Solar cell, solar cell module, and method for manufacturing a solar cell

Abstract

Solar cells that improve light absorption efficiency and suppress degradation of the conductive mirror layer. The objective is to provide solar cell modules and methods for manufacturing solar cells. [Solution] A substrate, a conductive mirror layer, a hole transport layer which is a p-type oxide semiconductor, and a light absorber A solar cell comprising, in this order, at least, an aberration layer and a solar cell.

Description

Technical Field

[0001] The present invention relates to a solar cell, a solar cell module, and a method for manufacturing a solar cell. .

Background Art

[0002] In solar cells, from the viewpoints of reducing mass production costs and preventing peeling of the light absorption layer, there has been a limit on the upper limit of the thickness of the light absorption layer. Therefore, there has been a problem that the light absorption efficiency of light such as sunlight cannot be made constant or higher in solar cells. Thus, attempts have been made to increase the light absorption efficiency without increasing the thickness of the light absorption layer. For example, in Non-Patent Document 1, sunlight that has passed through the light absorption layer because the light absorption layer cannot absorb it all is reflected from the back surface, and it has been studied to improve the light absorption efficiency in solar cells by causing the sunlight to be absorbed by the light absorption layer. .

Prior Art Documents

Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the solar cell described in Non-Patent Document 1, a metal mirror layer is formed on the back electrode, an oxide transparent conductive layer is formed thereon for the purpose of protecting the metal mirror layer and ensuring conductivity, and an extremely thin molybdenum or molybdenum selenide layer is further formed thereon.

[0005] ​​​​​​​However, the oxide transparent conductive layer cannot sufficiently protect the metal mirror layer, and it has been found that there is a problem that the conductive mirror layer is likely to deteriorate.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell that improve the light absorption efficiency and suppress the deterioration of the conductive mirror layer.

Means for Solving the Problems

[0007] A solar cell according to an embodiment of the present invention includes at least a substrate, a back electrode, a conductive mirror layer, a hole transport layer that is a p-type oxide semiconductor, and a light absorption layer in this order.

[0008] Since the solar cell includes a conductive mirror layer and there is a hole transport layer that is a p-type oxide semiconductor between the conductive mirror layer and the light absorption layer, the inventors have found that the light absorption efficiency of sunlight in the solar cell is improved and the deterioration of the conductive mirror layer can be suppressed.

[0009] A method for manufacturing a solar cell according to an embodiment of the present invention includes a laminate preparation step of preparing a laminate including at least a substrate, a back electrode, a conductive mirror layer, a hole transport layer that is a p-type semiconductor, and a precursor layer of a light absorption layer in this order, and a heat treatment step of heat-treating the laminate in at least one atmosphere selected from the group consisting of a sulfur atmosphere, a selenium atmosphere, a chlorine atmosphere, a bromine atmosphere, and an iodine atmosphere.

[0010] The laminate prepared in the laminate preparation step includes a conductive mirror layer, and ​​​​​​​​​​​​Between the precursor layer of the light absorption layer and the hole transport layer, which is a p-type oxide semiconductor, Furthermore, the solar cell manufactured by the above manufacturing method has improved its solar absorption efficiency, and Furthermore, the inventors have discovered that it is possible to suppress the deterioration of the conductive mirror layer. [Effects of the Invention]

[0011] According to the present invention, the absorption efficiency of light such as sunlight is improved, and the deterioration of the conductive mirror layer is reduced. To provide a solar cell, solar module, and method for manufacturing a solar cell that suppresses solar radiation. It is possible. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of a solar cell according to one embodiment of the present invention. [Figure 2] This is a graph showing the results of the simulation. [Modes for carrying out the invention]

[0013] Hereinafter, with reference to the drawings as necessary, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described. The present invention will be described in detail, but is not limited thereto. Various modifications are possible within the limits of not exceeding the specified dimensions. Note that identical elements are denoted by the same reference numeral in the drawings. We will omit redundant explanations. Furthermore, we will not specify the relative positions such as top, bottom, left, or right. As far as is concerned, the positional relationships shown in the drawings shall be as indicated. Furthermore, the dimensional ratios in the drawings shall be as shown in the illustrations. It's not limited.

[0014] 1. Solar cell Figure 1 is a schematic cross-sectional view of a solar cell according to one embodiment of the present invention. The solar cell 100 consists of a substrate 101, a back electrode 102, a conductive mirror layer 104, and a p-type The hole transport layer 105, which is an oxide semiconductor, and the light absorption layer 106 are arranged in this order, at least It is also possible to provide a back electrode 102 between the substrate 101 and the conductive mirror layer 104. Furthermore, between each layer, intermediate materials are added as needed, considering factors such as interlayer adhesion, bonding, and conductivity. Intermediate layers may be provided.

[0015] In this embodiment, the solar cell 100, viewed from the substrate 101, is configured to absorb sunlight from the light-absorbing layer 106 side. It generates electricity by receiving light such as sunlight. Here, in the solar cell 100 of this embodiment, By providing a conductive mirror layer 104 between the surface electrode 102 and the light-absorbing layer 106, The light absorption efficiency of the battery cell 100 tends to improve. The light absorption layer 106 was unable to absorb all of the light. The conductive mirror layer 104 reflects the reflected light, and the light-absorbing layer 106 absorbs the reflected light. It is thought that they exist.

[0016] Furthermore, the solar cell 100 of this embodiment has a hole transport layer 10 which is a p-type oxide semiconductor. It comprises 5. The conductive mirror layer 104 is preferably made of a material with high light reflectivity. However, such materials are prone to a decrease in light reflectivity due to oxidation and corrosion, therefore, they are not conductive. It is common to provide a layer that can protect the p-type oxide semiconductor layer 104. The hole transport layer 105, which is the main body, protects the conductive mirror layer 104, and the conductive mirror layer 104 This can suppress the decrease in the reflectivity of light. Furthermore, from the perspective of valence band position Because the p-type oxide semiconductor has good electrical compatibility with the light absorption layer 106, the back electrode 102 and Even if a hole transport layer 105 is provided between the light absorption layer 106 and the hole transport layer 105, the photoelectric conversion efficiency will decrease. It can be suppressed.

[0017] Furthermore, solar cells are generally heat-treated during the manufacturing process, but conductive mirrors As mentioned above, layer 104 is prone to a decrease in reflectivity, and heat treatment can also reduce its reflectivity. In this regard, the hole transport layer 105, which is a p-type oxide semiconductor, is connected to the conductive mirror layer 104. This protects the conductive mirror layer 104 and suppresses a decrease in its reflectivity.

[0018] The solar cell 100 is formed by making each layer sufficiently thin, thus creating a thin-film solar cell or thin-film solar cell. Flexible solar cells can be formed. Thin-film solar cells and thin-film flexible solar cells Because it is lightweight and highly flexible, it can be applied to a variety of locations. By forming a thin light-absorbing layer 106, it is possible to reduce mass production costs and prevent peeling of the light-absorbing layer. This is desirable. Here, the solar cell 100 is equipped with a conductive mirror layer 104. Therefore, even if the light-absorbing layer 106 is formed to be sufficiently thin, a decrease in light absorption efficiency can be suppressed.

[0019] The solar cell 100 consists of a substrate 101, a conductive mirror underlayer 103, and a conductive mirror layer. 104, the hole transport layer 105 which is a p-type oxide semiconductor, and the light absorption layer 106 are arranged in this order. It may at least include a substrate 101, a back electrode 102, and a conductive mirror. - The base layer 103, the conductive mirror layer 104, and the hole transport layer 10 which is a p-type oxide semiconductor 5 and the light-absorbing layer 106 may be provided in this order, at least. Alternatively, the solar cell The 100 consists of a substrate 101, a back electrode 102 on the substrate 101, and a conductive surface on the back electrode 102. A conductive mirror base layer 103, a conductive mirror layer 104 on the conductive mirror base layer 103, and a conductive A hole transport layer 105, which is a p-type oxide semiconductor, on the mirror layer 104, and a hole transport layer 10 5 may also include a light-absorbing layer 106 on the substrate 101. Alternatively, the solar cell 100 may include a light-absorbing layer 106 on the substrate 101. And, the back electrode 102 on the substrate 101 and the conductive mirror underlayer 103 on the back electrode 102 , conductive mirror layer 104 on conductive mirror base layer 103, and p on conductive mirror layer 104 A hole transport layer 105 which is a type oxide semiconductor, and a light absorption layer 106 on the hole transport layer 105 , comprising an electron transport layer 107 on a light absorption layer 106 and an electrode 108 on the electron transport layer 107 Alternatively, in the solar cell 100, the conductive mirror layer 104 is a hole transport layer 10 The conductive mirror base layer 103 is provided on the conductive mirror layer 104. This is also acceptable. Furthermore, in the solar cell 100, the light absorption layer 106 is a p-type oxide semiconductor. It may be provided on the hole transport layer 105. Also, in the solar cell 100, The hole transport layer 105 is provided on the light absorption layer 106, and the conductive mirror layer 104 is on the hole transport layer 1 Even if the conductive mirror base layer 103 is provided on 05 and provided on the conductive mirror layer 104 good.

[0020] The following provides a detailed explanation of each possible configuration included in solar cell 100.

