Perovskite solar cell

Abstract

The present application relates to a perovskite solar cell, which has: a conductive layer provided on a substrate, a plurality of solar cell units provided on the conductive layer, a plurality of electrodes electrically connecting the plurality of solar cell units, and an insulating film covering at least the solar cell units and the plurality of electrodes and insulating between adjacent electrodes, the film thickness of the insulating film on the conductive layer between the electrodes being half or less of the height of the electrodes.

Description

Technical Field

[0001] This invention relates to a perovskite solar cell. Background Technology

[0002] Perovskite solar cells are a type of solar cell that converts solar energy into electrical energy. A perovskite solar cell is formed by stacking a conductive layer, a solar cell unit with a photoelectric conversion layer, and a counter electrode on a substrate in this order (see, for example, Patent Documents 1-2). The counter electrode consists of multiple electrodes arranged separately on the solar cell unit.

[0003] Patent Document 1 describes the use of metals such as gold or metal oxides as electrodes disposed on a solar cell unit. Since the solar cell unit and electrodes are covered by a protective layer that protects the perovskite solar cell from the effects of oxygen, water, etc., a protective layer made of resin or the like exists between the electrodes.

[0004] Patent document 2 describes the use of carbon electrodes as electrodes configured on a solar cell unit.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-163938

[0006] Patent Document 2: Japanese Patent Application Publication No. 2020-88316

[0007] The perovskite solar cell described in Patent Document 1 has a problem: because the electrodes are covered by a sealing layer, and there is a sealing layer between the electrodes, metal elements in the electrodes can easily diffuse into the sealing layer, raising concerns about leakage current damaging the insulation between the electrodes. Furthermore, using gold, which has a low diffusion coefficient, as the electrode to ensure insulation between the electrodes increases the production cost of the perovskite solar cell.

[0008] The perovskite solar cell described in Patent Document 2 uses carbon with a low diffusion coefficient as the carbon electrode, thus reducing the production cost of perovskite solar cells while suppressing leakage current. However, since the carbon material constituting the carbon electrode is a condensed mass of particles, if a load is applied to the carbon electrode during the formation of the protective layer, some particles or condensed particles may detach between the electrodes, causing a short circuit between them. As a result, the voltage of the perovskite solar cell sometimes decreases, and its performance deteriorates. Summary of the Invention

[0009] This disclosure was made in view of the above-mentioned problems, and its object is to provide a perovskite solar cell that can insulate between multiple electrodes formed on a solar cell unit.

[0010] The perovskite solar cell disclosed herein is characterized by comprising: a conductive layer disposed on a substrate, a plurality of solar cell units disposed on the conductive layer, a plurality of electrodes electrically connecting the plurality of solar cell units, and an insulating film covering at least the plurality of solar cell units and the plurality of electrodes and insulating adjacent electrodes, wherein the thickness of the insulating film between the electrodes on the conductive layer is less than half the height of the electrode.

[0011] According to this configuration, since the thickness of the insulating film on the conductive layer between the electrodes is less than half the electrode height, there is little or no material that can act as a dielectric between the electrodes. Therefore, the electrostatic capacitance between the electrodes becomes extremely small, and elements in the electrodes are difficult to diffuse into the insulating film, suppressing the increase in leakage current and ensuring insulation between the electrodes. Furthermore, since metals other than gold or metal oxides can be used as electrodes, the production cost of perovskite solar cells can be reduced. Moreover, even when carbon electrodes, which have lower strength than metal electrodes, are used, the insulating film functions as a protective film for the carbon electrodes, so even when a protective layer for the solar cell unit is formed through heat pressing or other methods, a portion of the carbon electrode will not detach between the electrodes. Thus, a perovskite solar cell can be provided that ensures insulation between the electrodes while suppressing short circuits caused by electrode damage. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating the structure of a perovskite solar cell.

[0013] Figure 2 This is a planar schematic diagram of a perovskite solar cell.

