Photoelectric conversion elements and photoelectric conversion modules

Abstract

The photoelectric conversion element (10) of the tandem solar cell includes a top cell (11) disposed on the light-receiving side and a bottom cell (12) disposed on the back side. The electrode layer (surface grid electrode (111) and surface transparent electrode (112)) on the upper side of the top cell (11) and the electrode layer (back transparent electrode (124) and back grid electrode (125)) on the back side of the bottom cell (12) are divided into multiple regions. The divided regions in the electrode layer on the upper side correspond to the divided regions in the electrode layer on the back side.

Description

[Technical Field]

[0001] This invention relates to photoelectric conversion elements and photoelectric conversion modules in series solar cells. [Previous Technology]

[0002] To improve the power generation efficiency of solar cells, tandem solar cells in which different types of light-absorbing layers (or photoelectric conversion layers) are stacked have been proposed. As an example of a tandem solar cell, a perovskite / silicon thin-film solar cell (e.g., Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-910 [Summary of the Invention]

[0004] In tandem solar cells such as perovskite / silicon thin film solar cells, which have a photoelectric conversion layer (perovskite layer) using a perovskite compound, current concentration may occur within the cell due to partial short circuits (point defects), etc.

[0005] Figure 5 is a cross-sectional view showing a schematic structure of a conventional photoelectric conversion element 50 with a series configuration. As shown in Figure 5, the photoelectric conversion element 50 is composed of a top cell 51 and a bottom cell 52 stacked together, with the top cell 51 disposed on the top side and the bottom cell 52 disposed on the back side. Here, the top cell 51 is a perovskite solar cell, and the bottom cell 52 is a crystalline silicon solar cell.

[0006] The top battery 51, from top to bottom, sequentially comprises a surface gate electrode 511, a surface transparent electrode 512, a top battery electron transport layer 513, a top battery light absorption layer 514, and a top battery hole transport layer 515. The bottom battery 52, from top to bottom, sequentially comprises a bottom battery n-type doped layer 521, a bottom battery light absorption layer 522, a bottom battery p-type doped layer 523, a back transparent electrode 524, and a back gate electrode 525. Furthermore, an intermediate electrode 53 is provided between the top battery 51 and the bottom battery 52, and the top battery 51 and the bottom battery 52 are connected in series via the intermediate electrode 53. Interconnectors 60 are connected to the upper surface and the back surface of the photoelectric conversion element 50.

[0007] Figure 6 is a diagram illustrating the principle of current concentration within the battery caused by a short circuit. In the photoelectric conversion element 50 of Figure 6, a short circuit occurs at a location in the top battery light absorption layer 514.

[0008] When the top cell 51 is a thin-film solar cell, due to the thinness of each layer, a short circuit may occur inside the cell due to uneven film thickness or foreign matter intrusion. If a short circuit occurs anywhere inside the top cell 51, an in-plane current is generated in the electrode layers of the photoelectric conversion element 50 (surface grid electrode 511, surface transparent electrode 512, back transparent electrode 524, and back grid electrode 525) toward the short circuit. As a result, the current concentrates and flows into the short-circuited part inside the cell.

[0009] In addition to the short circuit mentioned above, current concentration in the battery may also be caused by the imbalance of photocurrent between the top and bottom of the series structure, or by the influence of the shadow on the solar cell unit.

[0010] For example, when the photocurrent of the photoelectric conversion element 50 in the bottom cell 52 is significantly greater than that in the top cell 51, a reverse voltage is applied to the top cell 51. In the case that the top cell 51 is a perovskite solar cell or the like, the top cell 51 has low voltage withstand capability and is misaligned in the area, thus causing current to concentrate in the part with low reverse voltage withstand capability.

[0011] Furthermore, in a photoelectric conversion module in which a plurality of photoelectric conversion elements 50 are connected in series, when a portion of an element is shaded by one of the photoelectric conversion elements 50, current from other elements connected before and after it that are not shaded flows into the shaded element. At this time, within the shaded element, the current is concentrated in the part that is not shaded and is operating.

[0012] If such current concentration occurs, it will cause battery degradation and overheating at the current concentration point, resulting in reduced reliability and performance degradation. This problem becomes particularly significant in the case of perovskite solar cells. Therefore, it is necessary to suppress current concentration within the battery.

[0013] This invention was made in view of the above-mentioned problems, and its object is to provide a photoelectric conversion element and a photoelectric conversion module capable of suppressing current concentration within a series-connected solar cell. Technical means to solve the problem

[0014] In order to solve the above problems, the following photoelectric conversion elements and photoelectric conversion modules are provided.

[0015] (1) Photoelectric conversion element The photoelectric conversion element disclosed herein is a photoelectric conversion element in a series solar cell, including a top cell disposed on the light-receiving side and a bottom cell disposed on the back side. The electrode layer on the upper side of the top cell and the electrode layer on the back side of the bottom cell are divided into a plurality of regions, and the divided regions in the electrode layer on the upper side and the divided regions in the electrode layer on the back side correspond to each other.

