Photoelectric conversion element and method for manufacturing photoelectric conversion element

Abstract

This disclosure provides a photoelectric conversion element capable of suppressing the increase of internal resistance and a method for manufacturing the photoelectric conversion element. The photoelectric conversion element of this disclosure includes: a first transparent electrode layer located on a substrate, a photoelectric conversion layer located on the first transparent electrode layer, a second transparent electrode layer located on the photoelectric conversion layer, and a conductor portion 15. The detailed configuration of the first transparent electrode layer, the photoelectric conversion layer, the second transparent electrode layer, and the conductor portion is as described in the specification.

Description

Technical Field

[0001] This disclosure relates to photoelectric conversion elements and methods for manufacturing photoelectric conversion elements. Background Technology

[0002] Patent Document 1 discloses a photoelectric conversion device. The photoelectric conversion device described in Patent Document 1 includes: a first conductive layer, a photoelectric conversion layer disposed on the first conductive layer, and a transparent second conductive layer disposed on the photoelectric conversion layer. The photoelectric conversion device described in Patent Document 1 has a region where the first conductive layer and the second conductive layer are in contact.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-045965 Summary of the Invention

[0004] However, in recent years, it has become known that tandem solar cells improve photoelectric conversion efficiency by using two photoelectric conversion elements overlapping each other. In tandem solar cells, the photoelectric conversion element positioned on the light incident side, i.e., the surface side, needs to transmit unabsorbed light to the back side.

[0005] In the photoelectric conversion element described above, to enable light transmission, the electrode layers on both sides need to be constructed as transparent electrode layers. Generally, transparent electrode layers have a higher resistance than non-transparent electrode layers, thus leading to an increase in internal resistance in the light-transmitting photoelectric conversion element described above.

[0006] It should be noted that while increasing the thickness of the transparent electrode layer is considered to suppress the increase in internal resistance, increasing the thickness of the transparent electrode layer reduces light transmittance, making it less desirable. Furthermore, the thickness of the transparent electrode layer must be determined taking into account optical interference within the transparent electrode layer, and cannot be easily adjusted.

[0007] This disclosure was made to solve such a problem, with the aim of providing a photoelectric conversion element that can suppress the increase of internal resistance and a method for manufacturing the photoelectric conversion element.

[0008] The photoelectric conversion element disclosed herein includes: a first transparent electrode layer located on a substrate, a photoelectric conversion layer located on the first transparent electrode layer, and a second transparent electrode layer located on the photoelectric conversion layer. The first transparent electrode layer is separated by a first trench structure extending substantially parallel to a first direction, and the photoelectric conversion layer and the second transparent electrode layer are separated by a second trench structure extending substantially parallel to the first direction. Furthermore, the photoelectric conversion element of this disclosure includes a third trench structure disposed on the photoelectric conversion layer and the second transparent electrode layer, branching from the second trench structure and extending substantially parallel to a second direction orthogonal to the first direction. In addition, the photoelectric conversion element of this disclosure includes a conductor portion extending such that one end is electrically connected to the second transparent electrode layer and the other end is electrically connected to the first transparent electrode layer in the third trench structure, exhibiting higher conductivity compared to the first and second transparent electrode layers.

[0009] In the photoelectric conversion element disclosed herein, one end of the conductor portion may extend at least to the middle position of the length of a second transparent electrode layer separated by the second groove structure in the second direction, and the other end may extend at least to the middle position of the length of the first transparent electrode layer in the second direction through the third groove structure.

[0010] In the photoelectric conversion element disclosed herein, on a second transparent electrode layer separated by the second trench structure, one end of the conductor portion and a plurality of third trench structures can be alternately arranged in the first direction.

[0011] In the photoelectric conversion element disclosed herein, when the length of the second direction of the portion of the conductor that is electrically connected to the second transparent electrode layer is set as L1, and the length of the second direction of the entire conductor portion is set as L3, the relationship 1.2 ≤ L1 / L3 can be satisfied. Furthermore, the length L2 of the first direction from the conductor portion to the third groove structure can be 20 mm or less.

[0012] In the method for manufacturing the photoelectric conversion element disclosed herein, firstly, a substrate having a first transparent electrode layer is prepared. Next, a first trench structure extending substantially parallel to a first direction is formed on the first transparent electrode layer. Next, a photoelectric conversion layer is deposited on the first transparent electrode layer. Next, a second transparent electrode layer is deposited on the photoelectric conversion layer. Next, a second trench structure extending substantially parallel to the first direction is formed on the photoelectric conversion layer and the second transparent electrode layer. Next, a third trench structure is formed, branching from the second trench structure and extending substantially parallel to a second direction orthogonal to the first direction. Finally, a conductor portion is formed, extending such that one end is electrically connected to the second transparent electrode layer and the other end is electrically connected to the transparent electrode of the first trench structure in the third trench structure, exhibiting higher conductivity compared to the first and second transparent electrode layers.

[0013] According to this disclosure, a photoelectric conversion element capable of suppressing the increase of internal resistance and a method for manufacturing the photoelectric conversion element can be provided.

[0014] The above and other features, characteristics and advantages of this disclosure will be more fully understood through the following detailed description and accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram showing the configuration of the photoelectric conversion element according to the first embodiment.

[0016] Figure 2 This is a top view schematic diagram showing the configuration of the photoelectric conversion element according to the first embodiment.

