Perovskite film forming apparatus and perovskite film forming method

Abstract

A perovskite film forming apparatus 10 according to an embodiment forms a perovskite film by crystallizing a perovskite precursor on a base material 1 which is coated with a solution that contains the perovskite precursor and a solvent. The perovskite film forming apparatus 10 is characterized by comprising, as areas where the base material 1 passes: a solvent removal chamber 14 which is an area where the solvent is removed from the solution applied to the base material 1 without crystallizing the perovskite precursor; and a crystallization chamber 15 which is an area where the perovskite precursor is crystallized on the base material 1 after passing through the solvent removal chamber 14 so as to form a perovskite film.

Description

Perovskite film forming apparatus and perovskite film forming method

[0001] The present invention relates to a perovskite film forming apparatus and a perovskite film forming method.

[0002] In recent years, perovskite solar cells have attracted attention as a promising thin, lightweight, and highly efficient solar cell. Perovskite solar cells generate electricity by absorbing sunlight in a perovskite film and generating free electrons and holes.

[0003] In the method for manufacturing a perovskite film, a solution is first applied to a substrate. This application method is a so-called spin coating method, in which a solution containing a perovskite precursor and a solvent is ejected onto the substrate and the substrate is rotated to spread the solution over the substrate. The substrate to which the solution has been applied is then heated on a hot plate to remove the solvent and crystallize the perovskite precursor to form a perovskite film.

[0004] Furthermore, as described in Patent Document 1, it has also been proposed to apply a solution from a moving nozzle to a substrate, place the substrate after application in a reduced pressure environment to volatilize the solvent and promote crystallization of the perovskite precursor into perovskite (i.e., perovskite formation), and then place the substrate in a heated environment to further promote perovskite formation.

[0005] JP 2024-14770 A

[0006] However, in each of the above methods, the evaporation of the solvent and the formation of the perovskite film occur simultaneously. This leads to non-uniform crystallinity, which reduces power generation efficiency, and the formation of defects (voids) that cause short circuits. The current difficulty in forming high-quality perovskite films is hindering the widespread use of perovskite solar cells.

[0007] Other attempts have been made to improve the quality of perovskite films by modifying the solution, such as adding an ionic liquid to a solution containing a perovskite precursor, or the antisolvent method, in which a poor solvent is dropped onto the solution on the substrate during spin coating. However, these methods were only used in university experiments or at the research and development stage in companies, and were not suitable for mass-producing perovskite films, which is necessary for the widespread use of perovskite solar cells.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide an apparatus and method capable of mass-producing high-quality perovskite films.

[0009] A perovskite film formation apparatus according to an embodiment is an apparatus for forming a perovskite film on a substrate to which a solution containing a perovskite precursor and a solvent has been applied, by crystallizing the perovskite precursor, characterized in that the apparatus includes: a solvent removal chamber, through which the continuously transported substrate passes, in which the solution on the substrate is heated to a temperature at which the solvent evaporates but the perovskite precursor does not crystallize, thereby removing the solvent from the solution applied to the substrate without crystallizing the perovskite precursor; and a crystallization chamber, in which the perovskite precursor is heated to a crystallization temperature or higher on the substrate from which the solvent has been removed after passing through the solvent removal chamber, thereby crystallizing the perovskite precursor to form the perovskite film.

[0010] Furthermore, a perovskite film formation method according to an embodiment includes a step of forming a perovskite film on a substrate to which a solution containing a perovskite precursor and a solvent has been applied, by crystallizing the perovskite precursor to form a perovskite film, the step comprising: heating the solution on the substrate to a temperature at which the solvent evaporates but the perovskite precursor does not crystallize, thereby removing the solvent from the solution applied to the substrate without crystallizing the perovskite precursor; and, after the step of removing the solvent, heating the perovskite precursor on the substrate from which the solvent has been removed to a temperature equal to or higher than its crystallization temperature, thereby crystallizing the perovskite precursor to form the perovskite film.

[0011] According to the perovskite film forming apparatus, a high-quality perovskite film can be formed and mass-produced by passing a substrate through a solvent removal chamber and a crystallization chamber in that order. Also, according to the perovskite film forming method, a high-quality perovskite film can be formed and mass-produced by crystallizing a perovskite precursor after removing the solvent from a solution applied to a substrate.

[0012] 1 is a side view of a perovskite film-forming apparatus, a side view of a substrate to which a solution has been applied, a side view of a solvent removal chamber, a side view of a crystallization chamber, and a block diagram of a perovskite film-forming apparatus.

[0013] A perovskite film forming apparatus 10 according to one embodiment of the present invention will be described with reference to Figures 1 to 5. In the following description, the side in the direction of travel of the elongated substrate 1 will be referred to as the front, and the opposite side will be referred to as the rear. Furthermore, left and right refer to the left and right when viewed from the front to the rear.

