JP7735449B2 - solar cells - Google Patents

Description

The present disclosure relates to 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.

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 (electrode connection separation groove) that connects the first electrode and second electrode is formed in the functional layer by cutting, such as mechanical processing (mechanical scribing) or laser processing (laser scribing) (see, for example, Patent Documents 1 and 2).

JP 2011-077104 A JP 2013-149698 A

However, in the manufacture of such conventional solar cells, when the second cell formation structure is formed by cutting, there is significant variation in the properties (film quality, film thickness, hardness, etc.) of each deposited layer (e.g., functional layer), making it difficult to perform the cutting process stably. In other words, to enable efficient power generation from solar cells, the second cell formation structure should be cut to the desired depth (e.g., the position where it contacts the surface of the first electrode opposite the substrate). However, 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 consistently form the second cell formation structure to the desired depth, resulting in variation in the cutting depth.

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 will no longer be electrically connected. Furthermore, if the cutting strength is too weak, the second cell formation structure may not reach the first electrode (residual film of the functional layer may remain). This will increase the resistance between the first electrode and the second electrode. In either case, the variation in the characteristics of the solar cell will increase.

As such, conventional solar cell manufacturing methods fail to achieve good electrical connection between the first electrode and the second electrode, and as a result, the solar cell cannot achieve good power generation efficiency. 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.

Therefore, an object of the present disclosure is to provide a solar cell that can improve power generation efficiency.

In order to solve the above problems, the following solar cells of the first and second aspects are provided.

(1) Solar Cell of First Aspect
A solar cell according to a first aspect of the present disclosure is a solar cell having a plurality of solar cells formed by a plurality of cell formation structures in which a first electrode, a functional layer, and a second electrode are arranged in this order on one surface of a base, and the layer formed on the one surface of the base is 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 , wherein the second cell formation structure is made up of only a plurality of deep island-shaped portions and does not have a groove bottom other than the bottom of the island-shaped portions in the second cell formation structure, and the plurality of island-shaped portions are The plurality of cell forming structures include an island-shaped portion that penetrates consistently through a first electrode and the functional layer, the plurality of cell forming structures include a first cell forming structure that is a first separation groove that cuts the first electrode, the second cell forming structure and the first cell forming structure are formed in parallel, and the plurality of island-shaped portions include island-shaped portions that penetrate two or more of the first electrodes, arranged in a parallel direction parallel to the first cell forming structure and spaced apart, and a row of island-shaped portions that penetrate the first electrode, arranged in a vertical direction perpendicular to the first cell forming structure and spaced apart, in multiple rows .

(2) Solar Cell of Second Aspect A solar cell of a second aspect according to the present disclosure is a solar cell having a plurality of solar cells formed by a plurality of cell formation structures on one surface side of a base, in which a first electrode, a functional layer, and a second electrode are arranged in this order, and the layer formed on the one surface side of the base is 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 the second cell formation structure has a plurality of deep island-shaped portions, and the plurality of cell formation structures include a first cell formation structure that is a first separation groove that cuts the first electrode. the second cell forming structure and the first cell forming structure are formed in parallel, 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 forming structure, each row including two or more island-shaped portions arranged in parallel with each other in a parallel direction parallel to the first cell forming structure, the 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 .

This disclosure makes it possible to improve the power generation efficiency of solar cells.

1 is a cross-sectional view schematically illustrating an example of a schematic configuration of a solar cell according to a first embodiment. 1 is a process diagram of an example of a method for manufacturing a solar cell. FIG. 2 is a cross-sectional view schematically illustrating 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. 10 is a cross-sectional view schematically showing an example of a step of forming a first cell formation structure (first separation groove) in a manufacturing process (first step) common to the solar cell according to the first embodiment and a conventional solar cell. FIG. 1 is a cross-sectional view schematically illustrating an example of a step of forming a light absorbing layer and a second overcoat layer in a manufacturing process (first step) common to the solar cell according to the first embodiment and a conventional solar cell. FIG. 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). FIG. 10 is a cross-sectional view schematically illustrating an example of a step of forming a second electrode in a conventional solar cell manufacturing process (second step). 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). 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. 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. 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. 10 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. FIG. 4 is a cross-sectional view schematically illustrating 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. 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. FIG. 2 is a plan view of the α1 portion shown in FIG. 1 in the first embodiment. 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. FIG. 10 is a cross-sectional view schematically illustrating an example of the general configuration of a solar cell according to a second embodiment. FIG. 10 is a cross-sectional view schematically illustrating an example of a first cutting step for forming a groove in the manufacturing process (second step) of the solar cell according to the second embodiment. 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. FIG. 10 is a cross-sectional view schematically illustrating an example of a step of forming a second electrode in the manufacturing process (second step) of the solar cell according to the second embodiment. FIG. 10 is a cross-sectional view schematically illustrating 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. FIG. 10 is a plan view of the α2 portion shown in FIG. 9 in the second embodiment. 11B is a cross-sectional view of the α2 portion of the solar cell shown in FIG. 9 taken along line BB shown in FIG. 11A. FIG. 10 is a cross-sectional view schematically illustrating an example of the general configuration of a solar cell according to a third embodiment. FIG. 13 is a plan view of the α3 portion shown in FIG. 12 in the third embodiment. 13B is a cross-sectional view of the α3 portion of the solar cell shown in FIG. 12 taken along line BB shown in FIG. 13A. 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. FIG. 15 is a plan view of the α4 portion shown in FIG. 14 in the fourth embodiment-1. 15B is a cross-sectional view of the α4 portion of the solar cell shown in FIG. 14 taken along line BB shown in FIG. 15A. 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. FIG. 17 is a plan view of the α5 portion shown in FIG. 16 in the fourth embodiment-2. 17B is a cross-sectional view of the α5 portion of the solar cell shown in FIG. 16 taken along line BB shown in FIG. 17A. 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. FIG. 19 is a plan view of the α6 portion shown in FIG. 18 in the fourth embodiment-3. 19B is a cross-sectional view of the α6 portion of the solar cell shown in FIG. 18 taken along line BB shown in FIG. 19A. 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. FIG. 21 is a plan view of the α7 portion shown in FIG. 20 in the fifth embodiment-1. 21B is a cross-sectional view of the α7 portion of the solar cell shown in FIG. 20 taken along line BB shown in FIG. 21A. FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fifth embodiment-2, which is yet another example of the second embodiment. FIG. 23 is a plan view of the α8 portion shown in FIG. 22 in the fifth embodiment-2. 23B is a cross-sectional view of the α8 portion of the solar cell shown in FIG. 22 taken along line BB shown in FIG. 23A. FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a fifth embodiment-3, which is yet another example of the third embodiment. FIG. 25 is a plan view of the α9 portion shown in FIG. 24 in the fifth embodiment-3. 25B is a cross-sectional view of the α9 portion of the solar cell shown in FIG. 24 taken along line BB shown in FIG. 25A. FIG. 10 is a cross-sectional view schematically showing the general configuration of a solar cell according to a sixth embodiment-1, which is another example of the fourth embodiments-1 to 4th embodiments-3. FIG. 27 is a plan view of the α10 portion shown in FIG. 26 in the sixth embodiment-1. 27B is a cross-sectional view of the α10 portion of the solar cell shown in FIG. 26 taken along line BB shown in FIG. 27A. 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 5th embodiments-3. FIG. 29 is a plan view of the α11 portion shown in FIG. 28 in the sixth embodiment-2. 29B is a cross-sectional view of the α11 portion of the solar cell shown in FIG. 28 taken along line BB shown in FIG. 29A. FIG. 2 is a plan view of the solar cell according to the first to sixth embodiments, viewed from the second electrode side. FIG. 2 is a plan view showing an example of linear island portions of solar cells according to the first to sixth embodiments. FIG. 10 is a plan view showing another example of linear island portions of the solar cells according to the first to sixth embodiments. 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. 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. 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.

