Solar battery

Abstract

To provide a method of manufacturing a solar battery capable of improving power generation efficiency, and a solar battery.SOLUTION: A method of manufacturing a solar battery 25 includes: a first step of disposing a functional layer 4 on the side of a face of a first electrode 3, which is formed on the side of one face in a substrate 2, on an opposite side of the substrate 2; and a second step of forming a second cell formation structure P2 including a plurality of island-shaped parts Pb-Pb, which is island-shaped and deep, by performing cutting processing with respect to a layer which is formed on the side of one face in the substrate 2. The second cell formation structure P2 of the solar battery 25 includes the plurality of island-shaped parts Pb-Pb which is island-shaped and deep.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a solar cell having a plurality of solar cell cells in which a first electrode, a functional layer, and a second electrode are arranged in this order on one side of a substrate, and the layer formed on one side of the substrate is formed by a plurality of cell formation structures, and the solar cell. [Background technology]

[0002] When manufacturing a solar cell, first, a first electrode is formed on one surface of a substrate, then a functional layer (e.g., a functional layer including an electron transport layer, a light absorption layer, and a hole transport layer) is formed on the surface of the first electrode opposite the substrate, and then a second cell formation structure (a separation groove for electrode connection) that connects the first electrode and the second electrode is formed on the functional layer by cutting processing such as mechanical processing (mechanical scribing) or laser processing (laser scribing) (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-077104 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-149698 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional manufacturing of solar cells, when the second cell formation structure is formed by cutting, there is a large variation in the properties (film quality, film thickness, for example, hardness) of each deposited layer (e.g., functional layer), making it difficult to perform the cutting process stably. That is, to enable efficient power generation from solar cells, the second cell formation structure should be cut to a desired depth (e.g., a position contacting the surface of the first electrode opposite the substrate), but even when the same cutting conditions (cutting strength) are used for each solar cell, the cutting strength may be too strong or too weak for each deposited layer, making it impossible to stably form the second cell formation structure to the desired depth, resulting in variation in the cutting depth.

[0005] For example, if the cutting strength is too strong, the first electrode may be cut off. As a result, the first electrode and the second electrode are not electrically connected to each other. If the cutting strength is too weak, the second cell formation structure may not reach the first electrode (so-called residual functional layer film may occur). This increases the resistance between the first electrode and the second electrode. In either case, the variation in the solar cell characteristics increases.

[0006] As described above, conventional solar cell manufacturing methods fail to achieve good electrical connection between the first electrode and the second electrode, and as a result, fail to achieve good power generation efficiency of the solar cell. This is particularly noticeable when the functional layer has a light-absorbing layer containing an organic material, and the organic material contains a perovskite, or when the perovskite contains an organic material.

[0007] Therefore, an object of the present disclosure is to provide a solar cell and a method for manufacturing a solar cell that can improve power generation efficiency. [Means for solving the problem]

[0008] In order to solve the above problems, the following solar cell manufacturing method and solar cell are provided.

[0009] (1) Solar cell manufacturing method The method for manufacturing a solar cell according to the present disclosure is a method for manufacturing a solar cell in which a first electrode, a functional layer, and a second electrode are arranged in this order on one side of a substrate, and the layer formed on the one side of the substrate has a plurality of solar cell cells formed by a plurality of cell formation structures, and the plurality of cell formation structures include a second cell formation structure that connects the first electrode and the second electrode, and is characterized by comprising: a first step of arranging the functional layer on the side of the first electrode formed on the one side of the substrate opposite the substrate; and a second step of forming the second cell formation structure having a plurality of deep island-shaped portions by cutting the layer formed on the one side of the substrate.

[0010] (2) Solar cells The solar cell according to the present disclosure is a solar cell having a first electrode, a functional layer, and a second electrode arranged in this order on one side of a substrate, and a layer formed on the one side of the substrate having a plurality of solar cell formed by a plurality of cell formation structures, the plurality of cell formation structures including a second cell formation structure connecting the first electrode and the second electrode, and the second cell formation structure having a plurality of deep island-shaped portions. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to improve the power generation efficiency of solar cells. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically showing an example of the general configuration of a solar cell according to a first embodiment. [Figure 2] 1 is a process diagram of an example of a method for manufacturing a solar cell. [Figure 3A] FIG. 3 is a cross-sectional view schematically showing an example of a step of forming a first overcoat layer in the manufacturing process (first step) common to the solar cell according to the first embodiment and a conventional solar cell. [Figure 3B]FIG. 3 is a cross-sectional view schematically showing an example of a step of forming a first cell formation structure (first separation groove) in the manufacturing process (first step) common to the solar cell according to the first embodiment and a conventional solar cell. [Figure 3C] FIG. 3 is a cross-sectional view schematically showing an example of a step of forming a light absorbing layer and a second overcoat layer in the manufacturing process (first step) common to the solar cell according to the first embodiment and a conventional solar cell. [Figure 4A] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a second cell formation structure in a conventional solar cell manufacturing process (second step). [Figure 4B] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a second electrode in a conventional solar cell manufacturing process (second step). [Figure 4C] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a third cell formation structure (third separation groove) in a conventional solar cell manufacturing process (third step). [Figure 5] FIG. 10 is a cross-sectional view schematically showing the power generation state of a conventional solar cell in which a second cell formation structure is formed to a desired depth. [Figure 6A] FIG. 10 is a cross-sectional view schematically showing a state in which the second cell formation structure is deeper than a desired depth in a configuration example of a conventional solar cell. [Figure 6B] FIG. 10 is a cross-sectional view schematically showing a state in which the second cell formation structure is shallower than a desired depth in a configuration example of a conventional solar cell. [Figure 7A] 5 is a cross-sectional view schematically showing an example of a step of forming a second cell formation structure in the manufacturing process (second step) of the solar cell according to the first embodiment. FIG. [Figure 7B] 5 is a cross-sectional view schematically showing an example of a step of forming a second electrode in the manufacturing process (second step) of the solar cell according to the first embodiment. FIG. [Figure 7C] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a third cell formation structure (third separation groove) in the manufacturing process (third step) of the solar cell according to the first embodiment. [Figure 8A] 2 is a plan view of the α1 portion shown in FIG. 1 in the first embodiment. [Figure 8B]8B is a cross-sectional view of the α1 portion of the solar cell shown in FIG. 1 taken along the line BB shown in FIG. 8A. [Figure 9] FIG. 10 is a cross-sectional view schematically showing an example of the general configuration of a solar cell according to a second embodiment. [Figure 10A] 10 is a cross-sectional view schematically illustrating an example of a first cutting step for forming grooves in the manufacturing process (second step) of the solar cell according to the second embodiment. FIG. [Figure 10B] FIG. 10 is a cross-sectional view schematically illustrating an example of a second cutting step for forming island-shaped portions in the manufacturing process (second step) of the solar cell according to the second embodiment. [Figure 10C] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a second electrode in the manufacturing process (second step) of a solar cell according to the second embodiment. [Figure 10D] FIG. 10 is a cross-sectional view schematically showing an example of a step of forming a third cell formation structure (third separation groove) in the manufacturing process (third step) of the solar cell according to the second embodiment. [Figure 11A] 10 is a plan view of the α2 portion shown in FIG. 9 in the second embodiment. FIG. [Figure 11B] 11B is a cross-sectional view of the α2 portion of the solar cell shown in FIG. 9 taken along the line BB shown in FIG. 11A. [Figure 12] FIG. 10 is a cross-sectional view schematically showing an example of the general configuration of a solar cell according to a third embodiment. [Figure 13A] FIG. 13 is a plan view of the α3 portion shown in FIG. 12 in the third embodiment. [Figure 13B] 13B is a cross-sectional view of the α3 portion of the solar cell shown in FIG. 12 taken along the line BB shown in FIG. 13A. [Figure 14] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fourth embodiment-1, which is another example of the first embodiment. [Figure 15A] FIG. 15 is a plan view of the α4 portion shown in FIG. 14 in the fourth embodiment-1. [Figure 15B] 15B is a cross-sectional view of the α4 portion of the solar cell shown in FIG. 14 taken along the line BB shown in FIG. 15A. [Figure 16]FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fourth embodiment-2, which is another example of the second embodiment. [Figure 17A] FIG. 17 is a plan view of the α5 portion shown in FIG. 16 in the fourth embodiment-2. [Figure 17B] 17B is a cross-sectional view of the α5 portion of the solar cell shown in FIG. 16 taken along the line BB shown in FIG. 17A. [Figure 18] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fourth embodiment-3, which is another example of the third embodiment. [Figure 19A] FIG. 19 is a plan view of the α6 portion shown in FIG. 18 in the fourth embodiment-3. [Figure 19B] 19B is a cross-sectional view of the α6 portion of the solar cell shown in FIG. 18 taken along the line BB shown in FIG. 19A. [Figure 20] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fifth embodiment-1, which is yet another example of the first embodiment. [Figure 21A] FIG. 21 is a plan view of the α7 portion shown in FIG. 20 in the fifth embodiment-1. [Figure 21B] 21B is a cross-sectional view of the α7 portion of the solar cell shown in FIG. 20 taken along the line BB shown in FIG. 21A. [Figure 22] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to Fifth Embodiment-2, which is yet another example of the second embodiment. [Figure 23A] FIG. 23 is a plan view of the α8 portion shown in FIG. 22 in the fifth embodiment-2. [Figure 23B] 23B is a cross-sectional view of the α8 portion of the solar cell shown in FIG. 22 taken along the line BB shown in FIG. 23A. [Figure 24] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to Fifth Embodiment-3, which is yet another example of the third embodiment. [Figure 25A] FIG. 25 is a plan view of the α9 portion shown in FIG. 24 in the fifth embodiment-3. [Figure 25B] 25B is a cross-sectional view of the α9 portion of the solar cell shown in FIG. 24 taken along the line BB shown in FIG. 25A. [Figure 26] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to Sixth Embodiment-1, which is another example of Fourth Embodiment-1 to Fourth Embodiment-3. [Figure 27A] FIG. 27 is a plan view of the α10 portion shown in FIG. 26 in the sixth embodiment-1. [Figure 27B] 27B is a cross-sectional view of the α10 portion of the solar cell shown in FIG. 26 taken along the line BB shown in FIG. 27A. [Figure 28] FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a sixth embodiment-2, which is another example of the fifth embodiments-1 to -3. [Figure 29A] FIG. 29 is a plan view of the α11 portion shown in FIG. 28 in the sixth embodiment-2. [Figure 29B] 29B is a cross-sectional view of the α11 portion of the solar cell shown in FIG. 28 taken along the line BB shown in FIG. 29A. [Figure 30] FIG. 2 is a plan view of the solar cell according to the first to sixth embodiments, viewed from the second electrode side. [Figure 31A] FIG. 2 is a plan view showing an example of linear island portions of solar cells according to the first to sixth embodiments. [Figure 31B] FIG. 10 is a plan view showing another example of linear island portions of the solar cells according to the first to sixth embodiments. [Figure 32] FIG. 10 is a plan view showing still another example of the shape of the island-shaped portions of the solar cells according to the first to sixth embodiments. [Figure 33] FIG. 10 is a plan view showing still another example of the shape of the island-shaped portions of the solar cells according to the first to sixth embodiments. [Figure 34] FIG. 10 is a plan view schematically showing another example of the second cell formation structure of the solar cell according to the first to sixth embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. In the following description, identical components are assigned the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. As an example, the base side is expressed as the lower side and the opposite side as the upper side, but this is for convenience and does not relate to the installation direction or the recommended installation direction. As long as there is no contradiction, it is applicable even if the top and bottom are reversed or the left and right are rephrased.