[0014] (1) Overall Configuration of Perovskite Film Forming Apparatus 10 As shown in FIG. 1, the perovskite film forming apparatus 10 is configured with a coating chamber 13, a solvent removal chamber 14, a crystallization chamber 15, and an annealing chamber 16 lined up from rear to front. A first pressure adjustment chamber 17 is provided between the coating chamber 13 and the solvent removal chamber 14, a second pressure adjustment chamber 18 is provided between the solvent removal chamber 14 and the crystallization chamber 15, and a third pressure adjustment chamber 19 is provided between the crystallization chamber 15 and the annealing chamber 16. Each of the pressure adjustment chambers 17, 18, and 19 is separated from the adjacent areas on both sides by partition walls 29 (see FIGS. 3 and 4 ), each having an opening through which the substrate 1 can pass. The perovskite film forming apparatus 10 also includes an unwinding unit 11 and a surface treatment unit 12.

[0015] (2) Configuration of the Unwinding Section 11 and the Surface Treatment Section 12 The unwinding section 11 is provided with a winding shaft 20. The substrate 1 before being coated with a solution is wound around the winding shaft 20. The winding shaft 20 is rotated by the drive of a motor to unwind the substrate 1. Before being coated with a solution, the substrate 1 is formed by laminating a transparent conductive film and an electron transport layer on a transparent film such as a polyethylene terephthalate film. The width of the substrate 1 is, for example, 200 mm to 1000 mm.

[0016] The surface treatment section 12 is a section that performs surface treatment on the substrate 1 transported from the unwinding section 11. The surface treatment is a treatment that improves the wettability of the electron transport layer of the substrate 1, and is, for example, any one of corona treatment, plasma treatment, UV treatment, etc. The surface treatment section 12 also removes dust from the substrate 1.

[0017] (3) Configuration of Coating Chamber 13 The coating chamber 13 is provided with a die 21 and a backup roller 22 in front of the die 21. The backup roller 22 is one of the rollers that transport the substrate 1, and is rotated by being driven by a motor. The rotation axis of the backup roller 22 extends in the left-right direction. The substrate 1 transported from the surface treatment section 12, which is located below the backup roller 22, changes its transport direction at the backup roller 22 and is transported forward. In the vicinity of the die 21, the backup roller 22 transports the substrate 1 from bottom to top.

[0018] The die 21 ejects the solution toward the substrate 1 in contact with the backup roller 22, and applies the solution to a predetermined coating thickness across the entire width (left-right) of the substrate 1. The surface of the substrate 1 to which the solution is applied is the upper surface in the solvent removal chamber 14 and the crystallization chamber 15.

[0019] For reference, Fig. 2 shows the state in which the solution is applied to the substrate 1 to form a solution layer 2. Fig. 2 is a diagram showing the substrate 1 immediately after it enters the solvent removal chamber 14. In this specification, the substrate 1 after the solution has been applied may also be simply referred to as "substrate 1."

[0020] The solution contains a perovskite precursor and a solvent. The perovskite precursor is a material in a stage before it crystallizes to become a perovskite. For example, methylammonium lead iodide CH ３ NH ３ PbI ３ When it is desired to produce the perovskite precursor, lead iodide (PbI) is used. ２ and methylammonium iodide CH ３ NH ３ I is used. The solvent absorbs infrared light at a specific wavelength, for example, infrared light with a wavelength of 10 μm or less. The solvent and the perovskite precursor absorb different infrared wavelengths. Different infrared absorption wavelengths means different infrared absorption spectra. Specific examples of solvents include N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0021] (4) Structure of the Solvent Removal Chamber 14 The solvent removal chamber 14 is shown in Figure 3. The solvent removal chamber 14 has a rectangular parallelepiped exterior shape, is thermally insulated, and is isolated from other areas. The solvent removal chamber 14 also has an inlet for the substrate 1 at the rear and an outlet for the substrate 1 at the front. In the solvent removal chamber 14, multiple transport rollers 30 are lined up in the front-to-rear direction. Each transport roller 30 is rotated by a motor. The rotation axis of each transport roller 30 extends in the left-to-right direction. These transport rollers 30 transport the substrate 1 placed thereon. The transport rollers 30 also have the role of keeping the substrate 1 horizontal to prevent the applied solution from flowing.

[0022] A roller cooling device 33 (see FIG. 5) is provided to cool at least the outer circumferential surfaces of the plurality of conveying rollers 30. Although not shown, the roller cooling device 33 includes fluid flow paths formed inside the conveying rollers 30 and a circulation device for circulating a fluid (e.g., water or air) through the flow paths. Alternatively, the roller cooling device 33 includes Peltier elements provided on each of the conveying rollers 30 and a power source for supplying electricity to the Peltier elements.

