, dry air 21 is blown onto the coating film M, thereby performing initial drying and progressing the formation of the coating film M on the substrate W. As a result, immediately after the coating film M containing perovskite is formed on the substrate W, crystallization begins as the solvent evaporates.

[0020] Next, as shown in Fig. 1(B), the coating film M formed on the substrate W is placed in a decompression chamber 31, and the pressure inside the decompression chamber 31 is reduced by a decompression means 32 such as a vacuum pump. This lowers the boiling point of the solvent in the coating film M on the substrate W, and as the solvent evaporates, the coating film M is dried under reduced pressure. During this reduced pressure drying process, perovskite crystal nuclei are formed in the coating film M, and the longer the drying time, the more crystal nuclei are formed in the coating film M.

[0021] 1(C), the reduced-pressure dried coating film M is placed in a heating chamber 41, and is heated and dried (annealed) by a heater 42 to a temperature at which the coating film M can be fired or higher, thereby further volatilizing the solvent in the coating film M and finally firing the coating film M to form a perovskite film P. During this heating and drying process, perovskite crystals grow around the crystal nuclei, increasing the crystal size.

[0022] The coating film M formed on the substrate W by this method is dried in the following order: blowing dry air, drying under reduced pressure, and drying by heating. In each drying step, the solvent in the coating film M evaporates, thereby promoting crystallization of perovskite in the coating film M. Therefore, by adjusting the conditions in each drying step, it is possible to adjust the crystal size and grain boundaries of the perovskite that constitutes the perovskite film P.

[0023] For example, Figure 2 is a diagram schematically showing the state of crystal nuclei formation in a coating film M after reduced pressure drying and the state of crystal growth in a perovskite film P after heat drying. As shown in Figure 2, in the reduced pressure drying process, the slower the drying rate, the lower the density of crystal nuclei in the coating film M, and the faster the drying rate, the higher the density of crystal nuclei. As a result, in the perovskite film P after heat drying, the lower the density of crystal nuclei, the larger the crystal size and crystal grain boundaries, and the higher the density of crystal nuclei, the smaller the crystal size and crystal grain boundaries.

[0024] In order to investigate the relationship between the crystalline state of the perovskite film P and the photoelectric conversion efficiency (hereinafter simply referred to as "conversion efficiency") of the solar cell, the inventors of the present application fabricated solar cells using perovskite films P formed under different coating and drying conditions, and measured the crystal size of the perovskite film P, the gaps between the crystal grains (hereinafter referred to as "crystal gaps"), and the conversion efficiency of the solar cell for each solar cell fabricated.

[0025] Here, the "crystal size" refers to the average size of crystal particles per volume, and was measured using a scanning electron microscope (SEM).

[0026] The "crystal gap" is the average gap between crystal grains per volume, and was measured using a scanning electron microscope (SEM).

[0027] Figures 3 and 4 are graphs showing the results. Figure 3 is a graph qualitatively showing the relationship between crystal size and conversion efficiency, and Figure 4 is a graph qualitatively showing the relationship between crystal gap and conversion efficiency.

[0028] In Figure 3, the graphs indicated by A, B, and C show the cases where the crystal gaps are small, medium, and large, respectively, and in Figure 4, the graphs indicated by D, E, and F show the cases where the crystal size is large, medium, and small, respectively. For example, in both Figures 3 and 4, the points indicated by the same symbols (O, P, Q, and R) have the same crystalline state (crystal size and crystal gap), as shown in Figures 5(A), (B), (C), and (D). Here, arrow G indicates a crystal grain, and arrow S indicates a crystal gap.

[0029] As shown in Figure 3, when the crystal gap is small (graph A), the conversion efficiency of the solar cell increases as the crystal size increases, but when the crystal gap is large (graph C), the conversion efficiency of the solar cell does not change even if the crystal size increases. In other words, the conversion efficiency of a solar cell is not determined solely by the crystal size, but is also heavily dependent on the crystal gap.