[0016] (2) Photoelectric conversion module A photoelectric conversion module has a photoelectric conversion string formed by connecting a plurality of photoelectric conversion elements described above in series, wherein two adjacent photoelectric conversion elements in the photoelectric conversion string are electrically connected by a connecting member, and at least one connecting member is provided in a divided area in the upper electrode layer and the lower electrode layer of the photoelectric conversion element. Effects of the invention

[0017] In the photoelectric conversion element and photoelectric conversion module disclosed herein, the electrode layers on the upper side and the back side are divided into multiple regions, thereby suppressing current concentration in the battery.

Implementation Method

[0019] (First Embodiment) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. FIG1 shows a cross-sectional view of a simplified configuration of the photoelectric conversion element 10 according to one embodiment of the present invention.

[0020] The photoelectric conversion element 10 is a photoelectric conversion element of a series-connected solar cell using a perovskite solar cell. In FIG. 1, the upper side is the light-receiving surface. As shown in FIG. 1, the photoelectric conversion element 10 is composed of a top cell 11 and a bottom cell 12 stacked together, with the top cell 11 disposed on the upper side and the bottom cell 12 disposed on the lower side. Furthermore, in this disclosure, when simply referred to as the light-receiving surface side, it refers to the light-receiving surface side or the side mainly used as the light-receiving surface. Similarly, when simply referred to as the lower side, it refers to the lower side or the side mainly used as the lower side.

[0021] Furthermore, when the direction is described as "up" or "down", the light-receiving side of the component is described as "up" and the back side of the component is described as "down". Unless otherwise specified, this can be understood as such. Similarly, the light-receiving side refers to the upper side and the back side refers to the lower side.

[0022] Furthermore, the light-receiving surface refers to the side of a single-sided light-receiving solar cell where light directly enters the element. However, in a double-sided light-receiving solar cell, it is sufficient to consider any one side as the light-receiving surface. In this case, when any one side is considered as the light-receiving surface, the side opposite to it can be considered as the back surface. Therefore, if the structure disclosed herein is present when at least one side is considered as the light-receiving surface, then the structure disclosed herein is considered to be used. That is, it can be considered that even if the structure disclosed herein is not present when one side is considered as the light-receiving surface, the structure disclosed herein is used as long as the other side is considered as the light-receiving surface.

[0023] Furthermore, in this invention, a series-type solar cell refers to a solar cell in which part or all of the light (specifically, light of a certain wavelength band) incident from the light-receiving surface side of the photoelectric conversion element can be absorbed sequentially by two or more light-absorbing layers. Alternatively, in this invention, a series-type solar cell, if described in terms of configuration, may also mean a solar cell in which two light-absorbing layers are sequentially arranged from the light-receiving surface side to the back side of the photoelectric conversion element when viewed from the light-receiving surface side. Furthermore, when viewed from the light-receiving surface side, it is not necessary for the two light-absorbing layers to completely overlap; at least a partial overlap is sufficient. Additionally, it is sufficient for at least one light-absorbing layer to completely overlap with the other light-absorbing layer. Alternatively, in this invention, in other words, part or all of the light (specifically, light of a certain wavelength band) incident from the light-receiving surface side of the photoelectric conversion element can be incident through one light-absorbing layer to the other light-absorbing layer. Furthermore, the light-absorbing layer mentioned here does not need to be a single layer; it can be composed of multiple layers. Multiple layers here refer to, for example, a stacked structure formed by a PN junction.

[0024] Furthermore, the light-absorbing layer is a layer capable of absorbing light incident on the photoelectric conversion element to generate electrons and holes. The generation of electrons and holes by the light-absorbing layer is obvious as long as the solar cell functions as a solar cell. As long as the light-absorbing layer is made of appropriate materials, it is not necessary to confirm the light absorption and generation of electron-hole pairs, which are very difficult to confirm.

[0025] The top battery 11, from the top side, sequentially includes a surface gate electrode 111, a surface transparent electrode 112, a top battery electron transport layer 113, a top battery light absorption layer 114, and a top battery hole transport layer 115. The bottom battery 12, from the top side, sequentially includes a bottom battery n-type doped layer 121, a bottom battery light absorption layer 122, a bottom battery p-type doped layer 123, a back transparent electrode 124, and a back gate electrode 125. Furthermore, in the photoelectric conversion element 10, an intermediate electrode 13 is provided between the top battery 11 and the bottom battery 12 as an intermediate layer, and the top battery 11 and the bottom battery 12 are connected in series through the intermediate electrode 13.

[0026] In this embodiment, the top cell 11 is a perovskite solar cell, and the bottom cell 12 uses a crystalline silicon solar cell as a silicon-based solar cell. That is, the light-absorbing layer 114 of the top cell is a layer containing a perovskite compound as a photoelectric conversion material, which can be composed solely of the perovskite compound or contain substances other than the perovskite compound.

[0027] Furthermore, in the solar cell (or photoelectric conversion module) using the photoelectric conversion element 10, a surface interconnect 20A is connected to the upper surface of the photoelectric conversion element 10 (i.e., the upper surface of the top battery 11), and a back interconnect 20B is connected to the back surface of the photoelectric conversion element 10 (i.e., the lower surface of the bottom battery 12).

[0028] The photoelectric conversion element 10 shown in FIG1 can be fabricated by forming the layers required for the top battery 11 on the bottom 12. However, the fabrication order of the photoelectric conversion element 10 of this disclosure is not particularly limited. The photoelectric conversion element 10 can be fabricated by other methods, such as bonding these cells together after fabricating the top battery 11 and the bottom battery 12 respectively.