[0023] The roller cooling device 33 cools the transport rollers 30, thereby cooling the substrate 1 (see FIG. 2) placed on the transport rollers 30 from below. As will be described below, in the solvent removal chamber 14, the solvent evaporates from the solution layer 2 on the substrate 1, and in this process, latent heat of evaporation is removed from the surface (upper surface) of the solution layer 2. The cooling capacity of the roller cooling device 33 is set so that the cooled transport rollers 30 can remove from the substrate 1 an amount of heat equal to the amount of latent heat removed at this time.

[0024] One infrared irradiation device 31 is provided in the solvent removal chamber 14 above the conveying rollers 30. The infrared irradiation device 31 is a device that irradiates infrared rays of a wavelength that is absorbed by the solvent but not easily absorbed by the perovskite precursor. When a solvent that absorbs infrared rays with wavelengths of 10 μm or less is used, the infrared irradiation device 31 that irradiates infrared rays with wavelengths of 10 μm or less is used. Such an infrared irradiation device 31 that irradiates infrared rays in a specific wavelength range is realized by combining a device that irradiates infrared rays in a wider wavelength range with a filter that passes only infrared rays in a specific wavelength range (for example, a low-pass filter that passes only infrared rays with wavelengths of 10 μm or less).

[0025] The infrared irradiation device 31 is sufficiently large in both the front-rear and left-right directions (for example, formed in a planar shape) and is capable of irradiating infrared rays over a wide range in the front-rear direction and the entire left-right direction (width direction) of the substrate 1. The left-right length of the infrared irradiation device 31 is preferably long enough to allow the substrate 1 to be uniformly irradiated with infrared rays, and is preferably longer than the left-right length of the substrate 1, for example, and is further preferably longer than the left-right length of the conveying roller 30.

[0026] 3, the infrared rays from the infrared irradiation device 31 are irradiated onto the substrate 1, evaporating the solvent in the solution by radiation. By irradiating the infrared rays, the temperature of the solution becomes higher than the ambient temperature in the solvent removal chamber 14 (for example, to about 70°C), but does not rise to a temperature at which the perovskite precursor crystallizes (for example, to about 100°C).

[0027] The ambient temperature in the solvent removal chamber 14 is set to a temperature, for example, 30°C to 50°C, which is sufficiently lower than the temperature at which the perovskite precursor crystallizes to form perovskite.

[0028] In addition, a straightening device is provided in a position above the transport rollers 30 in the solvent removal chamber 14. The straightening device consists of an air blower 32a that blows air and an air suction device 32b that sucks in air. The air blower 32a is provided in a position above and behind the transport rollers 30 in the solvent removal chamber 14, and blows air forward and horizontally. The air suction device 32b is provided in a position forward and at the same height as the air blower 32a in the solvent removal chamber 14, and sucks in air blown from behind.

[0029] With this arrangement of the blower 32a and the suction device 32b, air is sent from the blower 32a to the suction device 32b, as shown by the solid arrow in Figure 3. Therefore, air flows over the substrate 1 on the transport roller 30 in the same direction as the transport direction of the substrate 1. The speed of the air flow is controlled to be the same as the transport speed of the substrate 1. The temperature of the air sent from the blower 32a is the same as the temperature of the air in the solvent removal chamber 14, for example, 30°C to 50°C.

[0030] (5) Structure of the Crystallization Chamber 15 The crystallization chamber 15 is shown in Figure 4. The crystallization chamber 15 has a rectangular parallelepiped exterior shape, is thermally insulated, and is isolated from other areas. The crystallization chamber 15 also has an entrance for the substrate 1 at the rear and an exit for the substrate 1 at the front. In the crystallization chamber 15, multiple transport rollers 40 are aligned in the front-to-rear direction. Each transport roller 40 is rotated by a motor. The rotation axis of each transport roller 40 extends in the left-to-right direction. These transport rollers 40 transport the substrate 1 placed thereon.

[0031] In the crystallization chamber 15, a plurality of nozzles 41 are arranged in the front-to-rear direction above the transport rollers 40. These nozzles 41 blow hot air onto the substrate 1 transported by the transport rollers 40, heating it to a temperature (e.g., around 100°C) or higher at which the perovskite precursor crystallizes, thereby causing crystallization. The interior of each nozzle 41 is a hot air flow path extending in the vertical direction. A front outlet 41a and a rear outlet 41b are formed at the bottom of each nozzle 41. The front outlet 41a is an outlet that blows the hot air inside the nozzle 41 obliquely forward and downward. The rear outlet 41b is an outlet that blows the hot air inside the nozzle 41 obliquely backward and downward.

[0032] In addition, suction ports 42 for sucking in hot air from within the crystallization chamber 15 are provided above the conveying rollers 40. The suction ports 42 and the nozzles 41 are arranged alternately in the front-to-rear direction, with the suction ports 42 disposed between adjacent nozzles 41. The suction ports 42 are located higher than the front outlets 41a and rear outlets 41b of the nozzles 41. With this structure, the hot air blown obliquely downward from the front outlets 41a and rear outlets 41b of the nozzles 41 rises in a relatively short time and is sucked into the suction ports 42. The flow of the hot air is shown by arrows in Figure 4. This flow of the hot air makes it less likely for the hot air to leak out of the crystallization chamber 15.

