Manufacturing method of perovskite thin film solar battery

Abstract

To provide a manufacturing method of a perovskite thin film system solar battery, capable of performing an evaporation coating film of a perovskite thin film using a simple evaporation coating installation.SOLUTION: A perovskite thin film formation step includes: a first evaporation coating step of heating a PbX2 powder material in a film formation chamber 110 by using an evaporation coating method using an evaporation coating device 100, and forming a film by performing a gasification; and a second evaporation coating step of forming a MAX material film onto a substrate substantially, performing a heat reaction between the PbX2 powder material and the MAX material film, and forming a perovskite thin film made of a MAPbX3. An evacuation pump 120 in the evaporation coating device at the time may only have an exhaust capacity until a medium vacuum region, and thus, an introduction of the evacuation pump 120 becomes relatively easier. Also, since a reaction film formation of each kind of perovskite precursor materials closes an exhaust valve 130 and completely tightly close the film formation chamber 110, an installation introduction of an external removing outer device of the reaction gas to be exhausted is not required, and has a small environmental load.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for producing a perovskite thin-film solar cell. [Background technology]

[0002] Known solar cells include crystalline silicon solar cells that use a crystalline silicon substrate in the photoelectric conversion section, and thin-film solar cells that use an inorganic thin film such as an amorphous silicon thin film in the photoelectric conversion section. Also known thin-film solar cells include perovskite thin-film solar cells that use a perovskite thin film, which is an organic thin film (more specifically, an organic / inorganic hybrid thin film), in the photoelectric conversion section.

[0003] An example of such a perovskite thin film is a thin film made of methylammonium lead halide MAPbX3 (X is a halogen atom including at least one of iodide I, bromide Br, chloride Cl, and fluoride F). Such a perovskite thin film can be obtained by thermally reacting a lead halide PbX2 material with a methylammonium halide MAX material.

[0004] Known methods for forming such perovskite thin films include wet processes such as printing, coating, and solution methods, and dry processes such as deposition. Patent Document 1 discloses a technique for forming a perovskite thin film using a solution method in which a solution in which a perovskite material (solute) is dissolved in a solvent is applied. More specifically, a perovskite thin film is formed using a mist CVD method (chemical vapor deposition method) in which the solution is misted and applied.

[0005] On the other hand, Patent Document 2 discloses a technique for forming a composite thin film of an organic material and an inorganic material by using a vapor deposition method. -6 The deposition chamber is evacuated to a high vacuum of Torr to carry out deposition deposition. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-119907 A [Patent Document 2] Special Publication No. 2018-528326 Summary of the Invention [Problem to be solved by the invention]

[0007] These methods for forming perovskite thin films each have their own advantages and disadvantages in terms of the difficulty of film formation and the properties of the resulting perovskite thin film. For example, the solution method is widely known as a simple film formation method because it can obtain a perovskite thin film by applying a solution in which a perovskite precursor material is dissolved. However, during the film formation stage, the film formation and thermal reaction of the perovskite material are carried out in an atmospheric pressure environment, so the thermal reaction between the lead halide PbX2 material and the methylammonium halide MAX material may be inhibited by moisture. Thus, while the solution method can relatively easily obtain a perovskite thin film, there is a concern that moisture may reduce the performance of the perovskite thin film.

[0008] On the other hand, in the deposition method, the film formation and thermal reaction of the perovskite material are carried out in a vacuum environment, so the performance of the perovskite thin film does not deteriorate due to moisture. However, the deposition method is more difficult to introduce than the solution method in terms of the equipment costs required to create the vacuum environment.

[0009] For example, due to the influence of factors such as the high gasification temperature of lead halide PbX2 material (e.g., vaporization temperature 250℃ to 350℃), deposition film production in a high vacuum range is required, and a vacuum exhaust pump with high exhaust capacity is necessary to create such a high vacuum environment.

[0010] In this regard, in the deposition method disclosed in Patent Document 2, the pressure in the deposition chamber is set to at least 10 -6 The chamber is evacuated to a high vacuum of Torr before deposition.

[0011] An object of the present invention is to provide a method for producing a perovskite thin film solar cell, which enables deposition formation of a perovskite thin film using simple deposition equipment. [Means for solving the problem]

[0012] The present invention is a method for manufacturing a perovskite thin-film solar cell, comprising: an evacuation step of reducing the pressure in a film formation chamber in which a perovskite thin film is formed on a film formation substrate; a heating step of heating a perovskite precursor material placed in the film formation chamber; an evacuation stop step of closing an exhaust valve in the film formation chamber to stop evacuation; and a deposition step of depositing the perovskite precursor material on the film formation substrate. This method allows the deposition of perovskite thin films by vacuum deposition. In particular, the exhaust stop step prevents reactive gases from leaking out during deposition, and the decomposition or combustion of exhaust gases by an external exhaust device is not required, making this a deposition method with low environmental impact. The method for producing a perovskite solar cell according to claim 1 may be configured such that the pressure inside the deposition chamber is set to 0.1 to 10 Pa in the exhausting step.