[0014] [First embodiment] FIG. 1 is a cross-sectional view schematically showing an example of the general configuration of a solar cell 25 according to the first embodiment.

[0015] As shown in FIG. 1, the solar cell 25 includes a base 2 (which may be the same as or include a substrate or a substrate; the same applies in the present disclosure), a first electrode 3 (3a-3c in the illustrated example) provided on one surface of the base 2 (on the base 2), a functional layer 4 (4a-4c in the illustrated example) provided on the surface of the first electrode 3 opposite the base 2 (on the first electrode 3), and a second electrode 8 (8a-8c in the illustrated example) provided on the surface of the functional layer 4 opposite the first electrode 3 (on the functional layer 4). That is, the solar cell 25 includes the first electrode 3, the functional layer 4, and the second electrode 8 arranged in this order on one surface of the base 2 (on the base 2). The solar cell 25 includes a plurality of solar cell cells, each of which is formed by a plurality of cell formation structures P-P (P1-P3 in this example) on one surface of the base 2. In the solar cell 25, the plurality of cell formation structures P-P includes a second cell formation structure P2. In this example, the solar cell 25 has a first electrode 3, a functional layer 4, and a second electrode 8 arranged or stacked in this order on a base 2. Note that although the description here is of the case where the base 2, the first electrode 3, the functional layer 4, and the second electrode 8 are arranged in contact with each other in this order, they do not necessarily have to be arranged in contact with each other. This does not exclude the presence of something else between them. In other words, the base 2, the first electrode 3, the functional layer 4, and the second electrode 8 may be arranged in this order. Furthermore, if there is something that can replace these four, the four items are not necessarily required.

[0016] The functional layer 4 is composed of an intermediate layer (including an overcoat layer, and also including an electron transport layer 5 and a hole transport layer 7) and a light absorbing layer 6 (6a to 6c in the illustrated example). Examples of the overcoat layer include an electron transport layer 5 and a hole transport layer 7 (7a to 7c in the illustrated example). In this example, the solar cell 25 has a first electrode 3, an electron transport layer 5 (5a to 5c in the illustrated example), a light absorbing layer 6 (6a to 6c in the illustrated example), a hole transport layer 7, and a second electrode 8 stacked in this order on the base 2. Note that the solar cell 25 may also have a first electrode 3, a hole transport layer 7, a light absorbing layer 6, an electron transport layer 5, and a second electrode 8 stacked in this order on the base 2.

[0017] The solar cell 25 has a plurality of solar cell cells 20-20 (20a-20c in the illustrated example). The solar cell 25 has a plurality of solar cell cells 20-20 formed by a plurality of cell formation structures P-P (P1-P3 in this example) formed on the base 2.

[0018] In the solar cell 25, the electron transport layer 5, the light absorption layer 6, and the hole transport layer 7 form the functional layer 4, and the plurality of first electrodes 3-3 (3a-3c), the plurality of functional layers 4-4 (4a-4c), and the second electrodes 8-8 (8a-8c) form the plurality of solar cell cells 20-20 (20a-20c). In the solar cell 25, adjacent solar cell cells 20, 20 are electrically connected in series. Therefore, the solar cell 25 is a series-connected solar cell. In the solar cell 25, the number of solar cell cells 20-20 connected in series is not particularly limited as long as it is plural.

[0019] The base 2 is a solar cell or a base of a solar cell, or a base of a solar cell and a solar cell, and is the same as or includes a substrate or base material. The base 2 may be hard and highly rigid, or may be flexible and low in rigidity. Examples of materials that can be used for the base 2 include glass and organic films. Specific examples of organic film materials include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyamideimide (PAI), and polyethylene naphthalate (PEN), but other resins can also be used as long as they meet the requirements. The thickness of the organic film that will become the base 2 is preferably approximately 50 μm to 100 μm.

[0020] The first electrode 3 is a conductive member. The first electrode 3 is provided on the substrate 2 and is an electrode for extracting a current generated by the photovoltaic power of the light absorption layer 6 of the solar cell 20. When the substrate 2 is the light incident side (also called the light receiving side), the first electrode 3 can be a transparent conductive film. The transparent conductive film can be made of a conductive transparent material such as aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), gallium-doped zinc oxide (GZO), tin oxide (SnO2), fluorine-doped tin oxide (FTO), or indium tin oxide (ITO). The transparent conductive film contains a transparent conductive oxide (TCO). The first electrode 3 may also be made of an oxide such as a conductive transparent material with a conductive metal such as silver or thin wires thereof patterned thereon. The term "transparent" means that light passes through, but does not exclude even slight reflection or absorption. It means that the film is provided on the light-receiving surface side of the solar cell (including the portion where light is incident, the same applies in this disclosure). Therefore, a film can be considered transparent simply by being provided on the light-receiving surface side. In other words, a transparent conductive film refers to a conductive film provided on the light-receiving surface side of a solar cell. The term "film" does not specify thickness or width, and includes patterned or island-shaped films and films with portions of different thickness. A film preferably has a substantially constant thickness. Unless otherwise specified, "approximately" or "approximately" refers to the range of manufacturing error, and preferably indicates that a variation of plus or minus 15% of the numerical value is allowed.

[0021] The sheet resistance of the first electrode 3 is preferably 10 Ω / sq or less. It is more preferable that the light transmittance of the first electrode 3 is 80% or more. Examples of methods for forming the first electrode 3 include a sputtering film formation method, a vacuum deposition method, and a formation method using a conductive paste coating / printing technique and a low-temperature firing technique.

[0022] When a transparent conductive film is formed on the base 2, the transparent conductive film formed on the base 2 is divided into individual solar cell 20. For example, the solar cell 25 shown in FIG. 1 includes three solar cell 20 (20a-20c), and therefore the transparent conductive film is divided by a first cell formation structure P1 (first separation groove for cutting the first electrodes), and three first electrodes 3 (3a-3c) are formed. The first cell formation structure P1 (first separation groove) may be filled with a light absorbing layer 6 or the like. Note that, as shown in FIG. 1, the fact that the transparent conductive film is separated into individual solar cell 20 means that it is possible to confirm that the transparent conductive film is divided by the first cell formation structure P1 (i.e., the first separation groove for cutting the first electrodes) in the observation of any cross section of the solar cell, and it is not necessary to observe multiple cross sections of the solar cell. Similarly, the fact that any film or layer of the solar cell is separated into individual solar cell 20 means that it is possible to confirm that the film or layer is separated in the observation of any cross section of the solar cell, and it is not necessary to observe multiple cross sections of the solar cell. Furthermore, when a film or layer of a solar cell is said to be connected to an adjacent solar cell, it is sufficient to confirm that the film or layer is connected between adjacent solar cells when observing any one cross-section of the solar cell; it is not necessary to observe multiple cross-sections of the solar cell.

[0023] The functional layer 4 is a layer including a light-absorbing layer. It may also include an electron transport layer or a hole transport layer. The functional layer 4 is provided on the first electrode 3. In this example, the functional layer 4 has an electron transport layer 5, a light-absorbing layer 6 provided on the electron transport layer 5, and a hole transport layer 7 provided on the light-absorbing layer 6. The functional layer may be formed only with a light-absorbing layer. Alternatively, the functional layer may also include an electron transport layer or a hole transport layer.

[0024] The functional layer may have a light-absorbing layer provided in the pores of the porous insulating layer. More specifically, the functional layer may have a light-absorbing portion provided in the pores of the porous insulating layer, the light-absorbing portion having a material used in the light-absorbing layer. In the present disclosure, the light-absorbing portion refers to a portion having a material used in the light-absorbing layer. The functional layer may have a light-absorbing layer or a light-absorbing portion provided in the pores of a porous electron transport layer or a porous hole transport layer. The functional layer may have a light-absorbing layer or a light-absorbing portion provided in the pores of at least one of a porous insulating layer, a porous electron transport layer, or a porous hole transport layer, or a mixture thereof. The functional layer may also have a light-absorbing layer or a light-absorbing portion provided in the pores of at least one of a light-absorbing layer, an electron transport layer (including a dense electron transport layer), a hole transport layer (including a dense hole transport layer), a porous insulating layer, a porous electron transport layer, or a porous hole transport layer, or a mixture thereof. Porous refers to a layer that can contain light-absorbing portions (e.g., a perovskite compound) in the pores. "Dense" refers to a state in which even if a light absorbing portion is present on one side (for example, the upper side) of a dense layer, no light absorbing portion is present on the other side (for example, the lower side). A dense layer can prevent the presence of a light absorbing portion penetrating the layer.

[0025] The electron transport layer 5 is a layer that transports electrons generated in the light-absorbing layer 6 to the first electrode 3. It is self-evident that an electron transport layer located on the electron transport side of the light-absorbing layer or on the electron transport side of the light-absorbing layer has the function of transporting electrons, so long as the solar cell functions as a solar cell, and no further confirmation is required. In other words, as long as the solar cell functions as a solar cell, any layer located on the electron transport side of the light-absorbing layer or on the electron transport side of the light-absorbing layer is referred to as an electron transport layer. The electron transport layer 5 is made of a material that allows electrons generated in the light-absorbing layer 6 to easily move to the electron transport layer 5 and that allows electrons in the electron transport layer 5 to easily move to the first electrode 3. The electron transport layer 5 may also be a seed layer for oriented growth of the light-absorbing layer 6. This can improve the crystalline quality of the perovskite compound that constitutes the light-absorbing layer 6. The electron transport layer 5 may be, for example, a titanium oxide (TiO2) layer. A TiN layer or a TiO2-xNx layer may be formed on the surface of the titanium oxide contained in the titanium oxide layer. The thickness of the electron transport layer 5 is, for example, about 100 nm or more and 250 nm or less.

[0026] For example, a titanium oxide (TiO2) layer constituting the electron transport layer 5 as the first intermediate layer can be formed on a transparent conductive film that will become the first electrode 3 with a thickness of approximately 100 nm to 250 nm. Examples of methods for forming the intermediate layer include sputtering, vacuum deposition, and a method using a conductive paste coating / printing technique and a low-temperature firing technique. For example, a titanium oxide (TiO2) paste for low-temperature firing can be applied to the transparent conductive film and fired at 150°C or less to form a seed layer. The crystalline structure of the TiO2 contained in the TiO2 layer is preferably a rutile structure. Alternatively, a TiN (NaCl structure) layer with a thickness of approximately 5 nm to 30 nm can be formed on the surface of the TiO2 by surface-modifying the surface of the TiO2 with nitrogen plasma.

[0027] The lattice constants of TiO2 (rutile structure) and TiN (NaCl structure) are relatively well matched, forming a good interface with few defects between the TiO2 layer made of TiO2 and the TiN layer made of TiN. The formation of the mixed crystal material TiO2-xNx near the interface causes a continuous change in the lattice constant, preventing the occurrence of interface defects. When the TiN layer is exposed to the atmosphere after surface modification treatment with nitrogen plasma, a re-oxidation layer several nanometers thick forms on the surface, but because the TiO2 layer formed is thin, structural relaxation of the lattice constant does not occur, and the lattice constant of the underlying TiN layer is maintained.

[0028] The electron transport layer may be made of a suitable material capable of transporting electrons, such as zinc oxide (ZnO), indium oxide (In2O3), or tin oxide (SnO2). The electron transport layer may also be capable of inhibiting the transport of holes (hole blocking). The electron transport layer may also be accompanied by a separate hole blocking layer. Alternatively, the electron transport layer may be omitted, and a hole blocking layer may be provided instead.