[0033] All of the nozzles 41 and all of the suction ports 42 are provided on the ceiling, not on the side surfaces, of the crystallization chamber 15. Therefore, in the crystallization chamber 15, hot air flows in the left-right direction are unlikely to occur, and temperature changes in the left-right direction are unlikely to occur.

[0034] Furthermore, the widths (left-right lengths) of the front outlet 41a, rear outlet 41b, and suction port 42 are each approximately the same as the left-right length of the transport roller 40, and are, for example, 100% to 120% of the left-right length of the transport roller 40. This makes it easy to heat the entire crystallization chamber 15 in the width direction (left-right direction). Note that the structure of the nozzle 41 is not limited to this structure, and any structure that can heat the substrate 1 evenly may be used.

[0035] The crystallization chamber 15 is maintained at a substantially uniform temperature throughout. The ambient temperature in the crystallization chamber 15 is the temperature at which the perovskite precursor crystallizes, for example, around 100°C.

[0036] An exhaust chamber 43 communicating with the suction port 42 is provided above the crystallization chamber 15. An air supply chamber 44 is also provided surrounded by the exhaust chamber 43, and air supply paths 45 are provided from the air supply chamber 44 to each of the nozzles 41. Air taken in from outside the perovskite film formation apparatus 10 is heated by a heater (not shown), and passes through the air supply chamber 44, the air supply path 45, and the nozzles 41 before being blown into the crystallization chamber 15. The air taken in through the suction port 42 passes through the exhaust chamber 43 and is discharged to the outside of the perovskite film formation apparatus 10.

[0037] (6) Configuration of Annealing Chamber 16 As shown in FIG. 1, the annealing chamber 16 is provided with an air intake port 51 that supplies hot air heated by a heater into the annealing chamber 16, and an exhaust port 52 that exhausts the air inside the annealing chamber 16 to the outside. The hot air supplied from the air intake port 51 maintains the ambient temperature of the annealing chamber 16 at a temperature lower than the temperature of the crystallization chamber 15 and higher than room temperature. Room temperature refers to the ambient temperature of the perovskite film formation apparatus 10 when the perovskite film formation apparatus 10 is in operation.

[0038] The annealing chamber 16 is also provided with a dehumidifier (not shown). The dehumidifier controls the humidity in the annealing chamber 16 to, for example, 30% or less. It is preferable that dehumidifiers are also provided in the coating chamber 13, the solvent removal chamber 14, and the crystallization chamber 15, and that the humidity in each chamber is controlled to, for example, 30% or less.

[0039] The annealing chamber 16 also serves as a take-up section that takes up the perovskite film laminate 3 in which a perovskite film is formed on the substrate 1. A take-up shaft 50 is disposed in the take-up section. The take-up shaft 50 is rotated by being driven by a motor, and takes up the perovskite film laminate 3.

[0040] (7) Configuration of Pressure Adjustment Chambers 17, 18, 19 The second pressure adjustment chamber 18 located between the solvent removal chamber 14 and the crystallization chamber 15 will now be described. As shown in Fig. 4, the second pressure adjustment chamber 18 is provided with an air inlet 23 and an exhaust port 24. Dampers 23a and 24a (see Fig. 5) are provided in the ducts leading to the air inlet 23 and the exhaust port 24, respectively, and the amount of air supplied from the air inlet 23 and the amount of air exhausted from the exhaust port 24 can be controlled by controlling the dampers 23a and 24a. A fan may be provided in the duct.

[0041] The solvent removal chamber 14 and the crystallization chamber 15, which are adjacent to the second pressure adjustment chamber 18, are provided with air pressure sensors 25a and 25b (see FIG. 5) for measuring air pressure, respectively.

[0042] The control unit 60, which will be described next, constantly monitors the difference in air pressure between the solvent removal chamber 14 and the crystallization chamber 15, measured by the air pressure sensors 25 a and 25 b. When a difference in air pressure occurs between these two zones (i.e., the solvent removal chamber 14 and the crystallization chamber 15) or when the difference in air pressure between these two zones exceeds a predetermined value, the control unit 60 controls the dampers 23 a and 24 a to supply or exhaust air to or from the second pressure adjustment chamber 18, thereby substantially eliminating the difference in air pressure between these two zones. For example, when the control unit 60 supplies air to the second pressure adjustment chamber 18, air supplied to the second pressure adjustment chamber 18 from the outside flows into the zone with the lower air pressure, thereby substantially eliminating the difference in air pressure between the two zones. When the control unit 60 exhausts air from the second pressure adjustment chamber 18, air from the zone with the higher air pressure passes through the second pressure adjustment chamber 18 and is exhausted to the outside, thereby substantially eliminating the difference in air pressure between the two zones.