[0013] According to this method, the exhaust capacity of the vacuum exhaust pump during evacuation is only required to reach a medium vacuum range, so that a high vacuum exhaust pump is not required. The method for producing a perovskite solar cell according to claim 1 can also be provided, in which lead halide PbX2 is used as a perovskite precursor material in the heating step, where X is a halogen atom including at least one of iodide I, bromide Br, chloride Cl, and fluoride F.

[0014] According to this method, a film can be formed using any lead halide, which is one of the perovskite precursor materials and is gasified by heating in a vacuum, and a film can be formed without any particular limitation on the type of halogen. The method for producing a perovskite solar cell according to claim 1 may further comprise using, as the perovskite precursor material in the heating step, at least one of methylammonium halide MAX and formamidinium halide FAX, or a mixture of these two materials. According to this method, a film can be formed using any of the perovskite precursor materials, which are at least one of the methylammonium halide MAX and the formamidinium halide FAX, or a mixture of both, that are gasified by heating in a vacuum, and a perovskite thin film can be formed without any particular limitations. The method for manufacturing a perovskite solar cell according to claim 3 may be configured such that, in the exhaust stopping step, the exhaust valve is closed immediately before the pressure inside the deposition chamber increases when the heater temperature of the lead halide PbX2 is in the range of 350°C to 400°C.

[0015] According to this method, the deposition chamber is completely sealed immediately before the lead halide PbX2 is gasified by heating, so that deposition can be performed without leakage of reactive gas to the outside. The method for manufacturing a perovskite solar cell according to claim 4 may also be provided, in which, in the exhaust stopping step, the exhaust valve is closed immediately before the pressure inside the deposition chamber increases when the heater temperature of at least one of the methylammonium halide MAX or the formamidinium halide FAX, or the mixture of the two materials, is in the range of 140°C to 200°C. According to this method, the deposition chamber is completely sealed immediately before at least one of the methylammonium halide MAX or the formamidinium halide FAX, or a mixture of the two materials, is gasified by heating, thereby enabling deposition to be performed without the reactive gas leaking to the outside.

[0016] A method for producing a perovskite thin film solar cell according to the present invention is a method for producing a perovskite thin film solar cell that uses a perovskite thin film as a photoelectric conversion section, and includes a perovskite thin film formation step of forming the perovskite thin film on a substrate. The perovskite thin film forming process includes a first deposition process in which a lead halide PbX2 powder material is heated and sublimated by a deposition method using a vacuum chamber to deposit a lead halide PbX2 material film on the substrate (wherein X is at least one of iodide I, bromide Br, chloride Cl and fluoride F), and a second deposition process in which at least one of a methylammonium halide MAX material film or a formamidinium halide FAX material film, or a mixed material film of the two materials, is deposited on the lead halide PbX2 material film in the same manner, and the lead halide PbX2 material film and the methylammonium halide MAX material film or the formamidinium halide FAX material film, or the mixed material film of the two materials are thermally reacted with each other to form the perovskite thin film made of methylammonium lead halide MAPbX3. Effect of the Invention

[0017] According to the present invention, in the deposition production of perovskite thin films, a deposition chamber can be prepared by evacuation using only a vacuum evacuation pump capable of exhausting up to a medium vacuum range, and the present invention proposes a deposition production method in a closed system in which no reactive gas is discharged to the outside during deposition production, making it a simpler production method with less environmental impact than conventional methods. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view illustrating an example of a solar cell according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a cross-sectional view showing another example of a solar cell according to the present embodiment. [Diagram 3] FIG. 1 is a diagram illustrating an example of a deposition apparatus according to an embodiment of the present invention. [Figure 4]FIG. 2 is a diagram showing an example of the interior of a film formation chamber in the deposition apparatus according to the present embodiment. [Diagram 5] FIG. 2 is a diagram showing an X-ray diffraction spectrum of the perovskite thin film of the sample of Example 1. [Figure 6] FIG. 1 shows an X-ray diffraction spectrum of a perovskite thin film sample of Example 2. [Figure 7] FIG. 2 is a diagram showing an X-ray diffraction spectrum of the perovskite thin film of the sample of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. For convenience, hatching and reference numerals may be omitted, in which case other drawings shall be referred to.

[0020] (Solar Cell) Fig. 1 is a cross-sectional view showing an example of a solar cell according to the present embodiment, and Fig. 2 is a cross-sectional view showing another example of a solar cell according to the present embodiment. The solar cell 1 shown in Figs. 1 and 2 is a perovskite thin-film solar cell using a perovskite thin film as a photoelectric conversion section. The solar cell 1 includes a substrate 10, a first electrode layer 21, a first carrier transport layer 31, a perovskite thin film 40, a second carrier transport layer 32, and a second electrode layer 22.