[0030] Furthermore, as shown in Figure 4, regardless of the crystal size, the larger the crystal gap, the lower the conversion efficiency of the solar cell. However, when the crystal gap is small, the conversion efficiency of the solar cell is not determined solely by the crystal gap, but is also heavily dependent on the crystal size.

[0031] These results are thought to be due to the fact that the perovskite film P with large crystal size has good crystal quality, which results in fewer defects in the band gap and reduced non-radiative recombination, resulting in high conversion efficiency.However, as the crystal gaps become larger, the interfaces between the crystal grains become wider, making it easier for non-radiative recombination of carriers to occur at the crystal grain boundaries, resulting in a decrease in conversion efficiency.

[0032] As such, the conversion efficiency of a solar cell depends on both the crystal size and the crystal gap. Therefore, in order to accurately predict the conversion efficiency of a solar cell, it is necessary to evaluate the crystalline state of the perovskite film P based on the crystal size and the crystal gap.

[0033] Based on this knowledge, the inventors of the present application have come up with the idea that by combining multiple optical evaluation methods, such as evaluating the crystal size based on the peak intensity of the emission spectrum obtained by photoluminescence and evaluating the crystal gap based on the transmittance of the perovskite film P, it is possible to evaluate the crystalline state of the perovskite film P in a short period of time, and have thus arrived at the present invention.

[0034] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0035] (Perovskite film evaluation method) 6 is a flowchart showing a method for evaluating a perovskite film in this embodiment. The perovskite film is used as a light absorption layer in a solar cell.

[0036] First, a perovskite film to be evaluated is prepared (step S101). For example, when evaluating the crystalline state of a perovskite film in-line during the manufacturing process of a solar cell, a transparent support is prepared by laminating a transparent electrode and a hole transport layer or an electron transport layer, and a perovskite film is formed thereon. Alternatively, when evaluating the crystalline state of a perovskite film separately from in-line evaluation, a perovskite film may be formed on a transparent substrate. Note that the perovskite film can be formed, for example, by the method illustrated in FIG. 1, but is not limited thereto and may be formed by other commonly used methods.

[0037] Next, the perovskite film to be evaluated is irradiated with excitation light having energy greater than the band gap of the crystals that make up the perovskite film, and the peak intensity (hereinafter simply referred to as "PL intensity") of the emission spectrum of photoluminescence (PL) emitted from the perovskite film is obtained (step S102).

[0038] Perovskite films with large crystal sizes have good crystal quality, which means fewer defects in the band gap and reduced non-radiative recombination, resulting in higher PL intensity in the emission spectrum. Therefore, the PL intensity in the emission spectrum can be used as an index to evaluate the crystal size of a perovskite film.

[0039] Separately from step S102, the perovskite film to be evaluated is irradiated with light having energy greater than the band gap of the crystals that make up the perovskite film, and the transmittance of the perovskite film is obtained (step S103).

[0040] When a perovskite film with large crystalline gaps is irradiated with light with energy greater than the band gap of the crystals that make up the perovskite film, the light that would normally be absorbed by the perovskite film passes through the crystalline gaps intact, increasing the transmittance of the perovskite film. Therefore, the transmittance of a perovskite film can be used as an index to evaluate the crystalline gaps of the perovskite film.

[0041] Thus, the PL intensity of the emission spectrum and the transmittance of the perovskite film can serve as indicators for evaluating the crystalline state (crystal size and crystal gaps) of the perovskite film, which is related to the conversion efficiency of solar cells.

[0042] Therefore, by evaluating the crystalline state of the perovskite film (step S104) based on a combination of the PL intensity and transmittance obtained in steps S102 and S103, the conversion efficiency of the solar cell can be predicted with high accuracy.

[0043] In the method for evaluating a perovskite film in this embodiment, the crystal size of the perovskite film is evaluated based on the peak intensity of the emission spectrum obtained by a photoluminescence method, and the crystal gaps are evaluated based on the transmittance of the perovskite film. By combining multiple optical evaluation techniques, it is possible to accurately evaluate the crystalline state of the perovskite film in a short period of time.