[0017] Figure 3 This is a top view schematic diagram showing the configuration of the photoelectric conversion element according to the first embodiment.

[0018] Figure 4 This is a flowchart illustrating a method for manufacturing a photoelectric conversion element according to the first embodiment.

[0019] Figure 5 This is a cross-sectional schematic diagram showing the configuration of a series-connected solar cell according to another embodiment. Detailed Implementation

[0020] <First Embodiment>

[0021] (Composition of photoelectric conversion element)

[0022] Hereinafter, the first embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. First, the configuration of the photoelectric conversion element of this embodiment will be described in detail.

[0023] Figure 1 , Figure 2 and Figure 3 This is a schematic diagram used to explain the configuration of the photoelectric conversion element in the first embodiment. More specifically, Figure 1 This is a cross-sectional schematic diagram showing the structure of the photoelectric conversion element according to the first embodiment. Figure 2 This is a top view schematic diagram showing the configuration of the photoelectric conversion element according to the first embodiment. Figure 3 It is Figure 2 The diagram shown is an enlarged version of a portion of the top view diagram.

[0024] It should be noted, of course, Figure 1 The right-handed xyz rectangular coordinate system shown in the other figures is used to facilitate the explanation of the positional relationships of the constituent elements. Furthermore, in this specification, the y-axis is sometimes referred to as the first direction, and the x-axis, which is orthogonal to the y-axis, is sometimes referred to as the second direction.

[0025] The photoelectric conversion element in this embodiment is a light-transmitting photoelectric conversion element. That is, the photoelectric conversion element in this embodiment converts light incident from either the positive or negative z-axis direction into electrical energy. Furthermore, the photoelectric conversion element in this embodiment transmits light that has not been converted into electrical energy along the incident direction to the side opposite to the incident side.

[0026] The photoelectric conversion element of this embodiment can be used, for example, as the upper or middle cell unit of a series-connected solar cell. Additionally, the photoelectric conversion element of this embodiment can also be used, for example, in the form of a solar cell used as window glass in a building.

[0027] like Figure 1 As shown, the photoelectric conversion element of this embodiment includes: a substrate 11, a first transparent electrode layer 12, a photoelectric conversion layer 13, a second transparent electrode layer 14, a conductor portion 15, a first end conductor portion 16, and a second end conductor portion 17.

[0028] like Figure 1 As shown, the photoelectric conversion element 1 of this embodiment sequentially includes a substrate 11, a first transparent electrode layer 12, a photoelectric conversion layer 13, and a second transparent electrode layer 14.

[0029] Furthermore, details will be discussed later, such as... Figure 2 As shown, in this embodiment, the second transparent electrode layer 14 of the photoelectric conversion element 1 is divided into three parts by the second trench structure P2. Furthermore, as... Figure 2 As shown, the photoelectric conversion element 1 of this embodiment has 22 conductor portions 15, and has a first end conductor portion 16 and a second end conductor portion 17 at both ends.

[0030] However, the number mentioned above is just an example, and the number can be changed appropriately.

[0031] The photoelectric conversion layer 13 is located between the first transparent electrode layer 12 and the second transparent electrode layer 14, which will be described later. The photoelectric conversion layer 13 excites electrons by absorbing incident light, generating holes and conducting electrons.

[0032] Holes and conduction electrons generated in the photoelectric conversion layer 13 are respectively introduced into either the first transparent electrode layer 12 or the second transparent electrode layer 14.

[0033] like Figure 1 As shown, the photoelectric conversion layer 13 is divided into multiple partitions by the second trench structure P2. Additionally, a third trench structure P3 is formed within the photoelectric conversion layer 13.

[0034] It should be explained that, for example Figure 1 , Figure 2 and Figure 3As shown, the second groove structure P2 is a linear groove extending approximately parallel to the y-axis, i.e., the first direction, separating the photoelectric conversion layer 13 and the second transparent electrode layer 14. Additionally, as... Figure 1 , Figure 2 and Figure 3 As shown, the third groove structure P3 is a linear groove formed in the photoelectric conversion layer 13 and the second transparent electrode layer 14. It branches from the second groove structure P2 and extends approximately parallel to the x-axis, i.e., the second direction.

[0035] It should be noted that the term "generally parallel" as used here includes not only "parallel" in the strict sense, but also "parallel" in which deviations are allowed within the scope of the intent of this application.

[0036] The photoelectric conversion layer 13 of this embodiment may contain, for example, a perovskite compound as one of the main components. That is, the photoelectric conversion element 1 of this embodiment may also be a so-called perovskite solar cell.

[0037] It should be noted that the perovskite compounds mentioned here refer to a group of compounds that can obtain a perovskite-type crystal structure.

[0038] In the above case, the photoelectric conversion layer 13 of this embodiment includes: a perovskite layer containing a perovskite compound as the main component, a hole transport layer for transporting holes generated in the perovskite layer, and an electron transport layer for transporting conduction electrons generated in the perovskite layer.

[0039] That is, the photoelectric conversion layer 13 in this embodiment does not necessarily have to be a single layer. In other words, the photoelectric conversion layer 13 in this embodiment can be used as a general term for multiple layers located between the first transparent electrode layer 12 and the second transparent electrode layer 14.

[0040] Compounds that can be used as the main component of the photoelectric conversion layer 13 in this embodiment include, for example, compounds represented by the following chemical formula (I).