[0021] In this embodiment, when a compound is referred to by a name, the pure compound itself is... In addition, the compound to which trace amounts of elements, etc., are added, to the extent that the properties of the compound are not lost. This also includes.

[0022] Furthermore, in this embodiment, the elements in each layer of the solar cell module are in different oxidation states. Because they can exist in various states, all oxidation states are, unless otherwise specifically stated, named after the element. They are called by their names. For example, "hydrogen element" can refer to a hydrogen atom, a hydrogen ion, a hydride ion, or a compound. This refers to hydrogen in its solid state, and hydrogen in its elemental state.

[0023] Furthermore, in this embodiment, the oxide is MO x When expressed as such (where M represents a metallic element), This includes not only compounds where the molar ratio of metal elements to oxygen elements is exactly 1:x, but also compounds where the molar ratio is slightly off. This also includes compounds that are expressed as NiO, where the molar ratio of Ni to O is 1:1. In addition to the compound, it contains small amounts of trivalent Ni and oxygen vacancies, which is due to the presence of Ni element and This also includes nickel oxide where the molar ratio of element O deviates from 1:1.

[0024] Furthermore, in this embodiment, when the numerical range is described as A to B, the numerical range is A to B. This means it is B or lower.

[0025] 1.1. Circuit board The solar cell 100 includes a substrate 101. The substrate 101 is not particularly limited, but for example... Examples include glass substrates; metal substrates such as stainless steel plates and aluminum foil; polyimide resin substrates, epoxy resin substrates. Resin substrates such as glass substrates can be used. Among these, glass substrates or metal substrates are available. Preferred. The light-absorbing layer 106 contains an alkali metal element, which is preferable for the solar cell 100. Performance tends to improve. Specifically, defects are passivated and the open-circuit voltage improves. There is a tendency to do so. In this respect, by using a glass substrate as the substrate 101, the glass substrate Alkali metal elements such as sodium contained in are diffused into the light-absorbing layer 106, which will be described later. This makes it possible to use a metal substrate. Also, by using a metal substrate, the substrate 101 can be used as an electrode. This eliminates the need to provide separate electrodes for the solar cell 100. Thinning tends to be achievable. Furthermore, when a metal substrate is used as the substrate 101, the metal base By using a metal to which alkali metal elements are added as the material for the plate, This makes it possible to diffuse the elements into the light-absorbing layer 106, which will be described later. The substance may be used alone, or two or more substances may be used in combination.

[0026] Alkali metal elements include sodium, potassium, rubidium, and cesium. Examples of elements include sodium and potassium.

[0027] The thickness of the substrate 101 is not particularly limited, but for example, it is 0.01 to 30.0 mm. The range is 0.05-25.0mm, 0.1-20.0mm, and 0.5-20.0mm. Yes, it is 1.0~10.0mm and 1.5~5.0mm. The thickness of substrate 101 is upper Being within the specified range tends to enable the thinning of solar cell 100. Furthermore, there is a trend towards achieving lighter weight and greater flexibility in solar cells.

[0028] 1.2. Back surface electrode The solar cell 100 includes a back electrode 102. The back electrode 102 is made of a conductive material. It is not particularly limited as long as it contains, for example, molybdenum, chromium, tungsten, Metallic conductive layers made from metals such as titanium; conductive inorganic compounds other than metals Conductive inorganic compound conductive layer; using a conductive organic compound conductive layer made of conductive organic compounds. This is possible. The substance contained in the back electrode 102 may be one type alone, or two or more types may be used. They can be used together.

[0029] When a metal is used as the material contained in the back electrode 102, the volume change due to heating is small. Metal is preferred. This tends to make it less likely for the back electrode 102 to peel off from the substrate 101. Yes, there are. Examples of such metals include tungsten and molybdenum. Furthermore, tungsten and molybdenum are preferable from a cost perspective.

[0030] The thickness of the back electrode 102 is not particularly limited, but for example, it is 100 to 800 nm. The wavelength range is 150-750 nm and 200-700 nm. The thickness of the back electrode 102 is within the above range. Being enclosed allows for sufficient current extraction without loss, while also enabling weight reduction and flexibility of the solar cell. There is a growing trend towards making them usable.

[0031] 1.3. Conductive Mirror Underlayer The solar cell 100 has a conductive mirror between the back electrode 102 and the conductive mirror layer 104. - A base layer 103 may be provided. By providing a conductive mirror base layer 103, The reflectivity of light in the mirror base layer 103 and the conductive mirror layer 104, described later, is further improved. Furthermore, thermal stability tends to improve as well.

[0032] The conductive mirror underlayer 103 preferably has a high light reflectivity. From this viewpoint, The mirror base layer 103 preferably contains a metal. The metal is face-centered cubic at room temperature. Metals that take on a substructure; metals that take on a structure other than a face-centered cubic lattice structure at room temperature (for example, titanium) However, from the viewpoint of improving the light reflectivity of the conductive mirror layer 103, at room temperature Metals that form a face-centered cubic lattice structure at room temperature are more preferable. Specifically, metals that have a face-centered cubic lattice structure include nickel, aluminum, and calcium. Umium, copper, strontium, rhodium, palladium, silver, iridium, platinum, gold, and lead It is preferable to include one or more selected from the group consisting of the following. Also, aluminum, calcium copper, strontium, rhodium, palladium, silver, iridium, platinum, gold, and lead It is more preferable to include one or more species selected from the following groups. Also, gold, aluminum, copper It is even more preferable to include one or more selected from the group consisting of , and silver. It is even more preferable to include one or more elements selected from the group consisting of um, copper, and silver. The substances contained in the electrolytic mirror base layer 103 may be used individually or in combination of two or more. You may do so.

[0033] The metal content in the conductive mirror base layer 103 is the total amount of the conductive mirror base layer 103. Preferably, it is 50-100% by mass, 60-100% by mass, and 70- 100% by mass, 80-100% by mass, 90-100% by mass, 95-1 It is 00% by mass.

[0034] The thickness of the conductive mirror underlayer 103 is preferably 5 to 75 nm, and 7 to 50 nm. The thickness is 10-30 nm. As a result, the light reflectivity tends to improve, and thermal stability also tends to improve.

[0035] 1.4. Conductive Mirror Layer The solar cell 100 includes a conductive mirror layer 104. It is not particularly limited as long as it can reflect light such as sunlight, but for example, Selected from the group consisting of gold, silver, aluminum, gold alloys, silver alloys, and aluminum alloys. It is preferable to include one or more of the following: silver, aluminum, silver alloys, and aluminum alloys. It is more preferable to include one or more elements selected from the group consisting of gold. The substances included may be used individually or in combination of two or more.

[0036] Note that the conductive mirror underlayer 103 and the conductive mirror layer 104 are made of different materials. This is preferable.

[0037] The conductive mirror layer 104 has a reflectivity of light having a wavelength range of 800 to 1140 nm. The percentage is between 60% and 98%.

[0038] The metal content in the conductive mirror layer 104 is, relative to the total amount of the conductive mirror layer 104. Preferably, 50-100% by mass, 60-100% by mass, and 70-100% by mass. This is a percentage by volume, 80-100% by mass, 90-100% by mass, and 95-100% by mass. It is a percentage.

[0039] The thickness of the conductive mirror layer 104 is preferably 5 to 75 nm, and 7 to 50 nm. The wavelength is 10-30 nm. The thickness of the conductive mirror underlayer 103 is within the above range, and light Reflectivity tends to improve.

[0040] 1.5. Hall Transport Layer The solar cell 100 includes a hole transport layer 105 which is a p-type oxide semiconductor. The transport layer 105 efficiently removes holes generated in the light absorption layer 106, for example, from the light absorption layer 106. To selectively extract the electrons and holes that are generated simultaneously in the light-absorbing layer 106, the recombination of electrons and holes is suppressed. It tends to be controllable.

[0041] The hole transport layer 105 is not particularly limited as long as it is a p-type oxide semiconductor, but molybdenum oxide is also an option. (MoO2, MoO3), nickel oxide (NiO), copper oxide (CuO), gallium copper oxide (CuGaO2), chromium copper oxide (CuCrO2), and aluminum copper oxide (CuAlO2) Preferably, it contains one or more metal oxides selected from 2), such as NiO, CuO, One or more metal oxides selected from CuGaO2, CuCrO2, and CuAlO2. It is preferable to include, and more preferably to include CuAlO2. Alternatively, MoO2, M Selected from metal oxides consisting of oO3, NiO, CuO, CuGaO2, and CuAlO2. It is preferable to include one or more of the following. The substance contained in the hole transport layer 105 may be one of the following alone. They may be used individually, or two or more may be used in combination.

[0042] The hole transport layer 105 contains one or more metal oxides selected from the above-mentioned metal oxides, The electrolytic mirror layer 104 can be better protected, and the photoelectric conversion efficiency of the solar cell 100 can be improved. This can suppress the decrease in the rate. In addition, the aforementioned metal oxides have excellent heat resistance and weather resistance. Similarly, the solar cell 100 using the metal oxide described above also exhibits excellent heat resistance and weather resistance. It's across the street.