[0044] The PL intensity of the emission spectrum can be measured using a known photoluminescence method. For example, as shown in Figure 7, excitation light 51 emitted from a light source 50 is passed through a beam splitter 52 and condensed by an objective lens 53, and is then irradiated onto the surface of a perovskite film P formed on a substrate W. Then, photoluminescent light and reflected light from the perovskite film P are passed through the objective lens 53 and separated into photoluminescent light 54 and reflected light by the beam splitter 52, and the spectrum of the photoluminescent light is detected by a spectroscope 55 and a photodetector 56.

[0045] The transmittance of a perovskite film P is defined as the proportion of incident light of a specific wavelength that passes through the perovskite film P, and can be measured by known methods. For example, as shown in Figure 8, it can be measured by irradiating light (incident light) 61 from a light source 60 onto the perovskite film P and detecting transmitted light 62 that passes through the perovskite film with a photodetector 63.

[0046] In both steps S102 and S103, the perovskite film to be evaluated is irradiated with light having an energy greater than the band gap of the crystals constituting the perovskite film. Therefore, by irradiating the perovskite film with such light once, the peak intensity of the emission spectrum and the transmittance of the perovskite film can be simultaneously obtained. This enables the crystalline state of the perovskite film to be evaluated in a shorter time. In this case, the measurement apparatus shown in FIGS. 7 and 8 may be configured such that the light sources 50 and 60 are shared, the spectrometer 55 that receives photoluminescence light 54 is positioned on the opposite side of the perovskite film P from the substrate W, and the light receiver 63 that receives transmitted light 62 through the perovskite film P is positioned on the substrate W side.

[0047] (Evaluation of the in-plane distribution of the crystalline state of perovskite films) In the measurement device shown in Figure 7, the light source 50 is linked to the spectrometer 55 and the photodetector 56 and moved in the X-axis direction and the Y-axis direction relative to the perovskite film P as shown in Figure 9, so that the process of step S102 (acquisition of PL intensity) can be performed at multiple measurement positions M on the plane of the perovskite film P.

[0048] Similarly, in the measurement device shown in Figure 8, the light source 60 is moved in the X-axis direction and the Y-axis direction relative to the perovskite film P in conjunction with the light receiver 63, so that the process of step S103 (obtaining the transmittance) can be performed at multiple measurement positions M on the plane of the perovskite film P.

[0049] As a result, in the process of step S104, the in-plane distribution of the crystalline state of the perovskite film P can be evaluated based on a combination of the PL intensities and transmittances acquired at a plurality of measurement positions M.

[0050] 10 and 11 show examples of the in-plane distribution of PL intensity and the in-plane distribution of transmittance on the plane of a perovskite film P, respectively, obtained by this method. The magnitudes of PL intensity and transmittance at each measurement position M are displayed in different patterns. As shown in FIGS. 10 and 11, the PL intensity and transmittance each exhibit different in-plane distributions. In other words, the in-plane distributions of crystal size and crystal gaps do not necessarily match, and the conversion efficiency of a solar cell cannot be accurately predicted based on the PL intensity or transmittance alone. Therefore, in order to accurately predict the conversion efficiency of a solar cell, it is necessary to evaluate the crystalline state of the perovskite film P based on a combination of PL intensity and transmittance.

[0051] Figure 12 shows the in-plane distributions of PL intensity and transmittance shown in Figures 10 and 11 superimposed on each other, and each pattern shown in the figure represents the magnitude of the numerical value when the PL intensity and transmittance are combined in the table shown in Figure 13. The higher the PL intensity and the lower the transmittance, the higher the conversion efficiency.

[0052] (Example of a variation of the perovskite film evaluation method) FIG. 14 is a diagram showing the crystal states of the surface and cross section of the perovskite film in different crystal states (A) and (B).

[0053] As shown in Figure 14, the crystalline state (A) with small intercrystalline gaps has a lower surface flatness than the crystalline state (B) with large intercrystalline gaps. Therefore, the glossiness, which indicates the surface flatness, can be measured and used as an index instead of transmittance to evaluate the intercrystalline gaps of the perovskite film.