[0041] X α Y β Z γ (I)

[0042] In chemical formula (I), the α:β:γ ratio is, for example, 3:1:1, where X represents a halide ion, Y represents a monovalent cation, and Z represents a divalent cation. The perovskite layer is preferably disposed adjacent to the electron transport layer. It should be noted that the α:β:γ ratio is, for example, 3:1.05:0.95 or 3:0.95:1.05, and is not necessarily 3:1:1. The α:β:γ ratio is, for example, 3:(0.95–1.05):(0.95–1.05).

[0043] In chemical formula (I), as X, examples include halide ions such as chlorine, bromine, and iodine. A single halide ion can be used alone, or two or more can be used together.

[0044] In the above chemical formula (I), Y can be, for example, an alkylamine compound ion (an organic compound having an amino group), such as methylammonium cation, ethylammonium cation, n-butylammonium cation, or formamidinium cation. It is not limited to organic chemical substances; alkali metal ions such as cesium cation, potassium cation, and rubidium cation can also be used. The aforementioned alkylamine compound ion and alkali metal ion can be used individually or in combination with two or more. Furthermore, organic chemical substances (alkylamine compound ions) and inorganic chemical substances (alkali metal ions) can be used together; for example, cesium ions and formamidinium ions can be used together.

[0045] In the above chemical formula (I), Z can be, for example, divalent metal ions such as lead, indium, antimony, tin, copper, bismuth, and germanium. A single divalent metal ion can be used alone, or two or more can be used in combination. Lead is preferred as a divalent metal ion, and even more preferably, lead and tin are used in combination.

[0046] As described above, the photoelectric conversion layer 13 can be a layer formed of a perovskite compound. There are no particular limitations on the method of forming the perovskite layer, and it can be appropriately selected according to the purpose. For example, methods such as coating with a solution containing a halogenated metal and a haloalkylamine and then drying it can be cited.

[0047] In addition, other methods for forming the above-mentioned perovskite layer include, for example, a two-step precipitation method in which a solution containing a dissolved or dispersed halide metal is coated, dried, and then immersed in a solution containing a dissolved halide alkylamine to form a perovskite compound.

[0048] Other methods for forming the perovskite layer include, for example, precipitating crystals by adding a solvent with low solubility (a solvent that is unsuitable for the perovskite compound) while coating a solution containing a dissolved or dispersed halide metal and a halide alkylamine.

[0049] In the above-mentioned method of adding undesirable solvents to precipitate crystals, the undesirable solvents may include, for example, hydrocarbons such as n-hexane and n-octane; alcohols such as methanol, ethanol, and 2-propanol; ethers such as diethyl ether and diisopropyl ether; ketones such as acetone and methyl isobutyl ketone; esters such as ethyl acetate, isobutyl acetate, and γ-butyrolactone; nitrile compounds such as acetonitrile and 3-methoxypropionitrile; aromatic hydrocarbons such as benzene, toluene, and chlorobenzene; halogen solvents such as dichloromethane and chloroform; and fluorinated solvents such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons.

[0050] In addition, other methods for forming the perovskite layer mentioned above include, for example, evaporating halide metals in a gas filled with methylamine or the like.

[0051] Furthermore, from the viewpoint of appropriately adjusting the crystal grain size of the perovskite compound that forms the perovskite layer, the method for forming the above-mentioned perovskite layer is particularly preferred by adding a poor solvent for the perovskite compound to precipitate crystals while coating a solution containing a halometal and a haloalkylamine.

[0052] There are no particular limitations on the method of applying the above solution; it can be appropriately selected according to the purpose. For example, dip coating, spin coating, spray coating, dip-coating, roller coating, and air knife coating can be used. Alternatively, the method of applying the above solution can also be, for example, by precipitation in a supercritical fluid such as carbon dioxide.

[0053] The method for forming the perovskite layer can also include, for example, a process for removing solvent after forming the perovskite layer (solvent removal process) or a process for preparing perovskite crystals (crystal preparation process).

[0054] The solvent removal process and the crystal preparation process described above can also be carried out by methods such as blowing dry air, heating with hot plates or ovens, or vacuum drying.

[0055] In the solvent removal process and the crystal preparation process described above, the heating temperature is preferably 50 to 200°C, and more preferably 70 to 180°C.

[0056] In the solvent removal process and the crystal preparation process described above, the heating time is preferably 1 to 150 minutes, and more preferably 5 to 60 minutes. Furthermore, the thickness of the photoelectric conversion layer 13 is not particularly limited, but from the viewpoint of further suppressing defects and performance degradation caused by peeling, it is preferably 50 to 1500 nm, and more preferably 200 to 1000 nm.

[0057] The method for forming the perovskite layer may also include a surface treatment step (surface treatment step) using a salt formed from one or more cations and one or more anions.