[0029] The light absorbing layer 6 (6a to 6c) is a layer that has the function of absorbing light. It is a layer that can absorb light incident on the solar cell and generate electrons and holes, and in that sense is also called a photoelectric conversion layer. The electrons move to the electron transport layer 5, and the holes move to the hole transport layer 7. The fact that the light absorbing layer absorbs light and generates electrons and holes is self-evident as long as the solar cell functions as a solar cell, and does not require confirmation. As long as a material with light absorption function is included, it can be considered that the light absorbing layer absorbs light and generates electrons and holes.

[0030] The light-absorbing layer may be a member occupying a certain area, but is not limited thereto. It may also be a member occupying a certain thickness, but is not limited thereto. The light-absorbing layer may be a layer of porous material in which a light-absorbing layer or a light-absorbing portion is provided. In other words, the light-absorbing layer may be a layer of porous material in which a light-absorbing layer or a light-absorbing portion is provided in the pores of the porous material. Although the term "light-absorbing layer" is used, a more appropriate term would be a light-absorbing portion that can be made of the same material as the light-absorbing layer. In other words, a more appropriate term would be a layer of porous material in which a light-absorbing portion is provided in the pores of the porous material. In this case, the intermediate layer, i.e., the electron transport layer and / or hole transport layer, may also be made of a porous material. In other words, the light-absorbing layer may have a portion in which a light-absorbing portion is provided in the pores of an intermediate layer made of a porous material. The light-absorbing layer may have a portion in which a light-absorbing portion is provided in the pores of an insulator or insulating layer made of a porous material. The light-absorbing layer may also be provided between the electron transport layer and the hole transport layer. Alternatively, the light absorbing portion may be provided between the electron transport layer and the porous electrode. In this case, the light absorbing portion may also be provided in the pores of the porous electrode.

[0031] A light-absorbing portion may be provided in the voids of the insulating layer. The light-absorbing portion refers to the same component as the light-absorbing layer, but the more specific term "portion" is used to avoid misunderstandings about the shape of the component. A "layer" preferably refers to a component having a constant thickness, but is not limited to this. It may have portions of different thicknesses, or may be patterned or island-like. However, generally, a "layer" refers to a component having portions arranged mainly in a constant direction, while a "portion" refers to a component having only portions arranged in a certain region. That is, a "layer" is preferably a component having a constant thickness that continues in a certain direction, a component having portions that continue in a certain direction but with different thicknesses, or a component having discrete pattern-like or island-like portions each arranged mainly in a certain direction. A "portion" can refer to a portion that is a certain region of a "layer." Each pattern or island portion of a discretely arranged pattern-like or island-like "layer" can be referred to as a "portion." In other words, a light-absorbing layer is provided in the gaps of the insulating layer, with discrete light-absorbing portions arranged in a direction that is primarily the same as the direction in which the insulating layer is arranged. Note that, when three-dimensional observation is possible, the pattern or island-like portion does not necessarily have to have multiple discrete portions, but may have a single pattern in which all patterns are connected. Observation is usually performed on a plane in which an arbitrary cross section is observed, and in such cases, the pattern or island-like portion is often divided into multiple discrete portions. In other words, when the insulating layer is observed in cross section, light-absorbing portions are provided in the gaps of the insulating layer, and the light-absorbing portions are arranged discretely in roughly the same direction as the insulating layer extends, and a certain portion of these light-absorbing portions can be collectively referred to as a light-absorbing layer.

[0032] The light absorbing layer 6 preferably contains a perovskite compound or an organic-inorganic hybrid compound. This compound can generate electrons and holes in the light absorbing layer 6. The film thickness of the light absorbing layer 6 is preferably within a range of approximately 500 nm to 1000 nm.

[0033] For example, as shown in FIG. 3B described later, after making a cut [first cell formation structure P1 (first separation groove)] by cutting processing such as mechanical processing or laser processing, a perovskite compound is formed on the first intermediate layer (electron transport layer 5), thereby forming the light absorption layer 6.

[0034] Perovskite compounds are composed of compounds represented by the general formula: ABX3 (1). While the composition ratio is preferably 1:1:3, it is not necessarily 1:1:3. The content of each element may vary as appropriate, and each constituent element does not necessarily have to be a single type. As long as the solar cell has photoelectric conversion function, there is a degree of freedom in the composition as described above. In general formula (1), A is an organic molecule (including an organic group or an organic cation, the same applies in the present disclosure) or an inorganic atom or molecule (including an inorganic group or an inorganic cation, the same applies in the present disclosure), or a combination thereof; B is a metal atom or molecule (including a metal cation, the same applies in the present disclosure); and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or a chalcogen anion, the same applies in the present disclosure). In general formula (1), the three Xs may be the same or different from one another. By being contained in a light absorption layer, a perovskite compound can absorb light and convert it into electricity, and this fact should also be taken into consideration. That is, a perovskite compound can be confirmed by, for example, detecting organic molecules, metal atoms, and halogen atoms. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long as the solar cell has a photoelectric conversion function. For example, molecules containing carbon, nitrogen, and hydrogen are suitable as organic molecules, and therefore, carbon, nitrogen, hydrogen, a metal element, and a halogen element or chalcogen element can be detected. Alternatively, a perovskite compound can be confirmed by detecting A, B, and X, for example, by detecting inorganic atoms, a metal atom, and a halogen atom. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long as the solar cell has a photoelectric conversion function. For example, cesium or rubidium is suitable as the inorganic atom, and therefore, cesium or rubidium, a metal element, and a halogen or chalcogen can be detected. Furthermore, it is not necessary to confirm that a compound is a perovskite compound, since it is a natural consequence that a solar cell must have a crystalline structure in order to have a photoelectric conversion function.The light absorbing layer may contain a compound other than a perovskite compound.

[0035] The light absorption layer may contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound refers to a compound containing both inorganic and organic elements. A solar cell using a perovskite compound contained in an organic-inorganic hybrid compound is also called an organic-inorganic hybrid solar cell. Organic typically refers to a material composed of multiple carbon elements. Carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon and carbon black that function as electrodes are not considered to be organic. In other words, organic refers to materials that contain multiple carbon elements, excluding carbon materials such as graphite. Inorganic refers to materials that are not organic.

[0036] In the general formula (1), examples of the organic molecule represented by A include alkylamine, alkylammonium, and nitrogen-containing heterocyclic compounds. In the perovskite compound (1), the organic molecule represented by A may be only one type of organic molecule, or may be two or more types of organic molecules.

[0037] Examples of alkylamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, and ethylbutylamine.

[0038] The alkylammonium is an ionized product of the alkylamine. Examples of the alkylammonium include methylammonium (CH3NH3), ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, dimethylammonium, diethylammonium, dipropylammonium, dibutylammonium, dipentylammonium, dihexylammonium, trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, tripentylammonium, trihexylammonium, ethylmethylammonium, methylpropylammonium, butylmethylammonium, methylpentylammonium, hexylmethylammonium, ethylpropylammonium, and ethylbutylammonium.

[0039] Examples of the nitrogen-containing heterocyclic compound include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. The nitrogen-containing heterocyclic compound may be an ionized compound. Phenethylammonium is preferred as the ionized nitrogen-containing heterocyclic compound.

[0040] In general formula (1), the organic molecule represented by A is preferably methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, methylammonium, ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, or phenethylammonium, more preferably methylamine, ethylamine, propylamine, methylammonium, ethylammonium, or propylammonium, and even more preferably methylammonium.

[0041] In general formula (1), examples of the metal atom represented by B include lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. In the perovskite compound, the metal atom represented by B may be only one type of metal atom, or may be two or more types of metal atoms. From the viewpoint of improving the light absorption properties and charge generation properties of the perovskite compound, the metal atom represented by B is preferably a lead atom or a tin atom. From the viewpoint of reducing lead, a tin atom is preferred.

[0042] In addition, in general formula (1), examples of halogen atoms represented by X include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, and examples of chalcogen atoms include oxygen atoms, sulfur atoms, selenium atoms, and tellurium atoms. In the perovskite compound, the halogen atoms or chalcogen atoms represented by X may be one type or two or more types. As the halogen atom represented by X, an iodine atom is preferred from the viewpoint of enabling the perovskite compound to utilize light in a wide wavelength range. Specifically, of the three Xs, it is preferred that at least one X represents an iodine atom, and it is more preferred that all three Xs represent iodine atoms.

[0043] The perovskite compound contained in the light absorbing layer 6 is preferably a compound represented by CH3NH3PbX3 (wherein X is a halogen atom), and more preferably a compound in which X is an iodine atom in the formula CH3NH3PbX3 (i.e., a compound represented by CH3NH3PbI3).

[0044] The perovskite compound that can be used to form the light-absorbing layer 6 can be synthesized by using a compound represented by AX and a compound represented by BX2 as raw materials. Specifically, the perovskite compound can be synthesized by mixing an AX solution and a BX2 solution, heating and stirring them (one-step method). Alternatively, the perovskite compound can be synthesized by applying a BX2 solution, for example, to the first intermediate layer (electron transport layer 5) to form a coating film, applying an AX solution to the coating film, and reacting BX2 with AX (two-step method). Both the one-step method and the two-step method can be used to form the light-absorbing layer 6 (perovskite compound layer). The coating method is not particularly limited, but examples include screen printing, dip coating, and inkjet printing.

[0045] Examples of organic solvents (contained in the coating liquid) used in the coating method for forming the light absorbing layer 6 include aromatic hydrocarbons such as toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; ethers such as tetrahydrofuran (THF), dioxane, dibenzyl ether, dimethoxymethyl ether, and 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, and isophorone; esters such as methyl benzoate, ethyl acetate, and butyl acetate; sulfur-containing solvents such as diphenyl sulfide; fluorine-based solvents such as hexafluoroisopropanol; aprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide; alcohols such as methanol, ethanol, and isopropanol; and glyme-based solvents such as ethylene glycol and diethylene glycol monomethyl ether. These can be used alone or as a mixed solvent. These solvents may contain water. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

[0046] In addition to this, the coating liquid may contain additives such as an antioxidant, a viscoelasticity modifier, a preservative, and a curing catalyst.

[0047] When forming a film of the perovskite compound that constitutes the light absorption layer 6, if the temperature of the substrate 2 during film formation is low, the perovskite compound may become needle-like crystals. The needle-like crystals preferably have a length of about 10 μm to 20 μm and a width of about 1 μm to 5 μm, and are particularly preferably shaped like bamboo leaves. An organic binder resin may be applied as a filler to the spaces between the needle-like crystals. The organic binder resin is preferably a transparent, amorphous, and highly insulating material. Examples of organic binder resins include vinyl resins such as polymethyl methacrylate, polystyrene, and polyvinyl chloride; thermoplastic resins such as polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, and polyphenylene oxide; thermosetting resins such as epoxy resin, silicone resin, polyurethane, phenolic resin, alkyd resin, melamine resin, phenoxy resin, polyvinyl butyral, and polyvinyl formal; partially crosslinked products of these resins; and copolymer resins containing two or more of the structural units contained in these resins (insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin). These film-forming resins can be used alone or in combination of two or more, but other resins can also be used as long as they meet the requirements.