[0029] Hereinafter, the structure of each layer in the photoelectric conversion element 10 will be described as an example. However, known technologies can be applied to the materials and film formation methods of each layer in the photoelectric conversion element 10. Therefore, the structure of each layer applicable to this embodiment is not limited to this example. That is, as long as it has the function of a photoelectric conversion element in a series solar cell, layers that can be omitted may be layers other than those described below, and a certain layer may also have the functions of other layers.

[0030] (Surface gate electrode, back gate electrode) The surface gate electrode 111 and the back gate electrode 125 are composed of a plurality of parallel conductive components. These conductive components extend along a first direction (the X direction shown in FIG. 2) and are arranged side-by-side and spaced apart from each other along a second direction (the Y direction shown in FIG. 2). The plurality of conductive components in the surface gate electrode 111 (back gate electrode 125) are connected by a gate electrode disposed on the interconnect 20 or at the bottom of the interconnect. Specifically, the interconnect 20 extends along the second direction and is configured to be orthogonal to the plurality of conductive components. The second direction is along the short side of the photoelectric conversion element 10; therefore, by configuring it to extend along this direction, the resistance of the interconnect 20 can be reduced.

[0031] The surface gate electrode 111 (back gate electrode 125) is also referred to as a finger electrode, and the interconnect 20 is also referred to as a bus electrode. The material of the conductive components is not particularly limited; for example, metals such as silver, copper, and aluminum can be used. The width of the conductive component in the surface gate electrode 111 (back gate electrode 125) is narrower than that of the interconnect 20, and light enters the interior of the photoelectric conversion element 10 through the gap between adjacent conductive components. Furthermore, the back gate electrode 125 is on the side opposite to the light-receiving surface, so a light-blocking structure can be adopted.

[0032] (Front transparent electrode, back transparent electrode) The front transparent electrode 112 and the back transparent electrode 124 are thin-film electrodes with conductivity and light transmittance. Examples of materials used as thin-film electrodes include conductive transparent materials such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (G / O). These materials can be used individually or in combination of two or more. Furthermore, since the back transparent electrode 124 is on the side opposite to the light-receiving surface, it can also be a non-transparent structure.

[0033] (Top Battery Electron Transport Layer) The top battery electron transport layer 113 is a layer that transports electrons generated in the top battery light absorption layer 114 to the surface transparent electrode 112. Preferably, the top battery electron transport layer 113 also functions as a hole blocking layer to suppress the movement of holes generated in the top battery light absorption layer 114 towards the surface transparent electrode 112. Examples of materials for the top battery electron transport layer 113 include tin oxide, titanium oxide, and zinc oxide.

[0034] Furthermore, as long as the top battery 11 has a photoelectric conversion function, it is obvious that it has the function of transmitting electrons in a portion that is closer to the electron transmission side (or the negative electrode side, which is the same in this disclosure) or located within the top battery light absorption layer 114 than the top battery light absorption layer 114, and it is not necessary to confirm an electron transmission function that is actually difficult to confirm. That is, as long as the top battery 11 has a photoelectric conversion function, a layer that is located on the electron transmission side or within the top battery light absorption layer 114 compared to the top battery light absorption layer 114, and is made of a suitable material, can be regarded as the top battery electron transmission layer 113.

[0035] In addition, the top battery electron transport layer 113 can also have the function of the surface transparent electrode 112, or vice versa. Therefore, the photoelectric conversion element 10 may not have both the surface transparent electrode 112 and the top battery electron transport layer 113, or it may have only one of the two functions.

[0036] (Top Battery Light Absorption Layer) The top battery light absorption layer 114 may be a layer containing a perovskite compound as a photoelectric conversion material. The top battery light absorption layer 114 is a layer capable of absorbing at least a portion of the light incident on the photoelectric conversion element 10 and generating electrons and holes. Electrons move towards the top battery electron transport layer 113, and holes move towards the top battery hole transport layer 115. The top battery light absorption layer 114 may be composed solely of a perovskite compound, or it may contain substances other than a perovskite compound.

[0037] The perovskite compound is composed of compounds represented by the general formula: ABX3・・・ (1). However, it is preferred that the composition ratio of each is 1:1:3, but it is not necessarily 1:1:3, and the content of each element can be adjusted appropriately.

[0038] In general formula (1), A is an organic molecule (containing an organic group or an organic cation, as is the case in this disclosure) or an inorganic atom or molecule (containing an inorganic group or an inorganic cation, as is the case in this disclosure) or a combination thereof, B is a metal atom or molecule (containing a metal cation, as is the case in this disclosure), and X is a halogen atom or molecule, or a chalcogen atom or molecule (containing a halide anion or a chalcogen anion, as is the case in this disclosure). In general formula (1), the three Xs may be the same as or different from each other.

[0039] In general formula (1), the organic molecule represented by A is preferably a molecule containing carbon, nitrogen and hydrogen, and the inorganic atom represented by A is preferably cesium or rubidium.

[0040] Furthermore, as a perovskite compound, it can be identified simply by knowing that the top battery light-absorbing layer 114 has photoelectric conversion function and contains A, B, and X; it is not necessary to confirm that it has a crystal structure. For example, it can be understood that it has organic molecules, metal atoms, and halogen atoms as A, B, and X, or it has inorganic atoms, metal atoms, and halogen atoms as A, B, and X, and thus it can be identified.