[0014] Figure 3 This is a schematic diagram of the longitudinal section of a perovskite solar cell according to other embodiments. Detailed Implementation

[0015] Hereinafter, embodiments of the perovskite solar cell and the method for manufacturing the perovskite solar cell according to the present disclosure will be described based on the accompanying drawings. However, the present disclosure is not limited to the following embodiments, and various modifications can be made without departing from its spirit.

[0016] [Brief Structure of Perovskite Solar Cells]

[0017] like Figure 1 As shown, the perovskite solar cell 100 includes a laminate 10 and an insulating film 5. The laminate 10 is formed by stacking a substrate 1, a conductive layer 2, a solar cell unit 3, and an electrode 4 in this order.

[0018] [Substrate]

[0019] Substrate 1 functions as a support for conductive layer 2 and solar cell unit 3, etc. Substrate 1 can be a transparent glass substrate, a semi-transparent glass substrate, a transparent resin substrate, etc., and possesses insulating properties. Figure 2 As shown, substrate 1 is rectangular when viewed along the Z direction.

[0020] like Figure 1 As shown, a conductive layer 2 is stacked on a substrate 1. The orientation of the perovskite solar cell 100 during use is not particularly limited, but it is preferable to use it in a direction in which light is incident from the substrate 1 towards the conductive layer 2. Hereinafter, the direction from the substrate 1 towards the conductive layer 2 will be referred to as the "Z1 direction" (an example of the stacking direction), and the opposite direction will be referred to as the "Z2 direction." The Z1 and Z2 directions will be collectively referred to as the "Z direction." Furthermore, one of the directions orthogonal to the Z direction will be referred to as the "X direction," and the direction orthogonal to both the Z and X directions will be referred to as the "Y direction" (see [reference]). Figure 2 Furthermore, one side in the X direction is called the "X1 side," and the opposite side is called the "X2 side." Additionally, Figure 2 It is observed along the Z direction. Figure 1 The diagram shows a perovskite solar cell 100.

[0021] [Conductive layer]

[0022] The conductive layer 2 is formed on one side (the Z1 side) of the substrate 1 by CVD (chemical vapor deposition), sputtering, or the like. In this embodiment, the conductive layer 2 is formed on the entire surface of one side of the substrate 1. The conductive layer 2 contains, for example, fluorine-doped tin oxide (FTO) or tin oxide (TO) as a material. A solar cell unit 3 is disposed (stacked) on the conductive layer 2 (the Z1 side).

[0023] [Solar Cell Unit]

[0024] In this embodiment, multiple (three) solar cell units 3 are arranged side-by-side along the X direction. When distinguishing between the three solar cell units 3, the solar cell unit 3 arranged on the X2 side is referred to as solar cell unit 3A, the solar cell unit 3 adjacent to solar cell unit 3A is referred to as solar cell unit 3B, and the solar cell unit 3 adjacent to solar cell unit 3B and arranged on the X1 side is referred to as solar cell unit 3C. Solar cell units 3A to 3C are configured to have the same size (area) when viewed along the Z direction.

[0025] The solar cell unit 3 converts light energy into electrical energy. The solar cell unit 3 has an electron transport layer 31, a photoelectric conversion layer 32, and a hole transport layer 33, which are arranged in this order along the Z1 direction. When viewed along the Z direction, each of the electron transport layer 31, photoelectric conversion layer 32, and hole transport layer 33 is rectangular. In this embodiment, when viewed along the Z direction, each of the electron transport layer 31, photoelectric conversion layer 32, and hole transport layer 33 has the same size (area).

[0026] An electron transport layer 31 is disposed on the Z1 side of the conductive layer 2. The electron transport layer 31 allows electrons received from the photoelectric conversion layer 32 (described later) to pass through (transport electrons). The electron transport layer 31 may contain, for example, metal oxides such as titanium oxide, tin oxide, or zinc oxide. In this embodiment, the electron transport layer 31 includes a plurality of (three in this embodiment) insulating layers 311 extending into a plurality of (three in this embodiment) recesses 21 formed by removing a portion of the conductive layer 2. The insulating layers 311 divide the conductive layer 2 in contact with each solar cell cell 3 into two parts (in...). Figure 1 In the example shown, each section is divided into two parts in the X direction. Electrons can move in the electron transport layer 31 along the Z direction, but it is difficult for them to move in directions orthogonal to the Z direction (X and Y directions), thus restricting their movement between the two partitions of the conductive layer 2. Furthermore, the electron transport layer 31 is sometimes referred to as a "barrier layer".