[0043] Furthermore, the hole transport layer 105 is subjected to heat treatment together with the precursor layer of the light absorption layer 106. Furthermore, the heat treatment is performed in a sulfur atmosphere, selenium atmosphere, chlorine atmosphere, bromine atmosphere, and iodine atmosphere. When carried out in a corrosive gas atmosphere such as ambient air at high temperatures (e.g., 500°C), the hole transport layer 105 may be degraded, at least partially. For example, in a sulfur atmosphere, a selenium atmosphere. Heat treatment at high temperatures (e.g., 500°C) in a gas, chlorine, bromine, or iodine atmosphere. The hole transport layer 105 subjected to this process undergoes, at least in part, sulfidation, selenization, chlorination, bromidation, and It may be iodized. The part of the above hall transport layer 105 is not particularly limited to, For example, this is a part of the surface of the hole transport layer 105 on the side of the light absorption layer 106. Even when subjected to heat treatment, most of layer 105 remains intact (for example, the light-absorbing layer of the hole transport layer 105). The entire surface (or the whole) of the 106 side will not degenerate. Also, at least a part of the hose will not degenerate. The hole transport layer 105, like the unmodified hole transport layer 105, is used in the solar cell 100. This can further suppress the decrease in photoelectric conversion efficiency.

[0044] Furthermore, the hole transport layer 105 may contain a metal oxide to which an alkali metal element has been added. Preferred. By adding alkali metal elements to the light-absorbing layer 106 described later, solar energy The performance of the pond cell 100 tends to improve. By adding alkali metal elements to the light-absorbing layer 106. One method involves heat treatment to transfer alkali metal elements from the substrate 101 to the light-absorbing layer 106. One method is diffusion. In this case, the hole transport layer 105 is used to transport alkali metal elements. By including the added metal compound, alkali metals are transferred from the substrate 101 to the light absorption layer 106. Elemental diffusion becomes more likely, which is preferable. In this embodiment, simply using a metallic acid is preferable. When we refer to "oxides," we mean not only metal oxides but also metal oxides to which alkali metal elements have been added. Includes objects.

[0045] In this embodiment, the metal oxide to which alkali metal elements are added is alkali metal Sometimes the empirical formula is expressed using the formula before the addition of group elements. For example, if the element sodium is In the added aluminum copper oxide, the molar ratio of Cu to Al is not 1:1. In some cases, however, aluminum copper oxide to which the element sodium has been added is called sodium It is sometimes described as CuAlO2 with added elements.

[0046] Alkali metal elements include sodium, potassium, rubidium, and cesium. Examples of elements include sodium and potassium.

[0047] Furthermore, the hole transport layer 105 is CuAlO2 or CuA with added alkali metal elements. It is preferable to include 1O2. This allows for better protection of the conductive mirror layer 104, and The performance of solar cells 100 tends to improve.

[0048] The content of alkali metal elements in the hole transport layer 105 is as follows: Preferably, the amount is 5 to 30 mol% and 10 to 25 moles relative to the total number of moles of metal elements. It is a percentage.

[0049] The alkali metal element content in the hole transport layer 105 is not particularly limited, but for example... If so, it can be measured using ICP, EDX, or SIMS.

[0050] The oxide content in the hole transport layer 105 is determined by the fact that the hole transport layer 105 is a p-type semiconductor. It is not particularly limited as long as it has the properties, but for example, with respect to the total amount of the hall transport layer 105, 80-100% by mass, 90-100% by mass, 95-100% by mass, 9 It is 9-100% by mass.

[0051] The thickness of the hole transport layer 105 is preferably 5 to 100 nm, and 7 to 80 nm. The thickness is 10-60 nm. Because the thickness of the hole transport layer 105 is within the above range, The holes generated in the light absorption layer 106 described later are efficiently extracted from the light absorption layer 106, and the light absorption layer 1 While suppressing the recombination of electrons and holes that occur simultaneously with holes in 06, the lightweight nature of the solar cell There is a tendency towards making things more flexible and adaptable.

[0052] 1.6. Light-absorbing layer The solar cell 100 includes a light-absorbing layer 106. The light-absorbing layer 106 is, for example, near-infrared It absorbs light such as near-infrared light, visible light, and ultraviolet light to generate electrons and holes. Examples of light sources such as ambient light include sunlight. The light-absorbing layer 106 is preferably made of a material that absorbs light. From the group consisting of lucopyrite compounds, kestelite compounds, and perovskite compounds It contains one or more selected types. The perovskite compound may be used alone, or two or more types. The above may be used in combination. One chalcopyrite compound may be used alone, or two or more may be used. They may be used in combination. Also, one type of kesterite compound may be used alone, or two or more types may be used. You may use them in combination.

[0053] The light-absorbing layer 106 consists of a chalcopyrite compound, a kestelite compound, and a perovsky compound. When it contains one or more compounds selected from the group consisting of t compounds, it reduces mass production costs and removes the light-absorbing layer. From the viewpoint of preventing separation, it is preferable to form the light-absorbing layer 106 thinly. Also, in this case... Even if the light-absorbing layer 106 is formed thinly, it will fully exhibit its function as a solar cell, From the perspective of reducing the weight and flexibility of the battery, it is preferable to form the light-absorbing layer 106 thinly. On the other hand, if the light-absorbing layer 106 is formed thinly, the light-absorbing layer 106 absorbs light such as sunlight. This process is insufficient, and the light absorption efficiency tends to decrease.

[0054] In this respect, the solar cell 100 has a conductive mirror layer 104, so the light absorption efficiency is It is showing an upward trend.

[0055] Furthermore, the light-absorbing layer 106 of the solar cell 100 is made of a chalcopyrite compound, kertely If it contains one or more selected from the group consisting of t compounds and perovskite compounds, The light absorption layer 106 is a p-type oxide semiconductor hole transport layer 105, and in terms of valence band position Therefore, they have good electrical compatibility. As a result, there is a hole between the back electrode 102 and the light absorption layer 106. Even with the addition of the transport layer 105, the decrease in photoelectric conversion efficiency tends to be further suppressed. Furthermore, even if the hole transport layer 105 is provided on the substrate 101 side surface of the light absorption layer 106, hole transport At the interface between layer 105 and the light-absorbing layer 106, the increase in electrical resistance is suppressed, and photoelectric This tends to better suppress the decrease in conversion efficiency.

[0056] Furthermore, the light-absorbing layer 106 contains a chalcopyrite compound, a kestelite compound, and a perob If the solar cell 100 contains one or more selected from the group consisting of skite compounds, the solar cell 100 is light The precursor layer of the absorption layer 106 is heat-treated in an atmosphere such as selenium gas or sulfur gas. It is fabricated. In this case, together with the precursor layer of the light-absorbing layer 106, the substrate 101 of the light-absorbing layer 106 The conductive mirror layer 104 and the hole transport layer 105 located on the side (lower side) are also subjected to the above heat treatment. The conductive mirror layer 104 is prone to a decrease in reflectivity due to oxidation, corrosion, etc. In the solar cell 100, a p-type oxide semiconductor is placed on the upper side of the conductive mirror layer 104. A gas transport layer 105 is formed. Therefore, the conductive mirror layer 104 is transported by selenium gas and sulfur. Even when subjected to heat treatment in an atmosphere such as yellow gas, the hole transport layer 105 and the conductive mirror layer 104 This tends to protect the conductive mirror layer 104 and suppress a decrease in its reflectivity.

[0057] Perovskite compounds include those represented by the general formula AMX3 and those represented by the general formula A2MX4. Examples include those represented by , where M is a divalent cation and A is a monovalent cation. X represents a monovalent anion.

[0058] The monovalent cation A is not particularly limited, and for example, it could be a cation of a Group 1 element of the periodic table. And organic cations are also mentioned. Among these, cesium ions, rubidium ions, Ammonium ions (including amidinium ions) which may have substituents, A phosphonium ion which may be present, or an amidinium ion which may have substituents A is preferred. An example of an ammonium ion that may have substituents is a primary ammonium ion. Examples include nium ions and secondary ammonium ions. They may have substituents. Specific examples of ammonium ions include alkylammonium ions and arylammonium ions. Examples include mu ions, amidinium ions, and guanidium ions. In particular, steric hindrance To avoid harm, monoalkylammonium ions are preferred, and from the viewpoint of improving stability. This involves using alkylammonium ions substituted with one or more fluorine atoms. It is preferable. Furthermore, a combination of two or more cations can be used as cation A. Yes. Examples of monovalent cation A include methylammonium ion and methyl monofluoride. ammonium ions, methylammonium difluoride ions, methylammonium trifluoride Umium ions, ethylammonium ions, isopropylammonium ions, n-prop Isobutylammonium ions, isobutylammonium ions, n-butylammonium ions t-butylammonium ion, dimethylammonium ion, diethylammonium Ions, phenylammonium ions, benzylammonium ions, phenethylammonium Nium ion, guanidium ion, formamidinium ion, acetamidinium ion Examples include ions and imidazolium ions.

[0059] The divalent cation M is not particularly limited and includes, for example, divalent metal cations and semi-metallic cations. Examples include cations of group 14 elements in the periodic table. A more specific example is lead cation (Pb 2+ ), tin cation (Sn 2+ ), and gel Manium cation (Ge 2+ ) are examples. In addition, there are two or more types of cation M. You can also use combinations of characters.

