Flexible perovskite solar cells and their manufacturing method

Abstract

Provided is a flexible perovskite solar cell that fully utilizes the flexibility of perovskite films. The flexible perovskite solar cell has, in order, a first electrode layer, a first carrier transport layer, a perovskite thin film, a second carrier transport layer, and a second electrode layer on a first main surface side of a second resin layer not in contact with a first resin layer of a base material comprising the first resin layer and the second resin layer. The flexible perovskite solar cell also comprises a resin layer in which the base material has flexibility and barrier properties.

Description

[Technical field]

[0001] The present invention relates to a perovskite solar cell and a method for producing the same. [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] Such perovskite thin films include methylammonium lead halide (MAPbX). 3 (X is a halogen atom including at least one of iodide I, bromide Br, chloride Cl, and fluoride F). Such a perovskite thin film is called lead halide PbX 2 It is obtained by thermally reacting the material with methylammonium halide MAX material.

[0004] Perovskite thin films are flexible and can be applied to flexible solar cells. In recent years, flexible perovskite solar cells using polymer materials or metal foil as a substrate have been attracting attention. Flexible perovskite solar cells have the advantages of being able to be attached to curved surfaces, allowing for a high degree of freedom in the installation location, and being thin and lightweight, making them easy to transport and install. Patent Document 1 discloses a technique for producing flexible perovskite solar cells by using resin, metal foil, or the like as a substrate and laminating a perovskite solar cell structure on the substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-152476 A Summary of the Invention [Problem to be solved by the invention]

[0006] The flexibility of flexible perovskite solar cells depends heavily on the flexibility of the substrate, and depending on the choice of substrate, the flexibility of the perovskite thin film may not be fully utilized. Although it is possible to improve flexibility by making the substrate thinner, if the barrier properties are lost as a result of the thinning, the perovskite thin film will react with moisture in the air and its performance will decrease. The barrier properties here refer to the ability to block gases, moisture, etc.

[0007] An object of the present invention is to provide a perovskite solar cell that uses a substrate that can fully utilize the flexibility of a perovskite thin film and has barrier properties, and a method for manufacturing the same. [Means for solving the problem]

[0008] The solar cell according to the present invention has a first electrode layer, a first carrier transport layer, a perovskite thin film, a second carrier transport layer, and a second electrode layer, arranged in this order on a first main surface side of the second resin layer that is not in contact with the first resin layer of a substrate consisting of a first resin layer and a second resin layer.

[0009] According to this configuration, by using a UV-curable resin as the base material, which is more flexible than commonly used base materials such as PEN (polyethylene naphthalate) film, it is possible to provide a flexible perovskite solar cell that makes full use of the flexibility of the perovskite film.

[0010] In the solar cell described above, the first resin layer and the second resin layer may be made of resins having different functional groups.

[0011] According to this configuration, the first resin layer has a functional group that can change the adhesive strength with the film-deposited plate described later, thereby enabling peeling between the film-deposited plate and the first resin layer in a peeling process described later, and the second resin layer has a barrier property and a functional group that does not react with the perovskite thin film, thereby making it possible to protect the perovskite power generation layer from moisture, gas, etc. In addition, the second resin layer can be reinforced by the first resin layer.

[0012] Furthermore, a method for manufacturing a solar cell according to the present invention includes a first resin layer formation step of forming the first resin layer on a film-deposited plate, a second resin layer formation step of forming the second resin layer on the first resin layer, a first electrode layer formation step of forming the first electrode layer on the second resin layer, a first carrier transport layer formation step of forming the first carrier transport layer on the first electrode layer, a perovskite thin film formation step of forming the perovskite thin film on the first carrier transport layer, a second carrier transport layer formation step of forming the second carrier transport layer on the perovskite thin film, a second electrode layer formation step of forming the second electrode layer on the second carrier transport layer, and a peeling step of peeling the film-deposited plate and the first resin layer.