[0058] Examples of the aforementioned cations include, for instance, inorganic cations such as lithium, sodium, potassium, rubidium, cesium, magnesium, and calcium; ammonium cations; methylamine; ethylamine; n-butylamine; isopentylamine; neopentylamine; formamidin; acetamidine; benzylamine; 2-phenylethylamine; 2-(4-methoxyphenyl)ethylamine; 4-fluorobenzylamine; 2-(4-fluorophenyl)ethylamine; 1,4-phenylenediamine; 5-aminovaleric acid; methyldiamine; ethylenediamine; p-phenylenediamine; m-phenylenediamine; 1,2-adamantanediamine; 1,3-gold Organic cations containing amino groups include alkyl diamine, N,N-dimethylethylenediamine, 1,3-diaminopropane, 1,4-diazabicyclo[2.2.2]octane, guanidine, aniline, pyrrole, imidazole, 1-ethylimidazolium, 2-ethylimidazolium, benzimidazole, morpholine, pyrrolidine, pyrazole, triazole, carbazole, etc.; and cations derived from heterocycles containing nitrogen atoms, such as pyridine, pyrazine, pyridazine, pyrimidine, quinoline, isoquinoline, phenanthroline, 2,2'-bipyridine, 4,4'-bipyridine, etc.

[0059] Examples of the aforementioned anions include, for instance, halogen ions such as fluoride ions, chloride ions, bromide ions, and iodide ions; carboxylic acid ions such as formate ions and acetate ions; isocyanate ions, thiocyanate ions, tetrafluoroborate ions, hexafluorophosphate ions; and trifluoromethanesulfonyl imide ions.

[0060] Salts composed of the above-mentioned cations and anions are preferably dissolved in one or more solvents.

[0061] Examples of solvents mentioned above include alcohols such as isopropanol (2-propanol), ethanol (EtOH), methanol (MeOH), and n-butanol; nitriles such as acetonitrile and propionitrile; and aromatic solvents such as toluene, chlorobenzene, and 1,2-dichlorobenzene. One of these solvents may be used alone, or two or more may be used in combination.

[0062] The above surface treatment process is performed by applying a solution containing the above salt onto the formed perovskite layer and then drying it.

[0063] There are no particular restrictions on the method of applying the above solution, and it can be appropriately selected according to the purpose. For example, dipping, spin coating, spraying, dip coating, roller coating, and air knife coating can be used.

[0064] In the above surface treatment process, a heat treatment can be performed after the coating. The heating temperature is preferably 50–200°C, more preferably 70–180°C. The heating time is preferably 1–150 minutes, more preferably 5–60 minutes. There are no particular limitations on the film thickness of the coating solution.

[0065] As an example of a compound that can be used as the main component of a hole transport layer, inorganic hole transport materials or organic hole transport materials can be used.

[0066] Examples of inorganic hole transport materials include, for instance, compound semiconductors containing monovalent copper such as CuI, CuInSe2, and CuS; and compounds containing metals other than copper such as GaP, NiO, FeO, Bi2O3, MoO3, and Cr2O. From the viewpoint of more effectively receiving only holes and obtaining higher hole mobility, inorganic hole transport materials are preferably semiconductors containing monovalent copper, and more preferably CuI or CuSCN. Examples of the aforementioned organic hole transport materials include, for instance, polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyvinyldioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetratetra(N,N-di-p-methoxyphenylamino)-9,9'-spirodifluorene (Spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); diphenylamine derivatives; polysilane derivatives; and polyaniline derivatives. From the viewpoint of more effectively receiving only holes and obtaining higher hole mobility, the aforementioned organic hole transport materials are preferably triphenylamine derivatives, fluorene derivatives, etc., and more preferably PTAA, Spiro-OMeTAD, etc.

[0067] To further improve hole transport properties, organic hole transport materials may include, for example, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), silver bis(trifluoromethanesulfonyl)imide, zinc bis(trifluoromethanesulfonyl)imide, ammonium bis(trifluoromethanesulfonyl)imide, lithium bis(nonafluorobutyryl)imide, sodium bis(nonafluorobutyryl)imide, lithium nonafluoro-N-[(trifluoromethane)sulfonyl]butanesulfonylimide, and lithium nonafluoro-N-[(trifluoromethane)] Oxidizing agents include potassium [sulfonyl]butanesulfonylimide, nonafluoro-N-[(trifluoromethane)sulfonyl]butanesulfonylimide, lithium N,N-hexafluoro-1,3-disulfonylimide, sodium N,N-hexafluoro-1,3-disulfonylimide, silver trifluoromethanesulfonate, NOSbF6, SbCl5, SbF5, tris(2-1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide]. Additionally, the hole transport layer may contain basic compounds such as tert-butylpyridine (TBP), 2-methylpyridine, and 2,6-dimethylpyridine. The amounts of the aforementioned oxidizing agents and basic compounds are, for example, those commonly used in the past. From the viewpoint of more effectively receiving only holes and obtaining higher hole mobility, the thickness of the hole transport layer is, for example, 1 nm to 500 nm or 2 nm to 300 nm.

[0068] Furthermore, as a hole transport material in the inversion structure, for example, a hole transport compound that forms a monolayer (hereinafter also referred to as a "monomer hole transport compound") can be used. The aforementioned monoomer hole transport compound preferably has an anchoring group in the inversion structure that is chemically bonded to ITO or the like, which serves as a transparent electrode. Examples of such anchoring groups include, for example, phosphonic acid groups (-P=O(OH)2), carboxyl groups (-COOH), sulfonyl groups (-SO3H), borate groups (-B(OH)2), trihalomylsilyl groups (-SiX3, where X is a halogen atom), or trialkoxysilyl groups (-Si(OR)3, where R is an alkyl group), and their salts may also be used. Examples of such salts include, for example, alkali metal salts with potassium, sodium, etc., and quaternary ammonium salts with tetramethylamine, tetra-n-butylamine, etc. Phosphonic acid groups, trihalomylsilyl groups, and trialkoxysilyl groups are particularly preferred.

