Solar cells and methods for manufacturing the same

Abstract

The present invention provides a solar cell and a manufacturing method thereof, comprising: a perovskite solar cell including a light absorbing layer containing a perovskite compound; and a conductive charge transfer layer provided on at least one of one and other surfaces of the light absorbing layer, wherein one surface of the light absorbing layer is located closer to a sunlight incidence surface than the other surface of the light absorbing layer, an optical band gap inside the light absorbing layer becomes the same or smaller from the one surface to the other surface, and the optical band gap of the one surface of the light absorbing layer is larger than the optical band gap of the other surface of the light absorbing layer.

Description

[Technical Field]

[0001] This invention relates to solar cells, and more specifically to solar cells using perovskite solar cells. [Background technology]

[0002] Conventionally, tandem solar cells have been proposed in which perovskite solar cells are stacked on a substrate-type solar cell. Perovskite solar cells absorb short-wavelength light, while substrate-type solar cells absorb long-wavelength light. Therefore, to improve the efficiency of tandem solar cells, it is necessary for the perovskite solar cells to absorb short-wavelength light well, transmit long-wavelength light well, and transmit the long-wavelength light well to the substrate-type solar cell.

[0003] When a perovskite solar cell is thick, it is difficult to transmit long-wavelength light, so it is preferable to make the perovskite solar cell thinner. However, when the thickness of the perovskite solar cell is reduced, there is a problem in that the current decreases.

[0004] Therefore, there is a need to manufacture perovskite solar cells that are thin, transmit long-wavelength light well, and can increase current. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This invention was devised to solve the aforementioned problems of the conventional solar cell, and aims to provide a solar cell that can improve efficiency by increasing the current while forming a thin perovskite solar cell.

[0006] Furthermore, the present invention aims to provide a method for manufacturing a solar cell that allows for easy adjustment of the halogen element content in the light-absorbing layer by using a vapor deposition process. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a perovskite solar cell comprising a light-absorbing layer containing a perovskite compound and a conductive charge transfer layer provided on at least one of the two surfaces of the light-absorbing layer, wherein one surface of the light-absorbing layer is located closer to the incident surface of sunlight than the other surface of the light-absorbing layer, the optical band gap inside the light-absorbing layer is constant or decreases from one surface to the other, and the optical band gap of one surface of the light-absorbing layer is larger than the optical band gap of the other surface of the light-absorbing layer.

[0008] The light-absorbing layer contains a first halogen element and a second halogen element, the optical band gap of the first halogen element is greater than the optical band gap of the second halogen element, the content of the first halogen element contained on one surface of the light-absorbing layer is greater than the content of the first halogen element contained on the other surface of the light-absorbing layer, and the content of the second halogen element contained on one surface of the light-absorbing layer is less than the content of the second halogen element contained on the other surface of the light-absorbing layer.

[0009] The present invention also provides a perovskite solar cell having a light-absorbing layer containing a perovskite compound, and a conductive charge transfer layer provided on at least one of the two surfaces of the light-absorbing layer, wherein one surface of the light-absorbing layer is located closer to the incident surface of sunlight than the other surface of the light-absorbing layer, the light-absorbing layer contains a first halogen element and a second halogen element, the content of the first halogen element inside the light-absorbing layer is constant or decreases from one surface to the other, and the content of the first halogen element on one surface of the light-absorbing layer is greater than the content of the first halogen element on the other surface of the light-absorbing layer.

[0010] The content of the second halogen element contained in one surface of the light-absorbing layer may be less than the content of the second halogen element contained in the other surface of the light-absorbing layer.

[0011] The optical band gap of the first halogen element may be larger than the optical band gap of the second halogen element.

[0012] The light absorption layer may further include a third halogen element having an optical band gap smaller than the optical band gap of the first halogen element and larger than the optical band gap of the second halogen element.

[0013] The light absorption layer includes a first layer having the lowest optical band gap, a second layer having an intermediate optical band gap, and a third layer having the highest optical band gap, the first layer may be adjacent to the other surface of the light absorption layer, and the third layer may be adjacent to one surface of the light absorption layer.

[0014] The light absorption layer includes a first halogen element and a second halogen element, the optical band gap of the first halogen element is larger than the optical band gap of the second halogen element, the first layer includes the second halogen element and does not include the first halogen element, the second layer includes both the first halogen element and the second halogen element, and the third layer may include the first halogen element and not include the second halogen element.

[0015] The light absorption layer includes a first halogen element and a second halogen element, the optical band gap of the first halogen element is larger than the optical band gap of the second halogen element, each of the first layer, the second layer, and the third layer includes both the first halogen element and the second halogen element, the content of the first halogen element is the highest in the third layer and the lowest in the first layer, and the content of the second halogen element may be the highest in the first layer and the lowest in the third layer.

[0016] The light absorption layer may further include a third halogen element having an optical band gap smaller than the optical band gap of the first halogen element and larger than the optical band gap of the second halogen element, and the content of the third halogen element may be more in the second layer than in the first layer or more in the second layer than in the third layer.

[0017] The light-absorbing layer further contains a third halogen element having an optical band gap smaller than that of the first halogen element and larger than that of the second halogen element, and the content of the third halogen element may be uniform in the first, second, and third layers.

[0018] The perovskite solar cell may further include a buffer layer and a substrate-type solar cell provided on the buffer layer.

[0019] The present invention also provides a method for manufacturing a solar cell, comprising the steps of forming a light-absorbing layer containing a perovskite compound, and forming a conductive charge transfer layer on at least one surface of the light-absorbing layer, wherein the step of forming the light-absorbing layer includes reacting at least one compound selected from amine compounds and amidine compounds, an organometallic compound containing a divalent cation, and at least one hydrogen halide, wherein one surface of the light-absorbing layer is located closer to the incident surface of sunlight than the other surface of the light-absorbing layer, and the optical band gap of one surface of the light-absorbing layer is larger than the optical band gap of the other surface of the light-absorbing layer.

[0020] The hydrogen halide includes a first hydrogen halide and a second hydrogen halide, wherein the optical band gap of the first halogen element contained in the first hydrogen halide is greater than the optical band gap of the second halogen element contained in the second hydrogen halide, the amount of the first hydrogen halide introduced when forming one surface of the light-absorbing layer is greater than the amount of the first hydrogen halide introduced when forming the other surface of the light-absorbing layer, and the amount of the second hydrogen halide introduced when forming one surface of the light-absorbing layer is less than the amount of the second hydrogen halide introduced when forming the other surface of the light-absorbing layer.

[0021] The hydrogen halide includes a first hydrogen halide and a second hydrogen halide, wherein the optical band gap of the first halogen element contained in the first hydrogen halide is greater than the optical band gap of the second halogen element contained in the second hydrogen halide, the amount of the first hydrogen halide introduced when forming one surface of the light-absorbing layer is greater than the amount of the second hydrogen halide introduced when forming one surface of the light-absorbing layer, and the amount of the first hydrogen halide introduced when forming the other surface of the light-absorbing layer is less than the amount of the second hydrogen halide introduced when forming the other surface of the light-absorbing layer.