Embodiments of the present disclosure will be described below 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 will be referred to as the lower side and the opposite side as the upper side, but this is for convenience and does not relate to the installation orientation or recommended installation orientation. As long as there is no contradiction, the top and bottom can be reversed or the left and right can be used interchangeably.

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

As shown in FIG. 1, the solar cell 25 comprises a base 2 (the same as or including a substrate or base material; the same applies throughout this 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 has 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 has multiple solar cell cells, each of which is formed by multiple cell formation structures P-P (P1-P3 in this example) on one surface of the base 2. In the solar cell 25, the multiple cell formation structures P-P include 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 while the explanation here is of the case where the base 2, first electrode 3, functional layer 4, and 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, first electrode 3, functional layer 4, and second electrode 8 may be arranged in this order. Furthermore, if there are alternatives to these four, the four items are not necessarily required.

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 absorption layer 6 (6a-6c in the illustrated example). Examples of overcoat layers include the electron transport layer 5 and the hole transport layer 7 (7a-7c in the illustrated example). In this example, the solar cell 25 has a first electrode 3, an electron transport layer 5 (5a-5c in the illustrated example), a light absorption layer 6 (6a-6c in the illustrated example), a hole transport layer 7, and a second electrode 8 stacked in this order on the base 2. The solar cell 25 may also have a first electrode 3, a hole transport layer 7, a light absorption layer 6, an electron transport layer 5, and a second electrode 8 stacked in this order on the base 2.

The solar cell 25 has multiple solar cell cells 20-20 (20a-20c in the illustrated example). The solar cell 25 has multiple cell formation structures P-P (P1-P3 in this example) formed on the base 2, forming multiple solar cell cells 20-20.

In the solar cell 25, the functional layer 4 is made up of an electron transport layer 5, a light absorption layer 6, and a hole transport layer 7, and multiple first electrodes 3-3 (3a-3c), multiple functional layers 4-4 (4a-4c), and second electrodes 8-8 (8a-8c) make up multiple 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 considered a series-connected solar cell. There is no particular limit to the number of solar cell cells 20-20 connected in series in the solar cell 25, as long as there is more than one.

The base 2 is a solar cell or a base for a solar cell, or a base for a solar cell and a solar cell, and is the same as or includes the substrate or base material. The base 2 may be hard and highly rigid, or it may be flexible and low in rigidity. 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.

The first electrode 3 is a conductive member. The first electrode 3 is provided on the base 2 and is an electrode for extracting current generated by photovoltaic power of the light absorption layer 6 of the solar cell 20. When the base 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 (SnO ₂ ), fluorine-doped tin oxide (FTO), or indium tin oxide (ITO). The transparent conductive film includes a transparent conductive oxide (TCO). Alternatively, the first electrode 3 may be made of an oxide of a conductive transparent material, on which a conductive metal such as silver or thin wires thereof are patterned. Note that "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 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 side. In other words, a transparent conductive film refers to a conductive film provided on the light-receiving side of the 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.

It is preferable that the sheet resistance of the first electrode 3 is 10 Ω/sq or less. It is even 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 sputtering, vacuum deposition, and methods that combine conductive paste coating/printing and low-temperature firing.