[0013] This method makes it possible to provide a method for producing flexible perovskite solar cells that fully utilizes the flexibility of the perovskite film by using a UV-curable resin as the substrate, which is more flexible than commonly used substrates such as PEN film.

[0014] In addition, in the above-mentioned method for manufacturing a solar cell, in the first resin layer formation process and the second resin layer formation process, the first resin layer and the second resin layer may be formed by pressing a resin with glass whose surface has been treated with a release agent.

[0015] According to this method, a resin surface can be produced that takes advantage of the smoothness of the release-treated glass surface, and as a result, it is possible to provide a method for producing a flexible perovskite solar cell in which the film thickness distribution of each of the layers to be stacked on the resin surface, i.e., the first electrode layer, the first carrier transport layer, the perovskite thin film, the second carrier transport layer, and the second electrode layer, is uniform. Effect of the Invention

[0016] According to the present invention, it is possible to provide a flexible perovskite solar cell and a manufacturing method thereof, which have low adhesion to a film-deposited plate, enable peeling from the film-deposited plate by a first resin layer that reinforces the second resin layer, and ensure barrier properties by the second resin layer. [Brief description of the drawings]

[0017] [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] 5A to 5C are diagrams illustrating an example of a first resin layer forming step. [Figure 4] 6A to 6C are diagrams illustrating an example of a second resin layer forming step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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.

[0019] (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 thin film. 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.

[0020] 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.

[0021] The substrate 10 is a substrate made of a first resin layer 2 and a second resin layer 3. The first resin layer 2 is preferably flexible, light-transmitting, and insulating. The second resin layer 3 is preferably barrier, flexible, light-transmitting, insulating, and adhesive to the first resin layer. Examples of resin materials constituting the first resin layer 2 and the second resin layer 3 include UV (Ultraviolet) curable resins and thermosetting resins. Examples of resin materials constituting the first resin layer 2 and the second resin layer 3 include acrylic, silicone, epoxy, imide, urethane, methacrylic, ester, and fluorine. The first resin layer 2 may have barrier properties. The barrier properties here refer to the property of blocking gases, moisture, and the like. The barrier properties can be determined using the values ​​published by the manufacturer. If the manufacturer does not publish the values, they can be obtained from the values ​​actually measured.

[0022] The resin material constituting the first resin layer 2 desirably has a functional group that allows it to be peeled off from the film-deposited plate 100 in the peeling process due to a change in adhesion. The functional group that allows it to be peeled off is not particularly limited because it depends on the type of the film-deposited plate 100, but examples of such functional groups include alkyl groups, phenyl groups, hydroxy groups, ether groups, fluoro groups, alkoxy groups, acetyl groups, cyano groups, amide groups, imide groups, silyl groups, and ester groups. In addition, the resin material constituting the second resin layer 3 desirably has a functional group that does not react with the perovskite thin film 40. The functional group that does not react with the perovskite thin film 40 is not particularly limited because it depends on the components constituting the perovskite thin film, but examples of such functional groups include alkyl groups, phenyl groups, hydroxy groups, aldehyde groups, carbonyl groups, carboxy groups, ether groups, and fluoro groups.

[0023] The substrate 10 is not necessarily limited to two layers, and may have three or more resin layers, such as a third resin layer and a fourth resin layer, in addition to the first resin layer 2 and the second resin layer 3.

[0024] 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 film (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 and IWO (indium tungsten oxide) in which tungsten is added to indium oxide are widely known.

[0025] 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.

[0026] Specifically, in FIG. 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. The main materials of the first carrier transport layer 31 as the hole transport layer (HTL) are nickel oxide (NiO), copper oxide (Cu 2 O), PTAA(Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)), or Spiro-MeOTAD(N 2 ,N 2 ,N 2 ',N 2 ',N 7 ,N 7 ,N 7 ',N7'-octakis(4-methoxyphenyl)-9,9'-spirobi[9H-fluorene]-2,2',7,7'-tetramine) and the like.

[0027] 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. Titanium oxide (TiO 2 ), zinc oxide (ZnO), or tin oxide (SnO 2 ) etc.