[0022] The method further comprises the steps of forming a substrate-type solar cell and forming a buffer layer on the substrate-type solar cell before forming the light-absorbing layer and the conductive charge transfer layer, wherein the light-absorbing layer and the conductive charge transfer layer can be formed on the buffer layer. [Effects of the Invention]

[0023] According to the present invention as described above, the following effects are obtained.

[0024] According to one embodiment of the present invention, by forming an optical band gap in the light-absorbing layer within a range of varying sizes, it is possible to improve the current and thus the efficiency of the solar cell while making the perovskite solar cell thinner.

[0025] According to one embodiment of the present invention, a perovskite compound is produced by reacting at least one compound selected from amine compounds and amidine compounds, an organometallic compound containing a divalent cation, and two or more hydrogen halides through a chemical vapor deposition (CVD) process, making it easy to adjust the optical band gap of the light-absorbing layer.

[0026] According to one embodiment of the present invention, a thin film can be formed at room temperature to 200°C or lower, preferably 50 to 150°C, through a chemical vapor deposition (CVD) process or atomic layer deposition (ALD) process. This prevents organic matter in the final ferrovskite compound from decomposing during the CVD or ALD process.

[0027] According to one embodiment of the present invention, the light absorption rate, optical band gap, carrier mobility, and material stability of the final perovskite compound can be controlled by the type of organometallic compound containing the divalent cation. [Brief explanation of the drawing]

[0028] [Figure 1] This is a cross-sectional view of a solar cell according to one embodiment of the present invention. [Figure 2] This graph shows the change in optical band gap from the bottom to the top surface of the light-absorbing layer according to various embodiments of the present invention. [Figure 3] This graph shows the change in optical band gap from the bottom to the top surface of the light-absorbing layer according to various embodiments of the present invention. [Figure 4] This graph shows the change in optical band gap from the bottom to the top surface of the light-absorbing layer according to various embodiments of the present invention. [Figure 5A] This is a cross-sectional view showing a process for manufacturing a solar cell according to one embodiment of the present invention. [Figure 5B] This is a cross-sectional view showing a process for manufacturing a solar cell according to one embodiment of the present invention. [Figure 5C] This is a cross-sectional view showing a process for manufacturing a solar cell according to one embodiment of the present invention. [Figure 5D] This is a cross-sectional view showing a process for manufacturing a solar cell according to one embodiment of the present invention. [Figure 6A] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 6B] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 6C] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 6D] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 6E] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 7A] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 7B] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 7C] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 7D] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Figure 7E] This is a cross-sectional view showing a process for manufacturing a solar cell according to another embodiment of the present invention. [Modes for carrying out the invention]

[0029] The advantages and features of the present invention, as well as methods for achieving them, will become apparent by referring to the embodiments described below in detail with accompanying figures. However, the present invention is not limited to the embodiments disclosed below and can be embodied in a variety of different forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform those who are ordinary skill in the art to which the invention pertains of the invention of the scope of the invention, and the present invention is defined only by the claims.

[0030] The shapes, sizes, proportions, angles, numbers, etc., disclosed in the figures illustrating embodiments of the present invention are illustrative, and the present invention is not limited to what is shown in the figures. Throughout the specification, the same reference numeral refers to the same component. In the description of the present invention, if a specific description of related prior art is deemed to unnecessarily obscure the gist of the invention, such detailed description will be omitted. Where the words "includes," "has," "consists of," etc., used in the present invention, other parts may be added unless "only" is used. When a component is expressed singly, it includes cases where it includes multiple components unless otherwise explicitly stated.

[0031] In interpreting the constituent elements, even without further explicit mention, they shall be interpreted as including a margin of error.

[0032] When describing a spatial relationship, for example, when the positional relationship between two parts is described using phrases like "on top," "above," "below," or "beside," one or more other parts may be located between the two parts, unless "immediately" or "directly" is used.

[0033] When describing temporal relationships, for example, when a temporal sequence is described using phrases like "after," "following," "next," or "before," it can include non-continuous sequences unless "immediately" or "directly" is used.

[0034] The terms "first," "second," etc., are used to describe various components, but these components are not limited by these terms. These terms are simply used to distinguish one component from another. Therefore, the first component referred to below may also be the second component within the technical concept of the present invention.

[0035] The term "at least one" should be understood to include all possible combinations of one or more related items. For example, "at least one of item 1, item 2, and item 3" can mean not just each of item 1, item 2, or item 3 individually, but all possible combinations of items that can be presented from two or more of items 1, item 2, and item 3.

[0036] The features of each of the various embodiments of the present invention can be combined or linked together, either partially or as a whole, and are technically capable of various interlocking and driving mechanisms. Each embodiment can be implemented independently of the others or together in a related manner.

[0037] Preferred embodiments of the present invention will be described in detail below with reference to the figures.

[0038] Figure 1 is a cross-sectional view of a solar cell according to one embodiment of the present invention, which relates to a tandem solar cell in which perovskite solar cells are stacked on a crystalline solar cell.

[0039] As can be seen from Figure 1, a solar cell according to one embodiment of the present invention includes a crystalline solar cell 100, a buffer layer 200 formed on one surface of the crystalline solar cell 100, for example, the upper surface, a perovskite solar cell 300 formed on one surface of the buffer layer 200, for example, the upper surface, a first electrode 400 formed on one surface of the perovskite solar cell 300, for example, the upper surface, and a second electrode 500 formed on one surface of the crystalline solar cell 100, for example, the lower surface.

[0040] The crystalline solar cell 100 includes a semiconductor substrate 110 such as a wafer, a first semiconductor layer 120 on one side of the semiconductor substrate 110 doped with a predetermined dopant, and a second semiconductor layer 130 on the other side of the semiconductor substrate 110 doped with a predetermined dopant.

[0041] On the other hand, although the figure shows that one surface of the semiconductor substrate 110 has an uneven structure, and that the first semiconductor layer 120 also has a shape corresponding to the uneven structure, the present invention is not necessarily limited to this. One surface of the semiconductor substrate 110 can have a flat structure, and the first semiconductor layer 120 can also have a flat structure.

[0042] Furthermore, although the figure shows that the other surface of the semiconductor substrate 110 has a flat structure, and the second semiconductor layer 130 is formed to have a flat structure as a result, it is not necessarily limited to this, and the other surface of the semiconductor substrate 110 can also be formed to have an uneven structure, and the second semiconductor layer 130 can have a shape that corresponds to the uneven structure of the other surface of the semiconductor substrate 110.

[0043] The semiconductor substrate 110 can be made of a p-type or n-type wafer, the first semiconductor layer 120 can be doped with a dopant having a different polarity from the semiconductor substrate 110, and the second semiconductor layer 130 can be doped with a dopant having the same polarity as the semiconductor substrate 110. For example, the semiconductor substrate 110 can be made of a p-type wafer, the first semiconductor layer 120 can be doped with an n-type dopant, and the second semiconductor layer 130 can be doped with a p-type dopant to form a P+ layer.