When a transparent conductive film is formed on the substrate 2, the transparent conductive film formed on the substrate 2 is divided into individual solar cell cells 20. For example, the solar cell 25 shown in FIG. 1 includes three solar cell cells 20 (20a-20c), and therefore the transparent conductive film is divided by a first cell formation structure P1 (first separation grooves for first electrode separation), and three first electrodes 3 (3a-3c) are formed. The first cell formation structure P1 (first separation grooves) may be filled with a light-absorbing layer 6 or the like. Note that "the transparent conductive film is separated into individual solar cell cells" refers to the fact that, as shown in FIG. 1, observation of any cross-section of the solar cell confirms that the transparent conductive film is divided by the first cell formation structure P1 (i.e., the first separation grooves for first electrode separation). It is not necessary to observe multiple cross-sections of the solar cell. Similarly, "any film or layer of the solar cell is separated into individual solar cell cells" refers to the fact that, as shown in FIG. 1, observation of any cross-section of the solar cell confirms that the film or layer is separated. 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.

The functional layer 4 is a layer that includes 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 includes 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 solely of a light-absorbing layer. Alternatively, the functional layer may also include an electron transport layer or a hole transport layer.

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 comprising a material used in the light-absorbing layer. In this disclosure, the light-absorbing portion refers to a portion comprising 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 combination 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 combination 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 light-absorbing portions are present on one side of the dense layer (for example, the upper side), no light-absorbing portions are present on the other side (for example, the lower side). A dense layer can prevent light-absorbing portions from being present throughout the layer.

The electron transport layer 5 is a layer that has the function of transporting 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 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 can be, for example, a titanium oxide (TiO ₂ ) layer. Furthermore, a TiN layer or a TiO ₂ -xNx layer may be formed on the surface of the titanium oxide contained in this titanium oxide layer. The thickness of the electron transport layer 5 is, for example, about 100 nm or more and 250 nm or less.

For example, a titanium oxide (TiO ₂ ) 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 seed layer can be formed by applying a titanium oxide (TiO ₂ ) paste for low-temperature firing to the transparent conductive film and firing it at 150°C or less. The crystalline structure of the TiO ₂ contained in the TiO ₂ layer is preferably a rutile structure. Furthermore, a TiN (NaCl structure) layer with a thickness of approximately 5 nm to 30 nm can be formed on the surface of the TiO ₂ by surface-modifying the surface of the TiO ₂ with nitrogen plasma.

The lattice constants of TiO ₂ (rutile structure) and TiN (NaCl structure) are relatively well matched, and a good interface with few defects is formed between the TiO ₂ layer made of TiO ₂ and the TiN layer made of TiN. The formation of the mixed crystal material TiO ₂ -xNx near the interface causes a continuous change in the lattice constant, making it possible to suppress the occurrence of interface defects. When the TiN layer is exposed to the atmosphere after surface modification treatment using nitrogen plasma, a re-oxidation layer several nanometers thick is formed on the surface, but because the formed TiO ₂ layer is thin, structural relaxation of the lattice constant does not occur, and the lattice constant of the underlying TiN layer is maintained.

The electron transport layer may be made of a suitable material capable of transporting electrons, such as zinc oxide (ZnO), indium oxide (In ₂ O ₃ ), or tin oxide (SnO ₂ ). 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.

The light-absorbing layer 6 (6a-6c) is a layer with 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. These electrons move to the electron transport layer 5, and the holes move to the hole transport layer 7. 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 it contains a material with light-absorbing function, it can be considered that the light-absorbing layer absorbs light and generates electrons and holes.

The light-absorbing layer may be a component occupying a certain area, but is not limited to this. It may also be a component occupying a certain thickness, but is not limited to this. 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, it 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.

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 component's shape. A "layer" preferably refers to a component having a uniform thickness, but is not limited to this. It may have portions of varying thickness, or may be patterned or island-like. However, generally, a "layer" refers to something having portions primarily arranged in a uniform direction, while a "portion" refers to something having portions arranged in a specific region. In other words, a "layer" is preferably a component having a uniform thickness that is continuous in a uniform direction, a component having portions that are continuous in a uniform direction but with different thicknesses, or a component having discrete pattern-like or island-like portions, each of which is primarily arranged in a specific direction. A "portion" can refer to a portion that is a specific region of a "layer." Each individual 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 primarily in the same direction as the insulating layer's primarily fixed orientation. Note that, when three-dimensional observation is possible, the pattern or island-like portions do not necessarily have to have multiple discrete portions; they may have a single pattern in which all of the 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 portions are 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. A certain portion of these light-absorbing portions can be collectively referred to as the light-absorbing layer.

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 in the range of approximately 500 nm to 1000 nm.

For example, as shown in Figure 3B (described below), a cut [first cell formation structure P1 (first separation groove)] can be made by cutting, such as mechanical processing or laser processing, and then a perovskite compound can be formed on the first intermediate layer (electron transport layer 5), thereby forming the light absorption layer 6.

The perovskite compound is composed of a compound represented by the general formula: _ABX3 (1). While the composition ratio of each element is preferably 1:1:3, it does not necessarily have to be 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 functionality, there is a degree of freedom in the configuration 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, so 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, 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, so 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, the fact that a compound is a perovskite compound does not necessarily mean that it has a crystalline structure, 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 absorption layer may contain compounds other than perovskite compounds.

The light-absorbing layer may also contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound is a compound containing both inorganic and organic elements. Solar cells using perovskite compounds contained in organic-inorganic hybrid compounds are also called organic-inorganic hybrid solar cells. "Organic" typically refers to a material composed of multiple carbon elements. Graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon materials such as 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.

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

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.

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.

Examples of nitrogen-containing heterocyclic compounds include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. The nitrogen-containing heterocyclic compound may be an ionized compound. A preferred example of an ionized nitrogen-containing heterocyclic compound is phenethylammonium.

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.

In general formula (1), examples of metal atoms 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 a single type of metal atom, or two or more types of metal atoms. From the perspective of improving the light absorption 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 perspective of reducing lead, a tin atom is preferred.

