Method for manufacturing solar cell module, and solar cell module

Abstract

To provide a method of manufacturing a solar cell module capable of sufficiently improving an open voltage of the solar cell module, and to provide the solar cell module.SOLUTION: A manufacturing method of a solar battery module 1 in which a hole transport layer 11, a photoelectric conversion layer 12, and an electron transport layer 13 are laminated includes a step of preparing a first base material 14 on which a hole transport layer 11 is formed, a step of performing hydrophilic treatment on a surface of the hole transport layer 11 formed on the first base material 14, a step of adsorbing moisture on a surface of the hole transport layer 11, a step of forming a photoelectric conversion layer 12 from a precursor 12A of the photoelectric conversion layer 12 by heating the precursor 12A and evaporating the moisture adsorbed on the surface of the hole transport layer 11, a step of forming a plurality of pores 2 on an interface 25 of the photoelectric conversion layer 12 in contact with the hole transport layer 11 by forming the moisture on the surface of the hole transport layer 11, and a step of forming the electron transport layer 13 on the surface of the photoelectric conversion layer 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a solar cell module, and to a solar cell module. [Background technology]

[0002] As an example of this type of technology, Patent Document 1 discloses a method for manufacturing a perovskite solar cell. This manufacturing method includes the steps of applying a solution that is a precursor of the perovskite layer to the surface of the hole transport layer and drying the applied solution to form a perovskite layer from the solution. This hole transport layer contains nickel oxide, and prior to applying the precursor of the perovskite layer, the nickel oxide is further oxidized to form nickel vacancies in the hole transport layer. This can improve the hole extraction efficiency of the hole transport layer. Note that these nickel vacancies are electronic vacancies, not physical vacancies. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-538996 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the perovskite solar cell manufactured by the manufacturing method shown in Patent Document 1, the improvement in open circuit voltage is insufficient, and there is room for improvement.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a method for manufacturing a solar cell module that can improve the open-circuit voltage of the solar cell module, and a solar cell module. [Means for solving the problem]

[0006] Incidentally, when manufacturing this type of solar cell module, it has generally been thought that forming a photoelectric conversion layer so as not to form physical voids will result in stable power generation performance. However, in light of the above-mentioned problems, the inventors conducted extensive research and discovered a new finding that providing physical voids at specific positions in the photoelectric conversion layer improves the open-circuit voltage of the solar cell module. The present invention is based on this new finding of the inventors. Note that hereinafter, in this application, voids refer to physical voids unless otherwise specified.

[0007] Based on this finding, the present invention provides a method for manufacturing a solar cell module including a stack of a hole transport layer, a photoelectric conversion layer, and an electron transport layer, the method comprising the steps of: preparing a substrate on which the hole transport layer is formed; hydrophilizing the surface of the hole transport layer formed on the prepared substrate; adsorbing moisture onto the hydrophilized surface of the hole transport layer; applying a precursor of the photoelectric conversion layer to the surface of the hole transport layer on which the moisture has been adsorbed; heating the applied precursor to form the photoelectric conversion layer from the precursor and evaporating the moisture adsorbed on the surface of the hole transport layer to form a plurality of voids at the interface of the photoelectric conversion layer in contact with the hole transport layer; and forming the electron transport layer on the surface of the photoelectric conversion layer.

[0008] The method for manufacturing a solar cell module according to the present invention involves adsorbing moisture onto the surface of a hydrophilically treated hole transport layer, then applying a precursor of the photoelectric conversion layer to the surface of the hole transport layer to which the moisture has been adsorbed, and then heating the surface. This heating evaporates the moisture adsorbed on the surface of the hole transport layer, thereby forming multiple voids at the interface of the photoelectric conversion layer in contact with the hole transport layer. In a solar cell module with such voids, when the photoelectric conversion layer is irradiated with light such as sunlight, the light energy is converted to generate free electrons and holes. The holes migrate from the photoelectric conversion layer to the hole transport layer. Since the holes cannot pass through the voids formed at the interface of the photoelectric conversion layer in contact with the hole transport layer, they migrate by avoiding the voids. Therefore, the holes tend to gather between the voids, thereby suppressing non-radiative recombination at the interface. As a result, the open-circuit voltage of a solar cell module manufactured by this manufacturing method can be improved.

[0009] Here, as long as pores can be formed by the hydrophilization treatment and water adsorption, the specific treatment method for the hydrophilization treatment is not particularly limited, and may be, for example, a non-contact hydrophilization treatment such as plasma treatment, ultraviolet ray ozone treatment, or corona treatment, or a chemical treatment in which a hydrophilizing agent is brought into contact, etc. However, in a more preferred embodiment, the hydrophilization treatment is carried out by plasma treatment or ultraviolet ray ozone treatment in the step of hydrophilizing the surface of the hole transport layer.

[0010] According to this aspect, it is easy to adsorb moisture floating in the atmosphere onto the surface of the hole transport layer, and it is also easy to uniformly apply the precursor to the surface of the hole transport layer on which moisture has been adsorbed. In particular, by performing hydrophilization treatment using plasma treatment, it is possible to adsorb moisture floating in the atmosphere in a short time.

[0011] Here, examples of the plasma treatment include atmospheric pressure plasma treatment and vacuum plasma treatment. In a more preferred embodiment, the plasma treatment is vacuum plasma treatment, and in the vacuum plasma treatment, the integrated intensity representing the irradiation intensity per unit irradiation area of ​​the plasma is 509 mJ / cm. 2 The plasma is irradiated onto the surface of the hole transport layer so as to achieve the above.