[0028] 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. ABX 3 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.

[0029] Among these, in the case of the vapor deposition method (dry process), the organic atom A is methylammonium MA (CH 3 NH 3 ) is preferable, 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 is preferably methylammonium lead halide MAPbX 3 (CH 3 NH 3 PbX 3 ), e.g. MAPbI 3 , MAPbBr 3 , MAPbCl 3 The halogen atom X may include a plurality of types. For example, when the perovskite thin film 40 includes an 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) (CH 3 NH 3 PbI y X (3-y) ), e.g. MAPbI y Br (3-y) , MAPbI y Cl (3-y) etc. (y is any positive integer).

[0030] Methylammonium lead halide MAPbX 3 (CH 3 NH 3 PbX 3 ) thin film is lead halide PbX 2The material and the methylammonium halide MAX material are deposited in sequence, and the thin films of these materials are reacted at a reaction temperature. y X (3-y) (CH 3 NH 3 PbI y X (3-y) ) thin films are, for example, lead halide PbX 2 A thin film of methylammonium lead iodide (MAPbI) is formed by sequentially depositing a thin film of methylammonium lead iodide (MAI) and a thin film of methylammonium lead iodide (MAI) at a reaction temperature. 3 (CH 3 NH 3 PbI 3 ) The thin film is made of lead iodide (PbI 2 The material and methylammonium iodide (MAI) material are deposited in sequence, and the thin films of these materials are reacted at a reaction temperature to form the film.

[0031] 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.

[0032] 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. Titanium oxide (TiO 2 ), zinc oxide (ZnO), or tin oxide (SnO 2 ) etc.

[0033] 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. The main materials of the second carrier transport layer 32 as the hole transport layer (HTL) are nickel oxide (NiO), copper oxide (Cu 2 O), PTAA (Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)), or Spiro-MeOTAD.

[0034] 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.

[0035] With this configuration, the solar cell 1 generates a current according to light incident from the substrate 10 side, and outputs the current to the first electrode layer 21 and the second electrode layer 22.

[0036] (Solar Cell Manufacturing Method) Next, the method for manufacturing the solar cell of the present embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing an example of a first resin layer forming step for forming a first resin layer 2 on the substrate 10, and Fig. 4 is a diagram showing an example of a second resin layer forming step for forming a second resin layer 3 on the substrate 10.

[0037] First, a release agent is applied to the surface of a flat glass and dried to produce glass with release agent 101. This makes it easier for the resin and glass to be peeled off in the subsequent process. The components that make up the release agent are not particularly limited, but examples include oil / silicone-based, wax-based, surfactant-based, and fluorine-based agents.

[0038] Next, a film-coated plate 100 having rigidity and a smooth surface is prepared. The type of film-coated plate is not particularly limited, but examples thereof include a glass plate and a metal plate. Note that the film-coated plate 100 may be surface-treated so that the film-coated plate 100 and the substrate 10 can be easily peeled off in the peeling process described below. The surface treatment here may include, for example, application of a release agent.

[0039] Next, the first resin layer 2 is formed on the substrate 10 (first resin layer forming process). As shown in Fig. 3, a UV-curable resin for forming the first resin layer 2 is dropped onto the film-formed plate 100, and UV irradiation is performed while pressing the plate from above with glass 101 with a release agent, thereby curing the first resin layer 2. After curing, the glass 101 with the release agent is peeled off from the first resin layer 2.

[0040] Next, the second resin layer 3 is formed on the substrate 10 (second resin layer forming process). As shown in Fig. 4, a UV-curable resin for forming the second resin layer 3 is dropped onto the first resin layer 2, and UV irradiation is performed while pressing the second resin layer 3 from above with a glass 101 with a release agent, thereby curing the second resin layer 3. After curing, the glass 101 with a release agent is peeled off from the second resin layer 3.

[0041] Next, a transparent conductive film is formed on the second resin layer 3 as the first electrode layer 21 (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) using a vacuum chamber, an RPD method (reactive plasma deposition method), a sputtering method, or the like.