[0044] The buffer layer 200 is formed on the first semiconductor layer 120. By forming the first semiconductor layer 120 with an uneven structure, the buffer layer 200 has a shape corresponding to the uneven structure. However, the present invention is not necessarily limited thereto. One surface of the semiconductor substrate 110 has a flat structure, and the buffer layer 200 can also have a flat structure.

[0045] The buffer layer 200 is provided between the crystalline solar cell 100 and the perovskite solar cell 300, so that the solar cell according to one embodiment of the present invention has the structure of a tandem solar cell via a tunnel junction.

[0046] The buffer layer 200 is preferably made of a material that allows long-wavelength light transmitted through the perovskite solar cell 300 to be incident on the crystalline solar cell 100 without loss. For example, the buffer layer 200 may be made of a transparent conductive oxide, a carbonaceous conductive material, a metallic material, or a conductive polymer, and in some cases, the material may be doped with an n-type or p-type dopant.

[0047] The perovskite solar cell 300 includes conductive charge transfer layers 321, 322 and a light absorption layer 310.

[0048] The perovskite solar cell 300 may include one or more conductive charge transfer layers 321, 322. For example, the perovskite solar cell 300 may include a first conductive charge transfer layer 321 provided on the buffer layer 200, a light absorption layer 310 provided on the first conductive charge transfer layer, and a second conductive charge transfer layer 322 provided on the light absorption layer 310. However, the present invention is not limited thereto, and the conductive charge transfer layers 321, 322 may be arranged on only one of the two surfaces of the light absorption layer 310.

[0049] The first conductive charge transfer layer 321 may consist of an electron transport layer and the second conductive charge transfer layer 322 may consist of a hole transport layer, or the first conductive charge transfer layer 321 may consist of a hole transport layer and the second conductive charge transfer layer 322 may consist of an electron transport layer.

[0050] The electron transport layer may consist of a compound containing an N-type organic substance such as BCP (Bathocuproine), C60, or PCBM (Phenyl-C61-butyric acid methyl ester), or various N-type metal oxides known in the industry such as ZnO, c-TiO2 / mp-TiO2, SnO2, or IZO, in addition to various organic and inorganic substances.

[0051] The hole transport layer may also consist of various N-type organic substances known in the art, such as Spiro-MeO-TAD, Spiro-TTB, polyaniline, polypinol, poly-3,4-ethylenedioxythiophene-polystyrene sulfonate (PEDOT-PSS), or poly-[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-diyl) (P3HT), etc. It may also consist of a compound containing various P-type metal oxides known in the art, such as Ni oxide, Mo oxide, or V oxide, W oxide, Cu oxide, etc., in addition to various organic and inorganic substances.

[0052] The light-absorbing layer 310 may contain a perovskite compound.

[0053] A perovskite compound according to one embodiment of the present invention comprises at least one selected from a monovalent organic cation of an amine compound and a monovalent organic cation of an amidine compound, a divalent cation of an organometallic compound, and one or more halogen elements. It can be represented by the general formula ABX3.

[0054] In ABX3, A may consist of a monovalent organic cation of the amine compound, or a monovalent organic cation of the amidine compound, or it may contain both the monovalent organic cation of the amine compound and the monovalent organic cation of the amidine compound. A may have a structure in which the monovalent organic cation of the amine compound is contained in an x ​​ratio and the monovalent organic cation of the amidine compound is contained in a y ratio. Here, x and y are each greater than 0, and x + y = 1.

[0055] In ABX3, B consists of the divalent cation of the organometallic compound.

[0056] In the aforementioned ABX3, X consists of one or more halogen elements.

[0057] The amine compound can be selected from the group consisting of methylamine, ethylamine, and phenethylamine.

[0058] The amidine compound can consist of formamidine.

[0059] The divalent cation of the organometallic compound can be derived from an organometallic compound containing a divalent cation. The organometallic compound containing a divalent cation can contain a metal selected from the group consisting of Pb, Sn, Ge, Sb, Bi, and Ba.

[0060] Specifically, the organometallic compound containing the divalent cation is represented by the following Chemical Formula 1:

[0061]

Chemical Formula

[0062] (In the formula, R ~R 12 each independently consists of hydrogen or an alkyl group, and X is selected from the group consisting of Pb, Sn, Ge, Sb, Bi, and Ba).

[0063] Alternatively, the organometallic compound containing the divalent cation can be selected from the group consisting of Pb(CH3) 4、 Pb(C2H5) 4、 Pb(SCN) 2、 (C2H5)3PbOCH2C(CH3) 3、 Pb(C 11 H 19 O2) 2、 Pb((CH3)3C-COCHCO-C(CH3)3) 2、 Pb((C6H5)2PCH2P(C6H5)2) 2、 Pb(N(CH3)2C(CH3)2OH) 2、 and C 12 H 28 N2O2Pb.

[0064] Depending on the type of organometallic compound containing the divalent cation, the light absorption rate, optical band gap, carrier mobility, and material stability of the final perovskite compound can be controlled.

[0065] The aforementioned halogen element may be derived from a hydrogen halide. The hydrogen halide can be selected from the group consisting of HI, HBr, HF, and HCl. The type of hydrogen halide can be used to adjust the optical band gap of the final perovskite compound.

[0066] The amine compound, the amidine compound, the organometallic compound containing a divalent cation, and the hydrogen halide are substances that vaporize at temperatures ranging from room temperature to 200°C, preferably at temperatures ranging from 50°C to 150°C. This allows the process of producing the ABX3 compound to be carried out at temperatures of 200°C or lower, preferably 150°C or lower, through a chemical vapor deposition (CVD) process or atomic layer deposition (ALD) process, thereby preventing the organic matter in the final ABX3 compound from decomposing during the CVD or ALD process. On the other hand, it is also possible to apply plasma when performing the CVD or ALD process.

[0067] Perovskite compounds according to other embodiments of the present invention include at least one selected from monovalent organic cations of amine compounds and monovalent organic cations of amidine compounds, at least one monovalent cation of an alkali metal compound, a divalent cation of an organometallic compound, and one or more halogen elements. They can be represented by the general formula CABX3.

[0068] In CABX3, A may consist of a monovalent organic cation of the amine compound, or a monovalent organic cation of the amidine compound, or may comprise a monovalent organic cation of the amine compound and a monovalent organic cation of the amidine compound.

[0069] In the CABX3 described above, C can consist of at least one alkali metal.

[0070] The CA can have a structure in which a monovalent organic cation of the amine compound is contained in a ratio of x, a monovalent organic cation of the amidine compound is contained in a ratio of y, and a monovalent cation of the alkali metal is contained in a ratio of z. Here, x, y, and z are all greater than 0, and x + y + z = 1.

[0071] In the CABX3 described above, B consists of the divalent cation, and X consists of one or more halogen elements.