[0012] According to this aspect, in the manufactured solar cell module, the plurality of voids can be formed so that the ratio of the total length of the surface of the hole transport layer adjacent to the plurality of voids to the total length of the hole transport layer facing the photoelectric conversion layer is 20% or more in a cross section obtained by cutting the hole transport layer and the photoelectric conversion layer along the thickness direction, thereby improving the open circuit voltage of the solar cell module.

[0013] Furthermore, as long as a plurality of pores can be formed, the upper limit of the integrated intensity in the vacuum plasma treatment is not particularly limited. However, in a more preferred embodiment, the integrated intensity in the vacuum plasma treatment is 1528 mJ / cm 2 The plasma is irradiated onto the surface of the hole transport layer as follows.

[0014] According to this aspect, in the manufactured solar cell module, the plurality of voids can be formed so that the ratio of the total length of the surface of the hole transport layer adjacent to the plurality of voids to the total length of the hole transport layer facing the photoelectric conversion layer is 30% or less on a cut surface obtained by cutting the hole transport layer and the photoelectric conversion layer along the thickness direction. As a result, even when a plurality of solar cell modules are manufactured, an increase in the series resistance of each solar cell module can be stably suppressed.

[0015] In addition, in view of the above-mentioned problems, the solar cell module of the present invention is a solar cell module in which a hole transport layer, a photoelectric conversion layer, and an electron transport layer are stacked, and the plurality of voids are formed at the interface of the photoelectric conversion layer that contacts the hole transport layer.

[0016] According to the present invention, when holes converted from light in the photoelectric conversion layer move from the photoelectric conversion layer to the hole transport layer, they avoid vacancies formed at the interface of the photoelectric conversion layer in contact with the hole transport layer. Therefore, the holes are more likely to move densely between multiple vacancies. This makes it possible to suppress non-radiative recombination at the interface between the photoelectric conversion layer and the hole transport layer. As a result, the open-circuit voltage of the solar cell module can be improved.

[0017] In consideration of the improvement in the open-circuit voltage of the solar cell module due to such voids, the proportion of the voids is not limited as long as the voids are formed at the interface of the photoelectric conversion layer in contact with the hole transport layer. However, in a more preferred embodiment, in a cross section obtained by cutting the hole transport layer and the photoelectric conversion layer along the thickness direction, the proportion of the total length of the surface of the hole transport layer adjacent to the plurality of voids to the entire length of the hole transport layer facing the photoelectric conversion layer is 20% or more.

[0018] According to this embodiment, by setting the pore formation rate to 20% or more, holes are concentrated between the pores and tend to flow more easily, thereby enabling a further improvement in the open circuit voltage of the solar cell module.

[0019] In a more preferred embodiment, the ratio of the total length of the surface of the hole transport layer adjacent to the plurality of holes to the total length of the hole transport layer facing the photoelectric conversion layer is 30% or less.

[0020] According to this aspect, even when a plurality of solar cell modules are manufactured, an increase in the series resistance of each solar cell module can be stably suppressed. [Effects of the Invention]

[0021] According to the present invention, the open circuit voltage of the solar cell module can be improved. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing a cross-sectional configuration of a solar cell module according to an embodiment of the present invention. [Figure 2] 1A and 1B are schematic diagrams for explaining the effects achieved by the solar cell module according to the present embodiment. [Figure 3] 3 is a flowchart showing a method for manufacturing a solar cell module according to the present embodiment. [Figure 4A] FIG. 4 is an explanatory diagram corresponding to step S1 shown in the flowchart of FIG. [Figure 4B] FIG. 4 is an explanatory diagram corresponding to step S2 shown in the flowchart of FIG. [Figure 4C] FIG. 4 is an explanatory diagram corresponding to step S3 shown in the flowchart of FIG. [Figure 4D] FIG. 4 is an explanatory diagram corresponding to step S4 shown in the flowchart of FIG. [Figure 4E] FIG. 4 is an explanatory diagram corresponding to step S5 shown in the flowchart of FIG. [Figure 5A] FIG. 4F is a schematic diagram for explaining the step shown in FIG. 4E in more detail. [Figure 5B] FIG. 4F is a schematic diagram for explaining the step shown in FIG. 4E in more detail. [Figure 6] 1(A) and 1(B) are cross-sectional structural photographs of the hole transport layer and the photoelectric conversion layer of the solar cell modules according to Example 1-1 and Comparative Example 1, respectively. [Figure 7] 1 is a table showing evaluation results of pore formation rates and power generation performance for Examples 1-1 to 1-3 and Comparative Example 1. [Figure 8] 2A is a graph showing the open circuit voltage of the solar cell modules according to Examples 2-1 to 2-6 and Comparative Example 2. FIG. 2B is a graph showing the series resistance of the solar cell modules according to Examples 2-1 to 2-6 and Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0023] [Embodiment] Hereinafter, embodiments of the present invention will be described in detail with reference to Figures 1 to 5B. Note that the embodiment described below is one aspect of the present invention and does not limit the technical scope of the present invention.

[0024] <Configuration> FIG. 1 is a schematic diagram showing a cross-sectional configuration of a solar cell module 1 according to this embodiment. The solar cell module 1 includes a layered power generation section 10. The power generation section 10 is a section in which a hole transport layer 11, a photoelectric conversion layer 12, and an electron transport layer 13 are sequentially stacked. The solar cell module 1 includes first and second electrodes 15 and 16. A first electrode 15 is formed on one surface of the power generation section 10 (specifically, on the surface of the hole transport layer 11), and a second electrode 16 is formed on the other surface (specifically, on the surface of the electron transport layer 13). In this embodiment, the solar cell module 1 further includes first and second base materials 14 and 18 that sandwich the power generation section 10 on which the first and second electrodes 15 and 16 are formed. The first base material 14 is disposed in contact with the first electrode 15, and the second base material 18 is disposed on the side of the second electrode 16. The solar cell module 1 further includes an adhesive sealant 17 that fills the gap between the first base material 14 and the second base material 18 and seals the power generation section 10 and the like entirely.