[0041] In general formula (1), the organic molecules represented by A include, for example, alkylamines, alkylammonium compounds, and nitrogen-containing heterocyclic compounds. In perovskite compounds (1), the organic molecules represented by A can be only one organic molecule or two or more organic molecules.

[0042] Alkylamines include, for example, methylamine, ethylamine, propylamine, butylamine, pentanamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentanamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentanamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentanamine, hexylmethylamine, ethylpropylamine, and ethylbutylamine, etc.

[0043] Alkylammonium is the ionization product of the above-mentioned alkylamines. Alkylamines include, for example, 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, etc.

[0044] Nitrogen-containing heterocyclic compounds include, for example, imidazoles, azoles, pyrroles, aziridines, nitrogen-containing heterocyclic propenes, nitrogen-containing heterocyclic butanes, nitrogen-containing heterocyclic butadienes, azoles, imidazolines, and zozides. Nitrogen-containing heterocyclic compounds can also be ionized products. Phenylacetium is preferably used as an ionized product of a nitrogen-containing heterocyclic compound.

[0045] 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 phenylacetium, amine, ethylamine, propylamine, methylammonium, ethylammonium or propylammonium is more preferred, and methylammonium is more preferred.

[0046] In general formula (1), the metal atom represented by B includes, for example, lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. In perovskite compounds, the metal atom represented by B can be only one type of metal atom or two or more types of metal atom. From the viewpoint of improving the light absorption and charge generation properties of perovskite compounds, the metal atom represented by B is preferably a lead atom or a tin atom. From the viewpoint of reducing lead content, a tin atom is preferred.

[0047] In general formula (1), examples of halogen atoms represented by X include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Examples of chalcogen atoms include oxygen atoms, sulfur atoms, selenium atoms, and tellurium atoms. In perovskite compounds, X may represent one or more halogen or chalcogen atom. From the viewpoint that perovskite compounds can utilize a wide range of light, the halogen atom represented by X is preferably an iodine atom. Specifically, of the three X's, at least one X preferably represents an iodine atom, and more preferably all three X's represent iodine atoms.

[0048] As a perovskite compound, a compound represented by the general formula "CH3NH3PbX3 (where X represents a halogen atom)" is preferred, and CH3NH3PbI3 is more preferred. By using a compound represented by the general formula "CH3NH3PbX3" (especially CH3NH3PbI3) as a perovskite compound, electrons and holes can be generated more effectively in the perovskite compound, and as a result, the photoelectric conversion efficiency of the solar cell unit can be further improved.

[0049] As a method for forming the top solar cell light absorption layer 114 containing a perovskite compound, an example is a method of forming a film by coating a precursor solution obtained by dissolving a precursor compound of the perovskite compound in an organic solvent using a known method such as spin coating or bar coating.

[0050] (Top Battery Hole Transport Layer) The top battery hole transport layer 115 is a layer that transports holes generated in the top battery light absorption layer 114 to the intermediate electrode 13. The top battery hole transport layer 115 preferably also functions as an electron blocking layer to suppress the movement of electrons generated in the top battery light absorption layer 114 to the intermediate electrode 13.

[0051] The top battery hole transport layer 115 is constructed primarily of a hole transport material. Specifically, the top battery hole transport layer 115 preferably contains 70% by mass or more of a hole transport material, more preferably 85% by mass or more and 100% by mass or less. Examples of hole transport materials include p-type organic semiconductors, conductive polymers, metal oxides, and metal sulfides (e.g., Cu2O, NiO, ZnS), with spiro-OMeTAD being the most preferred.

[0052] Furthermore, as long as the top battery 11 has a photoelectric conversion function, it is obvious that the portion of the top battery light absorption layer 114 located on the hole transport side (or the positive electrode side, which is the same in this disclosure) or within the top battery light absorption layer 114 can perform hole transport, and it is not necessary to confirm a hole transport function that is actually difficult to confirm. That is, as long as the top battery 11 has a photoelectric conversion function, a layer located on the hole transport side or within the top battery light absorption layer 114 compared to the top battery light absorption layer 114, and made of a suitable material, can be regarded as the top battery hole transport layer 115.

[0053] (Intermediate Layer) In this disclosure, an intermediate electrode 13 is exemplified as the intermediate layer. The intermediate electrode 13 is an electrode that electrically connects the top cell and the bottom cell, and is configured such that light not absorbed by the top cell 11 can reach the bottom cell 12. That is, the material of the intermediate electrode 13 can be a conductive and transparent material, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), gallium-doped zinc oxide (GZO), and other conductive and transparent materials. One of the above materials can be used alone, or two or more can be used in combination. In addition, the intermediate layer is not limited to the intermediate electrode 13, and other highly doped impurity doped layers, highly doped PN junction layers, tunnel junction layers, etc., can also be used in a structure disposed between a known series-connected top cell and a bottom cell. Furthermore, as an intermediate layer, any structure positioned between the top and bottom cells of a series-connected solar cell is sufficient. As long as the solar cell functions as a solar cell, there is no need to verify the conductivity, transmittance, or other physical properties of the intermediate layer; its function as an intermediate layer is self-evident. Alternatively, an intermediate layer may not be necessary. A structure identical to the intermediate layer can be used between the layer on the top cell near the bottom cell and the layer on the bottom cell near the top cell. In this case, the same conductivity, transmittance, and other physical properties are not required. As long as the top and bottom cells of the series-connected solar cell function as a series-connected solar cell, it can naturally function as a substitute for an intermediate layer.