[0043] Since the difference in air pressure between the solvent removal chamber 14 and the crystallization chamber 15 is almost eliminated, there is almost no air flow between the solvent removal chamber 14 and the crystallization chamber 15, and conditions such as temperature are maintained in each of the solvent removal chamber 14 and the crystallization chamber 15.

[0044] The first pressure adjustment chamber 17 and the third pressure adjustment chamber 19 have the same structure as the second pressure adjustment chamber 18, and are controlled in the same manner as the second pressure adjustment chamber 18. This makes it difficult for air to flow between the areas on either side of the pressure adjustment chambers 17 and 19, and conditions such as temperature are maintained in those areas.

[0045] (8) Electrical Configuration of Perovskite Film Forming Apparatus 10 The perovskite film forming apparatus 10 is equipped with a control unit 60 consisting of a computer. As shown in Fig. 5, the control unit 60 is connected to the infrared irradiation device 31, roller cooling device 33, air blower 32a, air intake device 32b, dampers 23a and 24a, and air pressure sensors 25a and 25b. Although not shown, the control unit 60 is also connected to the motors that rotate the various rollers, heaters that heat the air, and the like. The control unit 60 controls the connected devices.

[0046] (9) Perovskite Film Formation Method In this embodiment, one long substrate 1 is unwound from a take-up shaft 20 at an unwinding section 11, and is wound around a take-up shaft 50 in an annealing chamber 16. As a result, the substrate 1 is continuously transported through the coating chamber 13, first pressure adjustment chamber 17, solvent removal chamber 14, second pressure adjustment chamber 18, crystallization chamber 15, third pressure adjustment chamber 19, and annealing chamber 16 in this order. The transport speed of the substrate 1 from the unwinding section 11 to the annealing chamber 16 is adjusted as appropriate, and is, for example, 5 to 20 m / min.

[0047] In the coating chamber 13, the solution is ejected from the die 21 toward the substrate 1 which is in contact with the backup roller 22, and the solution is coated on the surface of the substrate 1 on the electron transport layer side (the surface opposite to the film side).

[0048] In the solvent removal chamber 14, the substrate 1 is transported over a plurality of transport rollers 30. In the solvent removal chamber 14, the substrate 1 is placed with the surface coated with the solution facing up. Thereafter, the substrate 1 is transported horizontally with the surface coated with the solution facing up until just before it is taken up around the take-up shaft 50 in the annealing chamber 16.

[0049] As the substrate 1 is transported through the solvent removal chamber 14, an infrared irradiation device 31 above irradiates it with infrared rays of a wavelength that is absorbed by the solvent but not easily absorbed by the perovskite precursor. This causes the solvent in the solution to evaporate through radiation and be removed from the substrate 1. Note that, as a result of the infrared irradiation, the temperature of the solution rises to a temperature at which the solvent evaporates (for example, around 70°C), but does not rise to a temperature at which the perovskite precursor crystallizes (for example, around 100°C). Therefore, perovskite is not produced in the solvent removal chamber 14.

[0050] When the solvent evaporates, the latent heat of evaporation is taken from the solution, causing a drop in the temperature of the surface (upper surface) of the solution layer 2. If the temperature of the substrate 1 side remains high despite a drop in the surface temperature of the solution layer 2, convection will occur in the solution, causing Bénard cells to form. When the perovskite precursor crystallizes in a state where Bénard cells have formed, the boundaries of the cells become grain boundaries, which are prone to cracking. The term "Bénard cells" refers to a regularly separated cellular convection structure that occurs when a thin layer of fluid is heated uniformly from below.

[0051] However, in the solvent removal chamber 14 of the present embodiment, the conveying rollers 30 are cooled by the roller cooling device 33, and the substrate 1 is cooled from the underside by the conveying rollers 30. As a result, the surface temperature of the solution layer 2 and the temperature on the substrate 1 side become approximately equal, and convection is less likely to occur in the solution.

[0052] Additionally, above the substrate 1 being transported through the solvent removal chamber 14, a rectifying device blows air in the same direction as the transport direction of the substrate 1, at a speed controlled to be the same as the transport speed of the substrate 1. This makes it difficult for air convection to occur above the solution layer 2 on the substrate 1, and prevents the formation of irregularities as wind ripples in the solution layer 2. Another advantage is that the evaporated solvent is carried by the air from the blower 32a and sucked into the air suction device 32b, and then discharged to the outside of the solvent removal chamber 14.