[0025] The first base material 14 is made of a light-transmitting material such as glass or resin. Examples of light-transmitting resins include polyimide resin, polyamide resin, and polyethylene terephthalate resin. Here, the first base material 14 corresponds to the base material in the present invention, and may be in the form of a substrate, a sheet, or a film. When the solar cell module 1 is flexible, the first base material 14 is preferably a resin film.

[0026] The first electrode 15 is a positive electrode that collects holes H and is made of a transparent conductive oxide (TCO) that is conductive and optically transparent. Examples of transparent conductive oxides include indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof. Among these, indium-based composite oxides containing indium oxide as the main component are preferred from the viewpoint of high conductivity and transparency, and elements such as Sn, W, Zn, and Ti may be further added as dopants. In this embodiment, the first electrode 15 is made of a translucent metal oxide material, such as ITO (indium tin oxide) or IZO (indium zinc oxide).

[0027] The second substrate 18 may be in the form of a substrate, sheet, or film and may be made of the same material as the first substrate 14. In this embodiment, because the solar cell module 1 receives light, such as sunlight, from the first substrate 14, the second substrate 18 does not need to be optically transparent. Similarly, the second electrode 16 is a paired electrode with the first electrode 15 and is a negative electrode in this embodiment. The second electrode 16 may be made of the same material as the first electrode 15, but for the same reason, the second electrode 16 also does not need to be optically transparent. In this case, the second electrode 16 is preferably made of a metal such as copper, silver, gold, or platinum, and may have a multilayer structure including, for example, the above-mentioned transparent conductive oxide layer. However, when a tandem solar cell unit is adopted in which a silicon-based solar cell module is further disposed opposite the power generation unit 10 of the solar cell module 1, the second substrate 18 and the second electrode 16 are made of a material with the same optical transparency as the first substrate 14 and the first electrode 15.

[0028] The first and second electrodes 15, 16 may be formed, for example, by vapor deposition, or by applying a solution or dispersion corresponding to a precursor of the electrodes and then drying it. The formation method is a commonly known method and is not particularly limited.

[0029] The hole transport layer 11 is formed of, for example, a p-type semiconductor, and is a layer that receives charges (holes) generated in the photoelectric conversion layer 12 and transfers them to the first electrode 15. The hole transport layer 11 is optically transparent and mainly made of PTAA (Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)), Fluoro-PTAA, Poly-TPD ([N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine]), F8BT ([Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)]]), or the like.

[0030] The photoelectric conversion layer 12 is capable of converting irradiated light energy into electrical energy and is a layer that absorbs light received by the solar cell module 1 and converts it into free electrons and holes. In this embodiment, the photoelectric conversion layer 12 is capable of converting irradiated light energy into electrical energy and is primarily made of a compound having a perovskite crystal structure. In this embodiment, a perovskite layer is exemplified as the photoelectric conversion layer 12 below, but the photoelectric conversion layer 12 is not particularly limited as long as it can convert absorbed light into electrons and holes. In this embodiment, the photoelectric conversion layer 12 is a perovskite layer and is primarily made of a compound having a perovskite crystal structure. Examples of this compound include methylammonium lead halide and methylammonium lead iodide. Alternatively, some of the halogen atoms may contain bromine atoms or chlorine atoms.

[0031] The electron transport layer 13 is formed of, for example, an n-type semiconductor, and is a layer that receives charges (free electrons) generated in the photoelectric conversion layer 12 and transfers them to the second electrode 16. The electron transport layer 13 contains PCBM ([6,6]-Phenyl-C61-Butylic Acid Methyl Ester) or BCP (Bathocuproine) as a main material. The electron transport layer 13 may be a layer in which a layer of PCBM and a layer of BCP are stacked.

[0032] At the interface 25 of the photoelectric conversion layer 12 in contact with the hole transport layer 11, a plurality of (n) voids 21, which are hollow portions, are formed. In this embodiment, the size and proportion of the plurality of voids 21 are defined in a cross section obtained by cutting the hole transport layer 11 and the photoelectric conversion layer 12 along the thickness direction. Specifically, as shown in FIG. 1, when n voids 21 are formed, the length of the surface 11a of the hole transport layer 11 adjacent to the void 21 is a1 to a n Each of these ranges from several hundred nm to several μm. The thickness of the photoelectric conversion layer 12 is 100 nm or more and 1000 nm or less, and the height of the pores 21 is preferably 20% or more and 50% or less of the thickness of the photoelectric conversion layer 12, for example, to more easily exhibit the effects described below. The multiple pores 21 are densely packed within a range of several tens of μm, and are formed in an island shape (dentrite shape) due to the method of forming the pores 21 described later. As will be described in detail in the examples described later, the pore formation rate is preferably 20% or more, and more preferably 30% or less. The pore formation rate referred to here is the ratio of a1 to a n The ratio of the sum of (i.e., a1 to a n (The value obtained by dividing the sum of the voids 21 by L and multiplying the result by 100. In the embodiment of the present application, the void formation rate is defined as above, but this void formation rate may be specified at any cross section of the hole transport layer 11 and the photoelectric conversion layer 12 along the layer thickness direction. It is difficult to measure the total surface area of ​​the photoelectric conversion layer 12 adjacent to the voids 21 at the interface between the hole transport layer 11 and the photoelectric conversion layer 12. In addition, since there is a correlation between the void formation rate defined above and the power generation performance of the solar cell module 1 in the examples described later, the inventors defined the void formation rate in this way.