[0027] Since the substrate 1, conductive layer 2 and electron transport layer 31 are transparent, sunlight, indoor light and other light are not absorbed (or are not absorbed) by the substrate 1, conductive layer 2 and electron transport layer 31 and are guided to the photoelectric conversion layer 32.

[0028] The photoelectric conversion layer 32 absorbs light energy and converts it into electrical energy. Specifically, the photoelectric conversion layer 32 absorbs light, causing excited electrons and holes to move to perform photoelectric conversion. The photoelectric conversion layer 32 comprises a perovskite layer made of a perovskite compound. In addition, the photoelectric conversion layer 32 may further comprise a porous oxide semiconductor layer (e.g., a porous titanium layer).

[0029] The hole transport layer 33 allows holes received from the photoelectric conversion layer 32 to pass through (transport holes). The hole transport layer 33 contains, for example, an organic compound such as chlorobenzene as a material. An electrode 4 is disposed on the hole transport layer 33 (the surface on the Z1 side) of each solar cell unit 3. Therefore, the perovskite solar cell 100 in this embodiment has a plurality of electrodes 4 (three in this embodiment).

[0030] [electrode]

[0031] Electrode 4 is conductive and functions as the positive electrode. Electrode 4 is electrically connected to the busbar (not shown) via conductive layer 2. Figure 1 and Figure 2 As shown, multiple electrodes 4 are arranged side-by-side, each separated by a predetermined distance along the X direction. Each electrode 4 is disposed on a portion of the Z1 side surface of the conductive layer 2, extending from the Z1 side surface of the hole transport layer 33 along the Z direction and passing through the X1 side surface of each solar cell unit 3. Thus, solar cell units 3A and 3B are electrically connected via the electrodes 4 and the conductive layer 2, and solar cell units 3B and 3C are electrically connected via the electrodes 4 and the conductive layer 2. Solar cell units 3A to 3C are connected in series. Multiple electrodes 4 protrude from the Z1 side surface and the X1 side surface of the solar cell unit 3 by the thickness of the electrode 4 to the Z1 side or X1 side. A space 41 is formed between adjacent electrodes 4 (between opposing electrodes 4).

[0032] Electrode 4 can be formed using metal monomers such as gold, platinum, silver, and copper, their alloys, or oxide conductors such as FTO and indium tin oxide (ITO). Alternatively, electrode 4 can be a carbon electrode, incorporating materials such as graphite, carbon black, carbon nanotubes, carbon nanofibers, carbon fibers, graphene, and fullerenes. Electrode 4 may contain only one of the above materials or may contain two or more materials.

[0033] Sunlight and other light are incident on the perovskite solar cell 100 along the Z1 direction. After passing through the substrate 1, conductive layer 2, and electron transport layer 31, the light reaches the photoelectric conversion layer 32, where it is absorbed, resulting in the generation of electrons and holes. Electrons generated in the photoelectric conversion layer 32 move to the conductive layer 2 (negative electrode) via the electron transport layer 31. Simultaneously, holes generated in the photoelectric conversion layer 32 move to the electrode 4 (positive electrode), which is electrically connected to the hole transport layer 33. When a load (not shown) is connected between the conductive layer 2 and the electrode 4, the holes combine with the electrons coming from the load. As a result, electricity is generated. The electricity flows, for example, in the following order: the conductive layer 2 (separated by the insulating layer 311, located on the X2 side), the solar cell unit 3A, the electrode 4 formed on the solar cell unit 3A, the conductive layer 2 connecting the solar cell units 3A and 3B, the solar cell unit 3B, the electrode 4 formed on the solar cell unit 3B, the conductive layer 2 connecting the solar cell units 3B and 3C, and the solar cell unit 3C. Furthermore, although electrons moving in the electron transport layer 31 can smoothly move along the Z2 direction and reach the conductive layer 2, as described above, their movement in directions orthogonal to the Z direction is restricted by the insulating layer 311. That is, the perovskite solar cell 100 is configured to prevent short circuits.