[0053] In the crystallization chamber 15, the substrate 1 from which the solvent has been removed is transported over a plurality of transport rollers 40. During this transport, the perovskite precursor is heated and crystallized on the substrate 1 by hot air from the nozzles 41, forming a perovskite film. Since the substrate 1 from which the solvent has been removed is transported, evaporation of the solvent and perovskite formation do not proceed simultaneously, resulting in a uniform crystalline state and less formation of defects (voids) that could cause short circuits. Furthermore, because convection is less likely to occur in the solution on the substrate 1 as described above and the entire crystallization chamber 15 has a substantially uniform temperature, a perovskite film of uniform quality is formed over the entire substrate 1.

[0054] In the annealing chamber 16, the perovskite film laminate 3, in which a perovskite film is formed on the substrate 1, is taken up around the take-up shaft 50 and finally formed into a large roll. The perovskite film is heated from the time the perovskite film laminate 3 enters the annealing chamber 16 until the time the rolled perovskite film laminate 3 is removed from the annealing chamber 16. Heating in the annealing chamber 16 relieves stress in the perovskite film. Note that the annealing chamber 16 has a lower temperature than the crystallization chamber 15, so the perovskite film laminate 3 is not rapidly cooled when removed from the annealing chamber 16, and cracks are less likely to occur in the perovskite film.

[0055] The perovskite film laminate 3 removed from the annealing chamber 16 is carried to another device, where a hole transport layer and an electrode are laminated on the perovskite film in the perovskite film laminate 3 to form a perovskite solar cell.

[0056] (10) Effects The perovskite film forming apparatus 10 of this embodiment includes a solvent removal chamber 14, which is a zone in which the solvent is removed from the solution applied to the substrate 1 without crystallizing the perovskite precursor, and a crystallization chamber 15, which is a zone in which the perovskite precursor is crystallized on the substrate 1 after passing through the solvent removal chamber 14 to form a perovskite film. This prevents the removal of the solvent and the crystallization of the perovskite from proceeding simultaneously, making it possible to form a high-quality perovskite film with a uniform crystal structure and few defects. Furthermore, because the perovskite film can be formed by passing the substrate 1 through the solvent removal chamber 14 and the crystallization chamber 15 in sequence, perovskite films can be continuously manufactured, enabling mass production.

[0057] The high quality of the perovskite film as described above allows perovskite solar cells to have high power generation efficiency and good durability. Furthermore, the ability to form high-quality perovskite films improves yields during mass production. These factors are expected to lead to the widespread use of perovskite solar cells, reducing the use of fossil fuels for power generation and the associated carbon dioxide emissions.

[0058] The perovskite film forming apparatus 10 is also provided with an unwinding section 11 that unwinds the substrate 1 before the solution is applied thereto, and a winding section (annealing chamber 16) that winds up the perovskite film laminate 3 in which a perovskite film has been formed on the substrate 1. Between the unwinding section 11 and the winding section, a coating chamber 13, a solvent removal chamber 14, and a crystallization chamber 15 are provided. As a result, a single long substrate 1 is unwound from the unwinding section 11 on one side and wound up in the winding section on the other side. During the transport of the substrate 1 from the unwinding section 11 to the winding section as described above, the solution can be applied to the substrate 1, the solvent can be removed from the solution, and the perovskite precursor can be crystallized. This allows for more efficient mass production of the perovskite film laminate 3.

[0059] The solvent removal chamber 14 is also provided with an infrared irradiator 31 that irradiates the solution with infrared light of a wavelength that is absorbed by the solvent but not easily absorbed by the perovskite precursor. The infrared irradiator 31 irradiates the solution with infrared light. This allows the solvent to evaporate, but the solution is heated to a temperature at which the perovskite precursor does not crystallize, thereby removing the solvent. This allows the solvent to be removed from the solution without raising the temperature of the perovskite precursor to a temperature at which it crystallizes, preventing solvent removal and crystallization from proceeding simultaneously.

[0060] The solvent removal chamber 14 is also provided with transport rollers 30 for transporting the substrate 1 thereon, and a roller cooling device 33 for cooling the transport rollers 30. The transport rollers 30 are configured to transport the substrate 1 with the surface coated with the solution facing up. Therefore, by cooling the transport rollers 30, the substrate 1 can be cooled from the underside, and the temperature of the substrate 1 side in the solution layer 2 can be lowered. This prevents a temperature difference from occurring within the solution layer 2 and convection from occurring, even if the temperature of the surface (upper surface) of the solution layer 2 drops due to evaporation of the solvent, and prevents the formation of Benard cells and the resulting cracks.

[0061] Furthermore, in the solvent removal chamber 14, a rectifying device that sends air above the transport rollers 30 is provided, so that the air flow can be rectified above the solution layer 2 on the substrate 1, thereby preventing the formation of irregularities in the solution layer 2. Here, since the direction of the air sent by the rectifying device is the same as the transport direction of the substrate 1, irregularities as wind ripples are less likely to form in the solution layer 2.