[0042] 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 (physical vapor deposition 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.

[0043] Next, the perovskite thin film 40 is formed on the first carrier transport layer 31 (perovskite thin film formation step). The method for forming the perovskite thin film 40 is not particularly limited, but examples thereof include a dry process such as a vapor deposition method, and a wet process such as a printing method, a coating method, or a solution method.

[0044] 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.

[0045] 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.

[0046] Next, a metal film is formed as the second electrode layer 22 on the second carrier transport layer 32 (second electrode layer forming step). The method for forming the metal film is not particularly limited, but examples thereof 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.

[0047] Next, the film-made plate 100 is peeled off from the substrate 10 (peeling step). The peeling method is not particularly limited, but examples thereof include mechanical peeling and thermal peeling.

[0048] As a result of the above, the flexible perovskite solar cell 1 of this embodiment shown in FIG. 1 or FIG. 2 is obtained.

[0049] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various changes and modifications are possible.

[0050] The above-described embodiment can also be applied to the manufacture of a perovskite 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 solar cell. EXAMPLES

[0051] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples. Example 1 Using the substrate formation method in the manufacturing method for a flexible perovskite solar cell of the present embodiment, a sample was produced as Example 1 in which a UV-curable resin was applied to a glass substrate (film-formed plate) as a substrate.

[0052] The resin used for the first resin layer was an acrylic UV-curable resin, and the resin used for the second resin layer was a silicone-acrylic UV-curable resin. The resin used for the first resin layer was selected to have low adhesion to glass.

[0053] As the glass with a release agent, a glass substrate was prepared by coating the surface with a fluorine-based release agent and drying it at room temperature for one and a half hours. The resin to be the first resin layer was dropped onto the film-formed plate and pressed with glass with a release agent, and then UV generated by a metal halide lamp (DYMAX, Porta-Ray400) was irradiated to harden the first resin layer. After hardening, the glass with the release agent was peeled off from the first resin layer. Next, the resin to be the second resin layer was dropped onto the first resin layer and pressed with glass with a release agent, and then UV generated by a metal halide lamp was irradiated to harden the second resin layer. After hardening, the glass with the release agent was peeled off from the second resin layer. The UV irradiation time was 1 minute for both the first resin layer and the second resin layer. The distance between the lamp and the sample was approximately 130 mm. The thickness of the first resin layer was approximately 150 μm, and the thickness of the second resin layer was approximately 150 μm. The thickness was adjusted by inserting a spacer when pressing from above with glass with a mold release agent. (Rating 1) When the substrate prepared in Example 1 was peeled off from the film-forming plate with tweezers, the first resin layer and the second resin layer could be peeled off together without tearing the film. [Explanation of symbols]

[0054] 1. Flexible perovskite solar cells 2.First resin layer 3.Second resin layer 10. Base material 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. Film plate 101.Glass with release agent

Claims

1. A method for manufacturing a solar cell having, in order, a first electrode layer, a first carrier transport layer, a perovskite thin film, a second carrier transport layer, and a second electrode layer on a first main surface side of the second resin layer not in contact with the first resin layer of a substrate consisting of a first resin layer and a second resin layer, a first resin layer forming step of forming the first resin layer on a film-forming plate; a second resin layer forming step of forming the second resin layer on the first resin layer; a first electrode layer forming step of forming the first electrode layer on the second resin layer; a first carrier transport layer forming step of forming the first carrier transport layer on the first electrode layer; a perovskite thin film forming step of forming the perovskite thin film on the first carrier transport layer; a second carrier transport layer forming step of forming the second carrier transport layer on the perovskite thin film; a second electrode layer forming step of forming the second electrode layer on the second carrier transport layer; a peeling step of peeling the film-formed plate and the first resin layer; The manufacturing method comprising the steps of:

2. 2. The method according to claim 1, wherein in the first resin layer forming step and the second resin layer forming step, the first resin layer and the second resin layer are formed by pressing the resin with glass whose surface has been treated with a release agent.

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