[0033] Using FIG. 2 , the general principle of power generation by the solar cell module 1 according to this embodiment and the unique effects of the solar cell module 1 will be described. First, when sunlight or other light is irradiated from the first base material 14 side of the solar cell module 1, as described above, the hole transport layer 11, the first base material 14, and the first electrode 15 are translucent, so the light passes through these parts and reaches the photoelectric conversion layer 12. Of the light that reaches the photoelectric conversion layer 12, specific wavelengths are absorbed by the photoelectric conversion layer 12. The absorbed light is converted into a plurality of holes H and free electrons E. The converted holes H and free electrons E move to the hole transport layer 11 and the electron transport layer 13, respectively, and are then collected by the first electrode 15 and the second electrode 16. This allows the solar cell module 1 to generate electricity.

[0034] Here, when holes H move to the hole transport layer 11, they cannot pass through the vacancies 21 because the vacancies 21 are hollow portions. Therefore, the holes H move to the hole transport layer 11, avoiding the vacancies 21. As a result, the holes H tend to gather between the vacancies 21, which can suppress non-radiative recombination at the interface 25 of the photoelectric conversion layer 12. As a result, the open-circuit voltage of the solar cell module 1 can be improved. The appropriate range of the vacancy formation rate at the interface 25 will be explained in the examples below.

[0035] <Manufacturing method> The method for manufacturing the solar cell module 1 according to this embodiment will be described using the flowchart shown in FIG. 3, with reference to FIGS. 4A to 5E for the main steps. First, in step S1, a first base material 14 having a hole transport layer 11 and a first electrode 15 formed thereon is prepared. Specifically, as shown in FIG. 4A, the first electrode 15 is formed on the surface of the first base material 14 by the method described above, and the hole transport layer 11 is formed so as to cover the surface of the first electrode 15. To form the hole transport layer 11, a solution of an organic substance such as the above-described PTAA is applied to the first base material 14 having the first electrode 15 formed thereon, and the precursor (solution) that becomes the hole transport layer 11 is dried.

[0036] Next, in step S2, the surface 11a of the hole transport layer 11 formed on the prepared first substrate 14 is hydrophilized. An example of hydrophilization using vacuum plasma treatment will be described below. Specifically, as shown in FIG. 4B, the first substrate 14 on which the hole transport layer 11 and other components are formed is placed in a chamber 3, and a vacuum is drawn using a vacuum pump (not shown) via an exhaust pipe 31 to reduce the pressure in a space E1 within the chamber 3. Next, plasma P is supplied to the space E1 via a supply pipe 32, and the surface 11a of the hole transport layer 11 is irradiated with the plasma P. The vacuum plasma treatment can increase the number of functional groups that contribute to hydrophilicity on the surface 11a, thereby improving the hydrophilicity of the surface 11a.

[0037] This hydrophilization treatment is a treatment that enhances surface modification so that the surface 11a of the hole transport layer 11 has higher hydrophilicity than a hydrophilization treatment that aims only to increase the wettability of the solution that becomes the precursor 12A of the photoelectric conversion layer 12. That is, in this embodiment, the surface 11a of the hole transport layer 11 is irradiated with plasma P having higher energy than in a hydrophilization treatment that aims only to increase the wettability of the solution that becomes the precursor 12A of the photoelectric conversion layer 12, thereby increasing the hygroscopicity (water adsorption) of the surface 11a of the hole transport layer 11. By performing the vacuum plasma treatment, the hydrophilicity of the surface 11a of the hole transport layer 11 can be increased in a shorter treatment time.

[0038] Such hydrophilic treatment may be atmospheric pressure plasma treatment, which is a plasma treatment, or ultraviolet (UV) ozone treatment. When the hydrophilic treatment is UV ozone treatment, the hydrophilic treatment may be performed for a longer treatment time than the usual hydrophilic treatment (such as Comparative Example 1 described later).

[0039] Next, in step S3, moisture 22 is adsorbed onto the surface 11a of the hydrophilized hole transport layer 11. Specifically, as shown in FIG. 4C, the space E2 in the chamber 4 is humidified to a predetermined humidity level, and the first substrate 14 on which the hydrophilized hole transport layer 11 and other components are formed is placed in the chamber 4. When the hydrophilized surface 11a is exposed to the humidified atmosphere, moisture suspended in the space E2 is adsorbed onto the surface 11a of the hole transport layer 11. That is, in step S3, moisture present around the surface 11a of the hole transport layer 11 is absorbed by the surface 11a, resulting in minute moisture particles being uniformly adsorbed onto the surface 11a of the hole transport layer 11. Unlike condensed water, the moisture adsorbed onto the surface 11a of the hole transport layer 11 is in an amount that is not visible as droplets. Note that, hereinafter, the surface 11a on which moisture 22 is adsorbed will be referred to as surface 11b.

[0040] In step S3, the amount of moisture adsorbed onto the surface 11a of the hole transport layer 11 can be controlled by controlling the humidity in the space E2 in the chamber 4 and the time for introducing the hole transport layer 11 into the space E2. However, if the amount of moisture adsorbed onto the surface 11a of the hole transport layer 11 can be controlled, moisture may be adsorbed onto the surface 11a of the hole transport layer 11 without storing it in the chamber 4.

[0041] Next, in step S4, a precursor 12A of the photoelectric conversion layer 12 is applied to the surface 11b of the hole transport layer 11 that has adsorbed moisture 22. Specifically, as shown in FIG. 4D , the ink-like precursor 12A of the photoelectric conversion layer 12 is applied to the surface 11b by, for example, a die coating method. More specifically, the precursor 12A is supplied into the slit die 5, and while the slit die 5 or the hole transport layer 11 is relatively moved in a direction perpendicular to the plane of the paper in FIG. 4D , the precursor 12A is discharged from the inside of the slit die 5, and the precursor 12A is uniformly applied to the surface 11b.