[0072] Since the amine series compounds, the amidine series compounds, the organometallic compounds containing divalent cations, and the hydrogen halides are the same as described above, a repeated explanation will be omitted.

[0073] The alkali metal compound is given by the following chemical formula 2:

[0074] [ka]

[0075] (In the formula, R 1 ~R 6 The compounds can consist of a compound where each element independently consists of hydrogen or an alkyl group, and Y is an alkali metal.

[0076] Thus, according to other embodiments of the present invention, the instability of monovalent organic cations, which are vulnerable to moisture, heat, and plasma, can be compensated for by adding at least one alkali metal compound to the reactants.

[0077] The lower surface and the upper surface of the light-absorbing layer 310 have different optical band gaps. Specifically, the lower surface of the light-absorbing layer 310 has an optical band gap smaller than that of the upper surface of the light-absorbing layer 310. In the present invention, the optical band gap refers to the energy region between the valence band and the conduction band where the density of electronic states is zero, and the energy difference between them, with a unit of eV.

[0078] By adjusting the optical band gaps of the lower and upper surfaces of the light-absorbing layer 310, the current can be increased while making the perovskite solar cell 300 thinner. Specifically, since the upper surface of the light-absorbing layer 310 is located relatively closer to the surface into which sunlight enters compared to the lower surface of the light-absorbing layer 310, the current of the perovskite solar cell 300 can be increased by making the optical band gap of the upper surface of the light-absorbing layer 310 larger than the optical band gap of the lower surface of the light-absorbing layer 310. Throughout this specification, it is assumed that the upper surface of the light-absorbing layer 310 is located relatively closer to the surface into which sunlight enters compared to the lower surface of the light-absorbing layer 310. However, if the lower surface of the light-absorbing layer 310 were located relatively closer to the surface into which sunlight enters compared to the upper surface of the light-absorbing layer 310, the explanation for that would be reversed.

[0079] According to one embodiment of the present invention, the optical band gap inside the light-absorbing layer 310 may be the same or smaller from the top surface to the bottom surface.

[0080] Figures 2 to 4 are graphs showing the change in the optical band gap from the bottom surface to the top surface of the light-absorbing layer 310 according to various embodiments of the present invention.

[0081] As can be seen from Figure 2, in the case of the light-absorbing layer 310 according to one embodiment of the present invention, the optical band gap can be gradually increased from the bottom surface to the top surface. In particular, as shown in the figure, the optical band gap can be gradually increased from the bottom surface to the top surface of the light-absorbing layer 310 with a constant slope, but it is not necessarily limited to this, and the slope does not have to be constant.

[0082] The perovskite compound contained in the light-absorbing layer 310 may contain a first halogen element (X1) and a second halogen element (X2).

[0083] The perovskite compound containing the first halogen element (X1) and the second halogen element (X2) is AB(X1) m (X2) n It can be expressed as follows: Here, A and B are the same as described above, m and n are each greater than 0, and m+n=3.

[0084] The first halogen element (X1) has an optical band gap that is larger than the optical band gap of the second halogen element (X2). In this case, the amount of the first halogen element (X1) contained in the upper surface of the light-absorbing layer 310 may be greater than the amount of the first halogen element (X1) contained in the lower surface of the light-absorbing layer 310, and the amount of the second halogen element contained in the upper surface of the light-absorbing layer 310 may be less than the amount of the second halogen element (X2) contained in the lower surface of the light-absorbing layer 310.

[0085] Furthermore, on the lower surface of the light-absorbing layer 310, the content of the second halogen element (X2) having a relatively small optical band gap may be greater than the content of the first halogen element (X1) having a relatively large optical band gap, and on the upper surface of the light-absorbing layer 310, the content of the first halogen element (X1) having a relatively large optical band gap may be greater than the content of the second halogen element (X2) having a relatively small optical band gap.

[0086] The content of the first halogen element (X1) inside the light-absorbing layer 310 is the same or decreases from the top surface to the bottom surface, and the content of the second halogen element (X2) is the same or increases from the top surface to the bottom surface. In particular, the content of the first halogen element (X1) gradually decreases and the content of the second halogen element (X2) gradually increases from the top surface to the bottom surface of the light-absorbing layer 310, and the content of the second halogen element (X2) gradually decreases and the content of the first halogen element (X1) gradually increases from the bottom surface to the top surface of the light-absorbing layer 310.

[0087] The general formula of the aforementioned perovskite compound is AB(X1) m (X2) n To explain further, as you move from the upper surface to the lower surface of the light-absorbing layer 310, m decreases and n increases. Conversely, as you move from the lower surface to the upper surface of the light-absorbing layer 310, m increases and n decreases.

[0088] The aforementioned perovskite compound (AB(X1) m (X2) n Of the first and second halogen elements of the compound, the higher the content of the first halogen element (X1), which has a large optical band gap, the higher the optical band gap of the perovskite compound can be, and the higher the content of the second halogen element (X2), which has a small optical band gap, the lower the optical band gap of the perovskite compound can be.

[0089] Of fluoro(F), chlorine(Cl), bromine(Br), and iodine(I), fluoro(F) has the largest optical band gap, followed by chlorine(Cl), then bromine(Br), and finally iodine(I) with the smallest optical band gap. Specifically, the optical band gap of chlorine(Cl) is 3.1 eV, and the optical band gap of iodine(I) is 1.6 eV.

[0090] When the perovskite compound contains chlorine (Cl) and iodine (I), the optical band gap of the perovskite compound increases as the content of chlorine (Cl), which has a relatively large optical band gap, increases, and the optical band gap of the first perovskite compound decreases as the content of iodine (I), which has a relatively small optical band gap, increases. Therefore, when the perovskite compound in the light-absorbing layer 310 contains chlorine (Cl) and iodine (I), the content of iodine (I) is greater than the content of chlorine (Cl) at the lower surface of the light-absorbing layer 310, and the content of chlorine (Cl) is greater than the content of iodine (I) at the upper surface of the light-absorbing layer 310. In particular, the content of iodine (I) increases from the upper surface to the lower surface of the light-absorbing layer 310, and the content of chlorine (Cl) can increase from the lower surface to the upper surface of the light-absorbing layer 310.

[0091] Furthermore, according to another embodiment of the present invention, the perovskite compound contained in the light-absorbing layer 310 may further contain a third halogen element (X3) in addition to the first halogen element (X1) and the second halogen element (X2). Here, the perovskite compound containing the first halogen element (X1), the second halogen element (X2), and the third halogen element (X3) is AB(X1) m (X2) n (X3) o It can be represented as follows. The above m, n, and o are all greater than 0, and m+n+o=3.

[0092] The third halogen element (X3) has an optical band gap smaller than that of the first halogen element (X1) and larger than that of the second halogen element (X2), so that the content of the third halogen element (X3) can increase and then decrease again from the bottom surface to the top surface of the light-absorbing layer 310. That is, the AB(X1) of the perovskite compound m (X2) n (X3) oIn this case, the amount of "o" can increase from the bottom surface to the top surface of the light-absorbing layer 310, and then decrease. In some cases, the content of the third halogen element (X3) can be uniform throughout the light-absorbing layer 310. If the first halogen element (X1) is chlorine (Cl) and the second halogen element (X2) is iodine (I), the third halogen element (X3) can be bromine (Br).