Furthermore, 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. The halogen atom represented by X is preferably an iodine atom, from the viewpoint of enabling the perovskite compound to utilize light in a wide wavelength range. Specifically, of the three Xs, it is preferable that at least one X represents an iodine atom, and it is more preferable that all three Xs represent iodine atoms.

The perovskite compound contained in the light-absorbing layer 6 is preferably a compound represented by CH ₃ NH ₃ PbX ₃ (wherein X is a halogen atom), and more preferably a compound in which X in the formula CH ₃ NH ₃ PbX ₃ is an iodine atom (i.e., a compound represented by CH ₃ NH ₃ PbI ₃ ).

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 (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.

Examples of organic solvents (contained in the coating solution) 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 in combination. These solvents may contain water. Of these solvents, non-halogen organic solvents are preferred due to considerations for the global environment.

In addition to this, the coating liquid may also contain additives such as antioxidants, viscoelasticity modifiers, preservatives, and curing catalysts.

When forming the perovskite compound film that constitutes the light absorption layer 6, if the temperature of the substrate 2 is low during film formation, the perovskite compound may form needle-like crystals. The needle-like crystals are preferably approximately 10 μm to 20 μm in length and 1 μm to 5 μm in width, with a bamboo leaf shape being particularly desirable. 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, but other resins can also be used as long as they meet the requirements.

The organic binder resin may also contain a hole transport material. 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, polyphenylenevinylene compounds, polythienenevinylene 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 ensure crystallization of the hole transport material, the organic binder resin or a plasticizer may be incorporated to prevent crystallization. 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 or toluene may be used. The coating method is not particularly limited, but it is preferable to use methods such as dip coating, spray coating, and slide hopper coating.

By coating the surfaces of the needle-shaped crystals of the perovskite compound and the exposed surface of the first intermediate layer (electron transport layer 5) with the aforementioned filler, current leakage between the first electrode 3 and the second electrode 8 can be prevented. Furthermore, the filler solidifies the spaces between the needle-shaped crystals, improving the rigidity of the perovskite crystals. Furthermore, because the needle-shaped 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) from the solar cell 20. Furthermore, by reducing the film thickness of the functional layer 4, a high open-circuit voltage can be obtained.

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 the 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 the function of transporting holes, 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 composed of, for example, an inorganic material having a band gap of 2 eV or more and an ionization potential greater (shallow) 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 (Cu ₂ O) 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.

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 substrate 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 to connect the first electrode 3 of one solar cell 20 (20a or 20b) of two adjacent solar cells 20, 20 (20a, 20b), (20b, 20c) to the hole transport layer 7 and second electrode 8 of the other solar cell 20 (20b or 20c). The second cell formation structure P2 ensures electrical connection between the first electrode 3 and second electrode 8 and connects the first electrode 3 and second electrode 8.

Here, examples of how the second cell formation structure P2 connects the first electrode 3 and the second electrode 8 include not only cases where the first electrode 3 and the second electrode 8 are in physical contact through the second cell formation structure P2, but also cases where 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, it also includes cases where the first electrode 3 and the second electrode 8 are electrically connected through the second cell formation structure P2 via a separate conductive material. In this case, the separate conductive material provided in the second cell formation structure P2 and the second electrode 8 can be referred to as the second electrode 8.

It is desirable to electrically connect the first electrode 3 and the second electrode 8 embedded in the second cell formation structure P2 directly. The second cell formation structure P2 will be described in more detail later.

Note that the term "layer" does not specify thickness or width, and includes patterned or island-shaped layers, as well as layers with portions of varying thickness. It is preferable for a layer to have a roughly uniform thickness.

The second electrode 8 (8a-8c) is disposed on the second intermediate layer (hole transport layer 7) and is used to extract current generated by photovoltaic power from the functional layer 4 (4a-4c) of the solar cell 20 (20a-20c). It does not necessarily have to be disposed on the second intermediate layer (hole transport layer 7) and can be disposed on the functional layer. The presence of the second intermediate layer (hole transport layer 7) is preferred. Examples of the second electrode 8 include a metal film with a work function of 5 eV or greater. By forming the second electrode 8 from a metal with a high work function (5 eV or greater), a band structure bending occurs at the interface between the hole transport layer 7 and the second electrode 8, allowing for smooth hole flow. Examples of materials for the second electrode 8 include metals such as Ni, Pt, and Pd. The film thickness of the second electrode 8 is preferably approximately 50 nm to 150 nm. The hole transport layer 7 or the second electrode 8 can be formed by, for example, sputtering or vacuum deposition. Additionally, conductive materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon black can be used. Basically, any material that is conductive is not excluded from application.

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.

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

Note that although the above description is based on 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.

In addition, 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, there is no problem with a structure in which a transparent conductive film is provided on the side opposite the substrate side of the light absorbing layer. There is also no problem with a structure in which a transparent conductive film is provided on the substrate side of the light absorbing layer and on the opposite side of the substrate.

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

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

(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 step of forming a first overcoat layer (electron transport layer 5), an example of a step of forming a first cell formation structure P1 (first separation groove), and an example of a step of 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.

<First step>
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).

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 (transparent conductive film, specifically 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 Figure 3A).

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 the first cell formation structure P1 (first separation groove) (S1-2: see Figure 3B). Here, mechanical processing and laser processing are conventionally known processing techniques, and involve processing using a cutting blade and cutting laser light, respectively. This cutting processing is also the same as the cutting processing used to form the second cell formation structure P2 and third cell formation structure P3 (third separation groove), which will be described later.

Next, a light-absorbing layer 6 containing perovskite (PVSK: PeroVSKite) is formed within the first cell formation structure P1 (first separation groove) and on the first overcoat layer (electron transport layer 5), and then a hole transport layer 7 or 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 Figure 3C).