[0042] In the manufacturing method of the solar cell module 1 according to this embodiment, the precursor 12A is applied by die coating. However, the application method is not limited as long as the precursor 12A can be applied to a uniform thickness. For example, the precursor 12A may be applied by inkjet printing, spraying, spin coating, or other methods. Examples of the precursor 12A include an ink (solution) prepared by dissolving lead iodide or methylammonium iodide in a solvent such as DMF or DMSO. The applied precursor 12A coating is heated and dried. During the solvent evaporation process, the constituent ions crystallize into perovskite-type crystals. Before proceeding to step S5, a solvent (poor solvent) that does not easily dissolve the perovskite compound may be dropped into the applied precursor 12A (solution) to promote the formation of seed crystals of the perovskite compound. This allows for the production of a perovskite layer (photoelectric conversion layer 12) with good film quality, thereby improving the conversion efficiency of the solar cell module 1.

[0043] Next, in step S5, the applied precursor 12A is heated to form the photoelectric conversion layer 12 from the precursor 12A. At the same time, the moisture 22 adsorbed on the surface 11a of the hole transport layer 11 is evaporated, thereby forming a plurality of pores 21 at the interface 25 of the photoelectric conversion layer 12 that contacts the hole transport layer 11.

[0044] Specifically, as shown in FIG. 4E, a first substrate 14 having a precursor 12A applied to the surface 11b of the hole transport layer 11 is placed in a chamber 6 having a heater 61 provided thereon. By operating the heater 61, the temperature of the space E3 within the chamber 6 is raised, and by placing the first substrate 14 into the chamber 6, the precursor 12A is heated. As a result, as shown in FIG. 5A, the moisture 22 adsorbed on the surface 11b thermally expands, and further, as shown in FIG. 5B, the constituent ions of the precursor 12A crystallize into perovskite-type crystals, forming the photoelectric conversion layer 12.

[0045] Specifically, as shown in Fig. 5A, before the constituent ions of precursor 12A crystallize, moisture 22 adsorbed on surface 11b of hole transport layer 11 expands in volume due to heat, pushing away precursor 12A in contact with surface 11b of hole transport layer 11. In this state, crystallization of the constituent ions of precursor 12A progresses, and as shown in Fig. 5B, a plurality of voids 21 are formed at interface 25 of photoelectric conversion layer 12 that contacts hole transport layer 11. In step S5, first substrate 14 may be heated directly with a heater (heating plate) without using chamber 6 shown in Fig. 4E.

[0046] Here, the pores 21 are formed so as to recess from the interface 25 toward the photoelectric conversion layer 12, and there are many of them. The pore formation rate of the pores 21 described above can be adjusted as follows. Specifically, the amount of moisture 22 adsorbed on the surface 11b of the hole transport layer 11 can be adjusted by changing either the irradiation intensity and irradiation time (i.e., cumulative intensity) of the plasma P or the like in step S2, or the humidity and exposure time in the exposure atmosphere in step S3. For example, increasing the cumulative intensity of the plasma P in step S2 increases the number of functional groups contributing to hydrophilicity, thereby increasing the amount of moisture 22 adsorbed. Similarly, increasing the humidity in the exposure atmosphere in step S3 or extending the exposure time increases the amount of moisture 22 adsorbed. In this way, the number and size of the pores 21 formed can be changed depending on the amount of moisture 22 adsorbed on the surface 11b of the hole transport layer 11. As a result, the pore formation rate of the pores 21 can be adjusted.

[0047] Next, in step S6, an electron transport layer 13 is formed from a precursor for the electron transport layer (not shown) using a method similar to the method for forming the hole transport layer 11 (the method described in step S1). Next, in step S7, a second electrode 16 is formed so as to be in contact with the electron transport layer 13. Finally, in step S8, the hole transport layer 11, photoelectric conversion layer 12, electron transport layer 13, etc. are sealed with an adhesive sealant 17. Then, a second base material 18 is adhered to the adhesive sealant 17, thereby completing the solar cell module 1. [Example]

[0048] Hereinafter, with reference to the drawings of FIGS. 6 to 8, examples of specific implementations of the present invention will be described together with comparative examples.

[0049] Example 1-1 A test specimen (hereinafter referred to as "test specimen") of the solar cell module 1 according to Example 1-1 was manufactured using the manufacturing method described below. A first electrode 15 (hereinafter referred to as "ITO 15") made of ITO was formed by sputtering on a first base material 14 (hereinafter referred to as "glass substrate 14") made of alkali-free glass. The transmittance in the visible region was 85% or more, and the sheet resistance was 10 Ω / or less. The glass substrate 14 with ITO 15, which had been processed into an arbitrary pattern by lithography, was subjected to wet cleaning using ultrasonic cleaning in 1-propanol and then ethanol. Next, dry cleaning was performed using a UV ozone generator ASM401OZ (manufactured by Asumi Giken) at 300 mW for 10 minutes.

[0050] Next, a hole transport layer 11 was formed on the surface of the glass substrate 14 with the ITO 15. Specifically, an HTL ink (precursor of the hole transport layer 11) prepared by dissolving 5.0 mg / ml of PTAA in 1-chlorobenzyl alcohol was dropped onto the ITO 15, and then a film was formed by spin coating at 2000 rpm for 40 seconds. Thereafter, the glass substrate 14 was placed on a hot plate, and the formed precursor was heated and dried at 100°C for 10 minutes, thereby forming the hole transport layer 11.