[0093] As can be seen from Figure 3, the optical absorption layer 310 according to another embodiment of the present invention includes a first layer (a) with the lowest optical band gap, a second layer (b) with an intermediate optical band gap, and a third layer (c) with the highest optical band gap, thereby allowing the optical band gap of the optical absorption layer 310 to increase in a stepwise manner from its lower surface to its upper surface. Here, the first layer (a) with the lowest optical band gap is the region adjacent to the lower surface of the optical absorption layer 310, and the third layer (c) with the highest optical band gap is the region adjacent to the upper surface of the optical absorption layer 310.

[0094] The perovskite compound in the light-absorbing layer 310 shown in Figure 3 may include a first halogen element (X1) and a second halogen element (X2) having an optical band gap lower than that of the first halogen element (X1).

[0095] Here, the first layer (a) with the lowest optical band gap contains the second halogen element (X2) but does not contain the first halogen element (X1), the second layer (b) with an intermediate optical band gap contains both the first halogen element (X1) and the second halogen element (X2), and the third layer (c) with the highest optical band gap contains the first halogen element (X1) but does not necessarily contain the second halogen element (X2).

[0096] Alternatively, each of the first layer (a), the second layer (b), and the third layer (c) may contain both the first halogen element (X1) and the second halogen element (X2), in which case the content of the first halogen element (X1) is highest in the third layer (c) and lowest in the first layer (a), and the content of the second halogen element (X2) is highest in the first layer (a) and lowest in the third layer (c).

[0097] The perovskite compound in the light-absorbing layer 310 shown in Figure 3 may also include a first halogen element (X1), a second halogen element (X2) having an optical band gap lower than that of the first halogen element (X1), and a third halogen element (X3) having an optical band gap lower than that of the first halogen element (X1) and higher than that of the second halogen element (X2).

[0098] In this case, the content of the first halogen element (X1) and the content of the second halogen element (X2) may be the same as described above, the content of the third halogen element (X3) may be greater in the second layer (b) than in the first layer (a), the content of the third halogen element (X3) may be greater in the second layer (b) than in the third layer (c), and in some cases, the content of the third halogen element (X3) may be uniform in the first layer (a), the second layer (b), and the third layer (c).

[0099] Alternatively, the first layer (a) may contain the second halogen element (X2) but not the first halogen element (X1) and the third halogen element (X3), the second layer (b) may contain the third halogen element (X3) but not the first halogen element (X1) and the second halogen element (X2), and the third layer (c) may contain the first halogen element (X1) but not the second halogen element (X2) and the third halogen element (X3).

[0100] As can be seen from Figure 4, the light-absorbing layer 310 according to yet another embodiment of the present invention comprises a first layer (a) having the lowest optical band gap, a second layer (b) having an intermediate optical band gap, a third layer (c) having the highest optical band gap, a fourth layer (d) provided between the first layer (a) and the second layer (b), and a fifth layer (e) provided between the second layer (b) and the third layer (c).

[0101] The first layer (a), the second layer (b), and the third layer (c) are the same as those shown in Figure 3 above.

[0102] The optical band gap of the fourth layer (d) can gradually increase from the optical band gap of the first layer (a) to the optical band gap of the second layer (b), and the optical band gap of the fifth layer (e) can gradually increase from the optical band gap of the second layer (b) to the optical band gap of the third layer (c). The configurations of the fourth layer (d) and the fifth layer (e) can be easily understood by referring to the configuration in Figure 2 described above.

[0103] The thin film of the perovskite compound constituting the light-absorbing layer 310 can be obtained by reacting at least one compound selected from amine-based compounds and amidine-based compounds, an organometallic compound containing a divalent cation, and at least one hydrogen halide.

[0104] The following scheme is a method for forming a thin film of a perovskite compound according to one embodiment of the present invention using a CVD process.

[0105] [ka]

[0106] As can be seen from Scheme 1 above, when methylamine, bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide as a hydrogen halide are reacted, lead methylammonium iodide (CH3NH3PbI3(MAPbI3)) is obtained as a perovskite compound, and hexamethyldisilazane (HMDS) is obtained as a byproduct.

[0107] Although not shown in the figure in Scheme 1, methylamine and hydrogen iodide can react to obtain the byproduct CH3NH3I (methylammonium iodide), and bis(bis(trimethylsilyl))aminolead can react with hydrogen iodide to obtain the byproduct PbI2.

[0108] In scheme 1, ethylamine or phenethylamine may be reacted instead of methylamine, hydrogen bromide (HBr) or hydrogen chloride (HCl) may be reacted instead of hydrogen iodide, and in bis(bis(trimethylsilyl))aminolead, organometallic compounds in which lead (Pb) is substituted with Sn, Ge, Sb, Bi, or Ba may be reacted.

[0109] The thin film of the perovskite compound obtained in Scheme 1 can constitute one of the first layer (a), second layer (b), and third layer (c) shown in Figure 3 above.

[0110] The following scheme 2 is a scheme for forming a thin film of a perovskite compound according to another embodiment of the present invention by a CVD process.

[0111] [ka]

[0112] As can be seen from Scheme 2 above, when formamidine is reacted with bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide as a hydrogen halide, a perovskite compound NH2CHNH2PbI3(FAPbI3) is obtained, along with hexamethyldisilazane (HMDS) as a byproduct.

[0113] Although not shown in the figure in Scheme 2, a byproduct of NH2CHNH2I (formamidinium iodide) can be obtained by the reaction of formamidine with hydrogen iodide, and a byproduct of PbI2 can also be obtained by the reaction of bis(bis(trimethylsilyl))aminolead with hydrogen iodide.

[0114] In scheme 2, hydrogen bromide (HBr) or hydrogen chloride (HCl) may be reacted instead of hydrogen iodide, and in bis(bis(trimethylsilyl))aminolead, organometallic compounds in which lead (Pb) is substituted with Sn, Ge, Sb, Bi, or Ba may be reacted.

[0115] The optical bandgap energy of the NH2CHNH2PbI3(FAPbI3) compound produced by Scheme 2 is 1.47 eV, while the optical bandgap energy of the CH3NH3PbI3(MAPbI3) compound produced by Scheme 1 is 1.57 eV. In other words, the optical bandgap energy of the NH2CHNH2PbI3(FAPbI3) compound produced by Scheme 2 is lower than that of the CH3NH3PbI3(MAPbI3) compound produced by Scheme 1. As a result, when the NH2CHNH2PbI3(FAPbI3) compound produced by Scheme 2 is used as the light absorption layer of a solar cell, it can absorb a wider solar spectrum compared to when the CH3NH3PbI3(MAPbI3) compound produced by Scheme 1 is used as the light absorption layer of a solar cell.