[0060] The monovalent anion X is not particularly limited and can be, for example, a halide ion or an acetate ion. Nitrate ions, sulfate ions, borate ions, acetylacetonate ions, carbonate ions , citrate ions, sulfur ions, tellurium ions, thiocyanate ions, titanate ions, Examples include zirconate ions, 2,4-pentanedionato ions, and fluoride ions. X may be one type of anion, or a combination of two or more types of anions. It is also acceptable to do so. X may be a halide ion, or a halide ion and other ions. It is preferable to use a combination with ON. An example of a halide ion X is chloride Examples include physical ions, bromide ions, iodide ions, and the like.

[0061] Examples of perovskite compounds include organic-inorganic perovskite compounds, particularly halide-based organic-inorganic perovskite compounds. Specific examples of perovskite compounds include CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CH3NH 3SnI3, CH3NH3SnBr3, CH3NH3SnCl3, CH3NH3PbI (3-x) Cl x , CH3NH3PbI (3-x) Br x , CH3NH3PbBr (3-x) Cl x , CH3NH3Pb (1-y) S n y I3, CH3NH3Pb (1-y) Sn y Br3, CH3NH3Pb (1-y) Sn y Cl3, CH3NH3 Pb (1-y) Sn y I (3-x) Cl x , CH3NH3Pb (1-y) Sn y I (3-x) Br x , and CH3NH3 Pb (1-y) Sn <00000​​​​​​​​​​​​​​Examples of such compounds include the I-III-VI2 chalcopyrite compounds. It is not defined, but for example, CuAlS2, CuAlSe2, CuAlTe2, CuGaS2, C uGaSe2, CuGaTe2, CuInS2, CuInSe2, CuInTe2, AgAl S2, AgAlSe2, AgAlTe2, AgGaS2, AgGaSe2, AgGaTe2, A Examples include gInS2, AgInSe2, AgInTe2, and combinations thereof. These combinations are not particularly limited, but include, for example, CuGaS2 and CuInS When combining e2, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0≦y≦ 1) is one example. Among these chalcopyrite compounds, CuGaS2, CuGa Se2, CuInS2, CuInSe2, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦ 1, 0 ≤ y ≤ 1) is preferred, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0 ≤y≦1) is more preferable. Note that in this embodiment, when referring to a CIS compound, it means C A chalcopyrite compound containing u, In, and Se, and referred to as a CIGS compound, C It is a chalcopyrite compound containing u, In, Ga, and Se, and is called a CIGSS compound. It is a chalcopyrite compound containing Cu, In, Ga, Se, and S.

[0063] Preferably, the kesterite compound is an I2-II-IV-VI4 kesterite compound. Compounds are one example. I2-II-IV-VI4 kestelite compounds are particularly limited. However, for example, Cu2ZnSnS4, Cu2ZnSnSe4, Cu2ZnGeS4, Cu2 ZnGeSe4, Cu2MnSnS4, Cu2MnSnSe4, Cu2MnGeS4, Cu2Mn GeSe4, Ag2ZnSnS4, Ag2ZnSnSe4, Ag2ZnGeS4, Ag2ZnGe Se4, Ag2MnSnS4, Ag2MnSnSe4, Ag2MnGeS4, Ag2MnGeSe 4. and combinations thereof. "These combinations" is not particularly limited. However, for example, when Cu2ZnSnS4 and Ag2ZnSnSe4 are combined (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4 (0≦x≦1) is one example. Cu2ZnSn(S x Se 1-x )4 (0≦x≦1, 0≦y≦1) are examples. Among these kestellite compounds However, Cu2ZnSnS4, Cu2ZnSnSe4, Ag2ZnSnS4, Ag2ZnSnSe4 , (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4 (0≦x≦1, 0≦y≦1) is preferred, (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4(0≦x≦1, 0≦y≦1) is more preferable. In this embodiment, when referring to a CZTS compound, it means a compound containing Cu, Zn, Sn, and S. It is a kestelite compound, and when referred to as an ACZTS compound, it is Ag, Cu, Zn, Sn It is a kestelite compound containing S, and when referred to as an ACZTSS compound, Ag, Cu, It is a kestelite compound containing Zn, Sn, S, and Se.

[0064] The light-absorbing layer 106 is a perovskite compound doped with alkali metal elements, alkali gold Chalcopyrite compounds with added elemental groups and kestella with added alkali metal elements It is preferable to include a ion compound. This tends to improve the performance of the solar cell 100. They are located in the opposite direction. Alkali metal elements include sodium, potassium, and rubidium. Among these, cesium is a good example, and sodium is preferred.

[0065] The alkali metal element content in the light-absorbing layer 106 is the total amount of gold contained in the light-absorbing layer 106. Preferably, the amount is 0.1 to 5 mol%, and 0.5 to 2 mol%, relative to the number of moles of the group element. The alkali metal element content in the light-absorbing layer 106 is within the above range. The performance of solar cells 100 tends to improve further.

[0066] The content of alkali metal elements in the light-absorbing layer 106 is not particularly limited, but for example, Measurements can be taken using ICP, EDX, and SIMS.

[0067] Perovskite compounds, chalcopyrite compounds and kestella in the light-absorbing layer 106 The amount of the ion compound is such that the light-absorbing layer 106 absorbs light such as visible light and ultraviolet light, and electrons and holes It is not particularly limited as long as it can generate the above. More specifically, it is not particularly limited, but The content of the above chalcopyrite compound and the above kestelite compound is as follows: Light absorption layer 106 It is 50-100% of the total mass, 60-100% of the total mass, and 70-10% of the total mass. It is 0% by mass, 80-100% by mass, and 90-100% by mass.

[0068] The light-absorbing layer 106 may also contain additives such as binders and surfactants in addition to the above materials. The amount of the above additive is not particularly limited, but for example, relative to the total mass of the light-absorbing layer 106 The amount is 0.1 to 10% by mass. The light-absorbing layer 106 does not necessarily have to contain the above additives.

[0069] The thickness of the light-absorbing layer 106 is preferably 0.5 to 5.0 μm, and 0.5 to 4.5 μm. The thickness is m and is 0.5 to 3.0 μm. The thickness of the light-absorbing layer 106 is within the above range. Furthermore, it can absorb light such as visible light and ultraviolet light to generate electrons and holes, and solar cells There is a trend towards making ponds lighter and more flexible. Also, the light-absorbing layer 106 peels off. This tends to prevent such occurrences.

[0070] The solar cell 100 of this embodiment may have two light-absorbing layers 106. In total, the material contained in the first light-absorbing layer 106 and the material contained in the second light-absorbing layer 106 are different. They may be the same, but it is preferable that they be different. (First and second light-absorbing layers 106) Solar cells that contain different materials are also called tandem solar cells. Since cell 100 has two layers of light-absorbing layer 106, the amount of light that the light-absorbing layer 106 can absorb is limited. There is a tendency to expand the wavelength range, and as a result, the performance of solar cell 100 tends to improve. It is in the direction. Furthermore, the solar cell 100 of this embodiment has three or more light-absorbing layers 106. It's okay to be there.

[0071] 1.7.Electron transport layer The solar cell 100 has an electron transport layer 10 on the side of the light absorption layer 106 that is opposite to the substrate 101. It is optional to include item 7, but it improves the photoelectric conversion efficiency of solar cell 100. From this viewpoint, it is preferable to have an electron transport layer 107.

[0072] The electron transport layer 107 efficiently removes electrons generated in the light absorption layer 106 from the light absorption layer 106. This suppresses the recombination of electrons with holes that are generated simultaneously with electrons in the light-absorbing layer 106. This is the tendency. The electron transport layer 107 is preferably an n-type semiconductor. The n-type semiconductor contains The substances used are not particularly limited, but examples include zinc oxide, tin oxide, titanium oxide, and acid Zinc sulfide (zinc oxide with added sulfur element), zinc magnesium oxide (magnesium element Zinc oxide with added tin, zinc tin oxide (zinc oxide with added tin), and oxidation Examples include metal oxides such as titanium zinc (zinc oxide with added titanium). Electron transport The substances contained in layer 107 may be used individually or in combination of two or more.

[0073] The electron transport layer 107, which is an n-type oxide semiconductor, is made of zinc oxide, tin oxide, titanium oxide, and oxide Substantially composed of zinc sulfide, zinc magnesium oxide, zinc tin oxide, or zinc titanium oxide. Preferably, zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium oxide, and tincture are used. It is preferable that the material is lead, zinc tin oxide, or zinc titanium oxide. Also, n-type oxide semiconductors are preferred. The electron transport layer 107 contains zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, and oxide. The content of metal oxides such as magnesium zinc, tin zinc oxide, or titanium zinc oxide is electronic. Preferably, the amount of transport layer 107 is 80-100% by mass, and 90-100% by mass. It is expressed as a percentage by volume, 95-100% by mass, and 99-100% by mass.

[0074] The thickness of the electron transport layer 107 is preferably 50 to 200 nm, and 55 to 175 nm. The thickness of the electron transport layer 107 is 60-150 nm and 65-125 nm. Within the above range, electrons generated in the light absorption layer 106 can be efficiently removed from the light absorption layer 106. This process extracts the electrons and suppresses the recombination of holes and electrons that are simultaneously generated in the light absorption layer 106. Meanwhile, there is a trend towards making solar cells lighter and more flexible.