(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 a 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 a 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 groove) in the manufacturing process (third step S3) of a conventional solar cell 25X. Fig. 5 is a cross-sectional view schematically showing a power generation state of a conventional solar cell 25X in which a second cell formation structure P2X is formed to a desired depth.

<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 base 2 using mechanical processing, laser processing, or other cutting processes (S2-1).

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

<3rd process>
In the third step S3 (see FIG. 2 ), as shown in FIG. 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 by mechanical processing, laser processing, or other cutting process.

Figure 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 a conventional solar cell 25X. Also, Figure 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 a conventional solar cell 25X.

In conventional solar cell 25X manufacturing, when the second cell formation structure P2X is formed by cutting the functional layer 4 using mechanical processing, laser processing, or other cutting processes, there is significant variation in the properties (film quality, thickness, e.g., hardness) of each deposited layer (e.g., functional layer 4), making it difficult to perform the cutting process stably. In other words, to enable efficient power generation from the solar cell 25X (see FIG. 5), the second cell formation structure P2X should be cut to the desired depth (e.g., a position contacting the top surface of the first electrode 3) (see FIG. 4C). However, even when the same cutting conditions (cutting strength) are used for each solar cell 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) deposited on the base 2, preventing the second cell formation structure P2X from being consistently formed to the desired depth, resulting in variation in the cutting depth (see FIGS. 6A and 6B).

For example, if the cutting strength is too strong (see Figure 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 Figure 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 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.

As such, conventional manufacturing methods for solar cell 25X fail to ensure reliable electrical connection between the first electrode 3 and the second electrode 8, ultimately resulting in reduced power generation efficiency for solar cell 25X. This is particularly pronounced when the functional layer 4 includes a light-absorbing layer 6 containing an organic material, and even more pronounced when the organic material contains perovskite.

In this regard, in the manufacturing method of the solar cell 25 according to this embodiment, the solar cell 25 is manufactured as follows.

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

Figure 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 a solar cell 25 according to the first embodiment. Figure 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 a solar cell 25 according to the first embodiment. Figure 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 a solar cell 25 according to the first embodiment.

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

<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-like 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 surface of the base 2 (on the base 2) using mechanical processing, laser processing, or other cutting processes.

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

For example, in the second step S2, the layers formed on one surface of the substrate 2 (electron transport layer 5, light absorption layer 6, and hole transport layer 7 in the illustrated example) are cut using 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.

<3rd process>
7C , in the third step S3 (see FIG. 2 ), 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.

In the solar cell 25 according to this embodiment, as shown in Figures 1, 8A, and 8B, the second cell formation structure P2 has multiple deep island-shaped portions Pb-Pb.

According to this embodiment, the second cell formation structure P2 has multiple deep island-shaped portions Pb-Pb, each of which is isolated. This prevents the first electrode 3 from being cut. Furthermore, even if there is significant variation in the properties (film quality, film thickness, hardness, etc.) of each layer (e.g., functional layer 4) formed among the individual solar cells 25-25, any of the multiple 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 has a light-absorbing layer 6 containing an organic material, and even more effective when the organic material contains perovskite.

The shapes of the multiple island portions Pb-Pb can be, for example, circular, square, or other dot-like shapes, or linear shapes such as oval, rectangular, or square with rounded corners.

For example, in the case of mechanical processing, a scribing wheel can be used to perform linear cutting. In the case of laser processing, a linear cutting can be performed by irradiating laser light so that each spot (pulse) overlaps after each predetermined number of laser scans. In addition, in the case of laser processing, a dot-like cutting can be performed by alternating between irradiation and non-irradiation of laser light.

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

In this case, since the second cell formation structure P2 consists of multiple island-shaped portions Pb-Pb, the second cell formation structure P2 can be easily fabricated.

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) for 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 island portions Pb-Pb in the manufacturing process (second step S2) for 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) for 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) for a solar cell 25 according to the second embodiment. FIG. 11A is a plan view of the α2 portion 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.

However, when the second cell formation structure P2 consists of multiple island portions Pb-Pb, as in the first embodiment, the multiple island portions Pb-Pb are formed directly on the layers formed on the base 2 (in the illustrated example, the electron transport layer 5, light absorption layer 6, and hole transport layer 7), which can make it difficult to stably ensure electrical continuity between the first electrode 3 and the second electrode 8.

-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 the grooves Pa. In the second cutting step S2-1-2, the bottoms Pa1 (bottom surfaces) of the grooves Pa are cut to form the plurality of island portions Pb-Pb. Here, the width of the grooves Pa can be, for example, 20 μm to 200 μm. The plurality of island portions Pb-Pb may overlap the edges of the grooves Pa.

In this case, in the second step S2, the layers (light absorbing layer 6 and hole transport layer 7 in the illustrated example) formed on one surface of the substrate 2 in the first cutting step S2-1-1 are scribed by mechanical processing or laser scanned by laser processing to cut grooves Pa at a cutting strength sufficient to avoid cutting through the first electrode 3 (enough to leave the first electrode 3). Here, the cutting strength is sufficient to avoid cutting through the first electrode 3, but it is preferable to set the cutting strength weaker than expected, taking into account that the amount of excavation of the light absorbing layer 6, electron transport layer 5, or hole transport layer 7 will change depending on the finished 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 only partway through the light absorbing layer 6, leaving a thin layer of the light absorbing layer 6; or only partway through the electron transport layer 5, leaving a thin layer of the electron transport layer 5. Next, in the second cutting process S2-1-2, the bottom Pa1 (bottom surface) of the groove Pa is scribed using mechanical processing or laser scanning using laser processing with enough cutting strength to reach the first electrode 3, cutting out multiple island portions Pb-Pb. As a result, even if the first cutting process S2-1-1 alone is unable to form grooves that reach the first electrode 3, resulting in insufficient electrical connection between the solar cell cells, the second cutting process S2-1-2 can reliably form grooves, island portions, or holes that reach the first electrode 3, ultimately improving the electrical connection between the solar cell cells.