[0116] The thin film of the perovskite compound obtained in Scheme 2 can constitute one of the first layer (a), second layer (b), and third layer (c) of Figure 3 described above.

[0117] The following scheme 3 is a scheme for forming a thin film of a perovskite compound according to the present invention or other embodiments using a CVD process.

[0118] [ka]

[0119] As can be seen from Scheme 3 above, when methylamine, formamidine, bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide as a hydrogen halide are reacted, the perovskite compound CH3NH3NH2CHNH2PbI3(MAFAPbI3) is obtained, along with hexamethyldisilazane (HMDS) as a byproduct.

[0120] Although not shown in Scheme 3 above, methylamine and hydrogen iodide can react to produce the byproduct CH3NH3I (methylammonium iodide), formamidine and hydrogen iodide can react to produce the byproduct NH2CHNH2I (formamidinium iodide), and bis(bis(trimethylsilyl))aminolead can react with hydrogen iodide to produce the byproduct PbI2.

[0121] In scheme 3, ethylamine or phenethylamine may be reacted instead of methylamine, hydrogen bromide (HBr) or hydrogen chloride (HCl) may be reacted instead of hydrogen iodide, and organometallic compounds in which lead (Pb) in bis(bis(trimethylsilyl))aminolead is substituted with Sn, Ge, Sb, Bi, or Ba may be reacted.

[0122] The CH3NH3NH2CHNH2PbI3(MAFAPbI3) compound produced by scheme 3 has multiple monovalent cations, and a perovskite solar cell with higher efficiency can be obtained than when the CH3NH3NH2CHNH2PbI3(MAFAPbI3) compound produced by scheme 3 is used as the light absorption layer of a solar cell.

[0123] The thin film of the perovskite compound obtained in Scheme 3 can constitute one of the first layer (a), second layer (b), and third layer (c) of Figure 3 described above.

[0124] The following scheme 4 is a scheme for forming a thin film of a perovskite compound according to the present invention or other embodiments in a CVD process.

[0125] [ka]

[0126] As can be seen from Scheme 4 above, when methylamine, formamidine, bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide and hydrogen bromide as hydrogen halides are reacted, a perovskite compound CH3NH3NH2CHNH2PbI is formed. 3-x Br x (x is an integer between 0 and 3) (MAFAPbI 3-x Br x A compound is obtained, along with hexamethyldisilazane (HMDS) as a byproduct.

[0127] Although not shown in the figure in Scheme 4, methylamine can react with hydrogen iodide to obtain the byproduct CH3NH3I (methylammonium iodide), formamidine can react with hydrogen iodide to obtain the byproduct NH2CHNH2I (formamidinium iodide), and bis(bis(trimethylsilyl))aminolead can react with hydrogen iodide to obtain the byproduct PbI2.

[0128] In scheme 4, ethylamine or phenethylamine may be reacted instead of methylamine, hydrogen chloride (HCl) may be reacted instead of hydrogen iodide or hydrogen bromide, and in bis(bis(trimethylsilyl))aminolead, organometallic compounds in which lead (Pb) is substituted with Sn, Ge, Sb, Bi, or Ba may be reacted.

[0129] In the aforementioned scheme 4, the reaction can also be carried out by decreasing the amount of hydrogen iodide added and increasing the amount of hydrogen bromide added as time passes.

[0130] CH3NH3NH2CHNH2PbI produced by scheme 4 described above 3-x Br x (x is an integer between 0 and 3) (MAFAPbI 3-x Br x The compound ) is obtained by doping with multiple halogen substances, and compared to the CH3NH3NH2CHNH2PbI3(MAFAPbI3) compound produced by scheme 3, it is possible to precisely control the optical band gap over a wider range.

[0131] The thin film of the perovskite compound obtained in Scheme 4 can constitute the light-absorbing layer in Figure 2 described above, and one of the fourth layer (d) and fifth layer (e) in Figure 4 described above.

[0132] The following scheme 5 is a scheme for forming a thin film of a perovskite compound according to the present invention or other embodiments by a CVD process.

[0133] [ka]

[0134] As can be seen from Scheme 5 above, when Cs(hexamethyldisilazane; HMDS), methylamine, formamidine are reacted as alkali metal compounds, bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide and hydrogen bromide as hydrogen halides, a perovskite compound (Cs(CH3NH3NH2CHNH2PbI 3-x Br x )(x is an integer from 0 to 3)(Cs(MAFAPbI 3-x Br x A compound is obtained, along with hexamethyldisilazane (HMDS) as a byproduct.

[0135] Although not shown in the figure in Scheme 5, methylamine and hydrogen iodide can react to obtain the byproduct CH3NH3I (methylammonium iodide), formamidine and hydrogen iodide can react to obtain the byproduct NH2CHNH2I (formamidinium iodide), and bis(bis(trimethylsilyl))aminolead can react with hydrogen iodide to obtain the byproduct PbI2.

[0136] In scheme 5 described above, the reaction can also be carried out by decreasing the amount of hydrogen iodide added and increasing the amount of hydrogen bromide added as time passes.

[0137] In scheme 5, the alkali metal compound may also be reacted in which cesium (Cs) is substituted with lithium (Li), sodium (Na), potassium (K), rubidium (Rb), or francium (Fr) in the alkali metal compound; ethylamine or phenethylamine may be reacted instead of methylamine; hydrogen chloride (HCl) may be reacted instead of hydrogen iodide or hydrogen bromide; and organometallic compounds may be reacted in which lead (Pb) in the bis(bis(trimethylsilyl))aminolead is substituted with Sn, Ge, Sb, Bi, or Ba. The thin film of the perovskite compound obtained in scheme 5 can constitute the light-absorbing layer in Figure 2 described above, and one of the fourth layer (d) and fifth layer (e) in Figure 4 described above.

[0138] The following scheme 6 is a scheme for forming a thin film of a perovskite compound according to the present invention or other embodiments in a CVD process.

[0139] [ka]

[0140] As can be seen from Scheme 6 above, when Cs(hexamethyldisilazane; HMDS) and Rb(hexamethyldisilazane; HMDS) are reacted as alkali metal compounds, methylamine, formamidine, bis(bis(trimethylsilyl))aminolead as an organometallic compound containing a divalent cation, and hydrogen iodide and hydrogen bromide as hydrogen halides, a perovskite compound CsRb(CH3NH3NH2CHNH2PbI 3-x Br x )(x is an integer from 0 to 3)(CsRb(MAFAPbI 3-x Br x A compound is obtained, along with hexamethyldisilazane (HMDS) as a byproduct.

[0141] Although not shown in the figure, in scheme 6 above, methylamine and hydrogen iodide may react to obtain the byproduct CH3NH3I (methylammonium iodide), formamidine and hydrogen iodide may react to obtain the byproduct NH2CHNH2I (formamidinium iodide), and bis(bis(trimethylsilyl))aminolead may react with hydrogen iodide to obtain the byproduct PbI2.