[0062] In addition, a second pressure adjustment chamber 18 is provided between the solvent removal chamber 14 and the crystallization chamber 15, and the intake and exhaust of air in the second pressure adjustment chamber 18 is controlled to eliminate the difference in air pressure between the solvent removal chamber 14 and the crystallization chamber 15. As a result, there is almost no difference in air pressure between the solvent removal chamber 14 and the crystallization chamber 15, air flow between the crystallization chamber 15 and the solvent removal chamber 14 is unlikely to occur, and conditions such as temperature are maintained in each of the crystallization chamber 15 and the solvent removal chamber 14. For example, it is unlikely that a situation will occur in which high-temperature air from the crystallization chamber 15 flows into the solvent removal chamber 14, causing the solvent removal chamber 14 to become hot, resulting in crystallization of the perovskite precursor in the solvent removal chamber 14.

[0063] In addition, pressure adjustment chambers 17, 19 are provided between the coating chamber 13 and the solvent removal chamber 14, and between the crystallization chamber 15 and the annealing chamber 16, so that air movement is less likely to occur between the coating chamber 13 and the solvent removal chamber 14, and between the crystallization chamber 15 and the annealing chamber 16, and the temperature of each zone is maintained at an appropriate value.

[0064] Furthermore, in the crystallization chamber 15, hot air is applied to the substrate 1 being transported by the transport rollers 40, thereby heating the substrate 1 to a temperature equal to or higher than the crystallization temperature of the perovskite precursor, thereby carrying out crystallization. Furthermore, since the substrate 1 is transported to the crystallization chamber 15 from which the solvent has been removed, evaporation of the solvent and perovskite formation do not proceed simultaneously, and when the perovskite precursor is crystallized by the hot air from the nozzle 41 to form a perovskite film, the crystallization is uniform, and defects (voids) that could cause short circuits are less likely to form.

[0065] Furthermore, in the crystallization chamber 15, a plurality of nozzles 41 each having hot air outlets 41a, 41b are arranged in the front-to-rear direction, and air inlets 42 are provided between adjacent nozzles 41, so that the hot air blown out from the outlets 41a, 41b is sucked into the inlets 42 and discharged in a relatively short time. Therefore, the temperature rise caused by the hot air is localized, and the temperature of the hot air is unlikely to be transmitted to the solvent removal chamber 14. This makes it possible to prevent the perovskite precursor from crystallizing in the solvent removal chamber 14.

[0066] Furthermore, since the annealing chamber 16 is provided as an area where the substrate 1 reaches after passing through the crystallization chamber 15, stress in the crystallized perovskite can be relaxed. Here, the perovskite film laminate 3 is wound up in the annealing chamber 16, so stress in the perovskite can be relaxed while the perovskite film laminate 3 is being wound up. Furthermore, since the temperature in the annealing chamber 16 is lower than the temperature in the crystallization chamber 15 and higher than room temperature, the perovskite film is not rapidly cooled when the perovskite film laminate 3 is moved from the crystallization chamber 15 to the annealing chamber 16 and when it is removed from the annealing chamber 16, and cracks are less likely to occur in the perovskite film.

[0067] Furthermore, by controlling the humidity in the annealing chamber 16 with a dehumidifier, it is possible to prevent deterioration of the perovskite film.

[0068] The perovskite film formation method of this embodiment also includes the steps of removing the solvent from the solution applied to the substrate 1 without crystallizing the perovskite precursor, and, after the solvent removal step, crystallizing the perovskite precursor on the substrate 1 to form a perovskite film. This allows the removal of the solvent to be performed separately from the crystallization of the perovskite precursor into perovskite, making it possible to form a high-quality perovskite film with a uniform crystal structure and few defects.

[0069] (11) Modifications The above disclosure is merely an example, and various modifications can be made.

[0070] For example, a blower may be provided in the solvent removal chamber 14 to blow air at a temperature equal to or lower than that of the solvent removal chamber 14 (for example, room temperature or a low temperature that does not cause condensation) toward the substrate 1, and the air from the blower may prevent the temperature of the perovskite precursor on the substrate 1 from rising.

[0071] Furthermore, instead of indirectly cooling the substrate 1 by cooling the transport roller 30 in the solvent removal chamber 14 , the substrate 1 may be cooled in advance at a stage prior to the solvent removal in the solvent removal chamber 14 .

[0072] Furthermore, the pressure adjustment chamber may be any chamber capable of reducing the pressure difference between the adjacent areas to the front and rear, and the specific configuration and control method may be different from those of the pressure adjustment chambers 17, 18, and 19 described above.

[0073] Alternatively, a winding shaft 50 may be disposed ahead of the annealing chamber 16, and the substrate 1 after passing through the annealing chamber 16 may be wound onto the winding shaft 50. In this case, the location where the winding shaft 50 is disposed can be said to be the winding section.