[0054] (Bottom Cell n-type Doped Layer, Bottom Cell Light Absorbing Layer, Bottom Cell p-type Doped Layer) The bottom cell n-type doped layer 121, bottom cell light absorbing layer 122, and bottom cell p-type doped layer 123 can adopt a structure used in known silicon solar cells. For example, by adding dopants to the surface of a crystalline silicon substrate, the bottom cell n-type doped layer 121 can be formed on one side of the bottom cell light absorbing layer 122, which is a crystalline silicon substrate, and the bottom cell p-type doped layer 123 can be formed on the other side. By adding phosphorus, arsenic, or the like as dopants, the bottom cell n-type doped layer 121 can be formed, and by adding boron, gallium, or the like, the bottom cell p-type doped layer 123 can be formed.

[0055] Furthermore, when using a heterojunction silicon structure, for example, a non-monocrystalline silicon thin film such as amorphous silicon or microcrystalline silicon can be formed as the n-type doped layer 121 and the p-type doped layer 123 of the bottom battery on a monocrystalline silicon substrate serving as the light absorption layer 122 of the bottom battery. Examples of materials for the silicon thin films used as the n-type doped layer 121 and the p-type doped layer 123 of the bottom battery include amorphous silicon, microcrystalline silicon, amorphous silicon alloys, and microcrystalline silicon alloys. Examples of silicon alloys include silicon oxide, silicon carbide, silicon nitride, and silicon germanium. One of these materials can be used alone, or two or more can be used in combination.

[0056] The photoelectric conversion element 10 shown in Figure 1 illustrates a configuration where the photocurrent flows downwards from the top of the figure. However, the direction of the photocurrent is not limited to this, and it can also be configured where the photocurrent flows upwards. In the case of a configuration where the photocurrent flows upwards, in the top cell 11, the positions of the top cell electron transport layer 113 and the top cell hole transport layer 115 are interchanged, and in the bottom cell 12, the positions of the bottom cell n-type doped layer 121 and the bottom cell p-type doped layer 123 are interchanged. In addition, the type of doped layer (bottom cell n-type doped layer 121 or bottom cell p-type doped layer 123) in the bottom cell 12 is not particularly limited. It can be any of PERC (Passivated Emitter and Rear Cell), TOPCon (Tunnel Oxide Passivated Contact), or heterojunction. In addition to the doped layer, a PERC section, a TOPCon section, or a heterojunction section can also be provided.

[0057] As shown in FIG. 1, in the photoelectric conversion element 10, the upper electrode layer (surface gate electrode 111 and surface transparent electrode 112) and the back electrode layer (back transparent electrode 124 and back gate electrode 125) are respectively divided into a plurality of regions. Specifically, a plurality of dividing grooves 14 are formed on the upper and back electrode layers, and the electrode layers are divided into a plurality of regions by the dividing grooves 14, or divided into a plurality of regions along a predetermined arrangement direction. The dividing grooves 14 can be formed by etching a portion of the electrode layer. Alternatively, a mask can be used during the deposition of the electrode layer so that the electrode layer is not initially formed in the region that becomes the dividing groove 14.

[0058] FIG2 is a top view showing a portion of a photoelectric conversion module 100 using photoelectric conversion elements 10. The photoelectric conversion module 100 has at least one column of photoelectric conversion strings formed by connecting a plurality of photoelectric conversion elements 10 in series. Alternatively, the photoelectric conversion module 100 may also be a photoelectric conversion array in which multiple columns of photoelectric conversion strings are connected in parallel. In FIG2, two adjacent photoelectric conversion elements 10 in the photoelectric conversion string are shown separately. Here, the photoelectric conversion element 10 on the upper side in the Y direction is designated as the first element 10A, and the photoelectric conversion element 10 on the lower side in the Y direction is designated as the second element 10B. Furthermore, the cross-sectional view of FIG1 is a cross-sectional view of the photoelectric conversion element 10 shown in FIG2 cut off by plane AA.

[0059] The first element 10A and the second element 10B are electrically connected via an interconnect 20. The interconnect 20 is a connecting component in which the surface interconnect 20A and the back interconnect 20B are integrally connected. In the interconnect 20 connecting the first element 10A and the second element 10B, the surface interconnect 20A is connected to the electrode layer on the upper side of the first element 10A, and the back interconnect 20B is connected to the electrode layer on the back side of the second element 10B. Furthermore, although an interconnect is illustrated herein, the connecting component is not limited to an interconnect, but refers to a component capable of widely electrically connecting elements to elements.