[0048] A hole transport material may also be contained in the organic binder resin. Examples of hole transport materials that can be used include pyrazoline compounds, arylamine compounds, stilbene compounds, enamine compounds, polypyrrole compounds, polyvinylcarbazole compounds, polysilane compounds, butadiene compounds, polysiloxane compounds having aromatic amines in the side chain or main chain, polyaniline compounds, polyphenylene vinylene compounds, polythienene vinylene compounds, and polythiophene compounds. However, butadiene compounds and bisbutadiene compounds are particularly preferred. Conductive particles such as carbon nanofibers and conductive polymers such as PEDOT / PSS can also be used. The hole transport material is preferably a compound that is resistant to crystallization. However, to reliably prevent crystallization of the hole transport material, a crystallization prevention material such as an organic binder resin or a plasticizer may also be included. When applying the organic solvent to the needle-shaped crystals, it is preferable to use a solvent that does not disturb the needle-shaped crystals. Specifically, chlorobenzene, toluene, and the like may be preferably used. The coating method is not particularly limited, but it is preferable to employ, for example, a dip coating method, a spray coating method, a slide hopper coating method, or the like.

[0049] By coating the surfaces of the needle-like crystals of the perovskite compound and the exposed surface of the first intermediate layer (electron transport layer 5) with the aforementioned filler, it is possible to prevent current leakage between the first electrode 3 and the second electrode 8. In addition, the filler solidifies the spaces between the needle-like crystals, improving the rigidity of the perovskite crystals. Furthermore, because the needle-like crystals are coated with the filler, light incident on the functional layer 4 is multiple-scattered, improving the light absorption efficiency. This increases the amount of carrier extraction (short-circuit current) of the solar cell 20. Furthermore, by reducing the film thickness of the functional layer 4, a high open-circuit voltage can be obtained.

[0050] The second intermediate layer (hole transport layer 7) functions to transport holes generated in the light-absorbing layer 6 to the second electrode 8. It is self-evident that a hole transport layer located on the hole transport side of the light-absorbing layer or on the hole transport side of the light-absorbing layer has a hole transport function, so long as the solar cell functions as a solar cell, and no further confirmation is required. In other words, as long as the solar cell functions as a solar cell, any layer located on the hole transport side of the light-absorbing layer or on the hole transport side of the light-absorbing layer is referred to as a hole transport layer. The hole transport layer 7 is formed on the light-absorbing layer 6 (6a-6c). The hole transport layer 7 is made of, for example, an inorganic material having a band gap of 2 eV or more and an ionization potential greater (shallower) than -5.3 eV. The thickness of the hole transport layer 7 can be, for example, approximately 30 nm to 100 nm. Specific materials for the hole transport layer 7 include oxides and sulfides such as copper oxide (CuO) and zinc sulfide (ZnS). The hole transport layer may also be capable of inhibiting electron transport (electron blocking). The hole transport layer may be accompanied by a separate electron blocking layer, or the hole transport layer may be omitted and an electron blocking layer may be provided instead.

[0051] After the second intermediate layer (hole transport layer 7) is formed, a second cell formation structure P2 is formed on the layers formed on the base 2 (first electrode 3, functional layer 4 (electron transport layer 5, light absorption layer 6, hole transport layer 7)) by cutting processes such as mechanical processing and laser processing in order to connect the first electrode 3 of one solar cell 20 (20a or 20b) of two adjacent solar cell units 20, 20 (20a, 20b), (20b, 20c) to the hole transport layer 7 and second electrode 8 of the other solar cell unit 20 (20b or 20c). The second cell formation structure P2 is used to ensure electrical connection between the first electrode 3 and the second electrode 8, and connects the first electrode 3 and the second electrode 8.

[0052] Here, examples of the manner in which the second cell formation structure P2 connects the first electrode 3 and the second electrode 8 include not only cases in which the first electrode 3 and the second electrode 8 are in physical contact through the second cell formation structure P2, but also cases in which the first electrode 3 and the second electrode 8 are electrically connected through the second cell formation structure P2 even if they are not in physical contact through the second cell formation structure P2. For example, a case in which the first electrode 3 and the second electrode 8 are electrically connected through the second cell formation structure P2 via another conductive material is also included. In this case, the second electrode 8 and the other conductive material provided in the second cell formation structure P2 can be collectively referred to as the second electrode 8.

[0053] It is desirable that the first electrode 3 and the second electrode 8 embedded in the second cell forming structure P2 are electrically connected directly to each other. The second cell forming structure P2 will be described in detail later.

[0054] The term "layer" does not specify the thickness or width, and includes a pattern or island shape, or a layer having portions of different thickness. Preferably, the layer has a substantially constant thickness.

[0055] The second electrodes 8 (8a to 8c) are provided on the second intermediate layer (hole transport layer 7) and are electrodes for extracting current generated by photovoltaic power of the functional layers 4 (4a to 4c) of the solar cell 20 (20a to 20c). The second electrodes 8 do not necessarily have to be provided on the second intermediate layer (hole transport layer 7) and may be provided on the functional layer. The presence of the second intermediate layer (hole transport layer 7) is preferable. The second electrodes 8 may be, for example, metal films with a work function of 5 eV or more. When the second electrodes 8 are made of a metal with a high work function (5 eV or more), a bending of the band structure occurs at the interface between the hole transport layer 7 and the second electrode 8, allowing holes to flow smoothly. The second electrodes 8 may be made of metals such as Ni, Pt, and Pd. The thickness of the second electrodes 8 is preferably about 50 nm to 150 nm. The hole transport layer 7 or the second electrodes 8 may be formed by, for example, sputtering or vacuum deposition. In addition, conductive materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, carbon black, etc. Basically, any material that is conductive is not excluded from application.

[0056] At the interface between the hole transport layer 7 and the light absorption layer 6, holes generated in the light absorption layer 6 flow through the hole transport layer 7 to the second electrode 8, where they are extracted. As for electrons, the hole transport layer 7 blocks the flow of electrons to the second electrode 8, which has the effect of suppressing carrier recombination at the interface between the hole transport layer 7 and the light absorption layer 6.

[0057] After the second electrode 8 is formed, in order to form a series-connected circuit of adjacent solar cell 20 (20a to 20c) on the base 2, a cutting process is performed to make a cut [third cell formation structure P3 (third separation groove for cutting the second electrode)] in the layers formed on the base 2 (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) (see Figures 4C and 7C described below).

[0058] Although the above description has been given of a structure in which an electron transport layer is provided on the substrate side of the light absorbing layer, a structure in which a hole transport layer is provided on the substrate side of the light absorbing layer may also be used.

[0059] Although the above description is based on a structure in which a transparent conductive film is provided on the substrate side of the light absorbing layer, a structure in which a transparent conductive film is provided on the side opposite the substrate side of the light absorbing layer may also be used, and a structure in which a transparent conductive film is provided on both the substrate side of the light absorbing layer and the side opposite the substrate may also be used.

[0060] [About solar cell manufacturing methods] FIG. 2 is a process diagram of an example of a method for manufacturing the solar cells 25, 25X.

[0061] As shown in FIG. 2, the method for manufacturing the solar cell 25 according to this embodiment and the conventional solar cell 25X includes a first step S1 to a third step S3.

[0062] (Manufacturing method common to the solar cell according to the present embodiment and the conventional solar cell) 3A to 3C are cross-sectional views that schematically show an example of a process for forming a first overcoat layer (electron transport layer 5), an example of a process for forming a first cell formation structure P1 (first separation groove), and an example of a process for forming a light absorption layer 6 and a second overcoat layer (hole transport layer 7), respectively, in the manufacturing process (first step S1) common to the solar cell 25 according to the first embodiment and the conventional solar cell 25X.

[0063] <1st process> As shown in Figures 3A to 3C, in the first step S1 (see Figure 2), a functional layer 4 is arranged (laminated) on the side of the first electrode 3 opposite the substrate 2 (on the first electrode 3) formed on one side of the substrate 2 (on the substrate 2).

[0064] Specifically, in the first step S1, an electron transport layer 5 (ETL: Electron Transport Layer) is formed as a first overcoat film on a first electrode 3 (a transparent conductive film, particularly a transparent conductor made of an oxide, i.e., a transparent conductive oxide (TCO)) on a substrate 2. This may be an electron transport material (ETM: Electron Transport Material). Alternatively, a hole transport layer 7 (HTL: Hole Transport Layer) is formed as a first overcoat film on the first electrode 3. This may be a hole transport material (HTM: Hole Transport Material). In this example, the electron transport layer 5 is formed (S1-1: see FIG. 3A).

[0065] Next, the first overcoat layer (here, the electron transport layer 5) is subjected to cutting processing such as mechanical processing or laser processing to form a first cell formation structure P1 (first separation groove) (S1-2: see FIG. 3B). Here, mechanical processing and laser processing are conventionally known processing techniques, and are processing using a cutting blade and cutting laser light, respectively. This cutting processing is also the same as the cutting processing when forming the second cell formation structure P2 and the third cell formation structure P3 (third separation groove), which will be described later.

[0066] Next, a light absorbing layer 6 containing perovskite (PVSKite) is formed in the first cell formation structure P1 (first separation groove) and on the first overcoat layer (electron transport layer 5), and further, a hole transport layer 7 or an electron transport layer 5 (hole transport layer 7 in this example) is formed on the light absorbing layer 6 as a second overcoat film (S1-3: see FIG. 3C).

[0067] (Conventional solar cell manufacturing method) FIG. 4A is a cross-sectional view schematically showing an example of a step of forming a second cell formation structure P2 in the manufacturing process (second step S2) of conventional solar cell 25X. FIG. 4B is a cross-sectional view schematically showing an example of a step of forming a second electrode 8 in the manufacturing process (second step S2) of conventional solar cell 25X. FIG. 4C is a cross-sectional view schematically showing an example of a step of forming a third cell formation structure P3 (third separation trench) in the manufacturing process (third step S3) of conventional solar cell 25X. FIG. 5 is a cross-sectional view schematically showing a power generation state of conventional solar cell 25X in which second cell formation structure P2X is formed to a desired depth.

[0068] <Second process> In the second step S2 (see FIG. 2), as shown in FIG. 4A, a second cell formation structure P2X (second separation groove) is formed by cutting the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on the substrate 2 using mechanical processing, laser processing, or other cutting processes (S2-1).

[0069] In the second step S2 (see FIG. 2), as shown in FIG. 4B, a second electrode 8 is formed in the second cell formation structure P2X and on the hole transport layer 7 (S2-2).

[0070] <3rd process> In the third step S3 (see Figure 2), as shown in Figure 4C, a third cell formation structure P3 (third separation groove) is formed by cutting the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, and second electrode 8) formed on the base 2 using mechanical processing, laser processing, or other cutting processes.

[0071] Fig. 6A is a cross-sectional view schematically showing a state in which the second cell formation structure P2X is deeper than the desired depth in an example configuration of conventional solar cell 25X, and Fig. 6B is a cross-sectional view schematically showing a state in which the second cell formation structure P2X is shallower than the desired depth in an example configuration of conventional solar cell 25X.

[0072] In the conventional manufacturing of solar cells 25X, when the second cell formation structure P2X is formed by cutting the functional layer 4 using mechanical processing, laser processing, or other cutting techniques, there is a large variation in the properties (film quality, thickness, e.g., hardness) of each layer (e.g., functional layer 4) formed, making it difficult to perform the cutting process stably. Specifically, to efficiently generate electricity from solar cells 25X (see FIG. 5), the second cell formation structure P2X should be cut to a desired depth (e.g., a position in contact with the upper surface of the first electrode 3) (see FIG. 4C). However, even when the same cutting conditions (cutting strength) are used for each of the solar cells 25X to 25X, the cutting strength may be too strong or too weak for each layer (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) formed on the base 2. This prevents the second cell formation structure P2X from being reliably formed to the desired depth, resulting in variations in the cutting depth (see FIGS. 6A and 6B).