[0021] The solar cell 1 shown in Fig. 1 and the solar cell 1 shown in Fig. 2 have different polarities. Specifically, in the solar cell 1 shown in Fig. 1, the first carrier transport layer 31 and the second carrier transport layer 32 are a hole transport layer (HTL) and an electron transport layer (ETL), respectively, and the first electrode layer 21 and the second electrode layer 22 are an anode and a cathode, respectively. On the other hand, in the solar cell 1 shown in Fig. 2, the first carrier transport layer 31 and the second carrier transport layer 32 are an electron transport layer (ETL) and a hole transport layer (HTL), respectively, and the first electrode layer 21 and the second electrode layer 22 are a cathode and an anode, respectively.

[0022] The substrate 10 is an insulating and light-transmitting transparent substrate, and may be made of glass, resin, or the like.

[0023] The first electrode layer 21 is formed on the substrate 10 and functions as an anode (FIG. 1) or a cathode (FIG. 2). The first electrode layer 21 is made of a transparent conductive oxide (TCO) having electrical conductivity and light transmission. As the material of the first electrode layer 21, a transparent conductive metal oxide, for example, indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof, etc. are used. Among these, an indium-based composite oxide containing indium oxide as a main component is preferable. From the viewpoint of high electrical conductivity and transparency, indium oxide is particularly preferable. Furthermore, in order to ensure reliability or higher electrical conductivity, it is preferable to add a dopant to indium oxide. Examples of the dopant include Sn, W, Zn, Ti, Ce, Zr, Mo, Al, Ga, Ge, As, Si, and S. For example, ITO (Indium Tin Oxide), in which tin is added to indium oxide, is widely known.

[0024] The first carrier transport layer 31 is formed on the first electrode layer 21 and functions as a hole transport layer (HTL) (FIG. 1) or an electron transport layer (ETL) (FIG. 2). The first carrier transport layer 31 is made of a semiconductor material having optical transparency.

[0025] 1, the first carrier transport layer 31 functions as a hole transport layer (HTL) that transports holes (first carriers) among carriers generated by photoelectric conversion in the perovskite thin film 40 to the first electrode layer 21. Examples of main materials of the first carrier transport layer 31 as a hole transport layer (HTL) include nickel oxide (NiO), copper oxide (Cu2O), PTAA (Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)), Spiro-MeOTAD (N2,N2',N2',N7,N7,N7',N7'-octakis(4-methoxyphenyl)-9,9'-spirobi[9H-fluorene]-2,2',7,7'-tetramine), and the like.

[0026] 2, the first carrier transport layer 31 functions as an electron transport layer (ETL) that transports electrons (first carriers) among carriers generated by photoelectric conversion in the perovskite thin film 40, to the first electrode layer 21. Examples of main materials of the first carrier transport layer 31 serving as the electron transport layer (ETL) include titanium oxide (TiO2), zinc oxide (ZnO), and tin oxide (SnO2).

[0027] The perovskite thin film 40 is formed on the first carrier transport layer 31 and functions as a photoelectric conversion layer. Examples of main materials for the perovskite thin film 40 include compounds represented by the following formula, which contain an organic atom A, a metal atom B, and a halogen atom X. ABX3 A includes an organic atom including at least one of a monovalent organic ammonium ion and an amidinium ion. B includes a metal atom including a divalent metal ion. X includes a halogen atom including at least one of an iodide ion I, a bromide ion Br, a chloride ion Cl, and a fluoride ion F.

[0028] Among these, in the case of the vapor deposition method (dry process), the organic atom A is preferably methylammonium MA (CH3NH3) or formamidinium FA (CH(NH2)2), the metal atom B is preferably lead Pb, and the halogen atom X is preferably at least one of iodide ion I, bromide ion Br, and chloride ion Cl. That is, in the case of a dry process such as a vapor deposition method, the main material of the perovskite thin film 40 may be methylammonium lead halide MAPbX3 (CH3NH3PbX3), such as MAPbI3, MAPbBr3, MAPbCl3, or formamidinium lead halide FAPbX3 (CH(NH2)2PbX3), such as FAPbI3, FAPbBr3, FAPbCl3, etc. Note that the halogen atom X may include multiple types. For example, in the case of containing iodide I and another halogen atom X, the main material of the perovskite thin film 40 may be methylammonium lead iodide MAPbI y X (3-y) (CH3NH3PbI y X (3-y) ), e.g. MAPbI y Br (3-y) , MAPbI y Cl (3-y) (y is any positive integer). In addition, the organic atom A may contain multiple types of atoms. For example, when methylammonium MA (CH3NH3) and formamidinium FA (CH(NH2)2) are contained, the main material of the perovskite thin film 40 may be MAFAPbX3((CH3NH3) z (CH(NH2)2) (1-z) PbX3), e.g. MA z FA (1-z) PbI3, MA z FA (1-z) PbBr3, MA z FA (1-z) Examples include PbCl3 (z is an arbitrary number).