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

In this case, an example of an embodiment in which, in the second step S2, laser processing involves irradiating laser light at a predetermined first cutting intensity to form groove portion Pa, while irradiating laser light at a predetermined second cutting intensity greater than the first cutting intensity, as in the first embodiment, to form multiple 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 light can be changed for each spot (pulse) within a single laser scan. Specifically, for each spot (scanning location) of each laser scan, laser light is irradiated at a first cutting intensity to the spot where groove portion Pa is to be formed, and laser light is irradiated at a second cutting intensity to the spot where island portion Pb is to be formed. Note that in the case of mechanical processing, a scribing wheel can be used to form groove portion Pa and multiple island portions Pb-Pb on layers (in the illustrated example, light absorption layer 6 and hole transport layer 7) formed on one surface of the substrate 2.

In this way, by cutting 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) to form the groove portion Pa, and then cutting the bottom portion Pa1 of the groove portion Pa to form multiple island portions Pb-Pb, the second cell formation structure P2 having the groove portion Pa and multiple island portions Pb-Pb can be efficiently produced.

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

According to the second embodiment, multiple island portions Pb-Pb are formed at the bottom Pa1 of the groove portion Pa, thereby ensuring stable conduction between the first electrode 3 and the second electrode 8.

When laser cutting is used, if the size of the island portions Pb-Pb is larger than the laser diameter, it is necessary to scan the laser beam multiple times on each of the island portions Pb-Pb. Here, unless otherwise specified, the size of the island portions Pb-Pb refers to the diameter if the island portions Pb-Pb are circular, the length of one side if the island portions Pb-Pb are square, the minor axis if the island portions Pb-Pb are elliptical, or the length of the short side if the island portions Pb-Pb are rectangular.

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

By doing this, it is possible to form multiple island portions Pb-Pb by performing a single laser scan on each island portion Pb-Pb. Here, unless otherwise specified, the "width" of the island portions Pb-Pb refers to the diameter if the island portions Pb-Pb are circular, the length of one side if the island portions Pb-Pb are square, the minor axis if the island portions Pb-Pb are elliptical, or the length of the short side if the island portions Pb-Pb are rectangular.

In this embodiment, in the first step S1, 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, leaving 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 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, leaving 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).

With this configuration, the groove portion Pa can be prevented from reaching the first electrode 3.

[Third embodiment]
Fig. 12 is a cross-sectional view schematically showing an example of the general configuration of a solar cell 25 according to the 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 B-B shown in Fig. 13A.

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

With this configuration, the groove portion Pa can be prevented from reaching the first electrode 3.

In the first to third embodiments, in the second step S2, multiple island portions Pb-Pb are formed so that they 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 multiple 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).

By doing so, the island portions Pb-Pb, which reach at least as far as the first electrode 3, can reliably ensure electrical continuity between the first electrode 3 and the second electrode 8. In this example, electrical continuity with the first electrode 3 can be achieved through the surfaces β1-β1 of the island portions Pb-Pb that run along the base 2 (i.e., surfaces parallel to the surface of the base) (see Figures 8B, 11B, and 13B).

[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 line B-B shown in Fig. 15A.

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

Furthermore, Figure 18 is a cross-sectional view schematically illustrating the general configuration of a solar cell 25 according to a fourth embodiment-3, which is another example of the third embodiment. Figure 19A is a plan view of the α6 portion shown in Figure 18 in the fourth embodiment-3. Figure 19B is a cross-sectional view of the α6 portion of the solar cell 25 shown in Figure 18 taken along line B-B in Figure 19A.

In the manufacturing methods of the solar cell 25 according to the fourth embodiment-1 to the fourth 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 multiple 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 the solar cell 25 according to the fourth embodiment-1 to the fourth embodiment-3, the multiple island portions Pb-Pb of the solar cell 25 according to the first embodiment to the third embodiment each include one or more island portions Pb-Pb that reach (remain inside) the first electrode 3.

With this configuration, in addition to electrical continuity with the first electrode 3 at the faces β1-β1 of the island-shaped portions Pb-Pb that are aligned with the base 2 (see Figures 15B, 17B, and 19B), electrical continuity with the first electrode 3 is also achieved at the side faces β2-β2 of the island-shaped portions Pb-Pb that are 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.

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 B-B shown in Fig. 21A.

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

Furthermore, Figure 24 is a cross-sectional view schematically illustrating the general configuration of a solar cell 25 according to a fifth embodiment-3, which is yet another example of the third embodiment. Figure 25A is a plan view of the α9 portion shown in Figure 24 in the fifth embodiment-3. Figure 25B is a cross-sectional view of the α9 portion of the solar cell 25 shown in Figure 24 taken along line B-B shown in Figure 25A.

In the manufacturing methods of solar cells 25 according to fifth embodiment-1 to fifth embodiment-3, in step S2 of the manufacturing methods of solar cells 25 according to the first to third embodiments, multiple 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 fifth embodiment-1 to fifth embodiment-3, the multiple island portions Pb-Pb of the solar cells 25 according to the first to third embodiments 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).

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

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 4th embodiments-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 line B-B shown in Fig. 27A.

Furthermore, Figure 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. Figure 29A is a plan view of the α11 portion shown in Figure 28 in the sixth embodiment 2. Figure 29B is a cross-sectional view of the α11 portion of the solar cell 25 shown in Figure 28 taken along line B-B shown in Figure 29A.

In the manufacturing method of the solar cell 25 according to the sixth embodiment-1, in the first step S1, the groove Pa is formed so that it reaches the first electrode 3 and all or a portion (all of the first electrode 3 in the illustrated example) remains. The groove Pa of the solar cell 25 according to the sixth embodiment-1 is dug so that it reaches the first electrode 3 and all or a portion (all of the first electrode 3 in the illustrated example) remains.