[0075] 1.8.Surface electrode The solar cell 100 has a surface electrode 108. The surface electrode 108 is, for example, light absorber. It is provided to extract the electric current generated by electrons in layer 106.

[0076] 1.8.1.Transparent electrode layer The surface electrode 108 may have a transparent electrode layer 109. A transparent electrode is a material with high electrical conductivity. This electrode uses a material that combines high electrical conductivity with high visible light transmittance. High electrical conductivity is particularly limited It is not fixed, but for example, the resistivity is 5.0 × 10 -3 This means it is less than or equal to Ωcm. High visible light transmittance is not particularly limited, but for example, in the wavelength range of 400 to 1300 nm. This means that the average transmittance is 80% or more. As for the material of the transparent electrode, known materials Materials can be used, for example, indium tin oxide (ITO), hydrogen-containing indium oxide. IOH (Ion), fluorine-containing tin oxide (FTO), boron-containing zinc oxide (ZnO:B), A Examples include luminium-containing zinc oxide (ZnO:Al), which is included in the transparent electrode layer 109. The substance may be used alone, or two or more substances may be used in combination.

[0077] When the second transparent electrode 109 is a transparent electrode, the content of the above material is: 9 is not particularly limited as long as it functions as a transparent electrode. More specifically, it is not particularly limited, but The content of the above material is 50-100% by mass relative to the total mass of the second transparent electrode 109. It is 60-100% by mass, 70-100% by mass, and 80-100% by mass. It is 90-100% by mass, and 95-100% by mass.

[0078] The thickness of the second transparent electrode 109 is not particularly limited, but for example, 100 to 1500 nm. Yes, it is between 200 and 1000 nm. The thickness of the second transparent electrode 109 is within the above range. This allows for efficient and lossless extraction of current while enabling lighter and more flexible solar cells. This tends to be the case.

[0079] 1.8.2. Grid electrodes The surface electrode 108 may have a grid electrode 110. The material of the grid electrode 110 and The material is not particularly limited as long as it is conductive, but for example, Mo, Cr, Ag, Metals such as Cu, Ni, Al, or Ti; conductive inorganic compounds other than metals; conductive organic compounds It can be used. The substances contained in the grid electrode 110 may be used individually. You may use two or more types in combination.

[0080] The content of the above material in the grid electrode 110 is such that the grid electrode 110 functions as an electrode. It is not particularly limited as long as it is possible. More specifically, it is not particularly limited, but the content of the above materials is The mass of the grid electrode 110 is 50-100% of the total mass, and 60-100% of the total mass. It is %, 70-100% by mass, 80-100% by mass, and 90-100% by mass. That is the case.

[0081] The thickness of the grid electrode 110 is not particularly limited, but for example, it is 5 to 50 μm. Because the thickness of the lid electrode 110 is within the above range, the current can be extracted sufficiently without loss. Furthermore, there is a trend towards making solar cells lighter and more flexible.

[0082] The surface electrode 108 may consist only of the transparent electrode 109, or it may consist only of the grid electrode 110. It may also be provided with a transparent electrode 109 and a grid electrode 110. Electrode 110 is preferable The device comprises a transparent electrode 109 and a grid electrode 110.

[0083] 2. Method for manufacturing solar cells The manufacturing method of the solar cell 100 of this embodiment involves a substrate 101, a back electrode 102, and a guide The electrolytic mirror layer 104, the hole transport layer 105 which is a p-type semiconductor, and the precursor of the light absorption layer 106. A laminate preparation step of preparing a laminate comprising a body layer and, in this order, at least, the laminate This refers to a group consisting of a sulfur atmosphere, a selenium atmosphere, a chlorine atmosphere, a bromine atmosphere, and an iodine atmosphere. This includes a heat treatment process in which heat treatment is performed in one or more selected atmospheres.

[0084] In the solar cell 100 manufactured by the manufacturing method of this embodiment, the conductive mirror layer Since a hole transport layer 105, which is a p-type semiconductor, exists between 104 and the light absorption layer 106, The above heat treatment process prevents the conductive mirror layer 104 from undergoing corrosion or other deformities, and the conductive mirror layer 1 This can suppress the decrease in the reflectivity of light 04.

[0085] The following describes in detail each step that may be included in the manufacturing method of the solar cell 100 of this embodiment. .

[0086] 2.1. Laminate preparation process The manufacturing method of the solar cell in this embodiment involves a substrate 101, a back electrode 102, and a conductive micro The precursor layers of the light absorption layer 106 consist of a LAR layer 104, a p-type semiconductor hole transport layer 105, and a light absorption layer 106. The process includes a laminate preparation step of preparing a laminate comprising, in this order, at least. One method for preparing a laminate is sputtering.

[0087] Specifically, back electrode 102 is laminated on substrate 101 using the sputtering method, A conductive mirror layer 104 is laminated on the surface electrode 102 using the sputtering method, and the conductive mirror A hole transport layer 105 is laminated on the Lar layer 104 using the sputtering method, and hole transport A precursor layer of the light-absorbing layer 106 may be laminated on layer 105 using a sputtering method. Furthermore, a back electrode 102 is laminated on the substrate 101 using the sputtering method, and the back electrode 1 A conductive mirror underlayer 103 is laminated on 02 using the sputtering method, and a conductive mirror A conductive mirror layer 104 is laminated on the base layer 103 using the sputtering method, and the conductive mirror A hole transport layer 105 is laminated on the Lar layer 104 using the sputtering method, and hole transport A precursor layer of the light-absorbing layer 106 may be laminated on layer 105 using a sputtering method. Furthermore, between each layer, spalls may be used as needed, considering factors such as interlayer adhesion, bonding, and conductivity. Even if an intermediate layer is provided by methods such as tarnishing, vapor deposition, or spray coating, good.

[0088] The sputtering method uses the material of each layer as a sputtering target and is performed under an argon atmosphere. This may be done by sputtering. For example, when forming the conductive mirror layer 104 by sputtering, Aluminum is used as the sputtering target, and sputtering is performed in an argon atmosphere. That's fine.

[0089] Additionally, if necessary, a sputtering target containing two or more compounds can be used. The tarling method may be used. Additionally, if necessary, an atmosphere other than argon, such as an oxygen atmosphere, may be used. The sputtering method may be performed in this atmosphere. For example, a hole transport layer containing CuAlO2. When forming 105 by sputtering, Cu2O and Al2O3 are sputtered. As a result, sputtering may be performed under an oxygen atmosphere. The targeting target may consist of two parts: Cu2O and Al2O3. It may also be one of the O3 mixtures. In addition, the sputtering target is made of material from each layer. In addition to the raw materials, additives such as binders may also be included. Also, the gas supplied during sputtering may be used. The concentration of the oxygen source in the system is not particularly limited, but for example, in terms of oxygen molecules, it is 0.2 to 1 It is 0.0 volume percent.

[0090] One method for adding alkali metal elements to the hole transport layer 105 is sputtering. One method involves using materials to which alkali metal elements have been added. The hole transport layer 105 containing CuAlO2 with alkali metal elements added is sputtered When formed by the 3D method, there are no particular limitations, but for example, CuO, Al2O3 and Na2O Two sputtering targets may be used, and a mixture of CuO and Al2O3 and Na Two sputtering targets of 2O may be used, and CuO, Al2O3 and Na2O A single sputtering target consisting of a mixture may also be used.

[0091] The amount of alkali metal elements added to the hole transport layer 105 is the amount of sputtering target This can be adjusted by controlling the amount of alkali metal elements in the mixture.

[0092] The precursor layer of the light-absorbing layer 106 is a material that will become the light-absorbing layer 106 through a heat treatment process described later. It contains quality. If the light-absorbing layer 106 contains a perovskite compound, the precursor of the light-absorbing layer 106 The layers are not particularly limited, but include, for example, laminates such as PbI2 or FAI. Light-absorbing layer 10 If 6 contains a chalcopyrite compound, the precursor layer of the light-absorbing layer 106 is not particularly limited. However, it includes, for example, a laminate of CuGa or In. The light-absorbing layer 106 is a kesterite compound. If it includes, the precursor layer of the light absorption layer 106 is not particularly limited, but for example, Zn or Sn or Includes laminates of materials such as Cu.

[0093] As a method for adding alkali metal elements to the light-absorbing layer 106, the heat treatment process described later is used. Therefore, alkali metal elements that may be contained in the substrate 101 and the hole transport layer 105 are included in the light absorption layer 10 Methods for diffusion up to 6, and methods for adding alkali metal elements to the precursor layer of the light-absorbing layer 106. One method for adding alkali metal elements to the precursor layer of the light-absorbing layer 106 is to use S One method involves using a puttering target that has alkali metal elements added to it. It can be done.

[0094] 2.2. Heat Treatment Process The solar cell manufacturing method of this embodiment involves the preparation of the laminate in the laminate preparation step, and sulfur Selected from the group consisting of atmosphere, selenium atmosphere, chlorine atmosphere, bromine atmosphere, and iodine atmosphere. This includes a heat treatment step in which heat treatment is performed in one or more atmospheres. The main body layer becomes the light-absorbing layer 106.