[0029] Methylammonium lead halide MAPbX3 (CH3NH3PbX3) thin film is formed by depositing lead halide PbX2 material and methylammonium halide MAX material in sequence, and then thermally reacting these thin films at reaction temperature. y X (3-y) (CH3NH3PbI y X (3-y) A methylammonium lead iodide (MAPbI3) thin film is formed, for example, by successively depositing a lead halide (PbX2) material and a methylammonium iodide (MAI) material, and then thermally reacting the thin films of these materials at a reaction temperature. In a more specific example, a methylammonium lead iodide (MAPbI3) thin film is formed by successively depositing a lead iodide (PbI2) material and a methylammonium iodide (MAI) material, and then thermally reacting the thin films of these materials at a reaction temperature.

[0030] Formamidinium lead halide FAPbX3 (CH(NH2)2PbX3) thin film is formed by depositing lead halide PbX2 material and formamidinium halide FAX material in sequence, and then thermally reacting these thin films at reaction temperature. Formamidinium lead iodide FAPbI y X (3-y) (CH(NH2)2PbI y X (3-y) A formamidinium lead iodide (FAPbI3) thin film is formed, for example, by successively depositing a lead halide (PbX2) material and a formamidinium iodide (FAI) material, and then thermally reacting the thin films of these materials at a reaction temperature. In a more specific example, a formamidinium lead iodide (FAPbI3) thin film is formed by successively depositing a lead iodide (PbI2) material and a formamidinium iodide (FAI) material, and then thermally reacting the thin films of these materials at a reaction temperature.

[0031] Furthermore, a mixture of methylammonium halide and formamidinium halide, methylammonium formamidinium lead halide MAFAPbX3((CH3NH3) z (CH(NH2)2) (1-z)The lead halide (PbX3) thin film is formed by depositing a mixture of lead halide (PbX2) material, methylammonium halide (MAX) material, and formamidinium halide (FAX) material in sequence, and then thermally reacting the thin films of these materials at reaction temperatures. y X (3-y) ((CH3NH3) z (CH(NH2)2) (1-z) PbI y X (3-y) The thin film is formed, for example, by depositing a lead halide PbX2 material and a mixed material of methylammonium iodide MAI material and formamidinium iodide FAI material in sequence, and then thermally reacting the thin films of these materials at a reaction temperature. In a more specific example, methylammonium formamidinium lead iodide MAFAPbI3((CH3NH3) z (CH(NH2)2) (1-z) The PbI3) thin film is formed by depositing a lead iodide (PbI2) material, a mixture of methylammonium iodide (MAI) material, and formamidinium iodide (FAI) material in sequence, and then thermally reacting the thin films of these materials at reaction temperatures.

[0032] The second carrier transport layer 32 is formed on the perovskite thin film 40, and functions as an electron transport layer (ETL) (FIG. 1) or a hole transport layer (HTL) (FIG. 2). The second carrier transport layer 32 is made of a semiconductor material having optical transparency.

[0033] 1, the second carrier transport layer 32 functions as an electron transport layer (ETL) that transports electrons (second carriers) among carriers generated by photoelectric conversion in the perovskite thin film 40, to the second electrode layer 22. Examples of main materials of the second carrier transport layer 32 serving as the electron transport layer (ETL) include titanium oxide (TiO2), zinc oxide (ZnO), and tin oxide (SnO2).

[0034] 2, the second carrier transport layer 32 functions as a hole transport layer (HTL) that transports holes (second carriers) among the carriers generated by photoelectric conversion in the perovskite thin film 40 to the second electrode layer 22. Examples of main materials of the second carrier transport layer 32 as a hole transport layer (HTL) include nickel oxide (NiO), copper oxide (Cu2O), PTAA (Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)), Spiro-MeOTAD (N2,N2',N2',N7,N7,N7',N7'-octakis(4-methoxyphenyl)-9,9'-spirobi[9H-fluorene]-2,2',7,7'-tetramine), and the like.

[0035] The second electrode layer 22 is formed on the second carrier transport layer 32 and functions as a cathode (FIG. 1) or an anode (FIG. 2). The second electrode layer 22 is a metal layer having electrical conductivity. Examples of materials for the second electrode layer 22 include Ag, Au, and Cu.

[0036] With this configuration, the solar cell 1 generates a current according to the light incident from the substrate 10 side, and outputs the current to the first electrode layer 21 and the second electrode layer 22. (Solar Cell Manufacturing Method) Next, the manufacturing method of this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a schematic diagram of a vacuum deposition facility, and Figure 4 is a schematic diagram of the inside of a film formation chamber. First, a transparent conductive film is formed as the first electrode layer 21 on the substrate 10 (first electrode layer forming step). The method for forming the transparent conductive film is not particularly limited, but may be a CVD method (chemical vapor deposition method), a PVD method (physical vapor deposition method), or a sputtering method using a vacuum chamber. Thereafter, the surface of the transparent conductive film may be washed (e.g., with pure water / IPA (isopropyl alcohol)), dried (e.g., at 150 degrees for 1 hour), and subjected to ozone treatment. Next, the first carrier transport layer 31 is formed on the first electrode layer 21 (first carrier transport layer forming step). The method for forming the first carrier transport layer 31 is not particularly limited, but examples thereof include dry processes such as a CVD method, a PVD method, or a sputtering method, and wet processes such as a coating method or a printing method. Among these, the sputtering method is preferred from the viewpoint of forming a dense film.