[0054] Fig. 15 is a flowchart showing a method for evaluating a perovskite film in this modified example. Note that detailed explanations of the content common to the method for evaluating a perovskite film shown in Fig. 6 of the above embodiment will be omitted.

[0055] First, a perovskite film to be evaluated is prepared (step S201).

[0056] Next, the perovskite film to be evaluated is irradiated with excitation light having an energy greater than the band gap of the crystals constituting the perovskite film, and the peak intensity (PL intensity) of the emission spectrum of photoluminescence emitted from the perovskite film is obtained (step S202). This PL intensity serves as an index for evaluating the crystal size of the perovskite film.

[0057] Separately from step S202, the perovskite film to be evaluated is irradiated with light to obtain the glossiness of the perovskite film surface (step S203). This glossiness serves as an index for evaluating the crystal gaps in the perovskite film.

[0058] The gloss level is measured by detecting reflected light from the perovskite film using a known method, but irradiating the perovskite film with light having an energy smaller than the band gap of the crystals that make up the perovskite film is undesirable because the light passes through the perovskite film. Therefore, it is preferable to irradiate the perovskite film with light having an energy larger than the band gap of the crystals that make up the perovskite film.

[0059] Note that light with energy greater than the band gap of the crystals that make up the perovskite film is partially absorbed and partially reflected by the perovskite film, but because gloss is calculated from the ratio of specularly reflected light to total reflected light, there is no problem as long as the ratio of specularly reflected light to total reflected light is calculated for light in the same wavelength range, regardless of absorption / reflection. Furthermore, when light with energy greater than the band gap of the crystals that make up the perovskite film is irradiated, photoluminescence light from the perovskite film will also be detected, but this is not a problem because the emission intensity of the photoluminescence light is negligible compared to the intensity of the reflected light.

[0060] Next, the crystalline state (crystal size and crystal gaps) of the perovskite film is evaluated (step S204) based on the combination of the PL intensity and glossiness obtained in steps S202 and S203. This allows the crystalline state of the perovskite film to be evaluated accurately in a short time by combining multiple optical evaluation methods.

[0061] The gloss of a perovskite film is defined as the ratio of reflected light from the perovskite film surface to reflected light from a reference surface, and can be measured, for example, as shown in Figure 16, by irradiating light (incident light) 71 from a light source 70 onto the surface of the perovskite film P at a specified angle of incidence, and detecting reflected light 72 reflected in the specular reflection direction with a photodetector 73.

[0062] In this modified example, the in-plane distribution of the crystalline state of the perovskite film can also be evaluated using a method similar to that shown in FIG. 9 of the above embodiment.

[0063] That is, in the measurement device shown in Figure 7, the light source 50 is linked to the spectrometer 55 and the photodetector 56 and moved in the X-axis direction and the Y-axis direction relative to the perovskite film P as shown in Figure 9, thereby performing the process of step S202 (acquisition of PL intensity) at multiple measurement positions M on the plane of the perovskite film P.

[0064] Similarly, in the measurement device shown in Figure 16, the light source 70 is moved in the X-axis direction and the Y-axis direction relative to the perovskite film P in conjunction with the light receiver 73, thereby performing the process of step S203 (obtaining the glossiness) at multiple measurement positions M on the plane of the perovskite film P.

[0065] As a result, in the process of step S204, the in-plane distribution of the crystalline state of the perovskite film P can be evaluated based on a combination of the PL intensity and glossiness acquired at multiple measurement positions M.

[0066] 17(A) and 17(B) are diagrams showing examples of the in-plane distribution of PL intensity and the in-plane distribution of glossiness, respectively, on the plane of a perovskite film P obtained by this method. The magnitude of PL intensity and glossiness at each measurement position M are displayed in different patterns.

[0067] Figure 17(C) shows the in-plane distributions of PL intensity and glossiness shown in Figures 17(A) and (B) superimposed on each other. Each pattern in the figure represents the magnitude of the numerical value when PL intensity and glossiness are combined. The higher the PL intensity and glossiness, the higher the conversion efficiency.