[0051] The surface 11a of the obtained hole transport layer 11 was subjected to hydrophilization treatment. Specifically, using a vacuum plasma device YHS-R (manufactured by Kaisha Semiconductor), the surface 11a of the hole transport layer 11 was irradiated with plasma P under the conditions of an irradiation range of 100 mm in diameter, an irradiation intensity of 40 W, and an irradiation time of 1 second. That is, under these conditions, in the vacuum plasma treatment, the integrated intensity representing the irradiation intensity of plasma P per unit irradiation area was 509 mJ / cm. 2The irradiation intensity of 40 W is higher than the irradiation intensity in a general hydrophilization treatment of the surface 11a of the hole transport layer 11, and this integrated intensity is higher than the integrated intensity in a general hydrophilization treatment.

[0052] Next, a glass substrate 14 including a hydrophilic hole transport layer 11 was placed under conditions of 25°C and 65% humidity for a certain period of time (specifically, 1 minute), and the surface 11a of the hydrophilic hole transport layer 11 was allowed to absorb moisture, thereby adsorbing moisture onto the surface 11a of the hole transport layer 11.

[0053] Next, a precursor 12A of the perovskite layer was applied to the surface 11b of the hole transport layer 11. The precursor 12A was in ink form and was prepared by using a 4:1 mixture of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) as the solvent. The solutes, lead iodide, cesium iodide, formamidine hydroiodide, and methylamine hydroiodide, were added at 1.2 M and heated at 150°C for 10 minutes. The precursor 12A was then dropped onto the surface 11b of the moisture-absorbed hole transport layer 11, and a film was formed by spin coating at 1000 rpm for 10 seconds and then at 6000 rpm for 20 seconds. To promote the formation of perovskite crystal nuclei, 200 μL of 1-chlorobenzene was dropped onto the surface 11b of the rotating hole transport layer 11 5 seconds before the end of spin coating. This was used as a poor solvent treatment. After the rotation was completed, the glass substrate 14 on which the film of precursor 12A had been formed was placed on a hot plate, and the formed film of precursor 12A was heated and dried at 100°C for 60 minutes to form a photoelectric conversion layer 12 (perovskite layer).

[0054] Next, an electron transport layer 13 was formed on the surface of the perovskite layer. Here, a film consisting of a layer of PCBM ([6,6]-Phenyl-C61-Butylic Acid Methyl Ester) and a layer of BCP (Bathocuproine) was formed as the electron transport layer 13. Specifically, an ink in which PCBM was dissolved at 12.0 g / L in 1-chlorobenzene was dropped onto the surface of the photoelectric conversion layer 12, and a film was formed by spin coating at 8000 rpm for 30 seconds, followed by heating and drying on a hot plate at 100 °C for 10 minutes. Next, an ink in which BCP was dissolved at 1.0 g / L in ultra-dehydrated 2-propanol was dropped onto the surface of the PCBM layer, and a film was formed by spin coating at 4000 rpm for 30 seconds, followed by drying.

[0055] In order to remove unnecessary portions of the power generation section 10 consisting of the hole transport layer 11, photoelectric conversion layer 12, and electron transport layer 13 formed on the surface of the glass substrate 14, trimming processing was performed using a UV laser processing machine MD-U1020C (manufactured by Keyence) with a laser wavelength of 355 nm, a laser output of 1.5 W, a sweep speed of 1500 mm / sec, and a frequency of 80 kHz.

[0056] Next, a silver electrode having a thickness of 100 nm was formed as the second electrode 16, which was an opposing electrode to the ITO 15. Specifically, a silver electrode having a thickness of 1.0×10 -3 A second electrode 16 made of silver was formed by depositing silver on the surface of the electron transport layer 13 by thermal evaporation under a high vacuum of 100 Pa or less. Finally, a barrier film PT / 25GT3 (manufactured by Oike Advanced Films) with low water vapor permeability was prepared as the second base material 18, and an adhesive sheet material TESA61562 (manufactured by Tesa Tape) was prepared as the adhesive sealant 17. Here, to prevent deterioration of the power generation unit 10 due to moisture and oxygen in the air, the adhesive sealant 17 was thermally laminated to the glass substrate 14 on which the power generation unit 10 was formed, together with the second base material 18, to completely seal the power generation unit 10 and the like.

[0057] Example 1-2 A test specimen was prepared in the same manner as in Example 1-1. Example 1-2 differs from Example 1-1 in that the plasma P was irradiated for 2 seconds, and the cumulative intensity was increased to 1018 mJ / cm2. 2 The point is that the surface was subjected to a hydrophilic treatment using vacuum plasma treatment.

[0058] Examples 1-3 A test specimen was prepared in the same manner as in Example 1-1. Example 1-3 differs from Example 1-1 in that the plasma P was irradiated for 3 seconds, and the cumulative intensity was 1528 mJ / cm 2 The point is that a hydrophilic treatment was carried out by vacuum plasma treatment.

[0059] Comparative Example 1 A test specimen was prepared in the same manner as in Example 1-1. Comparative Example 1 is a comparative example for evaluating the optimal hydrophilic treatment method. Comparative Example 1 differs from Example 1-1 in that the hydrophilic treatment method was UV ozone treatment and that moisture was not adsorbed. Specifically, the UV ozone treatment was carried out under the conditions of an irradiation range of 120 mm in diameter, an irradiation intensity of 300 mW, and an irradiation time of 3 minutes. That is, under these conditions, in the UV ozone treatment, the integrated intensity, which represents the irradiation intensity per unit irradiation area, was 378 mJ / cm. 2 This means that hydrophilic treatment has been carried out.