[0037] Next, a perovskite thin film 40 is formed on the first carrier transport layer 31 (perovskite thin film formation process). Specifically, a first vapor deposition process of depositing a lead chloride PbCl2 material film and a second vapor deposition process of depositing a methylammonium iodide MAI material film and reacting the lead chloride PbCl2 material film with the methylammonium iodide MAI material film to form a perovskite thin film made of methylammonium lead iodide MAPbI3 are performed in this order.

[0038] (1st vapor deposition process) First, a lead chloride (PbCl2) material film is formed by vapor deposition. 3, a deposition apparatus 100 includes a film formation chamber 110, a vacuum exhaust pump 120, and an exhaust valve 130 that connects the film formation chamber and the vacuum exhaust pump and opens and closes an exhaust port. The film formation chamber 110, the exhaust valve 130, and the vacuum exhaust pump 120 are connected in a single line, and the exhaust valve 130 is disposed to separate the film formation chamber 110 and the vacuum exhaust pump 120. By opening or closing the valve, the exhaust port between the film formation chamber 110 and the vacuum exhaust pump 120 is opened or closed, so that the vacuum exhaust pump 120 can evacuate or stop exhausting the film formation chamber 110.

[0039] 4, the film formation chamber 110 is provided with a substrate holder 111 for holding a film formation substrate, an evaporation crucible 112 for inserting an evaporation source therein and heating it, a heater 113 for heating the evaporation crucible 112, and a thermocouple 114 for measuring the temperature of the evaporation crucible 112. Therefore, during film formation, the film formation substrate 10 and the perovskite precursor material serving as the evaporation source can be placed in the same chamber. For example, in preparation for film formation, the film formation substrate 10 is placed on the substrate holder 111 inside the film formation chamber 110, and the perovskite precursor material is placed in the deposition crucible 112. In this state, the film formation chamber 110 is completely sealed. Then, there is an evacuation step in which the exhaust valve 130 is opened and the vacuum exhaust pump 120 is used to perform evacuation.

[0040] In the film formation, when the pressure inside the film formation chamber 110 reaches a pressure of about 0.1 to 10 Pa through the exhaust process, the deposition crucible 112 is heated using the heater 113, and the perovskite precursor material is heated through a heating process, and then the film is formed. Here, an exhaust stop step is provided in which the exhaust valve 130 is closed to stop the vacuum evacuation just before the perovskite precursor material reaches vapor pressure due to heating by the heater 113. Thereafter, the inside of the film formation chamber 110 is filled with the gas of the perovskite precursor material, and a perovskite film is formed on the film formation substrate.

[0041] For example, lead chloride PbCl2 material is put into an evaporation crucible 112 and heated by a heater 113 to gasify the lead chloride PbCl2 material. The gasified lead chloride PbCl2 material fills the inside of the deposition chamber 110 and adheres to the deposition substrate 10 held by a substrate holder 111 installed inside the deposition chamber 110, thereby depositing a lead chloride PbCl2 material film.

[0042] Here, the deposition conditions for the lead chloride (PbCl2) material film are as follows: Heater 113 temperature: 350°C or higher and 420°C or lower, preferably 400°C or higher and 420°C or lower Pressure inside the film formation chamber 110 before heating: 0.1 to less than 10 Pa, preferably less than 5 Pa. More preferably less than 2 Pa. In the example of Fig. 4, a deposition crucible is used to heat the deposition source, but the deposition source may be heated in a different manner. For example, a flat plate with good thermal conductivity may be used for heating. In particular, a flat plate is used for forming a film of lead chloride (PbCl2).

[0043] (Second vapor deposition process) Next, a methylammonium iodide (MAI) material film is formed by vapor deposition in the same manner as in the first vapor deposition step. For example, methylammonium iodide MAI material is put into a deposition crucible 112 and heated by a heater 113 to gasify the methylammonium iodide MAI material. The gasified methylammonium iodide MAI material fills the inside of the film formation chamber 110 and adheres to the film formation substrate 10 held by a substrate holder 111 installed inside the film formation chamber 110, thereby forming a methylammonium iodide MAI material film. In particular, when forming a perovskite film, a substrate on which a lead chloride (PbCl2) material film has been formed in advance is used, and the lead chloride (PbCl2) material reacts with the gasified methylammonium iodide (MAI) material to obtain a perovskite film.