[0073] For example, if the cutting strength is too strong (see FIG. 6A), the first electrode 3 is likely to be cut by the second cell formation structure P2X, and good electrical connection with the second electrode 8 is likely to be lost. On the other hand, if the cutting strength is too weak (see FIG. 6B), the second cell formation structure P2X will have difficulty reaching the first electrode 3 (so-called film residue of the functional layer 4 is likely to occur), and the resistance value between the first electrode 3 and the second electrode 8 will likely increase. In either case, the characteristics of the solar cell 25X will vary greatly.

[0074] Thus, in the conventional manufacturing method of the solar cell 25X, it is not possible to reliably electrically connect the first electrode 3 and the second electrode 8, which ultimately reduces the power generation efficiency of the solar cell 25X. This is particularly noticeable when the functional layer 4 has a light absorbing layer 6 containing an organic material, and is even more noticeable when the organic material contains a perovskite.

[0075] In this regard, in the method for manufacturing the solar cell 25 according to the present embodiment, the solar cell 25 is manufactured as follows.

[0076] Next, a method for manufacturing solar cell 25 according to this embodiment will be described below with reference to Figures 7A to 8B. As described above, the first step S1 is the same as the manufacturing process for conventional solar cell 25X, and therefore a description thereof will be omitted here.

[0077] Fig. 7A is a cross-sectional view schematically showing an example of a step of forming a second cell formation structure P2 in the manufacturing process (second step S2) of solar cell 25 according to the first embodiment. Fig. 7B is a cross-sectional view schematically showing an example of a step of forming a second electrode 8 in the manufacturing process (second step S2) of solar cell 25 according to the first embodiment. Fig. 7C is a cross-sectional view schematically showing an example of a step of forming a third cell formation structure P3 (third separation trench) in the manufacturing process (third step S3) of solar cell 25 according to the first embodiment.

[0078] Fig. 8A is a plan view of the α1 portion shown in Fig. 1 in the first embodiment, viewed from above. That is, Fig. 8A is a plan view of the α1 portion viewed from one side (the film-formed side or upper side) of the base 2 toward the other side (the non-film-formed side or lower side) of the base 2, in a direction perpendicular to the surface of the base 2. Fig. 8B is a cross-sectional view of the α1 portion of the solar cell 25 shown in Fig. 1, taken along line BB in Fig. 8A.

[0079] <Second process> In the second step S2 (see FIG. 2), as shown in FIG. 7A, a second cell formation structure P2 having a plurality of deep island-shaped portions Pb to Pb is formed by cutting the layers (in the illustrated example, the electron transport layer 5, the light absorption layer 6, and the hole transport layer 7) formed on one side of the substrate 2 (on the substrate 2) using mechanical processing, laser processing, or other cutting processes.

[0080] In the second step S2 (see FIG. 2), as shown in FIG. 7B, a second electrode 8 is formed in the second cell formation structure P2 and on the hole transport layer 7 (S2-2).

[0081] For example, in the second step S2, the layers (electron transport layer 5, light absorption layer 6, and hole transport layer 7 in the illustrated example) formed on one surface of the substrate 2 are cut by mechanical processing (mechanical scribing) or laser processing (laser scribing) to form the second cell formation structure P2. Examples of mechanical processing include processing using a scribing wheel. Examples of laser processing include processing in which laser light is irradiated in a dotted (spotted) manner, and processing in which overlapping spots of laser light are irradiated continuously in a linear manner.

[0082] <3rd process> In the third step S3 (see FIG. 2), as shown in FIG. 7C, a third cell formation structure P3 (third separation groove) is formed by cutting, such as mechanical processing or laser processing, in the layers (electron transport layer 5, light absorption layer 6, and hole transport layer 7 in the illustrated example) formed on the base 2. Here, the third cell formation structure P3 (third separation groove) is a groove that cuts the second electrode 8 without cutting the first electrode 3.

[0083] In the solar cell 25 according to the present embodiment, as shown in FIGS. 1, 8A and 8B, the second cell formation structure P2 has a plurality of deep island-shaped portions Pb to Pb.

[0084] According to this embodiment, the second cell formation structure P2 has a plurality of deep island-shaped portions Pb-Pb, each of which is isolated from the others. This prevents the first electrode 3 from being cut. Furthermore, even if there is significant variation in the properties (film quality, film thickness, e.g., hardness) of each layer (e.g., functional layer 4) formed among the individual solar cells 25, any of the plurality of island-shaped portions Pb-Pb of the second cell formation structure P2 can reach the first electrode 3. This ensures reliable electrical connection between the first electrode 3 and the second electrode 8, thereby improving the power generation efficiency of the solar cell 25. This is particularly effective when the functional layer 4 includes a light-absorbing layer 6 containing an organic material, and even more effective when the organic material contains perovskite.

[0085] The shape of the plurality of island-shaped portions Pb to Pb may be, for example, a circle, a square or other dot, an ellipse, a rectangle, or a line such as a square with rounded corners.

[0086] For example, in the case of mechanical processing, a scribing wheel is used to perform linear cutting, and in the case of laser processing, laser light is irradiated so that each spot (pulse) overlaps every predetermined number of laser scans to perform linear cutting. Also, in the case of laser processing, laser light irradiation and non-irradiation are alternately performed to perform point-like cutting.

[0087] In this embodiment, in the second step S2, the layers (electron transport layer 5, light absorption layer 6, and hole transport layer 7 in the illustrated example) formed on one surface of the base 2 are cut to form a second cell-forming structure P2 consisting only of a plurality of island-shaped portions Pb-Pb. The second cell-forming structure P2 consists only of a plurality of island-shaped portions Pb-Pb.

[0088] In this case, since the second cell forming structure P2 is made up of a plurality of island-shaped portions Pb to Pb, the second cell forming structure P2 can be easily fabricated.

[0089] [Second embodiment] FIG. 9 is a cross-sectional view schematically illustrating an example of the overall configuration of a solar cell 25 according to the second embodiment. FIG. 10A is a cross-sectional view schematically illustrating an example of a first cutting step S2-1-1 for forming grooves Pa in the manufacturing process (second step S2) of a solar cell 25 according to the second embodiment. FIG. 10B is a cross-sectional view schematically illustrating an example of a second cutting step S2-1-2 for forming islands Pb-Pb in the manufacturing process (second step S2) of a solar cell 25 according to the second embodiment. FIG. 10C is a cross-sectional view schematically illustrating an example of a step for forming a second electrode 8 in the manufacturing process (second step S2) of a solar cell 25 according to the second embodiment. FIG. 10D is a cross-sectional view schematically illustrating an example of a step for forming a third cell formation structure P3 (third separation groove) in the manufacturing process (third step S3) of a solar cell 25 according to the second embodiment. FIG. 11A is a plan view of the portion α2 shown in FIG. 9 according to the second embodiment. FIG. 11B is a cross-sectional view of the α2 portion of the solar cell 25 shown in FIG. 9 taken along the line BB shown in FIG. 11A.

[0090] However, when the second cell formation structure P2 is made up of a plurality of island-shaped portions Pb-Pb as in the first embodiment, the plurality of island-shaped portions Pb-Pb are formed directly on the layers (in the illustrated example, the electron transport layer 5, the light absorption layer 6, and the hole transport layer 7) formed on the base 2, so it may be difficult to stably ensure conduction between the first electrode 3 and the second electrode 8.

[0091] -Solar cell manufacturing method 1- In this regard, in this embodiment, the second step S2 includes a first cutting step S2-1-1 and a second cutting step S2-1-2. In the first cutting step S2-1-1, layers (in the illustrated example, the light absorption layer 6 and the hole transport layer 7) formed on one surface of the base 2 are cut to form grooves Pa. In the second cutting step S2-1-2, bottoms Pa1 (bottom surfaces) of the grooves Pa are cut to form a plurality of island portions Pb-Pb. Here, the width of the grooves Pa can be, for example, 20 μm to 200 μm. The island portions Pb-Pb may overlap the edges of the grooves Pa.

[0092] In this case, in the second step S2, in the first cutting step S2-1-1, the layers (light absorbing layer 6 and hole transport layer 7 in the illustrated example) formed on one surface of the substrate 2 are scribed by mechanical processing or laser scanned by laser processing at a cutting strength sufficient to not cut the first electrode 3 (enough to leave the first electrode 3). Here, the cutting strength is sufficient to not cut the first electrode 3, but is preferably set weaker than expected, taking into account that the depth of the light absorbing layer 6, electron transport layer 5, or hole transport layer 7 will change depending on the finish of the light absorbing layer 6. Therefore, in the first cutting step S2-1-1, cutting may only be performed partway through the hole transport layer 7, leaving a thin layer of the hole transport layer 7; or may only be performed partway through the light absorbing layer 6, leaving a thin layer of the light absorbing layer 6; or may only be performed partway through the electron transport layer 5, leaving a thin layer of the electron transport layer 5. Next, in the second cutting step S2-1-2, the bottoms Pa1 (bottom surfaces) of the grooves Pa are scribed by mechanical processing or laser scanned by laser processing to cut out the multiple island portions Pb to Pb with a cutting strength sufficient to reach the first electrodes 3. As a result, even if the first cutting step S2-1-1 alone is unable to form grooves that reach the first electrodes 3 and the electrical connection between the solar cells is ultimately insufficient, the second cutting step S2-1-2 can reliably form grooves, islands, or holes that reach the first electrodes 3, thereby ultimately improving the electrical connection between the solar cells.

[0093] -Solar Cell Manufacturing Method 2- In this embodiment, in the second step S2, the layers formed on one surface of the base 2 (in the illustrated example, the light absorption layer 6 and the hole transport layer 7) are cut to form a groove portion Pa, while forming a plurality of island-shaped portions Pb-Pb at the bottom Pa1 of the groove portion Pa.

[0094] In this case, in the second step S2, a laser beam is irradiated at a predetermined first cutting intensity by laser scanning to form the groove portion Pa, and then a laser beam is irradiated at a predetermined second cutting intensity greater than the first cutting intensity, as in the first embodiment, to form the plurality of island portions Pb-Pb. In other words, in the case of laser processing, variable cutting intensity processing is performed, in which the cutting intensity of the laser beam can be changed for each spot (pulse) within a single laser scan. Specifically, for each spot (scanning location) of each laser scan, the spot where the groove portion Pa is to be formed is irradiated with laser beam at a first cutting intensity, and the spot where the island portion Pb is to be formed is irradiated with laser beam at a second cutting intensity. In the case of mechanical processing, a scribing wheel can be used to form the groove portion Pa and the plurality of island portions Pb-Pb on layers (in the illustrated example, the light absorption layer 6 and the hole transport layer 7) formed on one surface of the substrate 2.

[0095] In this way, by cutting the layers (in the illustrated example, the light absorption layer 6 and the hole transport layer 7) formed on one surface of the base 2 to form the groove portion Pa, and then cutting the bottom portion Pa1 of the groove portion Pa to form multiple island-shaped portions Pb-Pb, it is possible to efficiently produce a second cell-forming structure P2 having the groove portion Pa and multiple island-shaped portions Pb-Pb.

[0096] In the solar cell 25 according to this embodiment, the second cell formation structure P2 has a groove portion Pa, and the plurality of island-shaped portions Pb to Pb are deep at the bottom portion Pa1 of the groove portion Pa in an island-like manner.

[0097] According to the second embodiment, since a plurality of island-shaped portions Pb to Pb are formed at the bottom Pa1 of the groove portion Pa, electrical continuity between the first electrode 3 and the second electrode 8 can be stably ensured.