[0142] In the aforementioned scheme 6, the reaction can also be carried out by decreasing the amount of hydrogen iodide added and increasing the amount of hydrogen bromide added over time.

[0143] In scheme 6, alkali metal compounds in which cesium (Cs) or rubidium (Rb) is substituted with lithium (Li), sodium (Na), potassium (K), or francium (Fr) may be reacted with the alkali metal compound; ethylamine or phenethylamine may be reacted instead of methylamine; hydrogen chloride (HCl) may be reacted instead of hydrogen iodide or hydrogen bromide; and organometallic compounds in which lead (Pb) in bis(bis(trimethylsilyl))aminolead is substituted with Sn, Ge, Sb, Bi, or Ba may be reacted with the bis(bis(trimethylsilyl))aminolead.

[0144] The thin film of the perovskite compound obtained in Scheme 6 can constitute the light-absorbing layer in Figure 2 described above, and one of the fourth layer (d) and fifth layer (e) in Figure 4 described above.

[0145] Referring again to Figure 1, the first electrode 400 is formed on the incident surface to which sunlight enters, and is therefore patterned in a predetermined shape. The second electrode 500 can also be patterned in a predetermined shape so that reflected sunlight enters the inside of the solar cell, but is not necessarily limited to this.

[0146] The above describes a tandem solar cell in which a perovskite solar cell is stacked on a crystalline solar cell. However, the present invention is not necessarily limited to tandem solar cells, and also includes perovskite solar cells equipped with the light-absorbing layer 310 described above.

[0147] Figures 5A to 5D are cross-sectional views showing the process for manufacturing a solar cell according to one embodiment of the present invention.

[0148] First, as can be seen from Figure 5A, a crystalline solar cell 100 is manufactured.

[0149] The crystalline solar cell 100 is manufactured through a process that involves etching one surface, particularly the upper surface, of a semiconductor substrate 110 such as a wafer to form an uneven structure, doping one surface of the semiconductor substrate 110 with a predetermined dopant to form a first semiconductor layer 120, and doping the other surface of the semiconductor substrate 110 with a predetermined dopant to form a second semiconductor 130.

[0150] By forming an uneven surface on one side of the semiconductor substrate 110, the first semiconductor layer 120 has a shape corresponding to the uneven structure.

[0151] On the other hand, the figure shows that the other surface of the semiconductor substrate 110, particularly the bottom surface, is formed with a flat structure, and as a result the second semiconductor layer 130 is also formed with a flat structure. However, this is not necessarily the only option, and the other surface of the semiconductor substrate 110 may also be formed with an uneven structure, and the second semiconductor layer 130 may have a shape corresponding to the uneven structure of the other surface of the semiconductor substrate 110. In some cases, the other surface of the semiconductor substrate 110, particularly the bottom surface, may be formed with an uneven structure, and one surface of the semiconductor substrate 110, particularly the top surface, may be formed with a flat structure.

[0152] The semiconductor substrate 110 consists of the p-type or n-type wafer described above, and therefore, a repeated explanation of the light absorption layer will be omitted.

[0153] Next, as can be seen from Figure 5B, a buffer layer 200 is formed on the crystalline solar cell 100.

[0154] The buffer layer 200 is formed on the first semiconductor layer 120. By forming the first semiconductor layer 120 with an uneven structure, the buffer layer 200 has a shape corresponding to the uneven structure.

[0155] The buffer layer 200 is provided between the crystalline solar cell 100 and the perovskite solar cell 300, which will be described later, so that the solar cell according to one embodiment of the present invention has the structure of a tandem solar cell via a tunnel junction.

[0156] The buffer layer 200 is preferably made of a material that allows long-wavelength light transmitted through the perovskite solar cell 300 to be incident on the crystalline solar cell 100 without loss, and therefore, a repeated explanation of the light absorption layer will be omitted.

[0157] Next, as can be seen from Figure 5C, a perovskite solar cell 300 is formed on the buffer layer 200.

[0158] The process for forming the perovskite solar cell 300 may include the steps of forming a first conductive charge transfer layer 321 on the buffer layer 200, forming a light absorption layer 310 on the first conductive charge transfer layer 321, and forming a second conductive charge transfer layer 322 on the light absorption layer 310.

[0159] The perovskite solar cell 300 can be formed by the CVD or ALD process as described above, and a repeated explanation of this process is omitted.

[0160] Next, as can be seen from Figure 5D, a first electrode 400 is formed on the upper surface of the perovskite solar cell 300, and a second electrode 500 is formed on the lower surface of the crystalline solar cell 100.

[0161] The first electrode 400 and the second electrode 500 are as described above, and a repeated explanation will be omitted.

[0162] Next, as can be seen in Figure 5E, a passivation layer 600 with an uneven structure is formed on the first electrode 400. Here, a portion of the passivation layer 600 is etched to expose the first electrode 400.

[0163] By forming the passivation layer 600 with an uneven structure, the amount of light incident on the perovskite solar cell 300 can be increased.

[0164] The passivation layer 600 can be made of polydimethylsiloxane, and by forming the polydimethylsiloxane on the perovskite solar cell 300, a micropyramidal uneven structure can be obtained.

[0165] Figures 6A to 6E are cross-sectional views showing a process for manufacturing a solar cell according to another embodiment of the present invention.

[0166] First, as can be seen from Figure 6A, a crystalline solar cell 100 is manufactured.

[0167] The crystalline solar cell 100 can be manufactured by etching the lower surface of a semiconductor substrate 110 to form an uneven structure, doping the upper surface of the semiconductor substrate 110 with a predetermined dopant to form a first semiconductor layer 120, and doping the lower surface of the semiconductor substrate 110 with a predetermined dopant to form a second semiconductor layer 130.

[0168] By forming an uneven surface on the lower surface of the semiconductor substrate 110, the second semiconductor layer 130 has a shape corresponding to the uneven structure.

[0169] The first semiconductor layer 120 can be doped with a dopant having a different polarity than the semiconductor substrate 110, and the second semiconductor layer 130 can be doped with a dopant having the same polarity as the semiconductor substrate 110.

[0170] Next, as can be seen from Figure 6B, a buffer layer 200 is formed on the upper surface of the crystalline solar cell 100.

[0171] The buffer layer 200 is formed on the first semiconductor layer 120. By forming the first semiconductor layer 120 with a flat structure, the buffer layer 200 also has a flat structure.

[0172] Since the buffer layer 200 is the same as in the embodiment described above, a repeated explanation will be omitted.

[0173] Next, as can be seen from Figure 6C, the perovskite solar cell 300 is formed on the buffer layer 200. By forming the buffer layer 200 in a flat structure, the perovskite solar cell 300 can also be formed in a flat structure. The perovskite solar cell 300 is the same as in the embodiment described above, so a repeated explanation will be omitted.

[0174] Next, as can be seen from Figure 6D, a first electrode 400 is formed on the upper surface of the perovskite solar cell 300, and a second electrode 500 is formed on the lower surface of the crystalline solar cell 100.