[0044] Here, the conditions for forming the methylammonium iodide (MAI) material film are as follows. Heater 113 temperature: 140°C to 190°C, preferably 180°C to 190°C Pressure inside the film formation chamber 110 before heating: 0.1 to less than 10 Pa, preferably less than 5 Pa. More preferably less than 2 Pa.

[0045] In the example of FIG. 4, the substrate holder 111 is installed directly above the deposition crucible so that the deposition substrate is horizontal to the opening of the deposition crucible, but the installation form of the substrate holder is not limited to this. For example, when a perovskite film is deposited by reaction with a gasified material filled in the deposition chamber, the substrate holder may be installed at any position in the deposition chamber as long as there is no barrier that blocks contact between the deposition substrate surface and the material gas. In particular, when a perovskite film is deposited by reacting a deposition substrate on which a lead chloride (PbCl2) material film has been previously deposited with a gasified methylammonium iodide (MAI) material, the substrate holder may be installed so that the deposition substrate is vertical to the opening of the deposition crucible.

[0046] Next, the second carrier transport layer 32 is formed on the perovskite thin film 40 (second carrier transport layer formation step). The method for forming the second carrier transport layer 32 is not particularly limited, but examples thereof include dry processes such as a CVD method, a PVD method, or a sputtering method, and wet processes such as a coating method or a printing method.

[0047] Although the sputtering method allows for the formation of a dense film, it may cause sputter damage to the perovskite thin film, which may reduce the conversion efficiency of the solar cell. From this perspective, coating methods or solution methods are generally used to form a carrier transport layer on a perovskite thin film.

[0048] Next, a metal film is formed as the second electrode layer 22 on the second carrier transport layer 32. The method for forming the metal film is not particularly limited, but examples include dry processes such as a CVD method, a PVD method, or a sputtering method using a vacuum chamber, and wet processes such as a printing method or a coating method. Among these, the sputtering method is preferable. In this manner, the perovskite thin film solar cell 1 of this embodiment shown in FIG. 1 or FIG. 2 is obtained. Here, known methods for forming perovskite thin films include wet processes such as printing, coating, and solution methods, and dry processes such as deposition. For example, in solution methods, a solution in which a perovskite material (solute) is dissolved in a solvent is applied to a substrate by spin coating or bar coating. On the other hand, in deposition methods, a vacuum chamber is used to gasify the perovskite material and layer it on the substrate.

[0049] In such a method for forming a perovskite thin film, the performance of the perovskite thin film may be reduced due to heat or moisture. For example, in the deposition method, the film formation and thermal reaction of the perovskite material are carried out in a vacuum environment, so the performance of the perovskite thin film is not reduced by moisture. However, in the deposition method, in order to form a dense film, the pressure inside the vacuum chamber must be reduced and the film must be formed in a high vacuum environment. For this reason, it has been necessary to install a vacuum chamber and a vacuum pump to create a high vacuum environment.

[0050] Regarding these points, in the manufacturing method of the perovskite thin film solar cell of this embodiment, a vapor deposition method in a medium vacuum region is adopted in the perovskite thin film formation process. In the first vapor deposition process for depositing a lead chloride PbCl2 material (PbX2 material) film, a vapor deposition method is used in which lead chloride PbCl2 powder material is heated in a deposition chamber, gasified, and deposited on a deposition substrate.

[0051] In the second deposition process for depositing a methylammonium iodide MAI material (MAX material) film, the methylammonium iodide MAI material is heated and gasified in the deposition chamber in the same manner as in the deposition method for the lead chloride PbCl2 material film (PbX2 material film), and reacted with the lead chloride PbCl2 material film (PbX2 material film) that has already been deposited to obtain a perovskite film.

[0052] In both the first and second deposition steps, evacuation to a medium vacuum region of about a few Pa is sufficient, and perovskite films can be obtained even in this vacuum environment. Therefore, a high vacuum evacuation pump required for evacuation to a high vacuum region is not required, making it easier to introduce the equipment and reducing film production costs.

[0053] In addition, in this embodiment, when the perovskite precursor material is heated and gasified, the exhaust valve is closed to stop the evacuation just before each material reaches its vapor pressure, so film formation is possible without the reaction gas leaking to the outside via the vacuum pump. This makes it unnecessary to have an external exhaust device for processing the reaction gas, making it easier to introduce the equipment and also making this a film formation method with a small environmental impact.

[0054] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications and variations are possible. For example, in the above-mentioned embodiments, a method for manufacturing a perovskite thin-film solar cell was mainly described in which a lead chloride PbCl2 material film and a methylammonium iodide MAI material film are formed, and the two are reacted to form methylammonium lead iodide MAPbI3. However, the present invention is not limited to this, and can be applied to various methods for manufacturing perovskite thin-film solar cells in which a lead halide PbX2 material film and a methylammonium halide MAX material film are formed, and the methylammonium lead halide MAPbX3 is formed by reaction.