[0095] The above laminate comprises a hole transport layer 105 which is a p-type semiconductor. Therefore, the conductive mirror layer 104 can be protected by the heat treatment process. - Prevents the layer 104 from undergoing degradation such as corrosion, and reduces the light reflectivity of the conductive mirror layer 104. This can suppress it.

[0096] The atmosphere used in the heat treatment process includes a sulfur atmosphere, a selenium atmosphere, a chlorine atmosphere, a bromine atmosphere, It is one or more atmospheres selected from the group consisting of a sulfur atmosphere and an iodine atmosphere. Specifically, a sulfur atmosphere Selected from the group consisting of ambient air, selenium atmosphere, chlorine atmosphere, bromine atmosphere, and iodine atmosphere. It may also be an atmosphere containing one of the above, or a mixed atmosphere containing two or more selected from the group consisting of the above. But that's fine. Alternatively, a heat treatment process can be performed in one atmosphere followed by another heat treatment process in a different atmosphere. This may be performed. Specifically, after the heat treatment process is carried out in a selenium atmosphere, in a sulfur atmosphere A heat treatment process may be performed.

[0097] If the light-absorbing layer 106 is a chalcopyrite compound or a kestelite compound, a sulfur atmosphere It is preferable that the heat treatment process be carried out in one or more atmospheres, either gas or selenium. Furthermore, after the heat treatment process is carried out in a selenium atmosphere, the heat treatment process is carried out in a sulfur atmosphere. More preferable.

[0098] If the light-absorbing layer 106 is a perovskite compound, a chlorine atmosphere, a bromine atmosphere and iodine It is preferable that the heat treatment process be carried out in one or more atmospheres selected from the group consisting of elemental atmospheres. It's nice.

[0099] In this embodiment, when referring to a sulfurous atmosphere, it means an atmosphere containing a gas that has the element sulfur. It means gas. That is, other gases that do not contain the element sulfur (e.g., nitrogen gas, argon gas). An atmosphere containing sulfur and a gas containing the element sulfur is included in a sulfur atmosphere. Selenium atmosphere The same applies to chlorine, bromine, and iodine atmospheres.

[0100] In the heat treatment process, the laminate is preferably heat-treated at a temperature of 60 to 600°C. It is more preferable that the material be heat-treated at a temperature of 150 to 600°C. More specifically, in a sulfur atmosphere In the case of ambient air and selenium atmosphere, the heat treatment temperature is preferably 300 to 600°C. The temperature range is 350-600°C, 400-600°C, and 450-600°C. Chlorine atmosphere In the case of gas, bromine atmosphere, and iodine atmosphere, the heat treatment temperature is preferably 60 to 230°C. The temperature range is 70-200°C and 80-170°C.

[0101] In the heat treatment process, the heat treatment time is preferably 1 minute or more and 30 minutes or less, and 3 minutes The duration is 15 minutes or less, and between 5 minutes and 15 minutes.

[0102] 2.3.Electron transport layer formation process The method for manufacturing a solar cell in this embodiment involves forming an electron transport layer 107. The process may include steps. The electron transport layer formation step may be carried out using a sputtering method. Specifically, zinc oxide and titanium oxide are sputtered onto the light-absorbing layer 106. As a first step, sputtering was performed under an argon atmosphere to produce n-type oxide containing titanium oxide zinc. A semiconductor electron transport layer may be formed. The sputtering target is the electron transport layer The formula may be modified as appropriate depending on the substance contained in 107.

[0103] 2.4. Surface electrode formation process The method for manufacturing a solar cell according to this embodiment includes a surface electrode formation step for forming the surface electrode 108. It may also include the following. The surface electrode formation process may be carried out using a sputtering method.

[0104] Specifically, a transparent electrode layer 109 is sputtered onto the light absorption layer 106 or the electron transport layer 107. The layer is constructed using the ring method, and the grid electrode 110 is sputtered onto the transparent electrode layer 109. It may be provided using the sputtering method. In the sputtering method, the material of each component is sputtered The ring target can also be operated under an argon atmosphere.

[0105] Alternatively, a method for forming the surface electrode 108 may involve combining sputtering with other methods. One method is to combine them. Specifically, on the light absorption layer 106 or the electron transport layer 107, Transparent electrode layers 109 are stacked using the sputtering method, and on the transparent electrode layers 109, a vapor deposition method is used. , a method of printing a paste-like conductive material, or a method of crimping conductive wires, A head electrode 110 may be provided.

[0106] 3. Solar cell modules In the solar cell module of this embodiment, multiple solar cells 100 are electrically connected in series. Alternatively, they are connected in parallel. A method of electrically connecting multiple solar cells 100 in series. For example, the back electrode 102 of one solar cell 100 and the metal ribbon, and the metal ribbon wire One method involves soldering the surface electrodes 108 of the other solar cell 100. One method for electrically connecting multiple solar cells 100 in parallel is to connect solar cell 1 A metal ribbon is soldered to the back electrode 102 of 00, and another metal ribbon is soldered to the front electrode 108. Prepare a plurality of soldered ones, and then solder the metal ribbons soldered to the back electrode 102 to electrically connect the ribbons to each other, and also electrically connect the metal ribbons soldered to the front electrode 108 to each other. A method of doing so can be cited.

[0107] In a solar cell module in which a plurality of solar cells 100 are electrically connected in series, it is preferable because a higher voltage can be obtained. Also, in a solar cell module in which a plurality of solar cells 100 are electrically connected in parallel, it is preferable because a higher current can be obtained and power generation can be performed more stably. Further, in a solar cell module in which a plurality of solar cells 100 are electrically connected in a combination of series and parallel, it is preferable because the voltage and current can be adjusted to a suitable range and power generation can be performed stably.

[0108] 4. Method of using the solar cell The solar cell 100 can be used in a normal temperature environment where the temperature of the solar cell is about 45 to 85°C, similar to a conventional solar cell. Also, unlike a conventional solar cell, the solar cell 100 can be suitably used even in a high-temperature environment where the temperature of the solar cell exceeds 85°C (for example, in space, the stratosphere, deserts, tropics, rooftops of buildings, roofs of automobiles, outer walls of airplanes, etc.).

[0109] In addition, the solar cell 100 can be thinned, and weight reduction and flexibility can be achieved. Therefore, the solar cell 100 can be attached to windows and wall surfaces of buildings such as buildings, windows and roofs of moving bodies such as cars, etc., and used as a power generation device. Furthermore, the solar cell 100 can be used as an independent power supply device for streetlights, sensors, digital signage, etc.

[0110] It can be used, and in doing so, the solar cell 100 can be bent or otherwise adapted to various environments. It can be used in conjunction with a mobile energy device. It can also be used as a snack. [Examples]

[0110] The present invention will be described in more detail below using examples and comparative examples. This is not limited in any way by the examples provided.

[0111] 1. Simulation experiment on conductive mirror layer Simulation software (manufactured by the National Institute of Advanced Industrial Science and Technology, thin-film solar cell) Using the characteristic simulation software (e-ARC), a conductive mirror layer is provided. The effects of the following were investigated. First, the glass substrate / back electrode / hole transport layer / light absorption layer / electron transport layer were investigated. Model 1 was fabricated, with each layer arranged in the order of transmission layer / surface electrode. Additionally, a glass substrate / backside electrode was constructed. The layers are arranged in the following order: conductive mirror layer, hole transport layer, light absorption layer, electron transport layer, and surface electrode. Model 2 was created. The configuration of each layer in Models 1 and 2 is as follows: ru. Substrate: 2mm thick glass Back electrode: A layer made of metallic molybdenum with a thickness of 400 nm. Conductive mirror layer: A layer made of metallic silver with a thickness of 50 nm. Hole transport layer: A layer made of CuAlO2 with a thickness of 50 nm. Light-absorbing layer: A layer consisting of CIGSS compounds with a thickness of 1-3 μm. Electron transport layer: A layer made of titanium zinc oxide with a thickness of 100 nm. Surface electrode: A layer made of ITO with a thickness of 350 nm.

[0112] Using models 1 and 2 described above, simulations were performed in which light was irradiated from the surface electrode side. The results are shown in Figure 2. Model 2, which has a conductive mirror layer, is superior to Model 1, which does not. Rather than the short-circuit current density J at each thickness of the light-absorbing layer, SC You can see that it's getting bigger. Therefore, by incorporating a conductive mirror layer, the light-absorbing layer absorbs more light. This indicates that the light absorption efficiency has improved.

[0113] 2. Fabrication of partial structures of solar cells [Example 1] In Example 1, a 2 mm thick glass substrate was used. Metallic molybdenum was placed on this substrate. A back electrode containing was formed with a thickness of 400 nm. During the formation of the back electrode, metallic molybdenum was used. The sputtering target was used, and the sputtering method was employed under an argon atmosphere.

[0114] A thick conductive mirror underlayer containing metallic nickel is applied to the back electrode using the sputtering method. It was formed at a thickness of 50 nm. During the formation of the conductive mirror underlayer, metallic nickel was sputtered. A sputtering method was used with a target under an argon atmosphere.

[0115] A thick layer of conductive mirror containing metallic silver is applied to a conductive mirror substrate using the sputtering method. It was formed at a thickness of 50 nm. During the formation of the conductive mirror layer, metallic silver was sputtered onto the target. The sputtering method was used under an argon atmosphere.