[0098] Incidentally, when laser cutting is used, if the size of the island-shaped portions Pb-Pb is larger than the laser diameter, it is necessary to perform laser scanning of the laser light multiple times on each of the island-shaped portions Pb-Pb. Here, unless otherwise specified, the size of the island-shaped portions Pb-Pb refers to the diameter if the island-shaped portions Pb-Pb are circular, the length of one side if the island-shaped portions Pb-Pb are square, the minor axis if the island-shaped portions Pb-Pb are elliptical, or the length of the short side if the island-shaped portions Pb-Pb are rectangular.

[0099] In this embodiment, in the second step S2, the island portions Pb-Pb are formed so that the size of each of the island portions Pb-Pb is the same as the laser diameter. The size of the island portions Pb-Pb can be, for example, 10 μm to 20 μm. In this case, the island portions Pb-Pb include island portions Pb with widths of 10 μm to 20 μm.

[0100] In this way, it is only necessary to perform one laser scan on each island portion Pb to Pb to form the multiple island portions Pb to Pb. Here, unless otherwise specified, the "width" of the island portions Pb to Pb refers to the diameter if the island portions Pb to Pb are circular, the length of one side if the island portions Pb to Pb are square, the minor axis if the island portions Pb to Pb are elliptical, or the length of the short side if the island portions Pb to Pb are rectangular.

[0101] In this embodiment, in the first step S1, the grooves Pa are formed so that they reach the electron transport layer 5 or hole transport layer 7 (electron transport layer 5 in the illustrated example) on the first electrode 3 and leave all or a portion (all of the electron transport layer in the illustrated example) of the electron transport layer or hole transport layer (electron transport layer 5 in the illustrated example). The functional layer 4 includes the electron transport layer 5 or hole transport layer 7 (electron transport layer 5 in the illustrated example) formed on the first electrode 3, and the grooves Pa are dug so that they reach the electron transport layer or hole transport layer (electron transport layer 5 in the illustrated example) on the first electrode 3 and leave all or a portion (all of the electron transport layer in the illustrated example) of the electron transport layer or hole transport layer (electron transport layer 5 in the illustrated example).

[0102] In this configuration, the grooves Pa can be prevented from reaching the first electrode 3.

[0103] [Third embodiment] Fig. 12 is a cross-sectional view schematically showing an example of the general configuration of a solar cell 25 according to a third embodiment. Fig. 13A is a plan view of the α3 portion shown in Fig. 12 in the third embodiment. Fig. 13B is a cross-sectional view of the α3 portion of the solar cell 25 shown in Fig. 12 taken along line BB shown in Fig. 13A.

[0104] In the present embodiment, in the first step S1, the grooves Pa are formed so as to reach the light absorbing layer 6 and leave all or a part (a part in the illustrated example) of the light absorbing layer 6. The functional layer 4 includes an electron transport layer 5 or a hole transport layer 7 (the electron transport layer 5 in the illustrated example) formed on the first electrode 3, and a light absorbing layer 6 formed on the electron transport layer 5 or the hole transport layer 7 (the electron transport layer 5 in the illustrated example), and the grooves Pa are dug so as to reach the light absorbing layer 6 and leave all or a part (a part in the illustrated example) of the light absorbing layer 6.

[0105] In this configuration, the grooves Pa can be prevented from reaching the first electrode 3.

[0106] In the first to third embodiments, in the second step S2, the plurality of island portions Pb-Pb are formed so as to include one or more island portions Pb-Pb that reach at least the first electrode 3 (in the illustrated example, the interface of the first electrode 3 with the functional layer 4). The plurality of island portions Pb-Pb include one or more island portions Pb-Pb that reach at least the first electrode 3 (in the illustrated example, the interface of the first electrode 3 with the functional layer 4).

[0107] This ensures electrical continuity between the first electrode 3 and the second electrode 8 by the island-shaped portions Pb-Pb that reach at least the first electrode 3. In this example, electrical continuity with the first electrode 3 can be achieved through the surfaces β1-β1 (see FIGS. 8B, 11B, and 13B) of the island-shaped portions Pb-Pb along the base 2 (i.e., surfaces parallel to the surface of the base).

[0108] [Fourth embodiment] Fig. 14 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fourth embodiment-1, which is another example of the first embodiment. Fig. 15A is a plan view of the α4 portion shown in Fig. 14 in the fourth embodiment-1. Fig. 15B is a cross-sectional view of the α4 portion of the solar cell 25 shown in Fig. 14 taken along the line BB shown in Fig. 15A.

[0109] Fig. 16 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fourth embodiment-2, which is another example of the second embodiment. Fig. 17A is a plan view of the α5 portion shown in Fig. 16 in the fourth embodiment-2. Fig. 17B is a cross-sectional view of the α5 portion of the solar cell 25 shown in Fig. 16 taken along the line BB shown in Fig. 17A.

[0110] Moreover, Fig. 18 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fourth embodiment-3, which is another example of the third embodiment. Fig. 19A is a plan view of the α6 portion shown in Fig. 18 in the fourth embodiment-3. Fig. 19B is a cross-sectional view of the α6 portion of the solar cell 25 shown in Fig. 18 taken along the line BB shown in Fig. 19A.

[0111] In the manufacturing methods of solar cell 25 according to fourth embodiment-1 to fourth embodiment-3, in second step S2 of the manufacturing methods of solar cell 25 according to the first embodiment to third embodiment, a plurality of island portions Pb-Pb are formed so as to include one or more island portions Pb-Pb that reach (remain inside) the first electrode 3. In solar cell 25 according to fourth embodiment-1 to fourth embodiment-3, the plurality of island portions Pb-Pb of solar cell 25 according to the first embodiment to third embodiment each include one or more island portions Pb-Pb that reach (remain inside) the first electrode 3.

[0112] In this configuration, in addition to electrical continuity with the first electrode 3 at the surfaces β1-β1 of the island-shaped portions Pb-Pb along the base 2 (see Figures 15B, 17B, and 19B), electrical continuity with the first electrode 3 can also be achieved at the side surfaces β2-β2 of the island-shaped portions Pb-Pb perpendicular to the base 2 (see Figures 15B, 17B, and 19B), thereby achieving low electrical resistance between the first electrode 3 and the second electrode 8.

[0113] [Fifth embodiment] Fig. 20 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fifth embodiment-1, which is yet another example of the first embodiment. Fig. 21A is a plan view of the α7 portion shown in Fig. 20 in the fifth embodiment-1. Fig. 21B is a cross-sectional view of the α7 portion of the solar cell 25 shown in Fig. 20 taken along line BB shown in Fig. 21A.

[0114] Fig. 22 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fifth embodiment-2, which is yet another example of the second embodiment. Fig. 23A is a plan view of the α8 portion shown in Fig. 22 in the fifth embodiment-2. Fig. 23B is a cross-sectional view of the α8 portion of the solar cell 25 shown in Fig. 22 taken along line BB shown in Fig. 23A.

[0115] Moreover, Fig. 24 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a fifth embodiment-3, which is yet another example of the third embodiment. Fig. 25A is a plan view of the α9 portion shown in Fig. 24 in the fifth embodiment-3. Fig. 25B is a cross-sectional view of the α9 portion of the solar cell 25 shown in Fig. 24 taken along line BB shown in Fig. 25A.

[0116] In the manufacturing methods of the solar cell 25 according to the fifth embodiment-1 to the fifth embodiment-3, in the second step S2 of the manufacturing methods of the solar cell 25 according to the first embodiment to the third embodiment, the plurality of island portions Pb-Pb are formed so as to include one or more island portions Pb-Pb that penetrate the first electrode 3 (reaching the interface with the first electrode 3 of the base 2). In the solar cells 25 according to the fifth embodiment-1 to the fifth embodiment-3, the plurality of island portions Pb-Pb of the solar cells 25 according to the first embodiment to the third embodiment each include one or more island portions Pb-Pb that penetrate the first electrode 3 (reaching the interface with the first electrode 3 of the base 2).

[0117] In this configuration, the conductive area between the first electrode 3 and the side surfaces β2 to β2 (see Figures 21B, 23B, and 25B) of the island portions Pb to Pb that are perpendicular to the base 2 can be maximized, and the electrical resistance between the first electrode 3 and the second electrode 8 can be kept low accordingly.

[0118] [Sixth embodiment] Fig. 26 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a sixth embodiment-1, which is another example of the fourth embodiments-1 to 3. Fig. 27A is a plan view of the α10 portion shown in Fig. 26 in the sixth embodiment-1. Fig. 27B is a cross-sectional view of the α10 portion of the solar cell 25 shown in Fig. 26 taken along the line BB shown in Fig. 27A.

[0119] Moreover, Fig. 28 is a cross-sectional view schematically showing the general configuration of a solar cell 25 according to a sixth embodiment-2, which is another example of the fifth embodiment-1 to the fifth embodiment-3. Fig. 29A is a plan view of the α11 portion shown in Fig. 28 in the sixth embodiment-2. Fig. 29B is a cross-sectional view of the α11 portion of the solar cell 25 shown in Fig. 28 taken along the line BB shown in Fig. 29A.

[0120] In the manufacturing method of the solar cell 25 according to the sixth embodiment-1, in the first step S1, the grooves Pa are formed so as to reach the first electrode 3 and leave all or a part (all in the illustrated example) of the first electrode 3. The grooves Pa of the solar cell 25 according to the sixth embodiment-1 are dug so as to reach the first electrode 3 and leave all or a part (all in the illustrated example) of the first electrode 3.

[0121] In this configuration, the grooves Pa can be prevented from reaching the base body 2.

[0122] 26 to 27B, in the method for manufacturing solar cell 25 according to Sixth Embodiment-1, in second step S2, a plurality of island-shaped portions Pb-Pb are formed so as to include one or more island-shaped portions Pb-Pb that reach (remain inside) the first electrode 3. The plurality of island-shaped portions Pb-Pb of solar cell 25 according to Sixth Embodiment-1 include one or more island-shaped portions Pb-Pb that reach (remain inside) the first electrode 3.

[0123] With this configuration, in addition to electrical continuity with the first electrode 3 at the surfaces β1-β1 of the island-shaped portions Pb-Pb along the base 2 (see FIG. 27B), electrical continuity with the first electrode 3 can be achieved at the side surfaces β2-β2 of the island-shaped portions Pb-Pb perpendicular to the base 2 (see FIG. 27B), thereby achieving low electrical resistance between the first electrode 3 and the second electrode 8. Additionally, with this configuration, the surfaces β1-β1 along the base 2 are made up of surfaces β1-β1 corresponding to the bottoms of the island-shaped portions Pb-Pb and surfaces β1-β1 corresponding to the bottoms of the groove portions Pa, and therefore electrical continuity with the first electrode 3 can be achieved even at the surfaces β1-β1 corresponding to the bottoms of the groove portions Pa, thereby achieving even lower electrical resistance between the first electrode 3 and the second electrode 8.

[0124] 28 to 29B, in the method for manufacturing a solar cell 25 according to Sixth Embodiment-2, in second step S2, a plurality of island portions Pb-Pb are formed so as to include one or more island portions Pb-Pb that penetrate the first electrode 3 (reaching the interface with the first electrode 3 of the base 2). The plurality of island portions Pb-Pb of the solar cell 25 according to Sixth Embodiment-2 include one or more island portions Pb-Pb that penetrate the first electrode 3 (reaching the interface with the first electrode 3 of the base 2).