[0055] Furthermore, the above-described embodiment can also be applied to the manufacture of a perovskite thin-film solar cell in a so-called tandem solar cell in which a crystalline silicon solar cell or an amorphous silicon thin-film solar cell is combined with a perovskite thin-film solar cell. EXAMPLES

[0056] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

[0057] Example 1 Using the method for forming a perovskite thin film by vapor deposition in the manufacturing method for a perovskite thin film solar cell of this embodiment, a sample in which a perovskite thin film was formed on a glass substrate having a transparent conductive film (SnO2 layer) was produced as Example 1. In forming the perovskite thin film of the sample of Example 1, the formation of a lead chloride PbCl2 material film (first vapor deposition step), the formation of a methylammonium iodide MAI material film, and the reaction between the lead chloride PbCl2 material film and the methylammonium iodide MAI material film (second vapor deposition step) were carried out in this order as follows.

[0058] <Deposition of lead chloride (PbCl2) material film: First deposition process> First, a lead chloride PbCl2 material film was formed by a deposition method using a deposition apparatus 100 shown in Fig. 3. The deposition conditions for the lead chloride PbCl2 material film were as follows.

[0059] <<Conditions for producing lead chloride (PbCl2) material films>> Lead chloride (PbCl2) powder material is heated and gasified using a heater 113 connected to an evaporation crucible 112 (flat plate). Pressure inside the deposition chamber: approx. 2 Pa (before heating begins), approx. 2 to 30 Pa (during deposition) Heater 113 temperature: 420℃ Film production time: 10 minutes During deposition, evacuation is stopped, so the pressure inside the deposition chamber increases due to an increase in partial pressure of the gasified material.

[0060] <Formation of Methylammonium Iodide (MAI) Material Film: Second Vapor Deposition Process> Next, a methylammonium iodide (MAI) material film was formed using the same deposition method as in the first deposition process, and the lead chloride (PbCl2) material film and the methylammonium iodide (MAI) material film were reacted to form a perovskite thin film made of methylammonium lead iodide (MAPbI3). The deposition conditions for the methylammonium iodide (MAI) material film were as follows:

[0061] <<Conditions for forming methylammonium iodide (MAI) material films>> Methylammonium iodide (MAI) powder material is heated and gasified using a heater 113 connected to an evaporation crucible 112. Pressure inside the deposition chamber: approx. 2 Pa (before heating begins), approx. 2 to 30 Pa (during deposition) Heater 113 temperature: 190℃ ·Substrate temperature: 80℃ Film production time: 30 minutes During deposition, evacuation is stopped, so the pressure inside the deposition chamber increases due to an increase in partial pressure of the gasified material.

[0062] Example 2 The sample of Example 2 differs from the sample of Example 1 in that a two-type mixed material is used in the second vapor deposition step by adding formamidinium iodide FAI material to methylammonium iodide MAI material as the perovskite precursor material.

[0063] <Deposition of lead chloride (PbCl2) material film: First deposition process> <<Conditions for producing lead chloride (PbCl2) material films>> Same as Example 1 <Deposition of a mixed material film of methylammonium iodide (MAI) and formamidinium iodide (FAI): Second deposition process> A mixed film of methylammonium iodide MAI material and formamidinium iodide FAI material was formed by using a deposition method similar to that in Example 1, and a perovskite thin film made of methylammonium formamidinium lead iodide MAFAPbI3 was formed by reacting a lead chloride PbCl2 material film with the mixed film of methylammonium iodide MAI material and formamidinium iodide FAI material. The film formation conditions for the mixed film of methylammonium iodide MAI material and formamidinium iodide FAI material are as follows.

[0064] <<Conditions for preparing mixed material films of methylammonium iodide (MAI) and formamidinium iodide (FAI)>> Methylammonium iodide (MAI) powder material and formamidinium iodide (FAI) powder material are heated and gasified using a heater 113 connected to an evaporation crucible 112. Pressure inside the deposition chamber: approx. 2 Pa (before heating begins), approx. 2 to 30 Pa (during deposition) Heater 113 temperature: 190℃ ·Substrate temperature: 50℃ Film production time: 30 minutes During deposition, evacuation is stopped, so the pressure inside the deposition chamber increases due to an increase in partial pressure of the gasified material.

[0065] Comparative Example 1 Using a perovskite thin film formation method using a spin coating method, a sample in which a perovskite thin film was formed on a glass substrate having a transparent conductive film (SnO2 layer) was produced as Comparative Example 1. In forming the perovskite thin film of the sample of Comparative Example 1, a film of methylammonium lead iodide (MAPbI3) material was formed using the spin coating method as follows.