[0068] (Method for forming perovskite film) 18 is a flowchart showing a method for forming a perovskite film in this embodiment. Here, the perovskite film is used as a light absorption layer of a solar cell.

[0069] In the method for forming a perovskite film according to the present embodiment, the steps of applying a coating solution containing dissolved constituent elements of a perovskite crystal onto a substrate to form a coating film, and then drying the coating film to form a crystallized perovskite film on the substrate can be performed by a known method, for example, the method illustrated in FIGS. 1(A) to 1(C).

[0070] First, the coating conditions for forming a coating film on a substrate are set (step S301).

[0071] Next, a solution (coating liquid) in which perovskite crystals are dissolved is coated onto the substrate to form a coating film containing perovskite (step S301).

[0072] Next, the drying conditions for the coating film formed on the substrate are set (step S303).

[0073] Next, the coating film is dried to form a crystallized perovskite film on the substrate (step S305). Note that the drying of the coating film can be performed by blowing dry air, drying under reduced pressure, drying by heating, or the like, and these can be combined as appropriate.

[0074] Next, the crystalline state of the perovskite film is evaluated using the perovskite film evaluation method described in the above embodiment (step S305). Here, the evaluation of the crystalline state of the perovskite film is performed based on a combination of peak intensity and transmittance, or peak intensity and glossiness.

[0075] Next, based on the evaluation results of the crystalline state of the perovskite film, the quality of the crystalline state is judged, and it is determined whether or not the coating conditions of the coating liquid and / or the drying conditions of the coated film need to be adjusted (step S306). If it is determined that adjustment is necessary, the settings of the coating conditions and / or drying conditions are changed in step S301 and / or step S303, and the coating step in step S303 and the drying step in step S305 are performed to form a perovskite film on the substrate.

[0076] According to the method for forming a perovskite film of this embodiment, the crystalline state of the perovskite film formed continuously in the solar cell manufacturing process can be evaluated in-line, and the perovskite film formation conditions (coating conditions and / or drying conditions) can be adjusted according to the evaluation results so as to improve the crystalline state of the perovskite film, thereby making it possible to efficiently manufacture solar cells with high conversion efficiency and stable quality.

[0077] In addition, in the perovskite film evaluation method shown in Figure 6, the process of step S102 (acquiring PL intensity) and the process of step S103 (acquiring transmittance) can be performed at multiple measurement positions M on the plane of the perovskite film, as shown in Figure 9, and the application conditions of the coating liquid and / or the drying conditions of the coated film can be adjusted based on the in-plane distribution of the crystalline state of the perovskite film so that the PL intensity at the multiple measurement positions M is equal to or greater than a predetermined value and the transmittance is equal to or less than a predetermined value.

[0078] Similarly, in the perovskite film evaluation method shown in Figure 15, the process of step S202 (acquiring PL intensity) and the process of step S203 (acquiring glossiness) are performed at multiple measurement positions M on the plane of the perovskite film, as shown in Figure 9, and the application conditions of the coating liquid and / or the drying conditions of the coated film can be adjusted based on the in-plane distribution of the crystalline state of the perovskite film so that the PL intensity and glossiness at the multiple measurement positions M are equal to or greater than a predetermined value.

[0079] For example, Figure 19 shows the in-plane distributions of PL intensity and transmittance when a perovskite film is formed under initially set drying conditions (A), and when a perovskite film is formed by adjusting the drying conditions based on this in-plane distribution so that the PL intensity is above a predetermined value and the transmittance is below a predetermined value (without changing the coating conditions) (B). As shown in Figure 19, it can be seen that the crystalline state of the perovskite film is improved by adjusting the drying conditions.

[0080] (Perovskite film formation device) 20 is a block diagram showing a perovskite film forming apparatus according to this embodiment, in which the perovskite film is used as a light absorbing layer in a solar cell.