[0060] Therefore, in the photoelectric conversion element 10, the electrode layer on the upper side of the top battery 11 and the electrode layer on the back side of the bottom battery 12 are divided into a plurality of regions, and the divided regions in the upper side electrode layer correspond to each other. Furthermore, in this disclosure, "the divided regions in the upper side electrode layer and the divided regions in the back side electrode layer correspond to each other" does not mean that the divided regions in the upper side electrode layer and the divided regions in the back side electrode layer are physically connected, but rather that the upper side electrode layer of the first element 10A is actually physically connected to the back side electrode layer of the second element 10B, which is an adjacent element. Therefore, this statement specifically refers to a structure having this correspondence. That is, a certain component (e.g., XA) in the first element 10A and a component (e.g., YB) in the second element 10B, which is an adjacent element, are at least physically connected by a connecting member. A component (e.g., YA) on the first element 10A that corresponds to component YB is called a "correspondence". Here, for example, constituent element XA refers to a segmented element of the upper electrode layer, and constituent elements YA and YB refer to a segmented element of the lower electrode layer.

[0061] As shown in FIG2, the dividing grooves 14 are formed along a direction parallel to the interconnect 20. That is, all the dividing grooves 14 in the photoelectric conversion element 10 are formed in parallel. FIG2 illustrates a configuration in which two dividing grooves 14 are provided on the electrode layers on the upper side and the back side of the photoelectric conversion element 10, but the number of dividing grooves 14 (i.e., the number of regions divided in the electrode layer) is not particularly limited. However, the divided regions in the electrode layer on the upper side correspond to the divided regions in the electrode layer on the back side, and the number of dividing grooves 14 in the electrode layers on the upper side and the back side is the same. In addition, by forming the dividing grooves 14 along a direction parallel to the inner connector 20, there is no top battery 11 on the bottom 12, and the area that can receive can be effectively set, which has the advantage that the current collection efficiency of the interconnect 20 does not decrease.

[0062] Alternatively, the number of segmented regions on the upper side and the back side may be the same, and the arrangement direction of the segmented regions on the upper side and the back side may be the same. In this case, the segmented regions in the electrode layer on the upper side and the segmented regions in the electrode layer on the back side of the photoelectric conversion element 10 not only correspond to each other, but the corresponding segmented regions on the upper side and the back side also have the same arrangement order along the arrangement direction. In addition, the corresponding segmented regions overlap each other in at least a portion when viewed from above, and more preferably completely overlap when viewed from above.

[0063] At least one interconnect 20 is connected to each of the segmented regions in the electrode layers on the top and back sides of the photoelectric conversion element 10. Figures 1 and 2 illustrate a configuration in which one interconnect 20 is connected to a segmented region of the electrode layer, but two or more interconnects 20 may also be connected to a segmented region.

[0064] In the photoelectric conversion element 10, the electrode layers on the top and back sides are divided into a plurality of regions, so that in-plane currents in these electrode layers are generated only within each region, and in-plane currents spanning the entire electrode layer are not generated. Therefore, for example, even if the photoelectric conversion element 10 is affected by current concentration due to reasons such as a short circuit, current concentration is generated only within the region containing that reason, and current concentration from other regions is not generated. Therefore, current concentration within the battery can be significantly suppressed. The suppression effect of current concentration in the photoelectric conversion element 10 increases with increasing number of regions in the electrode layers.

[0065] In the photoelectric conversion element 10, the layers other than the electrode layers on the top and back sides have low resistance in the direction perpendicular to the bonding surface of other layers (i.e., the film thickness direction), but high resistance in the direction parallel to the bonding surface (i.e., the in-plane direction). Alternatively, considering that there is a different scale difference (not shown) between the in-plane and film thickness directions, and that the layers have a certain resistivity with a large specific voltage, it can be said that current flows easily in the film thickness direction because the scale is small, while the scale in the in-plane direction is too large to generate in-plane current. Therefore, it is difficult to generate in-plane current in the layers other than the electrode layers on the top and back sides. If the photoelectric conversion element 10 only divides the electrode layers that easily generate in-plane current, a current concentration suppression effect can be obtained.

[0066] Furthermore, the intermediate electrode 13, which serves as an intermediate layer in the photoelectric conversion element 10, is formed to reduce the resistance in the film thickness direction between the top cell 11 and the bottom cell 12. In most cases, the film thickness of the intermediate layer or intermediate electrode 13 is extremely thin, resulting in high resistance in the in-plane direction. In this case, even if the intermediate layer or intermediate electrode 13 is not segmented, the effect of suppressing current concentration in the photoelectric conversion element 10 can be sufficiently obtained. However, by forming the same separation groove as the electrode layer to separate the intermediate layer or intermediate electrode 13, the effect of further suppressing current concentration can be obtained.

[0067] Furthermore, the reason for dividing not only the top electrode layer but also the back electrode layer in the photoelectric conversion element 10 is as follows. For example, in the photoelectric conversion module 100 shown in FIG2, consider a case where current concentration (short circuit) occurs on the side of the first element 10A. Moreover, the top electrode layer of the first element 10A is divided as shown, but assume that the back electrode layer of the second element 10B is not divided. In this case, the top electrode layer of the first element 10A and the back electrode layer of the second element 10B are connected by interconnects 20, thereby generating an in-plane current in the back electrode layer of the second element 10B, and the current concentrates in the three interconnects 20 in the first element 10A, in the interconnect 20 connected to the region where the current concentration occurs. Therefore, in the first element 10A, the effect of dividing the top electrode layer is not utilized, and current concentration occurs. By dividing not only the top electrode layer but also the back electrode layer, current concentration via the electrodes connected by interconnects 20 can be prevented.