[0060] <Results of cross-sectional observation> The cross sections of the specimens according to Examples 1-1 to 1-3 and Comparative Example 1 were observed using a scanning electron microscope (SEM). FIG. 6(A) shows a structural photograph of the cross section of the specimen according to Example 1-1, and FIG. 6(B) shows a structural photograph of the cross section of the specimen according to Comparative Example 1. As shown in FIG. 6(A), the specimen according to Example 1-1 had multiple voids 21 formed at the interface 25 of the photoelectric conversion layer 12 in contact with the hole transport layer 11. On the other hand, as shown in FIG. 6(B), the specimen according to Comparative Example 1 had no voids 21 formed at the interface 25 of the photoelectric conversion layer 12 in contact with the hole transport layer 11. Note that the specimens according to Examples 1-2 and 1-3 also had voids 21 formed at the interface 25 of the photoelectric conversion layer 12 in contact with the hole transport layer 11. Furthermore, the void formation rate of the voids 21 was measured from the cross sections of the specimens according to Examples 1-1 to 1-3. The results are shown in FIG. 7. As shown in FIG. 7, it was found that the void formation rate increased in proportion to the increase in the integrated intensity of the vacuum plasma treatment.

[0061] <Consideration> From the above, it was found that, as in Examples 1-1 to 1-3, when forming voids 21 at the interface 25, it is effective to apply a vacuum plasma treatment as a hydrophilic treatment and then adsorb moisture onto the surface 11a of the hole transport layer 11. The UV ozone treatment in Comparative Example 1 is a treatment intended solely to improve the wettability of the surface 11a of the hole transport layer 11 to the precursor 12A of the perovskite layer. Therefore, without a hydrophilic treatment such as UV ozone treatment, it is difficult to apply the precursor 12A of the perovskite layer with a uniform thickness, making it difficult to form a perovskite layer. However, if the hydrophilic treatment is performed for an irradiation time several times to several tens of times longer than that of Comparative Example 1 so as not only to improve the wettability of the surface 11a of the hole transport layer 11 but also to adsorb moisture floating in the atmosphere onto the surface 11a of the hole transport layer 11, it is believed that voids can be formed by the hydrophilic treatment using UV ozone treatment.

[0062] <Evaluation of power generation performance> Next, the test specimens according to Examples 1-1 to 1-3 and Comparative Example 1 were covered with a shadow mask having an opening smaller than the effective power generation area. Next, a solar simulator XI-05A1V2-L (manufactured by SERIC) was used to simulate sunlight 1 SUN (1000 W / m 2 ) using a source meter Keithley 2401 (Keithley) to sweep back and forth from -0.2 V to +1.2 V, and obtain the current value at each voltage to measure the power generation efficiency. The results are shown in Figure 7.

[0063] Regarding the power generation performance parameters shown in Figure 7, V OC is the open circuit voltage, J SC represents the short-circuit current density, FF represents the fill factor, and PCE represents the quantum efficiency. Note that each value of Examples 1-1 to 1-3 shown in FIG. 7 is a value (normalized value) divided by the value of Comparative Example 1. Therefore, these values ​​are ratios where each value of Comparative Example 1 is set to 1.00. As mentioned above, FIG. 7 also shows that applying vacuum plasma treatment as a hydrophilic treatment is advantageous when forming pores 21 at the interface 25. In addition, when the integrated intensity is 509 mJ / cm 2 to 1528 mJ / cm 2 It can be seen that by adjusting the irradiation time and irradiation intensity of the plasma P so that the void formation rate falls within the range of 20% to 30%, voids 21 can be formed at the interface 25 so that the void formation rate falls within the range of 20% to 30%. Furthermore, by setting the void formation rate within the range of 20% to 30%, V OC It can be seen that the PCE improves. OC and J SC and FF, and V OC It can be seen that the PCE also improves with the increase in V. OC Even if the improvement of J SC The decrease in FF is small, and V OC It can also be seen that the PCE is improved to the extent that the pore formation rate is improved. Since the variation in each value of the power generation performance in Examples 1-1 to 1-3 is small, it can be seen that the pore formation rate is improved regardless of the value as long as it is in the range of 20% to 30%. OCIt can be said that this will contribute to improving

[0064] Below, test specimens according to Example 2-1 to Example 2-6 and Comparative Example 2 were manufactured. In these examples, the variation in power generation performance of solar cell modules manufactured under the same conditions was confirmed, and in Examples 2-3 to 2-6, the power generation performance of solar cell modules after further hydrophilization treatment was confirmed.

[0065] [Examples 2-1 to 2-3] Four specimens according to Example 2-1 were prepared in the same manner as in Example 1-1. Four specimens according to Example 2-2 were prepared in the same manner as in Example 1-2. Four specimens according to Example 2-3 were prepared in the same manner as in Example 1-3. The void formation rates of these specimens were, on average, 20%, 25%, and 30%, respectively.

[0066] [Example 2-4] Four test specimens were prepared in the same manner as in Example 2-1. Example 2-4 differs from Example 2-1 in that the plasma P was irradiated for 4 seconds, resulting in an integrated intensity of 2036 mJ / cm 2 The porosity of the specimens was 35% on average.

[0067] Example 2-5 Four test specimens were prepared in the same manner as in Example 2-1. Example 2-5 differs from Example 2-1 in that the plasma P was irradiated for 5 seconds, resulting in an integrated intensity of 2545 mJ / cm 2 The porosity of the specimens was 40% on average.

[0068] [Example 2-6] Four test specimens were prepared in the same manner as in Example 2-1. Example 2-6 differs from Example 2-1 in that the plasma P was irradiated for 6 seconds, resulting in an integrated intensity of 3054 mJ / cm 2The porosity of the specimens was 45% on average.