[0069] The aforementioned single-molecule hole transport compounds may include, for example, compounds represented by chemical formula (II).

[0070] Ar-(L-Z)n...(II)

[0071] In chemical formula (II), Ar is a structure containing an aromatic ring. The atoms constituting the aromatic ring may or may not contain heteroatoms. Ar may or may not have substituents other than -L-Z. There may be one or more -L-Z groups. If there are multiple -L-Z groups, each L and each Z may be the same or different from each other. Each L is a group of atoms that bonds Ar to Z, or a covalent bond. Each Z is a group that can accept or accept charges between Ar and the transparent electrode layer 12 (or 14). The number of -L-Z groups is not particularly limited, for example, 1 to 4. For example, in chemical formula (II), L may be divalent substituents such as 1,1-methylene, 1,2-ethylene, and divalent alkoxy groups such as diethoxyethane. These may or may not have substituents other than the Z groups mentioned above. For example, in chemical formula (II), each Z can be a phosphonic acid group (-P=O(OH)2), a carboxyl group (-COOH), a sulfonyl group (-SO3H), a borate group (-B(OH)2), a trihalosilyl group (-SiX3, where X is a halogen atom), or a trialkoxysilyl group (-Si(OR)3, where R is an alkyl group).

[0072] Examples of compounds that can be used as the main component of an electron transport layer include, for example, semiconductor materials. The semiconductor materials are not particularly limited, and known materials can be used, such as elemental semiconductors, compound semiconductors, and organic n-type semiconductors. The elemental semiconductors are not particularly limited; examples include silicon and germanium. The compound semiconductors are not particularly limited; examples include metal chalcogenides, specifically oxides of titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, and tantalum; sulfides of cadmium, zinc, lead, silver, antimony, and bismuth; selenides of cadmium and lead; and tellurides of cadmium. Other compound semiconductors include, for example, phosphides of zinc, gallium, indium, and cadmium, gallium arsenide, copper-indium-selenide, and copper-indium-sulfide. The aforementioned organic n-type semiconductors are not particularly limited; examples include perylene tetracarboxylic anhydride, perylene tetracarboxydiimide compounds, naphthalene diimide-bithiophene copolymers, polybenzobisimidazole-benzophenanthreneroline, and C... 60 C 70 PCBM ([6,6]-phenyl-C 61 Fullerene compounds such as methyl butyrate, carbonyl-bridged thiazole compounds, ALq3 (tris(8-hydroxyquinoline)aluminum), terphenyl bipyridine compounds, silylopyrandobenzene compounds, and Diazole compounds, etc.

[0073] However, the photoelectric conversion element disclosed herein is not limited to perovskite type; for example, it can also be a CIS type, cuprous oxide type, or amorphous silicon type photoelectric conversion element. That is, the configuration of the photoelectric conversion element disclosed herein can be applied to any photoelectric conversion element, but from the viewpoint of light transmittance, it is preferably applied to thin-film type photoelectric conversion elements.

[0074] Furthermore, the configuration of the photoelectric conversion layer of this disclosure can be appropriately modified depending on the type of photoelectric conversion element used. The configuration of the photoelectric conversion layer of this disclosure can be arbitrary, as long as it is capable of exciting electrons by absorbing incident light and allowing unused light in electron excitation to be transmitted.

[0075] The first transparent electrode layer 12 is a layer located on the substrate 11, and has electrical conductivity and light transmittance. The first transparent electrode layer 12 conducts the charge generated in the photoelectric conversion layer 13.

[0076] like Figure 1 As shown, the first transparent electrode layer 12 is divided into multiple partitions by the first groove structure P1. It should be noted that the first groove structure P1 is a linear groove formed in the first transparent electrode layer 12, extending substantially parallel to the first direction.

[0077] The first transparent electrode layer 12 typically contains tin-doped indium oxide (ITO), impurity-doped indium oxide (In₂O₃), impurity-doped zinc oxide (ZnO), fluorine-doped tin dioxide (FTO), gold, silver, copper, aluminum, tungsten, titanium, chromium, nickel, cobalt, graphene, and metal nanowires as main components. Furthermore, these main components can be used individually or in combination of two or more.

[0078] Furthermore, the first transparent electrode layer 12 can be a single layer or multiple layers. When the first transparent electrode layer 12 has multiple layers, a portion of the layers in the first transparent electrode layer 12 can function as an anti-diffusion layer.

[0079] It should be noted that the first transparent electrode layer 12 may be combined with metal wiring, etc. The material of the metal wiring is not particularly limited; for example, aluminum, copper, silver, gold, platinum, and nickel are examples.

[0080] In addition, the first transparent electrode layer 12 can be formed in the form of a film with uniform thickness or in the form of a mesh film.

[0081] The second transparent electrode layer 14 is a layer located on the photoelectric conversion layer 13, and has conductivity and light transmittance. The second transparent electrode layer 14 collects the charges generated in the photoelectric conversion layer 13.

[0082] The second transparent electrode layer 14 typically contains indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide with impurities (ZnO), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide (ATO) as main components.

[0083] It should be noted that the first transparent electrode layer 12 and the second transparent electrode layer 14 may be made of the same material or may be made of different materials.