[0081] The perovskite film forming apparatus 80 in this embodiment includes a coating unit 81 that applies a solution (coating liquid) in which the constituent elements of perovskite crystals are dissolved onto a substrate to form a coating film containing perovskite, a drying unit 82 that dries the coating film to form a crystallized perovskite film on the substrate, and an evaluation unit 83 that evaluates the crystalline state of the perovskite film.

[0082] The evaluation unit 83 adjusts the application conditions of the application liquid in the application unit 81 and / or the drying conditions of the applied film in the drying unit 82 based on the crystalline state of the perovskite film evaluated by the perovskite film evaluation method in the above embodiment.

[0083] According to the perovskite film forming apparatus of this embodiment, the crystalline state of the perovskite film formed continuously in the solar cell manufacturing process can be evaluated in-line, and the perovskite film forming conditions (coating conditions and / or drying conditions) can be adjusted according to the evaluation results so as to improve the crystalline state of the perovskite film, thereby making it possible to efficiently manufacture solar cells with high conversion efficiency and stable quality.

[0084] In the perovskite film evaluation method shown in Figure 6, the evaluation unit 83 performs the process of step S102 (acquiring PL intensity) and the process of step S103 (acquiring transmittance) at multiple measurement positions M on the plane of the perovskite film, as shown in Figure 9, and can adjust the application conditions of the coating liquid and / or the drying conditions of the coated film based on the in-plane distribution of the crystalline state of the perovskite film so that the PL intensity at the multiple measurement positions M is equal to or greater than a predetermined value and the transmittance is equal to or less than a predetermined value.

[0085] Similarly, in the perovskite film evaluation method shown in Figure 15, the evaluation unit 83 performs the process of step S202 (acquiring PL intensity) and the process of step S203 (acquiring glossiness) at multiple measurement positions M on the plane of the perovskite film, as shown in Figure 9, and can adjust the application conditions of the coating liquid and / or the drying conditions of the coated film based on the in-plane distribution of the crystalline state of the perovskite film so that the PL intensity and glossiness at the multiple measurement positions M are equal to or greater than predetermined values.

[0086] Although the present invention has been described above with reference to preferred embodiments, such description is not intended to be limiting and various modifications are possible. [Explanation of symbols]

[0087] 10 stages 11 Slit nozzle 12 Manifold 13 Slit 14 Outlet 20 Air Knife 21 Dry Air 31 Decompression Chamber 32 Pressure reduction means 41 Heating Chamber 42 Heater 50, 60, 70 light sources 51 Excitation light 52 Beam Splitter 53 Objective Lens 54 Photoluminescence light 55 Spectrometer 56 Photodetector 61, 71 incident light 62 Transmitted light 63, 73 Receiver 72 Reflected light 80 Perovskite film formation device 81 Application part 82 Drying section 83 Evaluation Department

Claims

1. A method for evaluating a perovskite film used in a light absorption layer of a solar cell, comprising: a step (A) of irradiating the perovskite film to be evaluated with excitation light having an energy greater than the band gap of the crystals constituting the perovskite film, and acquiring the peak intensity of the emission spectrum of photoluminescence emitted from the perovskite film; a step (B) of irradiating the perovskite film to be evaluated with light having energy greater than the band gap of the crystals constituting the perovskite film, and acquiring the transmittance of the perovskite film; a step (C) of evaluating the crystalline state of the perovskite film based on a combination of the peak intensity and the transmittance obtained in the step (A) and the step (B); A method for evaluating a perovskite film.

2. 2. The method for evaluating a perovskite film according to claim 1, wherein the steps (A) and (B) involve irradiating the perovskite film to be evaluated with light having energy greater than the band gap of crystals constituting the perovskite film, thereby simultaneously obtaining the peak intensity of the emission spectrum and the transmittance of the perovskite film.

3. the steps (A) and (B) are performed at a plurality of measurement positions in a plane of the perovskite film; 2. The method for evaluating a perovskite film according to claim 1, wherein step (C) evaluates an in-plane distribution of a crystalline state of the perovskite film based on a combination of the peak intensity and the transmittance obtained at each measurement position.