[0069] Comparative Example 2 Four specimens were prepared in the same manner as in Comparative Example 1. As described above, Comparative Example 2 differs from the Examples in that UV ozone treatment was performed and moisture was not adsorbed. As with the results shown in Figure 6(B), no pores were formed in the photoelectric conversion layer of the specimens.

[0070] For each of four test specimens in Examples 2-1 to 2-6 and Comparative Example 2, the open-circuit voltage and series resistance were measured as an evaluation of the power generation performance described above. The results are shown in FIGS. 8(A) and 8(B), respectively. The graphs in FIGS. 8(A) and 8(B) are box plots of Examples 2-1 to 2-6 and Comparative Example 2. The values ​​for Examples 2-1 to 2-6 shown in FIG. 8(A) are ratios (normalized values) obtained by dividing the open-circuit voltage by the measured value of Comparative Example 1. The series resistance values ​​for Examples 2-1 to 2-6 shown in FIG. 8(B) are ratios (normalized values) obtained by dividing the series resistance by the measured value of Comparative Example 2.

[0071] As shown in FIG. 8(A), the open-circuit voltage V OC was larger than that of Comparative Example 2. This is thought to be because the specimens of Examples 2-1 to 2-6 have voids 21 formed at the interface 25 of the photoelectric conversion layer 12 that contacts the hole transport layer 11. On the other hand, as shown in FIG. 8(B), the series resistance R of the specimens of Examples 2-4 to 2-6 s The median of the box plot of Example 2-4 to Example 2-6 was larger than that of Example 2-1 to Example 2-3. However, the first quartile value and the minimum value of the box plot of Example 2-4 to Example 2-6 were larger than those of Example 2-1 to Example 2-3. s was approximately the same as the maximum value.

[0072] From the above, as in the specimens of Examples 2-4 to 2-6, the integrated intensity, which is the plasma irradiation condition, is 1528 mJ / cm 2Even if the void formation rate exceeds 30%, the open-circuit voltage V OC However, even in such cases, as the integrated intensity increases and the void formation rate increases, the series resistance R of the solar cell module decreases. s From the above, the manufacturing conditions are as follows: the cumulative intensity of the plasma irradiation conditions is 509 mJ / cm 2 It is preferable that the integrated intensity is 1528 mJ / cm or more, and more preferably, the integrated intensity is 1528 mJ / cm or more. 2 The pore formation rate is preferably 20% or more, and more preferably 30% or less.

[0073] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as set forth in the claims.

[0074] In this embodiment, an inverted-structure perovskite solar cell module has been described. However, for example, in FIG. 1, the power generation unit 10 may be configured as a forward-structure perovskite solar cell module having, in bottom order as shown in FIG. 1, an electron transport layer 13, a photoelectric conversion layer 12, and a hole transport layer 11. In this case, the order of the manufacturing process of the solar cell module shown in the embodiment is also different. Specifically, a second substrate 18 having a second electrode 16 and a hole transport layer 11 formed thereon is prepared, and the hole transport layer 11 and the photoelectric conversion layer 12 are subjected to the same treatment as in this embodiment, followed by forming a light-transmitting first electrode 15. Finally, a light-transmitting first substrate 14 is provided via an adhesive sealant 17, thereby obtaining a forward-structure perovskite solar cell module. [Explanation of symbols]

[0075] 1: solar cell module, 11: hole transport layer, 12: photoelectric conversion layer, 12A: precursor, 13: electron transport layer, 14: first base material (glass substrate), 21: hole, 25: interface

Claims

1. A method for manufacturing a solar cell module having a hole transport layer, a photoelectric conversion layer, and an electron transport layer stacked thereon, comprising: The manufacturing method includes: preparing a substrate on which the hole transport layer is formed; a step of hydrophilizing the surface of the hole transport layer formed on the prepared base material; a step of adsorbing moisture onto the hydrophilically treated surface of the hole transport layer; applying a precursor of the photoelectric conversion layer to the surface of the hole transport layer on which the moisture has been adsorbed; a step of heating the applied precursor to form the photoelectric conversion layer from the precursor and evaporating the moisture adsorbed on the surface of the hole transport layer, thereby forming a plurality of pores at the interface of the photoelectric conversion layer in contact with the hole transport layer; forming the electron transport layer on a surface of the photoelectric conversion layer.

2. 2. The method for manufacturing a solar cell module according to claim 1, wherein the step of hydrophilizing the surface of the hole transport layer comprises the hydrophilization treatment by plasma treatment or ultraviolet ozone treatment.

3. The plasma treatment is a vacuum plasma treatment, and in the vacuum plasma treatment, an integrated intensity representing the irradiation intensity per unit irradiation area of ​​the plasma is 509 mJ / cm ２ The method for manufacturing a solar cell module according to claim 2 , wherein the plasma is irradiated onto the surface of the hole transport layer so as to achieve the above.

4. In the vacuum plasma treatment, the integrated intensity is 1528 mJ / cm ２ The method for manufacturing a solar cell module according to claim 3 , wherein the plasma is irradiated onto the surface of the hole transport layer so that:

5. A solar cell module in which a hole transport layer, a photoelectric conversion layer, and an electron transport layer are stacked, A solar cell module, characterized in that a plurality of pores are formed at the interface of the photoelectric conversion layer in contact with the hole transport layer.

6. In a cross section obtained by cutting the hole transport layer and the photoelectric conversion layer along a thickness direction, 6. The solar cell module according to claim 5, wherein a ratio of a total length of a surface of the hole transport layer adjacent to the plurality of holes to an entire length of the hole transport layer facing the photoelectric conversion layer is 20% or more.

7. 7. The solar cell module according to claim 6, wherein a ratio of a total length of a surface of the hole transport layer adjacent to the plurality of holes to an entire length of the hole transport layer facing the photoelectric conversion layer is 30% or less.

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