[0084] From the viewpoint of suppressing the decrease in transmittance caused by optical interference, the thickness of the first transparent electrode layer 12 and the second transparent electrode layer 14 is preferably 50 nm to 100 nm, and more preferably 60 nm to 80 nm. If the thickness is within the above range, the sheet resistance of ITO with a thickness of 150 nm to 200 nm is relatively large, which is 20 Ω / □ to 40 Ω / □ compared to the conventional 10 Ω / □ to 20 Ω / □. However, according to the photoelectric conversion element of the present invention, by providing the conductor portion described later, the loss of the resistive component of the transparent electrode layer can be substantially halved.

[0085] The first transparent electrode layer 12 and the second transparent electrode layer 14 are electrically connected via the conductor portion 15. More specifically, in the photoelectric conversion element 1 of this embodiment, the first transparent electrode layer 12 separated by the first trench structure P1 and the second transparent electrode layer 14 separated by the second trench structure P2 are electrically connected in series. That is, the photoelectric conversion element 1 of this embodiment has a structure that is an integrated photoelectric conversion element.

[0086] The conductor portion 15 is a linear component with higher conductivity than the first transparent electrode layer 12 and the second transparent electrode layer 14. For example, it can be made of a metal material with low volume resistivity.

[0087] The conductor portion 15 extends such that one end is electrically connected to the second transparent electrode layer 14 and the other end is electrically connected to the first transparent electrode layer 12 in the third groove structure P3. In other words, the conductor portion 15 crosses the first groove structure P1 and extends from a point on the second transparent electrode layer 14 to a point on the first transparent electrode layer 12.

[0088] The conductor portion 15 is formed by coating a metal paste (silver, copper, aluminum, tin, nickel, gold, etc.) using a screen printing machine. Silver paste is preferred in terms of performance and manufacturing, but copper, aluminum, tin, nickel, gold, etc., pastes can also be used. Alternatively, it can be formed by vacuum evaporation using a mask.

[0089] The conductor portion 15 electrically connects the first transparent electrode layer 12 and the second transparent electrode layer 14. That is, the conductor portion 15 functions to collect current in a way that forms the shortest path for current flowing from the first transparent electrode layer 12 to the second transparent electrode layer 14, or vice versa. Specifically, by collecting the charge flowing in the first and second transparent electrode layers 12 and 14, the conductor portion 15 can compensate for conductivity, reduce the thickness of the first and second transparent electrode layers 12, and improve light transmittance. As a result, charge extraction efficiency is ensured, and the light transmittance of the first and second transparent electrode layers 12 and 14 is improved.

[0090] Here, preferably, one end of the conductor portion 15 extends at least to the middle position of the second transparent electrode layer 14 separated by the second groove structure P2 when viewed from the second direction, and preferably the other end extends at least to the middle position of the first transparent electrode layer 12 when viewed from the second direction through the third groove structure P3.

[0091] With this configuration, the contact area between the conductor portion 15 and the first transparent electrode layer 12 and the second transparent electrode layer 14 can be sufficiently ensured. As a result, the photoelectric conversion element 1 of this embodiment can further suppress the increase in internal resistance.

[0092] In addition, such as Figure 1 and Figure 3 As shown, when the length of the portion of the conductor portion 15 that is electrically connected to the second transparent electrode layer 14 in the second direction is set as L1, and the length of the conductor portion 15 as a whole in the second direction is set as L3, it is preferable to satisfy the relationship 1.2≤L1 / L3.

[0093] With this configuration, the contact area between the conductor portion 15 and the second transparent electrode layer 14 can be sufficiently ensured. As a result, the photoelectric conversion element 1 of this embodiment can further suppress the increase in internal resistance.

[0094] When the length from the multiple conductor sections to the multiple third groove structures P3 in the first direction is set to L2, it is preferable that L2 is 20 mm or less, preferably 5 mm to 10 mm.

[0095] With this configuration, the current-collecting effect of the conductor portion 15 in the second transparent conductive layer 14 can be obtained while reducing the area occupied by the conductor portion 15 with low light transmittance. As a result, the groove structure P3 of this embodiment can reliably suppress the increase in actual internal resistance.

[0096] In addition, such as Figure 2 As shown, the photoelectric conversion element 1 of this embodiment has multiple conductor portions 15 and multiple third trench structures P3 on a second transparent electrode layer 14 that is separated into a partition by the second trench structure P2. Furthermore, as... Figure 2 As shown, multiple conductor sections 15 and multiple third groove structures P3 are alternately arranged on the second transparent electrode layer 14 of one partition.

[0097] With this configuration, the photoelectric conversion element 1 of this embodiment can disperse the current flow path. As a result, the photoelectric conversion element 1 of this embodiment can disperse charge within the photoelectric conversion element 1.

[0098] Figure 2 The first end conductor portion 16 and the second end conductor portion 17 described herein are linear components disposed at both ends of the photoelectric conversion element 1. They have higher conductivity compared to the first transparent electrode layer and the second transparent electrode layer. From the viewpoint of suppressing manufacturing costs, the first end conductor portion 16 and the second end conductor portion 17 are preferably made of the same material as the conductor portion 15.

[0099] like Figure 2 As shown, the first end conductor portion 16 is disposed on the surface of the substrate 11 along the first direction at one end of the photoelectric conversion element 1 in the second direction, is electrically connected to one end of the conductor portion 15, and is separated from the adjacent second transparent electrode layer 14.