[0066] <Fabrication of methylammonium lead iodide (MAPbI3) material> First, a film of methylammonium lead iodide (MAPbI3) material was formed using a conventional spin coating method. The film formation conditions for the methylammonium lead iodide (MAPbI3) material were as follows:

[0067] <<Deposition conditions of methylammonium lead iodide (MAPbI3) material>> Lead iodide (PbI2) and methylammonium iodide (MAI) are dissolved in DMF or DMSO or a mixture (solvent), and the solution is heated and stirred. Next, the solution is dropped onto a glass substrate, and the glass substrate is then baked after being coated by spin coating. Ambient pressure: Atmospheric pressure Spin coat rotation speed: 1000~8000rpm

[0068] (Rating 1) XRD: Using an X-ray diffractometer (SmartLab, manufactured by Rigaku), 2θ scanning images of the perovskite thin films of the samples of the above-mentioned Examples and Comparative Examples were measured. The measurement results are shown in Figs. 5 to 7. Fig. 5 is a diagram showing the X-ray diffraction spectrum of the perovskite thin film of the sample of Example 1, Fig. 6 is a diagram showing the X-ray diffraction spectrum of the perovskite thin film of the sample of Example 2, and Fig. 7 is a diagram showing the X-ray diffraction spectrum of the perovskite thin film of the sample of Comparative Example 1. In Figs. 5 to 7, the horizontal axis is the diffraction angle 2θ, and the vertical axis is the spectrum intensity. As shown in Fig. 7, in Comparative Example 1, diffraction peaks derived from perovskite were measured at a diffraction angle 2θ of about 14 degrees and a diffraction angle 2θ of about 28 degrees. The diffraction peaks at a diffraction angle 2θ of 26 degrees to 27 degrees are diffraction peaks derived from the glass substrate SnO2. Diffraction peaks derived from perovskite (PVSK) + H2O were also confirmed at a diffraction angle 2θ of 6 degrees to 7 degrees, a diffraction angle 2θ of 23 degrees to 24 degrees, and a diffraction angle 2θ of 27 degrees to 28 degrees.

[0069] On the other hand, from the XRD spectra of the samples of Example 1 and Example 2 shown in FIG. 5 and FIG. 6, a diffraction peak originating from the (110) plane of the perovskite crystal, which appears at about 14 degrees, as in Comparative Example 1, and a characteristic peak originating from the (220) plane at about 28 degrees are confirmed, indicating the formation of a perovskite thin film.

[0070] By confirming the peaks derived from the perovskite crystals, it was found that in Examples 1 and 2, perovskite films were obtained that were comparable to those of Comparative Example 1. Furthermore, while diffraction peaks derived from perovskite (PVSK)+H2O were confirmed in Comparative Example 1, these peaks did not appear in Examples 1 and 2. It can be seen that even with the simple equipment proposed in the present invention, deposition film formation that is less susceptible to the effects of moisture as in the conventional vacuum deposition method is possible. [Explanation of symbols]

[0071] 1. Perovskite thin-film solar cells 10. Substrate 21. First electrode layer (anode or cathode) 22. Second electrode layer (cathode or anode) 31. First carrier transport layer (hole transport layer or electron transport layer) 32. Second carrier transport layer (electron transport layer or hole transport layer) 40. Perovskite thin films 100. Vapor deposition equipment 110. Film forming room 120. Vacuum exhaust pump 130. Exhaust valve 111. Substrate holder 112. Evaporation crucible 113. Heater 114. Thermocouple

Claims

1. A method for producing a perovskite thin-film solar cell, comprising the steps of: an evacuation step of reducing the pressure in a deposition chamber in which a perovskite thin film is deposited on a deposition substrate; A heating step of heating a perovskite precursor material placed in the deposition chamber; an exhaust stop step of closing an exhaust valve in the deposition chamber to stop exhaust; a deposition step of depositing the perovskite precursor material on the deposition substrate; Method for producing a perovskite thin-film solar cell having

2. A method for producing a perovskite thin-film solar cell, comprising the steps of: an evacuation step of reducing the pressure in a deposition chamber in which a perovskite thin film is deposited on a deposition substrate; A heating step of heating a perovskite precursor material placed in the deposition chamber; an exhaust stop step of closing an exhaust valve in the deposition chamber to stop exhaust; a deposition step of depositing the perovskite precursor material on the deposition substrate; Method for producing a perovskite thin-film solar cell having

3. In the heating step, lead halide PbX is used as a perovskite precursor material. ２ wherein X is a halogen atom comprising at least one of iodide I, bromide Br, chloride Cl, and fluoride F. The method for producing a perovskite solar cell of claim 1 .

4. 2. The method for producing a perovskite solar cell according to claim 1, wherein in the heating step, at least one of methylammonium halide MAX and formamidinium halide FAX, or a mixture of the two materials, is used as the perovskite precursor material.

5. In the exhaust stopping step, ２ The method for producing a perovskite solar cell according to claim 3, wherein the exhaust valve is closed immediately before the pressure inside the film formation chamber increases when the heater temperature is in the range of 350°C to 400°C.

6. The method for manufacturing a perovskite solar cell according to claim 4, wherein in the exhaust stopping step, the exhaust valve is closed immediately before the pressure inside the deposition chamber increases when the heater temperature of at least one of the methylammonium halide MAX or the formamidinium halide FAX, or the mixture of the two materials, is 140°C to 200°C.

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