With this configuration, the groove portion Pa can be prevented from reaching the base body 2.

As shown in Figures 26 to 27B, in the manufacturing method of the solar cell 25 according to the sixth embodiment-1, in the second step S2, multiple 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. The multiple island portions Pb-Pb of the solar cell 25 according to the sixth embodiment-1 include one or more island portions Pb-Pb that reach (remain inside) the first electrode 3.

With this configuration, in addition to electrical continuity with the first electrode 3 at the surfaces β1-β1 (see FIG. 27B) of the island portions Pb-Pb along the base 2, electrical continuity with the first electrode 3 is also achieved at the side surfaces β2-β2 (see FIG. 27B) of the island portions Pb-Pb perpendicular to the base 2, thereby achieving low electrical resistance between the first electrode 3 and the second electrode 8. In addition, with this configuration, the surfaces β1-β1 along the base 2 are composed of surfaces β1-β1 corresponding to the bottoms of the island portions Pb-Pb and surfaces β1-β1 corresponding to the bottoms of the groove portions Pa. Therefore, electrical continuity with the first electrode 3 is also achieved 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.

As shown in Figures 28 to 29B, in the manufacturing method of the solar cell 25 according to the sixth embodiment, in the 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 the sixth embodiment includes 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).

With this configuration, the conductive area between the first electrode 3 and the side surfaces β2-β2 (see Figure 29B) of the island 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, with this configuration, the surfaces β1-β1 along the base 2 are made up of the surfaces β1-β1 corresponding to the bottom of the groove portion Pa, so that the surfaces β1-β1 corresponding to the bottom of the groove portion 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.

However, if the light-absorbing layer 6 of the functional layer 4 [particularly a light-absorbing 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.

In this regard, in this embodiment, the multiple island portions Pb-Pb include island 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 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, making it easy to cut the light-absorbing layer 6 (particularly the light-absorbing layer containing an organic material (perovskite)) and improving the conduction width (margin) between the first electrode 3 and the second electrode 8.

[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.

The multiple cell forming structures P-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 Figure 30, the first cell forming structure P1 (first separation groove), second cell forming structure P2, and third cell forming structure P3 (third separation groove) are formed parallel to one another in this order.

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 the parallel direction W parallel to the first cell formation structure P1 (first separation groove) and the third cell formation structure P3 (third separation groove) (with the first electrode 3 not cut), to form a second cell formation 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 formation structure P2 has a conductive path between the first electrode 3 and the second electrode 8 by not completely cutting the first electrode 3 in the parallel direction W (with the first electrode 3 not cut).

By doing this, 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.

<Shape of island>
1 to 29B , in the second step S2, a plurality of island-shaped portions Pb-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-Pb are juxtaposed at intervals in the parallel direction W includes a plurality of island-shaped portions Pb-Pb arranged at intervals in a 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-Pb include a plurality of island-shaped portions Pb-Pb arranged at intervals in the vertical direction V, each of which is an island-shaped portion row Q(1) to Q(n) in which two or more island-shaped portions Pb-Pb are juxtaposed at intervals in the parallel direction W.

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

<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.

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

In the manufacturing method of the solar cell 25 according to the first to sixth embodiments, a plurality of island portions Pb-Pb are formed, each of which includes two or more linear island portions Pb-Pb. In the solar cell 25 according to the first to sixth embodiments, the plurality of island portions Pb-Pb includes two or more linear island portions Pb-Pb.

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

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

This allows for a more reliable connection between the first electrode 3 and the second electrode 8. Here, the two or more island-shaped portions Pb-Pb along the parallel direction W can be suitably formed by mechanical processing and laser processing.

Figure 32 is a plan view showing yet another example of the shape of the island portions Pb-Pb of the solar cell 25 according to the first to sixth embodiments.

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

This allows for a more secure connection between the first electrode 3 and the second electrode 8. The two or more island-shaped portions Pb-Pb along the vertical direction V can be suitably formed by laser processing. For example, one possible method is to periodically vary the cutting strength of the laser light.

Figure 33 is a plan view showing yet another example of the shape of the island portions Pb-Pb of the solar cell 25 according to the first to sixth embodiments.

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

This allows for a more reliable connection between the first electrode 3 and the second electrode 8. Two or more island-shaped portions Pb-Pb arranged diagonally relative to the first cell formation structure P1 (first separation groove) and the third cell formation structure P3 (third separation groove) can be suitably formed by laser processing. For example, one possible approach is to shift the cutting strength of the laser light by a predetermined number of spots per laser scan.

Here, the number (n) of island-shaped portion rows Q(1) to Q(n) is not limited, but as the number (n) of 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, correspondingly reducing the light-receiving area (power generation area) of the functional layer 4. This in turn reduces the power generation efficiency of the solar cell 25. For this reason, the number (n) of 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.

Figure 34 is a plan view schematically illustrating another example of the second cell formation structure P2 of the solar cell 25 according to the first to sixth embodiments.

In the manufacturing method of the solar cell 25 according to the first to sixth embodiments, the second step S2 involves forming a second cell formation structure P2 having a continuous cutting groove Pc between the first cell formation structure P1 (first separation groove) and the island portion row Q(n) closest to the first cell formation 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 formation structure P2 has a continuous cutting groove Pc between the first cell formation structure P1 (first separation groove) and the island portion row Q(n) closest to the first cell formation 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 this way, even if the cutting groove Pc on the first cell formation structure P1 (first separation groove) side cuts the first electrode 3, the first electrode 3 and the second electrode 8 can be made conductive at the side of the cutting groove Pc on the third cell formation structure P3 (third separation groove) side.

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).