[0100] In addition, such as Figure 2As shown, the second end conductor portion 17 is a wire-like component disposed on the end of the second transparent electrode layer 14 along the first direction on the other end side of the photoelectric conversion element 1 in the second direction and electrically connected to the other end side of the conductor portion 15. These first end conductor portions 16 and second end conductor portions 17 can be used as a pair of power extraction terminals of the photoelectric conversion element 1.

[0101] It should be noted that in the photoelectric conversion element of this disclosure, the first end conductor portion 16 and the second end conductor portion 17 are not essential structures. In other words, the structure of the ends is not particularly limited in the photoelectric conversion element of this disclosure.

[0102] As explained above, the photoelectric conversion element of this embodiment connects the first transparent electrode layer and the second transparent electrode through a conductor portion 15 having the configuration described above. With this configuration, the photoelectric conversion element of this embodiment can improve light transmittance by providing transparent electrode layers 12 and 14 with reduced thickness on the surface and back side, and utilize the conductor portion 15 to suppress the increase in the actual internal resistance of the photoelectric conversion element.

[0103] (Manufacturing method of photoelectric conversion element)

[0104] Next, the manufacturing method of the photoelectric conversion element of this embodiment will be described in detail. Figure 3 This is a flowchart illustrating a method for manufacturing a photoelectric conversion element according to the first embodiment.

[0105] In the manufacturing method of the photoelectric conversion element of this embodiment, firstly, a substrate having a first transparent electrode layer is prepared (step ST1). That is, in step ST1, a substrate 11 having a first transparent electrode layer 12 on the main surface is prepared.

[0106] It should be noted that process ST1 can be a process of forming the first transparent electrode layer 12 on the substrate 11, or it can be a process of preparing a commercially available transparent electrode substrate.

[0107] In the manufacturing method of the photoelectric conversion element of this embodiment, the first trench structure is formed next (step ST2). That is, in step ST2, the first transparent electrode layer 12 is separated by forming the first trench structure P1 on the first transparent electrode layer 12.

[0108] It should be noted that known methods such as laser etching and wet etching can be used to form the first trench structure P1. The method for forming the first trench structure P1 can be appropriately selected depending on the materials of the substrate 11 and the first transparent electrode layer 12.

[0109] In the manufacturing method of the photoelectric conversion element of this embodiment, the photoelectric conversion layer is then deposited (step ST3). That is, in step ST3, the photoelectric conversion layer 13 is deposited on the first transparent electrode layer 12.

[0110] As a method for forming a film on the photoelectric conversion layer 13, inkjet printing, spraying, molding, spin coating, vacuum evaporation, etc., can be appropriately used, for example.

[0111] It should be noted that when the photoelectric conversion layer 13 has multiple layers, the film formation methods of the multiple layers can be the same or different for each layer.

[0112] In the manufacturing method of the photoelectric conversion element of this embodiment, the second transparent electrode layer is then formed into a film (step ST4). That is, in step ST4, the second transparent electrode layer 14 is formed onto the photoelectric conversion layer 13.

[0113] As a method for forming the second transparent electrode layer 14, sputtering or CVD can be used. In addition, spraying, molding, spin coating, vacuum evaporation and other methods can also be used appropriately.

[0114] In the manufacturing method of the photoelectric conversion element of this embodiment, the second trench structure is formed next (step ST5). That is, in step ST5, the photoelectric conversion layer 13 and the second transparent electrode layer 14 are separated by forming the second trench structure P2 on the photoelectric conversion layer 13 and the second transparent electrode layer 14.

[0115] In the manufacturing method of the photoelectric conversion element of this embodiment, the third trench structure is then formed (step ST6). That is, in step ST6, the third trench structure P3 is formed on the photoelectric conversion layer 13 and the second transparent electrode layer 14.

[0116] It should be noted that laser etching is the preferred method for forming the second groove structure P2 and the third groove structure P3. Alternatively, known methods such as wet etching can also be used.

[0117] Furthermore, since the second groove structure P2 and the third groove structure P3 are continuous groove structures, they can also be formed in the same process.

[0118] It should be noted that the width of the grooves in the first groove structure P1, the second groove structure P2, and the third groove structure P3 can be appropriately formed in the range of 0.05 to 1.0 mm, preferably in the range of 0.1 to 0.5 mm.

[0119] Finally, the conductor portion is formed (step ST7), thereby completing the manufacturing method of the photoelectric conversion element of this embodiment. That is, by forming the conductor portion 15 in step ST7, the photoelectric conversion element 1 of this embodiment becomes as described above. Figure 1 and Figure 2 The state shown.

[0120] For example, in process ST7, the conductor portion 15 can be formed by performing screen printing of metal paste and inkjet printing of metal ink from point 1 on the second transparent electrode layer until point 1 is located in the third groove structure.

[0121] It should be noted that the conductor portion 15 can be appropriately formed with a width dimension in the range of 0.03 to 0.5 mm, preferably in the range of 0.05 to 0.3 mm.

[0122] The photoelectric conversion element 1 of this embodiment can be manufactured through the processes described above.

[0123] In addition, as described above, the photoelectric conversion element disclosed herein can be used as the upper battery cell in a series-connected solar cell. Figure 5 This is a cross-sectional schematic diagram showing the configuration of a series-connected solar cell according to another embodiment.