[0068] Furthermore, in the structure illustrated in FIG2, the surface gate electrode 111 and the surface transparent electrode 112 are used as the upper electrode layer, and the back transparent electrode 124 and the back gate electrode 125 are used as the back electrode layer, thus dividing all these electrodes. However, when the film thickness of the surface transparent electrode 112 and the back transparent electrode 124 is thin and the in-plane resistance of the surface transparent electrode 112 and the back transparent electrode 124 is sufficiently high, the surface transparent electrode 112 and the back transparent electrode 124 are not divided. Even if only the structure of the surface gate electrode 111 and the back gate electrode 125 is divided, the effects of the present invention can still be obtained. That is, the surface gate electrode 111 and the back gate electrode 125 can be regarded as only the upper and back electrode layers that need to be divided.

[0069] Furthermore, unless otherwise specified, the layers or films in this disclosure are not limited to thickness or width, and also include patterned or island-shaped layers, and layers having portions of varying thickness. A layer or film preferably refers to a component having approximately a certain thickness. Additionally, unless otherwise specified, "approximately" or "to a certain extent" refers to the magnitude of manufacturing error, preferably indicating a tolerance of +15% or -15%.

[0070] <Second Embodiment> FIG3 is a cross-sectional view showing the schematic structure of the photoelectric conversion element 10 according to the second embodiment of the present disclosure. In the photoelectric conversion element 10 of this embodiment, except as described below, the same configuration as that of the first embodiment can be adopted.

[0071] In this embodiment, the dividing groove 14 formed on the upper side of the photoelectric conversion element 10 divides not only the electrode layer (surface gate electrode 111 and surface transparent electrode 112), but also the other layers in the top battery 11 (top battery electron transport layer 113, top battery light absorption layer 114 and top battery hole transport layer 115) and the intermediate electrode 13. That is, in this embodiment, with the same layout as the electrode layer on the upper side, the dividing groove 14 divides the entire top battery 11 and the intermediate electrode 13 into multiple regions.

[0072] In the first embodiment, since the in-plane resistance of the layers other than the electrode layer in the top battery 11 and the intermediate electrode 13 is high, it is difficult for in-plane current to be generated in the layers other than the electrode layer and the intermediate electrode 13. If only the electrode layer is divided, the current concentration suppression effect is obtained. However, the layers other than the electrode layer and the intermediate electrode 13 are not completely free from in-plane current. Therefore, in this embodiment, by dividing the entire top battery 11 and the intermediate electrode 13 together by the dividing groove 14, the in-plane current in the top battery 11 and the intermediate electrode 13 can be cut off according to each divided top battery 11 and each intermediate electrode 13, and the current concentration suppression effect can be further improved.

[0073] The dividing groove 14 in this embodiment can be formed by etching away the layer forming the dividing groove 14, or by using a mask when the layer forming the dividing groove 14 is deposited. Alternatively, the dividing groove 14 can be formed by scribing (laser scribing or mechanical scribing).

[0074] In addition, as a variation of this embodiment, the top battery 11 is entirely divided by the dividing groove 14, and the intermediate electrode 13 may include an undivided structure. Alternatively, the electrode layers (surface gate electrode 111 and surface transparent electrode 112) and the intermediate electrode 13 of the top battery 11 are divided, but the other layers in the top battery 11 (top battery electron transport layer 113, top battery light absorption layer 114, and top battery hole transport layer 115) may include an undivided configuration. Furthermore, based on the division of the electrode layers (surface gate electrode 111 and surface transparent electrode 112) and the intermediate electrode 13 of the top battery 11, any one of the other layers (including the usable layers of the top battery electron transport layer 113, top battery light absorption layer 114, and top battery hole transport layer 115) may be divided, but other configurations that cannot be divided may be appropriately selected and not excluded.

[0075] <Third Embodiment> FIG4 is a cross-sectional view showing the schematic structure of the photoelectric conversion element 10 according to the third embodiment of the present disclosure. In the first and second embodiments, a two-junction type photoelectric conversion element 10 with two overlapping light absorption layers (photoelectric conversion layers) is shown, but in this embodiment, a three-junction type photoelectric conversion element 10 with three overlapping light absorption layers (photoelectric conversion layers) is shown. In addition, in the present invention, the term "two-junction type" refers to a light absorption layer that can sequentially absorb light in a series-connected solar cell with two layers, and the description of the structure of such light absorption layer can be applied to the description of a series-connected solar cell. Similarly, the term "three-junction type" refers to a light absorption layer that can sequentially absorb light in a series-connected solar cell with three layers, and the description of the structure of such light absorption layer can be applied to the description of a series-connected solar cell. Furthermore, the term "junction" used here does not refer to the word "junction" in the literal sense, but is a term used in the conventional sense to indicate the number of light absorption layers in a series-connected solar cell, and can be understood as "light absorption layer".