[0074] Although one embodiment of the present invention has been described above, this embodiment is presented by way of example and is not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0075] DESCRIPTION OF SYMBOLS 1...substrate, 2...solution layer, 3...perovskite film laminate, 10...perovskite film forming apparatus, 11...unwinding section, 12...surface treatment section, 13...coating chamber, 14...solvent removal chamber, 15...crystallization chamber, 16...annealing chamber, 17...first pressure adjustment chamber, 18...second pressure adjustment chamber, 19...third pressure adjustment chamber, 20...winding shaft, 21...die, 22...backup roller, 23...air inlet, 23a...damper, 24...exhaust port, 24a...damper, 25a... atmospheric pressure sensor, 25b... atmospheric pressure sensor, 29... partition wall, 30... conveying roller, 31... infrared irradiation device, 32a... blower device, 32b... suction device, 33... roller cooling device, 40... conveying roller, 41... nozzle, 41a... front outlet, 41b... rear outlet, 42... suction port, 43... exhaust chamber, 44... air supply chamber, 45... air supply path, 50... winding shaft, 51... air intake port, 52... exhaust port, 60... control unit

Claims

1. A perovskite film forming apparatus for forming a perovskite film on a substrate to which a solution containing a perovskite precursor and a solvent has been applied, by crystallizing the perovskite precursor, the apparatus comprising: a solvent removal chamber through which the continuously transported substrate passes, the solvent on the substrate being heated to a temperature at which the solvent evaporates but the perovskite precursor does not crystallize, thereby removing the solvent from the solution applied to the substrate without crystallizing the perovskite precursor; and a crystallization chamber which is an area on the substrate from which the solvent has been removed after passing through the solvent removal chamber, by heating the perovskite precursor to a temperature equal to or higher than its crystallization temperature, thereby crystallizing the perovskite precursor to form the perovskite film; the solvent and the perovskite precursor absorb different wavelengths of infrared light, and the solvent removal chamber is provided with an infrared irradiator which irradiates infrared light of a specific wavelength that is absorbed by the solvent. the infrared irradiation device irradiates the solution with infrared light of the specific wavelength to heat the solution at a temperature at which the solvent evaporates but the perovskite precursor does not crystallize, thereby evaporating and removing the solvent without crystallizing the perovskite precursor; the solvent removal chamber is provided with transport rollers on which the substrate is placed and transported, the transport rollers transport the substrate with the surface on which the solution has been applied facing up, and a roller cooling device is provided for cooling the transport rollers.

2. A perovskite film forming apparatus according to claim 1, further comprising an unwinding section that unwinds the substrate before the solution is applied, an application chamber that applies the solution to the substrate, and a winding section that winds up the substrate on which the perovskite film has been formed, and the solvent removal chamber and the crystallization chamber are provided in this order as areas between the application chamber and the winding section.

3. A perovskite film forming apparatus according to claim 1 or 2, wherein the solvent removal chamber is provided with transport rollers for transporting the substrate thereon, and a rectifier device above the transport rollers for sending air in the same direction as the substrate is transported.

4. The perovskite film forming apparatus according to claim 1 or 2, wherein in the crystallization chamber, the perovskite precursor from which the solvent has been removed is heated to a crystallization temperature or higher and crystallized by applying hot air from a plurality of nozzles.

5. The perovskite film forming apparatus according to claim 4, wherein a plurality of the nozzles, each having a hot air outlet, are arranged in a front-to-rear direction in the crystallization chamber, and an air inlet is provided between adjacent nozzles.

6. A perovskite film formation apparatus according to claim 1 or 2, wherein a pressure adjustment chamber is provided between the solvent removal chamber and the crystallization chamber, and intake and exhaust in the pressure adjustment chamber are controlled to eliminate the difference in air pressure between the solvent removal chamber and the crystallization chamber.

7. The perovskite film forming apparatus according to claim 1 or 2, wherein an annealing chamber is provided as a zone where the substrate reaches after passing through the crystallization chamber, and the temperature of the annealing chamber is lower than the temperature of the crystallization chamber and higher than room temperature.

8. A method for forming a perovskite film, comprising: heating the solution on the substrate to a temperature at which the solvent evaporates but the perovskite precursor does not crystallize, thereby removing the solvent from the solution applied to the substrate without crystallizing the perovskite precursor; and, after the solvent removal step, heating the perovskite precursor on the substrate from which the solvent has been removed to a temperature equal to or higher than the crystallization temperature, thereby crystallizing the perovskite precursor to form the perovskite film, wherein the solvent and the perovskite precursor absorb different wavelengths of infrared light; and in the solvent removal step, an infrared irradiation device irradiates the solution with infrared light of a specific wavelength absorbed by the solvent, thereby heating the solution, thereby evaporating and removing the solvent without crystallizing the perovskite precursor. the step of removing the solvent is carried out while transporting the substrate on transport rollers, and in the step of removing the solvent, the transport rollers transport the substrate with the surface on which the solution has been applied facing up, and cool the substrate from the underside.

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