[0034] [Insulating film]

[0035] like Figures 1-2 As shown, the insulating film 5 is configured to cover the conductive layer 2, the solar cell unit 3, and the electrode 4. Specifically, the insulating film 5 covers a portion of the Z1 side of the conductive layer 2, the side of the solar cell unit 3 not covered by the electrode 4, and the Z1 side of the electrode 4 and its side surface. Figure 1 As shown, the insulating film 5 is disposed in the space 41 formed between the electrodes 4, 4, thereby ensuring the insulation between adjacent electrodes 4, 4.

[0036] The thickness (Z-direction dimension) of the insulating film 5 is preferably less than half the height of the electrode 4, more preferably less than 1 / 5, and even more preferably less than 1 / 10. This is because if the thickness of the insulating film 5 is greater than half the height of the electrode 4, the elements contained in the electrode 4 will easily diffuse into the insulating film 5, leading to an increase in leakage current. By giving the insulating film 5 such a thickness, materials that can serve as dielectrics can be excluded from the space 41, allowing gases such as atmosphere to exist in the space 41, thus making the electrostatic capacitance between the electrodes 4, 4 close to zero. Therefore, electrical insulation between the electrodes 4, 4 can be ensured.

[0037] Furthermore, the thickness of the insulating film 5 disposed on the surface of electrode 4 can be different from the thickness of the insulating film 5 disposed on the surface of conductive layer 2 or solar cell unit 3. Additionally, as long as the insulating film 5 covers the surface of electrode 4, the insulating film 5 may not be disposed on the surface of conductive layer 2 (the surface on the Z1 side). This allows the electrostatic capacitance between electrodes 4 to approach zero.

[0038] When electrode 4 is a carbon electrode, during the formation of the carbon electrode, sometimes a particle or part of a condensate protrudes from its end, forming a protrusion. When an external force is applied to such a carbon electrode, the protrusion detaches from the carbon electrode, and a part of the carbon electrode is disposed between electrodes 4, 4, causing a short circuit. However, if the carbon electrode is covered by an insulating film 5, even if an external force is applied to the carbon electrode, it can prevent the carbon electrode from detaching, thus suppressing the resulting short circuit between electrodes 4, 4.

[0039] The insulating film 5 is preferably made of an insulating material soluble in alcohol solvents. Examples of alcohol solvents include isopropanol, isobutanol, and ethanol. Furthermore, the insulating material may include, for example, perfluorocarbon and polyvinyl acetal resins. Fluorine resins may also be used instead of polyvinyl acetal resins. Perfluorocarbon is preferably present in the insulating film 5 at 1-10% by weight. Since the insulating film 5 is made of an insulating material soluble in alcohol solvents, the insulating material can be dissolved in an alcohol solvent to prepare a solution, and the insulating film 5 can be formed by coating this solution onto the surface of the electrode 4.

[0040] [Manufacturing Method of Perovskite Solar Cells]

[0041] Next, the manufacturing method of the perovskite solar cell 100 will be described. The manufacturing method of the perovskite solar cell 100 in this embodiment includes a stack forming step for forming a stack 10 and an insulating film forming step for forming an insulating film 5 on the surface of the stack 10.

[0042] First, a laminate formation process is performed to form a laminate 10. In the laminate formation process, a conductive layer 2 is formed on the Z1 side surface of the substrate 1. The conductive layer 2 is preferably formed by, for example, CVD (chemical vapor deposition) or sputtering. Next, laser scribing is performed to partially remove the conductive layer 2 to form a recess 21. Then, a solar cell unit 3 and an electrode 4 are formed on the Z1 side surface of the conductive layer 2 using a known method.