[0125] In this configuration, the conductive area between the first electrode 3 and the side surfaces β2-β2 (see FIG. 29B) of the island-shaped portions Pb-Pb perpendicular to the base 2 can be maximized, thereby reducing the electrical resistance between the first electrode 3 and the second electrode 8. In addition, in this configuration, the surfaces β1-β1 along the base 2 are made up of the surfaces β1-β1 corresponding to the bottoms of the grooves Pa, and therefore the surfaces β1-β1 corresponding to the bottoms of the grooves Pa can also be conductive with the first electrode 3, thereby further reducing the electrical resistance between the first electrode 3 and the second electrode 8.

[0126] However, if the light absorption layer 6 of the functional layer 4 [particularly a light absorption layer containing an organic material (perovskite)] is finished thicker than the standard layer thickness, it may be difficult to cut unless the cutting strength is stronger than the standard strength, which will reduce the conduction width (margin) between the first electrode 3 and the second electrode 8.

[0127] In this regard, in the present embodiment, the plurality of island-shaped portions Pb-Pb include island-shaped portions Pb-Pb that penetrate the first electrode 3. Therefore, even if the light absorbing layer 6 (particularly the light absorbing layer containing an organic material (perovskite)) of the functional layer 4 is finished to be thicker than the reference layer thickness and is difficult to cut unless the cutting strength is stronger than the reference strength, the cutting strength can be set to be stronger than the reference strength, so that the light absorbing layer 6 (particularly the light absorbing layer containing an organic material (perovskite)) can be easily cut, and the conduction width (margin) between the first electrode 3 and the second electrode 8 can be improved.

[0128] [Configuration common to the first to sixth embodiments] FIG. 30 is a plan view of the solar cell 25 according to the first to sixth embodiments, viewed from the second electrode 8 side.

[0129] The multiple cell forming structures P to P further include a first cell forming structure P1 which is a first separation groove that cuts the first electrode 3, and a third cell forming structure P3 which is a third separation groove that cuts the second electrode 8. As shown in Fig. 30, the first cell forming structure P1 (first separation groove), the second cell forming structure P2, and the third cell forming structure P3 (third separation groove) are formed parallel to one another in this order.

[0130] In the manufacturing method of the solar cell 25 according to the first to sixth embodiments, in the second step S2, the first electrode 3 is not completely cut (in a state where the first electrode 3 is not cut) in the parallel direction W that is parallel to the first cell forming structure P1 (first separation groove) and the third cell forming structure P3 (third separation groove) to form a second cell forming structure P2 having a conductive path between the first electrode 3 and the second electrode 8. In the solar cell 25 according to the first to sixth embodiments, the second cell forming structure P2 does not completely cut (in a state where the first electrode 3 is not cut) the first electrode 3 in the parallel direction W to form a conductive path between the first electrode 3 and the second electrode 8.

[0131] In this way, electrical continuity between the first electrode 3 and the second electrode 8 can be ensured by a conductive path that does not completely cut through the first electrode 3 in the parallel direction W.

[0132] <Shape of the island> 1 to 29B , in the second step S2 of the method for manufacturing the solar cell 25 according to the first to sixth embodiments shown in FIGS. 1 to 29B , a plurality of island-shaped portions Pb to Pb are formed so that an island-shaped portion row Q(1) to Q(n) (n is an integer of 2 or more, n=3 in this example) in which two or more island-shaped portions Pb to Pb are juxtaposed at intervals in the parallel direction W includes a plurality of island-shaped portions Pb to Pb arranged at intervals in the vertical direction V perpendicular to the first cell forming structure P1 (first separation groove) and the third cell forming structure P3 (third separation groove). In the solar cell 25 according to the first to sixth embodiments, the plurality of island-shaped portions Pb to Pb include a plurality of island-shaped portions Pb to Pb arranged at intervals in the vertical direction V, each of which includes an island-shaped portion row Q(1) to Q(n) in which two or more island-shaped portions Pb to Pb are juxtaposed at intervals in the parallel direction W.

[0133] The island-shaped portions Pb~Pb can be arranged such that the positions of the island-shaped portions Pb~Pb in the parallel direction W between adjacent island-shaped portion rows [Q(1), Q(2)], ~, [Q(n-1), Q(n)] are aligned (see Figure 31A described below) or are staggered (see Figures 8A to 29B and Figure 31B described below).

[0134] <Dot-like shape> In the first to sixth embodiments, the island-shaped portions Pb to Pb each having a dot-like shape are formed so as to be aligned in parallel along the parallel direction W. In the first to sixth embodiments, two or more island-shaped portions Pb to Pb each having a dot-like shape are aligned in parallel along the parallel direction W. This allows the first electrode 3 and the second electrode 8 to be connected more reliably.

[0135] <Linear shape> 31A and 31B are plan views showing an example and another example of linear island portions Pb-Pb of a solar cell 25 according to the first to sixth embodiments, respectively.

[0136] In the manufacturing method of the solar cell 25 according to the first to sixth embodiments, a plurality of island-shaped portions Pb-Pb including two or more linear island-shaped portions Pb-Pb are formed. In the solar cell 25 according to the first to sixth embodiments, the plurality of island-shaped portions Pb-Pb include two or more linear island-shaped portions Pb-Pb.

[0137] In this configuration, two or more island-shaped portions Pb-Pb are linearly shaped, which increases the electrical contact area between the island-shaped portions Pb-Pb and the first electrode 3, thereby achieving a correspondingly lower electrical resistance between the first electrode and the second electrode.

[0138] In the first to sixth embodiments, the two or more linear island portions Pb to Pb are aligned along the parallel direction W.

[0139] This makes it possible to more reliably connect the first electrode 3 and the second electrode 8. Here, the two or more island-shaped portions Pb to Pb along the parallel direction W can be suitably formed by mechanical processing and laser processing.

[0140] FIG. 32 is a plan view showing still another example of the shape of the island-shaped portions Pb to Pb of the solar cell 25 according to the first to sixth embodiments.

[0141] In the first to sixth embodiments, the two or more linear island portions Pb to Pb are aligned along the vertical direction V.

[0142] This allows for a more reliable connection between the first electrode 3 and the second electrode 8. The two or more island-shaped portions Pb to Pb along the vertical direction V can be suitably formed by laser processing. For example, one embodiment is one in which the cutting strength of the laser light is periodically increased and decreased.

[0143] FIG. 33 is a plan view showing still another example of the shape of the island-shaped portions Pb to Pb of the solar cell 25 according to the first to sixth embodiments.

[0144] In the first to sixth embodiments, two or more linear island portions Pb to Pb are arranged obliquely relative to the first cell forming structure P1 (first separation groove) and the third cell forming structure P3 (third separation groove).

[0145] This allows the first electrode 3 and the second electrode 8 to be more reliably connected. The two or more island-shaped portions Pb-Pb extending diagonally relative to the first cell forming structure P1 (first separation groove) and the third cell forming structure P3 (third separation groove) can be suitably formed by laser processing. For example, one possible mode is to shift the cutting strength of the laser light by a predetermined number of spots per laser scan.

[0146] Here, the number (n) of the island-shaped portion rows Q(1) to Q(n) is not limited, but as the number (n) of the island-shaped portion rows Q(1) to Q(n) increases, the electrical resistance between the first electrode 3 and the second electrode 8 decreases, while the width of the second cell formation structure P2 increases, thereby reducing the light-receiving area (power generation area) of the functional layer 4. This reduces the power generation efficiency of the solar cell 25. For this reason, the number (n) of the island-shaped portion rows Q(1) to Q(n) can be appropriately set to a width of the second cell formation structure P2 that maintains the power generation efficiency of the solar cell 25.

[0147] FIG. 34 is a plan view schematically showing another example of the second cell formation structure P2 of the solar cell 25 according to the first to sixth embodiments.

[0148] In the manufacturing method of the solar cell 25 according to the first to sixth embodiments, in the second step S2, a second cell forming structure P2 is formed, which has continuous cutting grooves Pc between the first cell forming structure P1 (first separation groove) and the island portion row Q(n) closest to the first cell forming structure P1 (first separation groove) among the multiple rows of island portion rows Q(1) to Q(n) so as to cut the first electrode 3 in the parallel direction W. In the solar cell 25 according to the first to sixth embodiments, the second cell forming structure P2 has continuous cutting grooves Pc between the first cell forming structure P1 (first separation groove) and the island portion row Q(n) closest to the first cell forming structure P1 (first separation groove) among the multiple rows of island portion rows Q(1) to Q(n) so as to cut the first electrode 3 in the parallel direction W.

[0149] In this way, even if the cutting groove Pc on the side of the first cell formation structure P1 (first separation groove) cuts the first electrode 3, the first electrode 3 and the second electrode 8 can be made conductive on the side of the cutting groove Pc on the side of the third cell formation structure P3 (third separation groove).

[0150] In the present disclosure, the side surfaces or portions of the side surfaces of the separation grooves, groove portions, or deep island-like portions are described as being formed perpendicular to the substrate (i.e., relative to the surface of the substrate), but they do not necessarily have to be perpendicular and may be approximately perpendicular. Also, in the present disclosure, the side surfaces or portions of the side surfaces of the separation grooves, groove portions, or deep island-like portions may be inclined relative to the substrate. Also, in the present disclosure, opposing side surfaces or portions of the side surfaces of the separation grooves, groove portions, or deep island-like portions may be inclined relative to the substrate, and the opposing surfaces may be inverted V-shaped when viewed in cross section (i.e., the top end of the groove, island-like portion, or hole is wider than the bottom).

[0151] In the present disclosure, the bottom surface, bottom portion, or a portion thereof of the separation groove, groove portion, or deep island-like portion is described as being formed parallel to the substrate (i.e., to the surface of the substrate), but it does not necessarily have to be parallel and may be approximately parallel. Also, in the present disclosure, the bottom surface, bottom portion, or a portion thereof of the separation groove, groove portion, or deep island-like portion may be inclined with respect to the substrate. Also, in the present disclosure, the bottom surface, bottom portion, or a portion thereof of the separation groove, groove portion, or deep island-like portion may be inclined with respect to the substrate, and may have an inverted V-shape or a bowl-shape when viewed in cross section (i.e., a shape in which the groove, island-like portion, or hole is deeper near the center and shallower at the ends).

[0152] [Note] (1) A method for manufacturing a solar cell according to a first aspect of the present disclosure is a method for manufacturing a solar cell in which a first electrode, a functional layer, and a second electrode are arranged in this order on one side of a substrate, and a layer formed on the one side of the substrate has a plurality of solar cell cells formed by a plurality of cell formation structures, and the plurality of cell formation structures include a second cell formation structure that connects the first electrode and the second electrode, and includes a first step of arranging the functional layer on the side of the first electrode formed on the one side of the substrate opposite the substrate, and a second step of forming the second cell formation structure having a plurality of deep island-like portions by cutting the layer formed on the one side of the substrate.

[0153] (2) A second aspect of the present disclosure relates to a method for manufacturing a solar cell, in which, in the second step of the method for manufacturing a solar cell of the first aspect, a layer formed on the one surface side of the substrate is cut to form the second cell formation structure consisting only of the plurality of island-shaped portions.

[0154] (3) A third aspect of the present disclosure relates to a method for manufacturing a solar cell, and in the method for manufacturing a solar cell of the first aspect, the second step includes a first cutting step of cutting a layer formed on the one surface side of the base to form a groove portion, and a second cutting step of cutting a bottom of the groove portion to form the plurality of island-shaped portions.

[0155] (4) A fourth aspect of the present disclosure relates to a method for manufacturing a solar cell according to the first aspect, wherein in the second step, a layer formed on the side of the one surface of the substrate is cut to form a groove portion, while forming the plurality of island-shaped portions at the bottom of the groove portion.