[0116] A p-type semiconductor containing CuGaO2 is produced by sputtering on a conductive mirror layer. A hole transport layer was formed with a thickness of 50 nm. During the formation of the hole transport layer, Cu2O and Ga2O A mixture of 3 and 1, where the molar ratio of Cu to Ga is 1:1, is sputtered. As a sputtering target, a mixed gas atmosphere of argon gas: oxygen gas = 90 vol%: 10 vol% was used under an atmosphere (oxygen atmosphere), and the sputtering method was employed. In this way, the partial structure of the solar cell before heat treatment in Example 1 was prepared.

[0117] The partial structure of the solar cell before heat treatment was subjected to heat treatment at 500 °C for 10 minutes under a sulfur atmosphere (a mixed gas atmosphere of nitrogen gas: H2S gas = 95 vol% : 5 vol%). In this way, the partial structure of the solar cell after heat treatment in Example 1 was fabricated.

[0118] [Example 2] The partial structures of the solar cell before and after heat treatment in Example 2 were fabricated in the same manner as in Example 1, except that a hole transport layer which is a p-type semiconductor containing NiO with a thickness of 50 nm was used. When forming the hole transport layer, NiO was used as a sputtering target, and the sputtering method was employed under a mixed gas atmosphere of argon gas: oxygen gas = 90 vol%: 10 vol% (oxygen atmosphere).

[0119] [Example 3] The partial structures of the solar cell before and after heat treatment in Example 3 were fabricated in the same manner as in Example 1, except that a hole transport layer which is a p-type semiconductor containing MoO2 with a thickness of 50 nm was used. When forming the hole transport layer, MoO2 was used as a vapor deposition source, and the vapor deposition method was employed.

[0120] [Example 4] The partial structures of the solar cell before and after heat treatment in Example 4 were fabricated in the same manner as in Example 1, except that a hole transport layer which is a p-type semiconductor containing MoO3 with a thickness of 50 nm was used. When forming the hole transport layer, MoO3 was used as a vapor deposition source, and the vapor deposition method was employed.

[0121] ​​​​​​​​​[Example 5] A hole transport layer, which is a p-type semiconductor containing silver-doped NiO and has a thickness of 50 nm, is used. Except for the above, the process was the same as in Example 1, but the portion of the solar cell before and after heat treatment in Example 5 was the same. The structure was fabricated. In forming the hole transport layer, AgO and NiO were used to form Ag and Ni elements. A mixture prepared with a molar ratio of 1:99 is used as the sputtering target. Under a mixed gas atmosphere (oxygen atmosphere) of 90% by volume:10% by volume, The puttering method was used.

[0122] [Example 6] Aside from using a 50nm thick hole transport layer which is a p-type semiconductor containing CuAlO2, In the same manner as in Example 1, the partial structure of the solar cell before and after heat treatment of Example 6 was fabricated. In the formation of the hole transport layer, Cu2O and Al2O3 were used in the molar ratio of Cu to Al. A mixture prepared in a 1:1 ratio is used as the sputtering target, and argon gas: Under a mixed gas atmosphere of 90% oxygen gas:10% oxygen gas (oxygen atmosphere), sputtering The G method was used.

[0123] [Comparative Example 1] In Comparative Example 1, a 2 mm thick glass substrate was used. Metallic molybdenum was placed on this substrate. A back electrode containing was formed with a thickness of 400 nm. During the formation of the back electrode, metallic molybdenum was used. The sputtering target was used, and the sputtering method was employed under an argon atmosphere. In this manner, a partial structure of the solar cell of Comparative Example 1, before heat treatment, was prepared.

[0124] The partial structure of the solar cell before the above heat treatment was subjected to a sulfurous atmosphere (nitrogen gas: H2S gas = 95%). The sample was subjected to heat treatment at 500°C for 10 minutes under a mixed gas atmosphere with a volume of 5%. Then, a partial structure of the solar cell after heat treatment was fabricated for Comparative Example 1.

[0125] [Comparative Example 2] In Comparative Example 2, a 2 mm thick glass substrate was used. Metallic molybdenum was placed on this substrate. A back electrode containing was formed with a thickness of 400 nm. During the formation of the back electrode, metallic molybdenum was used. The sputtering target was used, and the sputtering method was employed under an argon atmosphere.

[0126] A conductive mirror layer containing metallic silver is formed on the back electrode using a sputtering method to a thickness of 50 nm. It was formed using [material]. When forming the conductive mirror layer, metallic silver was used as the sputtering target, and [material] The sputtering method was used under a Lugon atmosphere. In this way, the pre-heat treatment of Comparative Example 2 was performed. We prepared a partial structure for the solar cell.

[0127] The partial structure of the solar cell before the above heat treatment was subjected to a sulfurous atmosphere (nitrogen gas: H2S gas = 95%). The sample was subjected to heat treatment at 500°C for 10 minutes under a mixed gas atmosphere with a volume of 5%. Then, a partial structure of the solar cell after heat treatment was fabricated for Comparative Example 2.

[0128] [Comparative Example 3] In Comparative Example 3, a 2 mm thick glass substrate was used. Metallic molybdenum was placed on this substrate. A back electrode containing was formed with a thickness of 400 nm. During the formation of the back electrode, metallic molybdenum was used. The sputtering target was used, and the sputtering method was employed under an argon atmosphere.

[0129] A thick conductive mirror underlayer containing metallic nickel is applied to the back electrode using the sputtering method. It was formed at a thickness of 50 nm. During the formation of the conductive mirror underlayer, metallic nickel was sputtered. A sputtering method was used with a target under an argon atmosphere.

[0130] A thick layer of conductive mirror containing metallic silver is applied to a conductive mirror substrate using the sputtering method. It was formed at a thickness of 50 nm. During the formation of the conductive mirror layer, metallic silver was sputtered onto the target. The sputtering method was used under an argon atmosphere. In this way, Comparative Example 3 We prepared the partial structure of the solar cell before heat treatment.

[0131] The partial structure of the solar cell before the above heat treatment was subjected to a sulfurous atmosphere (nitrogen gas: H2S gas = 95%). The sample was subjected to heat treatment at 500°C for 10 minutes under a mixed gas atmosphere with a volume of 5%. Then, a partial structure of the solar cell after heat treatment, as in Comparative Example 3, was fabricated.

[0132] For the partial structure of each solar cell example, from the exposed side opposite the substrate, 800~1 Light with a wavelength in the 140 nm range was incident on the device, and the reflectance of the light was measured. This was performed on the substructure of a single battery cell before and after heat treatment, respectively.

[0133] The results for Examples 1-6 and Comparative Examples 1-3 are shown in Table 1.

[0134] [Table 1]

[0135] By incorporating a conductive mirror layer, the light reflectivity is improved, and by incorporating a conductive mirror base layer... This improves the light reflectivity and includes a hole transport layer that is a p-type semiconductor. This shows that the light reflectivity after heat treatment is improved.

[0136] [Example 7] The conductive mirror layer containing metallic silver with a thickness of 25 nm was used, and CuAlO The use of a hole transport layer that is a p-type semiconductor containing 2, and the formation of a conductive mirror underlayer. Except for the absence of certain features, the process is the same as in Example 6, but the portion of the solar cell before and after heat treatment in Example 7 is the same. The structure was fabricated.

[0137] [Example 8] This example is the same as Example 7, except that a 25 nm thick conductive mirror underlayer containing Al was used. Then, the partial structure of the solar cell before and after heat treatment of Example 8 was fabricated. Under a conductive mirror During the formation of the rock layers, Al was used as a sputtering target, and under an argon atmosphere, sputtering occurred. The Taring method was used.

[0138] [Example 9] A p-type semiconductor containing sodium-doped CuAlO2 with a thickness of 10 nm. Except for using a gal transport layer, the procedure for Example 9 was the same as in Example 8, but the sun before and after heat treatment was different. A partial structure of a battery cell was fabricated. During the formation of the hole transport layer, Na2O, Cu2O, and Al2 O3 was mixed with a mixture in which the molar ratio of Na:Cu:Al was 1:4:5. The mixture is used as the sputtering target, with argon gas:oxygen gas = 90% by volume:10% by volume. The sputtering method was used under a mixed gas atmosphere (oxygen atmosphere) of %.

[0139] [Example 10] The use of a 25nm thick conductive mirror layer containing Al, and a 25nm thick Ti Except for using a conductive mirror underlayer containing the above, Example 10 was carried out in the same manner as Example 9, Substructures of solar cells before and after heat treatment were fabricated. Al was used in the formation of the conductive mirror layer. The sputtering target was used, and the sputtering method was employed under an argon atmosphere. In forming the conductive mirror underlayer, Ti is used as the sputtering target, and an argon atmosphere is used. The sputtering method was used under controlled conditions.

[0140] [Example 11] Except for using a 25 nm thick conductive mirror underlayer containing Ag, this example is the same as Example 10. In this manner, the partial structure of the solar cell before and after heat treatment of Example 11 was fabricated. Conductive mirror - In forming the underlying layer, Ag was used as the sputtering target, and under an argon atmosphere, The puttering method was used.

[0141] For each example, the partial structure of the solar cell after heat treatment is shown from the exposed side opposite the substrate. Light with a wavelength range of 800 to 1140 nm was incident on the device, and the reflectance of the light was measured.