[0043] Next, an insulating film formation process is performed to form an insulating film 5 on the surface of the laminate 10. First, an insulating material is dissolved in an alcohol solvent to prepare a solution. When preparing the solution, it is preferable to adjust the concentration of the insulating material to achieve a specified viscosity (e.g., 20 to 300 cps). Next, the solution with adjusted concentration is coated onto the surface of the laminate 10. Coating is preferably performed using known methods such as inkjet printing, spin coating, dip coating, or screen printing. This allows for surface coating, resulting in an insulating film 5 with a large area and uniform thickness. After solution coating, the solvent in the laminate 10 is evaporated by vacuum drying or heating to obtain the perovskite solar cell 100.

[0044] [Second Implementation]

[0045] Reference Figure 3 The perovskite solar cell 100 according to the second embodiment will be described. The perovskite solar cell 100 according to this embodiment includes a protective layer 6 that protects the solar cell cell 3 and the electrode 4.

[0046] like Figure 3 As shown, the protective layer 6 has an insulating portion 61, a conductive portion 62, and a thin film portion 63. The insulating portion 61 preferably has adhesive, gas barrier, and waterproof properties, and is made of, for example, an olefin-based adhesive, an epoxy-based adhesive, or an acrylic-based adhesive. Furthermore, the insulating portion 61 may also contain a getter material that absorbs moisture or gas. The conductive portion 62 is conductive and contains metal oxides such as alumina or silicon oxide, or metals such as aluminum. The thin film portion 63 contains, for example, a resin such as polyethylene terephthalate. The protective layer 6 is formed by layering the insulating portion 61, the conductive portion 62, and the thin film portion 63 in this order.

[0047] The protective layer 6 is rectangular in plan view and is configured such that the insulating portion 61 faces the Z1 side of the solar cell unit 3 and the electrode 4. The protective layer 6 is attached to the Z1 side of the electrode 4 by heat pressing or the like, thus a load is applied to the electrode 4 during the pressing of the protective layer 6. At this time, if the electrode 4 is a relatively weak carbon electrode, and the insulating film 5 is not present, the load will act on the electrode 4 from the protective layer 6, causing a portion of the end of the electrode 4 or a protrusion protruding from the end to break off and fall between the electrodes 4 and 4 (i.e., carbon particles or these aggregates contained in the electrode 4 will fall off between the electrodes 4 and 4). In this embodiment, the electrode 4 is covered by the insulating film 5, protecting the end and protrusions of the electrode 4. Therefore, when the electrode 4 is a carbon electrode, even if a load is applied during the pressing of the protective layer 6, carbon particles or aggregates will not fall off between the electrodes 4 and 4. Therefore, even when a carbon electrode is used as the electrode 4, short circuits between the electrodes 4 and 4 can be prevented because the electrode 4 is protected by the insulating film 5.

[0048] In this embodiment, the protective layer 6 has approximately the same area as the substrate 1 in a plan view, but as long as it is a structure that protects the solar cell unit 3 and the electrode 4, it can be smaller or larger than the substrate 1.

[0049] In the above embodiments, the following configuration can be conceived.

[0050] (1) A perovskite solar cell 100, comprising: a conductive layer 2 disposed on a substrate 1, a plurality of solar cell units 3 disposed on the conductive layer 2, electrodes 4 electrically connected to the plurality of solar cell units 3, and an insulating film 5 covering at least the plurality of solar cell units 3 and the plurality of electrodes 4 and insulating adjacent electrodes 4, wherein the thickness of the insulating film 5 between the electrodes 4 on the conductive layer 2 is less than half the height of the electrodes 4.