[0076] The photoelectric conversion element 10 in FIG4 has a structure in which an intermediate battery 15 is stacked on top of the top battery 11 and the bottom battery 12. Specifically, the top unit 11 is disposed on the top side, the bottom unit 12 is disposed on the back side, and the intermediate unit 15 is disposed between the top unit 11 and the bottom unit 12. The top battery 11 and the bottom battery 12 in this embodiment can be configured to have the same structure as the top battery 11 and the bottom battery 12 in the first and second embodiments. Furthermore, as an intermediate layer, an intermediate electrode 131 is disposed between the top battery 11 and the intermediate battery 15, and an intermediate electrode 132 is disposed between the intermediate battery 15 and the bottom battery 12. The intermediate electrodes 131 and 132 can be formed to have the same structure as the intermediate layer or intermediate electrode 13 in the first and second embodiments.

[0077] The intermediate cell 15, from the top side, sequentially comprises an intermediate cell electron transport layer 151, an intermediate cell light absorption layer 152, and an intermediate cell hole transport layer 153. The intermediate cell 15 and the top cell 11 are both perovskite solar cells, but preferably at least a portion of the material is different from that of the top cell 11, and preferably the wavelength of the light converted by photoelectric conversion is different from that of the top cell 11. That is, more specifically, it is preferable that the wavelength bands of the light absorbed by the top cell light absorption layer 114 and the intermediate cell light absorption layer 152 are different. In particular, when the wavelength band of the light absorbed by the light absorption layer of the intermediate cell 15 is on the longer wavelength side compared to the wavelength band of the light that can be absorbed by the light absorption layer of the top cell 11, the photoelectric conversion efficiency of the element can be further improved.

[0078] In this triple-junction type photoelectric conversion element 10, similarly to the double-junction type, by dividing the upper electrode layer (surface gate electrode 111 and surface transparent electrode 112) and the back electrode layer (back transparent electrode 124 and back gate electrode 125) into multiple regions, a current concentration suppression effect can be obtained. That is, even if the main cause of current concentration, such as short circuit, is either the top cell 11 or the middle cell 15, current concentration can be suppressed.

[0079] Furthermore, in the configuration of FIG4, only the top-side electrode layer (surface gate electrode 111 and surface transparent electrode 112) and the back-side electrode layer (back transparent electrode 124 and back gate electrode 125) are region-divided. However, for each of the electron transport layer, light absorption layer, and hole transport layer in the top battery 11 and the middle battery 15, region-division may or may not be performed. The method of region division can appropriately and without contradiction apply the example described in the second embodiment.

[0080] The embodiments disclosed herein are merely examples in all respects and should not be construed as limiting. Therefore, the technical scope of this disclosure is not limited to the above-described embodiments, but is determined based on the description in the claims of the invention.

[0081] This application claims priority based on Japanese Patent Application No. 2024-146941, filed on August 28, 2024, and the entire contents of Japanese Patent Application No. 2024-146941 are incorporated herein by reference. [Simplified Explanation of the Diagram]

[0018] FIG1 is a cross-sectional view showing a simplified structure of the photoelectric conversion element according to the first embodiment of the present invention. FIG2 is a top view showing a portion of a photoelectric conversion module using the photoelectric conversion element. FIG3 is a cross-sectional view showing a simplified structure of the photoelectric conversion element according to the second embodiment. FIG4 is a cross-sectional view showing a simplified structure of the photoelectric conversion element according to the third embodiment. FIG5 is a cross-sectional view showing a schematic structure of a conventional photoelectric conversion element having a series structure. FIG6 is a diagram illustrating the principle of current concentration in a battery caused by a short circuit.

Claims

1. A photoelectric conversion element, which is a photoelectric conversion element in a series-connected solar cell, wherein, It includes a top battery disposed on the light-receiving side and a bottom battery disposed on the back side. The electrode layer on the upper side of the top battery and the electrode layer on the back side of the bottom battery are divided into multiple regions. The photoelectric conversion layer in the bottom battery is not divided into multiple regions. The segmented regions in the electrode layer on the upper side and the segmented regions in the electrode layer on the back side correspond to each other.

2. The photoelectric conversion element as described in claim 1, wherein, The electrode layer on the top side of the top battery and the electrode layer on the back side of the bottom battery are divided into a plurality of regions along a predetermined arrangement direction. The number of the divided regions in the top side electrode layer is the same as the number of the divided regions in the back side electrode layer, and the arrangement direction of the divided regions on the top side and the back side is the same.

3. The photoelectric conversion element as described in claim 1 or 2, wherein, The top battery as a whole is divided into multiple regions corresponding to the electrode layer on the upper side and the electrode layer on the back side.

4. The photoelectric conversion element as described in claim 1 or 2, wherein, It has an intermediate layer disposed between the top battery and the bottom battery, and the intermediate layer is divided into a plurality of regions corresponding to the electrode layer on the upper side and the electrode layer on the back side.

5. The photoelectric conversion element as described in claim 1 or 2, wherein, The top battery has a light-absorbing layer containing a perovskite compound.

6. The photoelectric conversion element as described in claim 1 or 2, wherein, It includes an intermediate battery configured between the top battery and the bottom battery.

7. A photoelectric conversion module comprising a photoelectric conversion string formed by connecting a plurality of photoelectric conversion elements described in any one of claims 1 to 6 in series, wherein, In the photoelectric conversion string, two adjacent photoelectric conversion elements are electrically connected by a connecting component. In the electrode layer on the upper side and the electrode layer on the back side of the photoelectric conversion element, at least one connecting component is provided in the divided area respectively.

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