[0156] (5) A fifth aspect of the present disclosure relates to a method for manufacturing a solar cell, wherein in the second step, the cutting process is laser processing, and the island portions are formed so that the size of the island portions is the same as the laser diameter.

[0157] (6) A solar cell according to a sixth aspect of the present disclosure is a solar cell having a first electrode, a functional layer, and a second electrode arranged in this order on one side of a base, and a layer formed on the one side of the base has a plurality of solar cell cells formed by a plurality of cell formation structures, and the plurality of cell formation structures include a second cell formation structure connecting the first electrode and the second electrode, and the second cell formation structure has a plurality of deep island-shaped portions.

[0158] (7) A solar cell according to a seventh aspect of the present disclosure is the solar cell according to the sixth aspect, wherein the second cell formation structure is composed only of the plurality of island-shaped portions.

[0159] (8) A solar cell according to an eighth aspect of the present disclosure is the solar cell of the sixth aspect, wherein the second cell formation structure has grooves, and the plurality of island-shaped portions are deep at the bottoms of the grooves.

[0160] (9) A solar cell according to a ninth aspect of the present disclosure is the solar cell of any one of the sixth to eighth aspects, wherein the plurality of island-shaped portions includes an island-shaped portion that reaches at least the first electrode.

[0161] (10) A solar cell according to a tenth aspect of the present disclosure is the solar cell of the ninth aspect, wherein the plurality of island-shaped portions includes an island-shaped portion that reaches inside the first electrode.

[0162] (11) A solar cell according to an eleventh aspect of the present disclosure is the solar cell according to the ninth aspect, wherein the plurality of island-shaped portions includes an island-shaped portion that penetrates through the first electrode.

[0163] (12) A solar cell according to a twelfth aspect of the present disclosure is a solar cell according to any one of the sixth to eleventh aspects, wherein the plurality of cell formation structures further include a first cell formation structure which is a first separation groove that cuts the first electrode, and a third cell formation structure which is a third separation groove that cuts the second electrode, wherein the first cell formation structure, the second cell formation structure, and the third cell formation structure are formed parallel to each other in this order, and the second cell formation structure does not completely cut the first electrode in a parallel direction parallel to the first cell formation structure and the third cell formation structure, and has a conductive path between the first electrode and the second electrode.

[0164] (13) A solar cell according to a thirteenth aspect of the present disclosure is the solar cell of any one of the sixth to twelfth aspects, wherein the plurality of island-shaped portions include island-shaped portions having a width of 10 μm or 20 μm to 200 μm, preferably 10 μm or 20 μm to 100 μm.

[0165] (14) A solar cell according to a fourteenth aspect of the present disclosure is the solar cell of any one of the sixth to thirteenth aspects, wherein the plurality of island-shaped portions include two or more island-shaped portions each having a linear shape.

[0166] (15) A solar cell according to a fifteenth aspect of the present disclosure is the solar cell of the fourteenth aspect, wherein the plurality of cell formation structures further include a first cell formation structure which is a first separation groove that cuts the first electrode, and a third cell formation structure which is a third separation groove that cuts the second electrode, wherein the first cell formation structure, the second cell formation structure, and the third cell formation structure are formed parallel to each other in this order, and the two or more island-shaped portions having a linear shape are aligned along a parallel direction parallel to the first cell formation structure and the third cell formation structure.

[0167] (16) A solar cell according to a sixteenth aspect of the present disclosure is the solar cell of the fourteenth aspect, wherein the plurality of cell formation structures further include a first cell formation structure that is a first separation groove that cuts the first electrode, and a third cell formation structure that is a third separation groove that cuts the second electrode, wherein the first cell formation structure, the second cell formation structure, and the third cell formation structure are formed parallel to each other in this order, and the two or more island-shaped portions having a linear shape are aligned along a vertical direction perpendicular to the first cell formation structure and the third cell formation structure.

[0168] (17) A solar cell according to a seventeenth aspect of the present disclosure is the solar cell of the fourteenth aspect, wherein the plurality of cell formation structures further include a first cell formation structure which is a first separation groove that cuts the first electrode, and a third cell formation structure which is a third separation groove that cuts the second electrode, wherein the first cell formation structure, the second cell formation structure, and the third cell formation structure are formed parallel to each other in this order, and the two or more linear island portions are aligned diagonally relative to the first cell formation structure and the third cell formation structure.

[0169] (18) A solar cell according to an eighteenth aspect of the present disclosure is a solar cell according to any one of the sixth to seventeenth aspects, wherein the plurality of cell formation structures further include a first cell formation structure that is a first separation groove that cuts the first electrode and a third cell formation structure that is a third separation groove that cuts the second electrode, the first cell formation structure, the second cell formation structure, and the third cell formation structure are formed parallel to one another in this order, the plurality of island-shaped portions include island-shaped portions arranged in a plurality of rows spaced apart in a vertical direction perpendicular to the first cell formation structure and the third cell formation structure, each row having two or more island-shaped portions arranged in a parallel direction parallel to the first cell formation structure and the third cell formation structure, the plurality of island-shaped portions being arranged in a plurality of rows spaced apart in a vertical direction perpendicular to the first cell formation structure and the third cell formation structure, and the second cell formation structure has a continuous linear groove between the first cell formation structure and the island-shaped portion row closest to the first cell formation structure among the plurality of island-shaped portion rows so as to cut the first electrode in the parallel direction.

[0170] (19) A solar cell according to a 19th aspect of the present disclosure is the solar cell of the 8th aspect, wherein the functional layer includes an electron transport layer or a hole transport layer formed on the first electrode, and the groove is dug so as to reach the electron transport layer or the hole transport layer on the first electrode and leave all or a part of the electron transport layer or the hole transport layer.

[0171] (20) A solar cell according to a twentieth aspect of the present disclosure is the solar cell of the eighth aspect, wherein the functional layer includes an electron transport layer or a hole transport layer formed on the first electrode, and a light absorbing layer formed on the electron transport layer or the hole transport layer, and the groove is dug so as to reach the light absorbing layer and leave all or part of the light absorbing layer.

[0172] (21) A solar cell according to a twenty-first aspect of the present disclosure is the solar cell of the eighth aspect, wherein the grooves are dug so as to reach the first electrode and leave all or part of the first electrode.

[0173] The present disclosure is not limited to the above-described embodiments, but can be implemented in various other forms. Therefore, the embodiments are merely examples in all respects and should not be interpreted as being limiting. The scope of the present disclosure is defined by the claims and is not bound by the text of the specification. Furthermore, all modifications and variations within the equivalent scope of the claims are within the scope of the present disclosure. [Explanation of symbols]

[0174] 2 Base 20 solar cells 25 Solar Cells 3 1st electrode 4 Functional Layer 5 Electron transport layer 6. Light absorption layer 7. Hole transport layer 8 Second electrode P~P Multiple cell formation structure P1 First cell formation structure (first separation groove) P2 Second cell formation structure P3 Third cell formation structure (third separation groove) Pa groove Pa1 bottom Pb~Pb Multiple islands Pc cutting groove Q(1)~Q(n) Island series S1 1st process S2 2nd process S2-1-1 1st cutting process S2-1-2 2nd cutting process S3 3rd process V vertical direction W parallel direction β1 Surface along the substrate β2 Side perpendicular to the substrate

Claims

1. A method for manufacturing a solar cell, comprising: arranging a first electrode, a functional layer, and a second electrode in this order on one surface of a base; a layer formed on the one surface of the base has a plurality of solar cells formed by a plurality of cell formation structures; and the plurality of cell formation structures includes a second cell formation structure that connects the first electrode and the second electrode, a first step of arranging the functional layer on a surface of the first electrode formed on one surface of the substrate opposite to the substrate; a second step of forming the second cell formation structure having a plurality of deep island-shaped portions by cutting a layer formed on the one surface of the base; A method for manufacturing a solar cell, comprising:

2. The method for manufacturing a solar cell according to claim 1, A method for manufacturing a solar cell, characterized in that in the second step, a layer formed on the one surface side of the base is cut to form the second cell formation structure consisting only of the plurality of island-shaped portions.

3. The method for manufacturing a solar cell according to claim 1, the second step includes a first cutting step of cutting a layer formed on the one surface of the base to form a groove portion, and a second cutting step of cutting a bottom of the groove portion to form the plurality of island-shaped portions.

4. The method for manufacturing a solar cell according to claim 1, The method for manufacturing a solar cell, characterized in that in the second step, a layer formed on the one surface of the base is cut to form grooves, and the plurality of island-shaped portions are formed at the bottom of the grooves.

5. A solar cell comprising: a first electrode, a functional layer, and a second electrode arranged in this order on one surface of a base; a layer formed on the one surface of the base has a plurality of solar cell cells formed by a plurality of cell formation structures; and the plurality of cell formation structures includes a second cell formation structure connecting the first electrode and the second electrode, The solar cell, wherein the second cell formation structure has a plurality of deep island-shaped portions.

6. The solar cell according to claim 5, The solar cell, wherein the second cell formation structure is composed only of the plurality of island-shaped portions.

7. The solar cell according to claim 5, the second cell formation structure has a groove portion, The solar cell, wherein the plurality of island-shaped portions are deep in an island shape at the bottom of the groove.

8. The solar cell according to claim 5, The solar cell, wherein the plurality of island-shaped portions include an island-shaped portion that reaches at least the first electrode.

9. The solar cell according to claim 8, The solar cell, wherein the plurality of island-shaped portions include island-shaped portions that reach the inside of the first electrode or island-shaped portions that penetrate through the first electrode.

10. The solar cell according to claim 5, the plurality of cell forming structures further include a first cell forming structure that is a first separation groove that cuts the first electrode, and a third cell forming structure that is a third separation groove that cuts the second electrode, the first cell forming structure, the second cell forming structure, and the third cell forming structure are formed in this order in parallel to each other, A solar cell characterized in that the second cell forming structure does not completely cut the first electrode in a parallel direction parallel to the first cell forming structure and the third cell forming structure, and has a conductive path between the first electrode and the second electrode.

11. The solar cell according to claim 5, The solar cell, wherein the plurality of island-shaped portions include two or more linear island-shaped portions.

12. The solar cell according to claim 5, the plurality of cell forming structures further include a first cell forming structure that is a first separation groove that cuts the first electrode, and a third cell forming structure that is a third separation groove that cuts the second electrode, the first cell forming structure, the second cell forming structure, and the third cell forming structure are formed in this order in parallel to each other, the plurality of island-shaped portions include island-shaped portions arranged in a plurality of rows at intervals in a vertical direction perpendicular to the first cell-forming structure and the third cell-forming structure, each row including two or more island-shaped portions arranged in parallel at intervals in a parallel direction parallel to the first cell-forming structure and the third cell-forming structure, a second cell forming structure having a continuous linear groove between the first cell forming structure and the island-shaped portion row closest to the first cell forming structure among the plurality of island-shaped portion rows, so as to cut the first electrode in the parallel direction.

13. The solar cell according to claim 7, the functional layer includes an electron transport layer or a hole transport layer formed on the first electrode, and the groove is dug to reach the electron transport layer or the hole transport layer on the first electrode, leaving all or a part of the electron transport layer or the hole transport layer; Or, the functional layer includes an electron transport layer or a hole transport layer formed on the first electrode, and a light absorbing layer formed on the electron transport layer or the hole transport layer, and the groove is dug so as to reach the light absorbing layer and leave all or a part of the light absorbing layer.

14. The solar cell according to claim 7, The solar cell, wherein the groove is dug so as to reach the first electrode and leave all or a part of the first electrode.

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