[0051] According to this configuration, since the thickness of the insulating film 5 on the conductive layer 2 between electrodes 4 is less than half the height of electrode 4, there is no material that can serve as a dielectric in the space 41 between electrodes 4, or its amount is very small. Therefore, the electrostatic capacitance between electrodes 4 becomes extremely small, and at the same time, elements (metal elements or carbon) in electrode 4 are difficult to diffuse into the insulating film 5, leakage current is suppressed, and the insulation between electrodes 4 can be ensured. In addition, since metals other than gold or metal oxides can be used as electrodes 4, the production cost of perovskite solar cell 100 can be reduced. Furthermore, even if carbon electrodes with lower strength than metal electrodes are used as electrodes 4, since the insulating film 5 functions as a protective film for electrodes 4, even if a protective layer 6 protecting the solar cell unit 3 is formed by heat pressing or the like, a portion of electrode 4 will not fall off between electrodes 4. Therefore, short circuits between electrodes 4 caused by electrode 4 damage can also be suppressed.

[0052] (2) In the perovskite solar cell 100 of (1), the electrode 4 is preferably a carbon electrode.

[0053] According to this configuration, since electrode 4 is a carbon electrode made of carbon material with a low diffusion coefficient, carbon is difficult to diffuse into the insulating film 5 disposed between electrodes 4, 4. Therefore, leakage current between electrodes 4, 4 is suppressed, and the insulation between electrodes 4, 4 is improved. Thus, short circuits between electrodes 4, 4 can be prevented, and voltage drop in the perovskite solar cell 100 is suppressed.

[0054] (3) In the perovskite solar cell 100 of (1) or (2), the insulating film 5 is preferably made of an insulating material that is soluble in alcohol solvents.

[0055] According to this configuration, by dissolving the insulating material in an alcohol solvent to prepare a solution, the solution can be coated onto the surface of the laminate 10 to form an insulating film 5. Therefore, an insulating film 5 with a uniform film thickness can be formed over a large area, thus the formation of the insulating film 5 can be easily performed.

[0056] (4) In any of (1) to (3) the perovskite solar cell 100 further comprises a protective layer 6 for protecting the solar cell unit 3 and the electrode 4, and the protective layer 6 is preferably disposed on the insulating film 5.

[0057] According to this configuration, since the protective layer 6 protects the solar cell unit 3 and the electrode 4, it can suppress the deterioration of the perovskite solar cell 100 caused by contact with oxygen, water, etc., and improve durability. Furthermore, since it is a particle aggregate, even if a carbon electrode with lower strength than a metal electrode is used, because the insulating film 5 functions as a protective film for the electrode 4, even if the protective layer 6 protecting the solar cell unit 3 is formed through methods such as heat pressing, a portion of the electrode 4 will not detach between the electrodes 4, 4. Therefore, short circuits between the electrodes 4, 4, caused by electrode 4 damage, can be prevented, and voltage drop of the perovskite solar cell 100 can be suppressed.

[0058] [Industry availability]

[0059] This disclosure can be used in perovskite solar cells having a solar cell unit disposed on a conductive layer and a plurality of electrodes electrically connected to the solar cell unit.

[0060] Explanation of reference numerals in the attached figures

[0061] 1: Substrate, 2: Conductive layer, 3: Solar cell unit, 4: Electrode, 5: Insulating film, 6: Protective layer, 100: Perovskite solar cell.

Claims

1. A perovskite solar cell, comprising: Conductive layers with conductivity disposed on the substrate Multiple solar cell units configured on the conductive layer, Multiple electrodes electrically connected to multiple solar cell units, and An insulating film that covers at least a plurality of the solar cell cells and a plurality of the electrodes and insulates adjacent electrodes from each other. The thickness of the insulating film on the conductive layer between the electrodes is less than half the height of the electrodes.

2. The perovskite solar cell as described in claim 1, wherein, The electrode is a carbon electrode.

3. The perovskite solar cell as described in claim 1, wherein, The insulating film is made of an insulating material that is soluble in alcohol solvents.

4. The perovskite solar cell according to any one of claims 1 to 3, wherein, It also has a protective layer that protects the solar cell unit and the electrodes. The protective layer is disposed on the insulating film.

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