[0124] like Figure 5 As shown, in another embodiment of the series-connected solar cell 100, the photoelectric conversion element 1 is used as the upper battery cell, and the second photoelectric conversion element 2 is used as the lower battery cell. In this embodiment of the series-connected solar cell 100, a portion of the light incident on the photoelectric conversion element 1 passes through the photoelectric conversion element 1 and irradiates the second photoelectric conversion element 2. With this configuration, the series-connected solar cell 100 of this embodiment can improve the photoelectric conversion efficiency.

[0125] The second photoelectric conversion element 2 has a third electrode layer 21, a silicon-containing layer 22, and a fourth electrode layer 23 sequentially from the incident side of the transmitted light of the photoelectric conversion element 1, i.e., the positive z-axis side.

[0126] It should be noted that in the second photoelectric conversion element 2, adjacent layers can also be stacked on top of each other through other constituent elements.

[0127] The silicon-containing layer 22 is located between the third electrode layer 21 and the fourth electrode layer 23. The silicon-containing layer 22 excites electrons by absorbing incident light, generating holes and conducting electrons.

[0128] The silicon-containing layer 22 can be, for example, a stack of amorphous silicon and monocrystalline silicon layers. Figure 5 As shown, the silicon-containing layer 22 of this embodiment comprises, from the positive z-axis side, an amorphous silicon layer (i / n) 221, an n-type monocrystalline silicon layer 222, and an amorphous silicon layer (i / p) 223.

[0129] As crystalline silicon, silicon wafers can be obtained, for example, by cutting silicon ingots, or by grinding the silicon wafers. Silicon wafers can be monocrystalline or polycrystalline, but monocrystalline is preferred.

[0130] Alternatively, as crystalline silicon, one can use crystalline silicon formed by crystallizing amorphous silicon on a substrate, or crystalline silicon formed by crystallizing silicon during film formation using methods such as CVD or sputtering.

[0131] The third electrode layer 21 is a transparent electrode layer, preferably in the same manner as the first transparent electrode layer 12 and the second transparent electrode layer 14. The fourth electrode layer 23 can, for example, be a laminate. Figure 5 As shown, in another embodiment, the fourth electrode layer 23 has an IWO layer 231 and an Ag layer 232 sequentially from the positive z-axis side.

[0132] While the present invention has been described above in conjunction with the above embodiments, the present invention is not limited to the configuration of the above embodiments, but also includes various modifications, alterations and combinations that can be implemented by those skilled in the art within the scope of the technical solutions claimed in this application.

[0133] As can be seen from the above, those skilled in the art will obviously recognize that the embodiments of this application can be modified in various ways without departing from the spirit and scope of this disclosure, and these modifications also fall within the scope of protection claimed by this invention.

Claims

1. A photoelectric conversion element comprising: a first transparent electrode layer on a substrate, a photoelectric conversion layer on the first transparent electrode layer, and a second transparent electrode layer on the photoelectric conversion layer. The first transparent electrode layer is separated by a first groove structure extending substantially parallel to the first direction. The photoelectric conversion layer and the second transparent electrode layer are separated by a second groove structure that extends substantially parallel to the first direction. Further features include: A third groove structure is disposed on the photoelectric conversion layer and the second transparent electrode layer, branching from the second groove structure and extending substantially parallel to a second direction, the second direction being orthogonal to the first direction; and The conductor portion extends such that one end is electrically connected to the second transparent electrode layer and the other end is electrically connected to the first transparent electrode layer in the third groove structure, and has higher conductivity than the first transparent electrode layer and the second transparent electrode layer.

2. The photoelectric conversion element according to claim 1, wherein, One end of the conductor extends at least to the midpoint of the length of the second transparent electrode layer separated by the second groove structure in the second direction, and the other end extends at least to the midpoint of the length of the first transparent electrode layer in the second direction through the third groove structure.

3. The photoelectric conversion element according to claim 2, wherein, On a second transparent electrode layer separated by the second groove structure, one end of the conductor portion and a plurality of third groove structures are alternately arranged in the first direction.

4. The photoelectric conversion element according to claim 2, wherein, When the length of the portion of the conductor that is electrically connected to the second transparent electrode layer in the second direction is defined as L1, and the length of the entire conductor in the second direction is defined as L3, the relationship 1.2 ≤ L1 / L3 is satisfied. The length L2 from the conductor portion to the third groove structure in the first direction is 20 mm or less.

5. A method for manufacturing a photoelectric conversion element, comprising: The process of preparing a substrate having a first transparent electrode layer; The process of forming a first groove structure extending substantially parallel to a first direction on the first transparent electrode layer; The process of forming a photoelectric conversion layer on the first transparent electrode layer; The process of forming a second transparent electrode layer on the photoelectric conversion layer; The process of forming a second groove structure that extends substantially parallel to the first direction on the photoelectric conversion layer and the second transparent electrode layer; The process of forming the third groove structure, wherein the third groove structure branches from the second groove structure and extends substantially parallel to the second direction, the second direction being orthogonal to the first direction; as well as In the process of forming the conductor portion, the conductor portion extends such that one end is electrically connected to the second transparent electrode layer and the other end is electrically connected to the first transparent electrode layer in the third groove structure, and has higher conductivity than the first transparent electrode layer and the second transparent electrode layer.

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