[0142] The results for Examples 7-11 are shown in Table 2.

[0143] [Table 2]

[0144] Furthermore, at the location of the hole transport layer in Example 11, sodium element is added to CuA Instead of a p-type semiconductor containing 1O2, a transparent conductive oxide layer called ITO is formed. Using the same method as in Example 11, the reflectance of light after heat treatment was measured. As a result, the reflectance of light It decreased significantly.

[0145] 3. Fabrication of solar cells [Example 12] In Example 1, a 2 mm thick glass substrate was used. Metallic molybdenum was placed on this substrate. A back electrode containing was formed with a thickness of 400 nm. During the formation of the back electrode, metallic molybdenum was used. The sputtering target was used, and the sputtering method was employed under an argon atmosphere.

[0146] A conductive mirror layer containing metallic silver is formed on the back electrode using a sputtering method to a thickness of 50 nm. It was formed using [material]. When forming the conductive mirror layer, metallic silver was used as the sputtering target, and [material] The sputtering method was used under a Lugon atmosphere.

[0147] A sodium-doped CuAl is produced on a conductive mirror layer using a sputtering method. A hole transport layer, which is a p-type semiconductor containing O2, was formed with a thickness of 10 nm. The shape of the hole transport layer During the formation process, Na2O, Cu2O, and Al2O3 are combined, with the molar ratio of Na:Cu:Al being A mixture in a 1:4:5 ratio is used as the sputtering target, and argon gas is used. Under a mixed gas atmosphere of 90% oxygen gas and 10% oxygen gas (oxygen atmosphere), sputtering The ng method was used.

[0148] A sputtering method is used on the hole transport layer to create a light absorption layer containing Cu, Ga, and In. A core layer was formed. Then, under a selenium atmosphere, it was heated at 400°C to 600°C for 5 to 30 minutes. After the intermediate heat treatment, the material is heated in a hydrogen sulfide atmosphere at 400°C to 600°C for 5 to 30 minutes. The intermediate heat treatment is performed to absorb light containing Cu(In,Ga)(Se,S)2 (CIGSS compound). A layer was formed. The light-absorbing layer was formed with a thickness of 2 μm.

[0149] On the light-absorbing layer of the heat-treated laminate, a sputtering method is used to apply a material containing titanium dioxide zinc. An electron transport layer made of n-type oxide semiconductor was formed with a thickness of 80 nm. A mixture of zinc oxide and titanium oxide is used as the sputtering target, and argon gas:oxygen Sputtering method under a mixed gas atmosphere of 90% by volume:10% by volume (oxygen atmosphere) I used it.

[0150] On this electron transport layer, using the sputtering method, hydrogen-containing indium oxide (IOH) A transparent electrode layer containing was formed with a thickness of 300 nm. On the electrode layer, metallic silver was deposited using a vapor deposition method. A grid electrode was formed with a thickness of 5 μm. In this way, the solar cell of Example 12 was formed. I prepared the lure.

[0151] [Comparative Example 4] Ho Instead of a transport layer, a 110 nm thick oxide transparent conductive layer containing ITO is sputtered. The solar cell of Comparative Example 4 was prepared in the same manner as in Example 12, except that it was formed by the law. did.

[0152] [Measurement of conversion efficiency] For the solar cells of Example 12 and Comparative Example 4, under standard test conditions for solar cells (minutes) Light with an AM1.5 light spectrum at an irradiance of 1 kW / m² 2 When incident light is applied, the solar cell temperature is 25°C. The IV curve was measured under the specified test conditions. The conversion efficiency was measured from the IV curve. This refers to the output at the optimal operating point in the IV curve (maximum output: P max ) the solar cell receives This is the value obtained by dividing by the light energy E. Conversion efficiency (%) = P max ÷E × 100

[0153] The conversion efficiency of the solar cell in Example 12 was 12.3%. On the other hand, the solar cell in Comparative Example 4 The conversion efficiency of the pond cell was 7.6%.

[0154] <Note> Embodiments of this disclosure include the following aspects: [1] A substrate, a back electrode, a conductive mirror layer, a hole transport layer which is a p-type oxide semiconductor, and light The absorption layer and, in this order, are at least: Solar cell. [2] A conductive mirror underlayer is provided between the back electrode and the conductive mirror layer. [1] The solar cell described above. [3] The conductive mirror underlayer contains a metal having a face-centered cubic lattice structure. [2] The solar cell described above. [4] The conductive mirror underlayer is selected from the group consisting of gold, aluminum, copper, and silver. Including more than one species, [2] or [3] The solar cell described above. [5] The conductive mirror layer is provided on the hole transport layer, The conductive mirror underlayer is provided on the conductive mirror layer. A solar cell as described in any one of [2] to [4]. [6] The hole transport layer consists of NiO, CuO, CuGaO2, CuCrO2, and CuAlO2. It includes one or more metal oxides selected from the following: A solar cell as described in any one of [1] to [5]. [7] The aforementioned metal oxide is a metal oxide to which an alkali metal element has been added. [6] The solar cell described above. [8] The hole transport layer contains CuAlO2 or CuAlO2 to which alkali metal elements have been added. nothing, A solar cell as described in any one of [1] to [7]. [9] The conductive mirror layer is made of gold, silver, aluminum, gold alloy, silver alloy, and aluminum alloy. Includes one or more types selected from the group consisting of gold, A solar cell as described in any one of [1] to [8].

[10] The light-absorbing layer is a chalcopyrite compound, a kestelite compound, and a perovskite It includes one or more compounds selected from the group consisting of compounds, A solar cell as described in any one of [1] to [9].

[11] A solar cell described in any one of [1] to

[10] is connected electrically in series or parallel with multiple other cells. Connected Solar cell module.

[12] A substrate, a back electrode, a conductive mirror layer, a p-type semiconductor hole transport layer, and a light absorption layer. A laminate preparation step is to prepare a laminate comprising a precursor layer and in this order, The laminate is subjected to a sulfur atmosphere, a selenium atmosphere, a chlorine atmosphere, a bromine atmosphere, and an iodine atmosphere. A heat treatment process in which heat treatment is performed in one or more atmospheres selected from a group consisting of gases, including, A method for manufacturing solar cells.

[13] In the heat treatment step, the laminate is heat-treated at a temperature of 60 to 600°C. The manufacturing method described in

[12] . [Industrial applicability]

[0155] The solar cell of the present invention has improved light absorption efficiency, such as sunlight, and is therefore suitable for various environments. It has industrial applicability as a solar cell used in [unspecified applications]. [Explanation of Symbols]

[0156] 100...Solar cell, 101...Substrate, 102...Back electrode, 103...Conductive mirror base Layers, 104...conductive mirror layer, 105...hole transport layer, 106...light absorption layer, 107...electron Transport layer, 108... Surface electrode, 109... Transparent electrode layer, 110... Grid electrode

Claims

1. The device comprises, in this order, at least, a substrate, a back electrode, a conductive mirror layer, a hole transport layer which is a p-type oxide semiconductor, and a light absorption layer. The back electrode and the conductive mirror layer contain different materials. The hole transport layer contains one or more metal oxides selected from NiO, CuO, CuGaO₂, CuCrO₂, and CuAlO₂. Solar cell.

2. A mirror underlayer is provided between the back electrode and the conductive mirror layer. The back electrode, the mirror underlayer, and the conductive mirror layer each contain different materials. The solar cell according to claim 1.

3. The mirror substrate contains a metal having a face-centered cubic lattice structure. The solar cell according to claim 2.

4. The mirror base layer contains one or more elements selected from the group consisting of gold, aluminum, copper, and silver. The solar cell according to claim 3.

5. The conductive mirror layer is provided on the hole transport layer, The mirror underlayer is provided on the conductive mirror layer. The solar cell according to claim 2.

6. The aforementioned metal oxide is a metal oxide to which an alkali metal element has been added. The solar cell according to claim 1.

7. The hole transport layer is CuAlO 2 Or CuAlO with added alkali metal elements 2 including, The solar cell according to claim 1.

8. The conductive mirror layer includes one or more selected from the group consisting of gold, silver, aluminum, gold alloys, silver alloys, and aluminum alloys. The solar cell according to claim 1.

9. The light-absorbing layer comprises one or more compounds selected from the group consisting of chalcopyrite compounds, kestelite compounds, and perovskite compounds. The solar cell according to claim 1.

10. A plurality of solar cells according to claim 1 are electrically connected in series or in parallel. Solar cell module.

11. A laminate preparation step is to prepare a laminate comprising, in this order, a substrate, a back electrode, a conductive mirror layer, a hole transport layer which is a p-type oxide semiconductor, and a precursor layer for a light absorption layer. A heat treatment step in which the laminate is heat-treated in one or more atmospheres selected from the group consisting of a sulfur atmosphere, a selenium atmosphere, a chlorine atmosphere, a bromine atmosphere, and an iodine atmosphere, Includes, The back electrode and the conductive mirror layer contain different materials. The hole transport layer contains one or more metal oxides selected from NiO, CuO, CuGaO₂, CuCrO₂, and CuAlO₂. A method for manufacturing solar cells.

12. In the heat treatment step, the laminate is heat-treated at a temperature of 60 to 600°C. The manufacturing method according to claim 11.

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