4. A method for evaluating a perovskite film used in a light absorption layer of a solar cell, comprising: a step (A) of irradiating the perovskite film to be evaluated with excitation light having an energy greater than the band gap of the crystals constituting the perovskite film, and acquiring the peak intensity of the emission spectrum of photoluminescence emitted from the perovskite film; (B) a step of irradiating the perovskite film to be evaluated with light and detecting the light reflected from the perovskite film to obtain the gloss of the perovskite film; a step (C) of evaluating the crystalline state of the perovskite film based on a combination of the peak intensity and the glossiness obtained in the step (A) and the step (B); A method for evaluating a perovskite film.

5. the steps (A) and (B) are performed at a plurality of measurement positions in a plane of the perovskite film; 5. The method for evaluating a perovskite film according to claim 4, wherein step (C) evaluates an in-plane distribution of the crystalline state of the perovskite film based on a combination of the peak intensity and the glossiness obtained at each measurement position.

6. A method for forming a perovskite film used in a light absorption layer of a solar cell, comprising: A step of applying a solution in which perovskite crystals are dissolved onto a substrate to form a coating film containing perovskite; and drying the coating film to form a crystallized perovskite film on the substrate, 5. A method for forming a perovskite film according to claim 1 or claim 4, wherein the coating conditions of the solution and / or the drying conditions of the coated film are adjusted based on the crystalline state of the perovskite film evaluated in step (C).

7. 7. The method for forming a perovskite film according to claim 6, wherein steps (A) and (B) are performed at a plurality of measurement positions on a plane of the perovskite film, and the coating conditions of the solution and / or the drying conditions of the coated film are adjusted based on the in-plane distribution of the crystalline state of the perovskite film evaluated in step (C) so that the peak intensity of the emission spectrum at the plurality of measurement positions is equal to or greater than a predetermined value and the transmittance of the perovskite film is equal to or less than a predetermined value.

8. 7. The method for forming a perovskite film according to claim 6, wherein steps (A) and (B) are performed at a plurality of measurement positions on a plane of the perovskite film, and the application conditions of the solution and / or the drying conditions of the coated film are adjusted based on the in-plane distribution of the crystalline state of the perovskite film evaluated in step (C) so that the peak intensity of the emission spectrum and the gloss of the perovskite film at the plurality of measurement positions are each equal to or greater than a predetermined value.

9. An apparatus for forming a perovskite film used in a light absorption layer of a solar cell, comprising: a coating unit that coats a substrate with a solution containing dissolved constituent elements of a perovskite crystal to form a coating film containing perovskite; a drying section that dries the coating film to form a crystallized perovskite film on the substrate; an evaluation unit that evaluates the crystalline state of the perovskite film; Equipped with 5. The perovskite film forming apparatus according to claim 1, wherein the evaluation unit adjusts the application conditions of the solution in the application unit and / or the drying conditions of the coated film in the drying unit based on the crystalline state of the perovskite film evaluated in step (C).

10. 10. The perovskite film forming apparatus according to claim 9, wherein in the evaluation method according to claim 1, steps (A) and (B) are performed at a plurality of measurement positions on a plane of the perovskite film, and the evaluation unit adjusts the application conditions of the solution and / or the drying conditions of the coated film based on the in-plane distribution of the crystalline state of the perovskite film evaluated in step (C) so that the peak intensity of the emission spectrum at the plurality of measurement positions is equal to or greater than a predetermined value and the transmittance of the perovskite film is equal to or less than a predetermined value.

11. 10. The perovskite film forming apparatus according to claim 9, wherein in the evaluation method according to claim 4, steps (A) and (B) are performed at a plurality of measurement positions on a plane of the perovskite film, and the evaluation unit adjusts the application conditions of the solution and / or the drying conditions of the coated film based on the in-plane distribution of the crystalline state of the perovskite film evaluated in step (C) so that the peak intensity of the emission spectrum and the gloss of the perovskite film at the plurality of measurement positions are each equal to or greater than a predetermined value.

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