In the present disclosure, the bottom surface, bottom portion, or portion thereof of the separation groove, groove portion, or deep island-shaped 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 portion thereof of the separation groove, groove portion, or deep island-shaped portion may be tilted relative to the substrate. Also, in the present disclosure, the bottom surface, bottom portion, or portion thereof of the separation groove, groove portion, or deep island-shaped portion may be tilted relative to the substrate, and may have an inverted V-shape or a bowl-shape when viewed in cross section (i.e., the groove, island-shaped portion, or hole is deeper near the center and shallower at the ends).

[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.

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

(3) A third aspect of the present disclosure relates to a solar cell manufacturing method according to the first aspect, wherein the second step includes a first cutting step of cutting a layer formed on the one surface of the base to form grooves, and a second cutting step of cutting the bottoms of the grooves to form the plurality of island-shaped portions.

(4) A fourth aspect of the present disclosure relates to a solar cell manufacturing method according to the first aspect, wherein in the second step, a layer formed on the one surface of the base is cut to form grooves, while the plurality of island-shaped portions are formed at the bottom of the grooves.

(5) A fifth aspect of the present disclosure relates to a method for manufacturing a solar cell according to any one of the first to fourth aspects, 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.

(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 surface of a base, and a layer formed on the one surface of the base having a plurality of solar cell cells 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.

(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 consists only of the plurality of island-shaped portions.

(8) A solar cell according to an eighth aspect of the present disclosure is the solar cell according to the sixth aspect, wherein the second cell formation structure has a groove, and the plurality of island-shaped portions are deep and island-like at the bottom of the groove.

(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.

(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 the interior of the first electrode.

(11) A solar cell according to an eleventh aspect of the present disclosure is the solar cell of the ninth aspect, wherein the plurality of island-shaped portions include island-shaped portions that penetrate the first electrode.

(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 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, and 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, 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.

(13) A solar cell according to a thirteenth aspect of the present disclosure is a solar cell according to 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.

(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 includes two or more linear island-shaped portions.

(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 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, and 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, and the two or more linear island portions are aligned in a direction parallel to the first cell formation structure and the third cell formation structure.

(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, and 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, and the two or more linear island portions are aligned along a vertical direction perpendicular to the first cell formation structure and the third cell formation structure.

(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 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, and 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, and the two or more linear island portions are aligned obliquely relative to the first cell formation structure and the third cell formation structure.

(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, and 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, and the plurality of island portions include island portion rows arranged in a vertical direction perpendicular to the first cell formation structure and the third cell formation structure, with two or more island portions arranged side by side at intervals in a parallel direction parallel 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 portion row closest to the first cell formation structure among the plurality of island portion rows so as to cut the first electrode in the parallel direction.

(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 grooves are dug so as to reach the electron transport layer or the hole transport layer on the first electrode, leaving all or part of the electron transport layer or the hole transport layer.

(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 grooves are dug so as to reach the light absorbing layer and leave all or part of the light absorbing layer.

(21) A solar cell according to a 21st aspect of the present disclosure is the solar cell of the 8th aspect, wherein the groove is dug so as to reach the first electrode and leave all or part of the first electrode.

The present disclosure is not limited to the embodiments described above and can be implemented in various other forms. Therefore, the embodiments are merely illustrative in all respects and should not be interpreted as 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 that fall within the equivalent scope of the claims are within the scope of the present disclosure.

2 Base 20 Solar cell 25 Solar cell 3 First electrode 4 Functional layer 5 Electron transport layer 6 Light absorption layer 7 Hole transport layer 8 Second electrodes P to P Multiple cell formation structures 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 island-shaped portions Pc; Cutting grooves Q(1)-Q(n): Row of island-shaped portions S1; First step S2; Second step S2-1-1: First cutting step S2-1-2; Second cutting step S3: Third step V: Vertical direction W; Parallel direction β1: Surface along the base body; β2: Side surface perpendicular to the base body

Claims (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 second cell-forming structure is composed only of a plurality of deep island-shaped portions, and
the second cell formation structure does not have a bottom of a groove portion other than a bottom of an island-shaped portion,
the plurality of island-shaped portions include island-shaped portions that penetrate the first electrode and the functional layer consistently;
the plurality of cell forming structures includes a first cell forming structure that is a first separation groove that cuts the first electrode;
the second cell forming structure and the first cell forming structure are formed in parallel,
The solar cell is characterized in that the plurality of island-shaped portions include a row of island-shaped portions that penetrate two or more of the first electrodes, the island-shaped portions being arranged in parallel with intervals in a parallel direction parallel to the first cell forming structure, and island-shaped portions that penetrate the first electrodes being arranged in multiple rows with intervals in a vertical direction perpendicular to the first cell forming structure . The solar cell according to claim 1 ,
the plurality of island-shaped portions include island-shaped portions having a linear shape,
the linear island-shaped portion is aligned along a vertical direction perpendicular to the first cell-forming structure;
Or,
The solar cell , wherein the linear island-shaped portion is aligned obliquely with respect to the first cell formation structure . The solar cell according to claim 1 ,
the functional layer includes at least one electron transport layer or hole transport layer provided on the first electrode;
a first separation groove of the first cell formation structure that cuts at least a first layer of the electron transport layer or the hole transport layer provided on the first electrode ; The solar cell according to claim 1 ,
The solar cell , wherein the plurality of island-shaped portions include two or more island-shaped portions that penetrate through the first electrode and have a linear shape . 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 second cell formation structure has a plurality of deep island-shaped portions,
the plurality of cell forming structures includes a first cell forming structure that is a first separation groove that cuts the first electrode;
the second cell forming structure and the first cell forming structure are formed in parallel,
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, each row including two or more island-shaped portions arranged in parallel with each other in a parallel direction parallel to the first 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 .