[0175] Since the first electrode 400 and the second electrode 500 are the same as those described in the previous embodiment, a repeated explanation will be omitted.

[0176] Next, as can be seen in Figure 6E, a passivation layer 600 with an uneven structure is formed on the first electrode 400. Here, a portion of the passivation layer 600 is etched to expose the first electrode 400.

[0177] By forming the passivation layer 600 with an uneven structure, the amount of light incident on the perovskite solar cell 300 can be increased.

[0178] The passivation layer 600 can be made of polydimethylsiloxane, and by forming the polydimethylsiloxane on the perovskite solar cell 300, a micropyramidal uneven structure can be obtained.

[0179] Figures 7A to 7E are cross-sectional views showing the process of manufacturing a solar cell according to one or more embodiments of the present invention.

[0180] First, as can be seen from Figure 7A, a crystalline solar cell 100 is manufactured.

[0181] The crystalline solar cell 100 can be manufactured by etching one surface and the other surface of a semiconductor substrate 110 to form an uneven structure, doping one surface of the semiconductor substrate 110 with a predetermined dopant to form a first semiconductor layer 120, and doping the other surface of the semiconductor substrate 110 with a predetermined dopant to form a second semiconductor layer 130.

[0182] By forming an uneven structure on one side and the other side of the semiconductor substrate 110, the first semiconductor layer 120 and the second semiconductor layer 130 each have shapes corresponding to the uneven structure.

[0183] The first semiconductor layer 120 can be doped with a dopant having a different polarity than the semiconductor substrate 110, and the second semiconductor layer 130 can be doped with a dopant having the same polarity as the semiconductor substrate 110.

[0184] Next, as can be seen from Figure 7B, a buffer layer 200 is formed on the upper surface of the crystalline solar cell 100.

[0185] The buffer layer 200 is formed on the first semiconductor layer 120. By forming the first semiconductor layer 120 with an uneven structure, the buffer layer 200 also has an uneven structure.

[0186] Since the buffer layer 200 is the same as in the embodiment described above, a repeated explanation will be omitted.

[0187] Next, as can be seen from Figure 7C, the perovskite solar cell 300 is formed on the buffer layer 200. By forming the buffer layer 200 with an uneven structure, the perovskite solar cell 300 can also be formed with an uneven structure. The perovskite solar cell 300 is the same as in the embodiment described above, so a repeated explanation will be omitted.

[0188] Next, as can be seen from Figure 7D, a first electrode 400 is formed on the upper surface of the perovskite solar cell 300, and a second electrode 500 is formed on the lower surface of the crystalline solar cell 100.

[0189] Since the first electrode 400 and the second electrode 500 are the same as those described in the previous embodiment, a repeated explanation will be omitted.

[0190] Next, as can be seen in Figure 7E, a passivation layer 600 is formed on the first electrode 400. Here, a portion of the passivation layer 600 is etched to expose the first electrode 400.

[0191] By forming the perovskite solar cell 300 with an uneven structure, the passivation layer 600 can also be formed with an uneven structure. The passivation layer 600 can be formed from various materials such as SiO, SiON, SiN, Al2O3, or MgF.

[0192] Although embodiments of the present invention have been described in more detail above with reference to the attached figures, the present invention is not necessarily limited to these embodiments and can be implemented in various ways without departing from the technical concept of the present invention. Therefore, the embodiments disclosed herein are for illustrative purposes only, not to limit the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such embodiments. Accordingly, the embodiments described above should be understood to be illustrative and not limiting in all respects. The scope of protection of the present invention should be interpreted by the claims, and all technical concepts within an equivalent scope should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. A perovskite solar cell comprising a light-absorbing layer containing a perovskite compound, and a conductive charge transfer layer provided on at least one of the two surfaces of the light-absorbing layer, One surface of the light-absorbing layer is located closer to the incident surface of sunlight compared to the other surface of the light-absorbing layer. The optical band gap within the light-absorbing layer is constant or decreases from one surface to the other. The optical band gap of one surface of the light-absorbing layer is larger than the optical band gap of the other surface of the light-absorbing layer. The light-absorbing layer comprises a first halogen element, a second halogen element, and a third halogen element. The first halogen element is Cl, the second halogen element is I, and the third halogen element is Br. The content of the first halogen element, Cl, on one surface of the light-absorbing layer is greater than the content of the first halogen element, Cl, on the other surface of the light-absorbing layer. The content of the second halogen element I contained in one surface of the light-absorbing layer is less than the content of the second halogen element I contained in the other surface of the light-absorbing layer. The light-absorbing layer includes a first layer with the smallest optical band gap, a second layer with an intermediate optical band gap, a third layer with the largest optical band gap, a fourth layer between the first and second layers, and a fifth layer between the second and third layers. The first layer is adjacent to the other surface of the light-absorbing layer, and the third layer is adjacent to the one surface of the light-absorbing layer. The optical band gaps of the first layer, the second layer, and the third layer are constant. The optical band gap of the fourth layer gradually increases from the optical band gap of the first layer to the optical band gap of the second layer. The optical band gap of the fifth layer gradually increases from the optical band gap of the second layer to the optical band gap of the third layer. A solar cell in which the content of the third halogen element, Br, is uniform in the first layer, the second layer, and the third layer.

2. The solar cell according to claim 1, wherein the content of the first halogen element, Cl, inside the light-absorbing layer is constant or decreases from one surface to the other.

3. The solar cell according to claim 1, wherein the first layer contains the second halogen element I but does not contain the first halogen element Cl, the second layer contains both the first halogen element Cl and the second halogen element I, and the third layer contains the first halogen element Cl but does not contain the second halogen element I.

4. Each of the first, second, and third layers contains both the first halogen element, Cl, and the second halogen element, I. The solar cell according to claim 1, wherein the content of the first halogen element, Cl, is highest in the third layer and lowest in the first layer, and the content of the second halogen element, I, is highest in the first layer and lowest in the third layer.

5. The solar cell according to claim 1, further comprising a buffer layer provided on the perovskite solar cell and a substrate-type solar cell provided on the buffer layer.

6. A step of forming a light-absorbing layer containing a perovskite compound, and The process includes forming a conductive charge transfer layer on at least one surface of the light absorption layer, The step of forming the light-absorbing layer includes a step of reacting at least one compound selected from amine compounds and amidine compounds, an organometallic compound containing a divalent cation, and at least one hydrogen halide, The one surface of the light-absorbing layer is located closer to the incident surface of sunlight compared to the other surface of the light-absorbing layer. The optical band gap of one surface of the light-absorbing layer is larger than the optical band gap of the other surface of the light-absorbing layer. The light-absorbing layer comprises a first halogen element, a second halogen element, and a third halogen element. The first halogen element is Cl, the second halogen element is I, and the third halogen element is Br. The content of the first halogen element, Cl, on one surface of the light-absorbing layer is greater than the content of the first halogen element, Cl, on the other surface of the light-absorbing layer. The content of the second halogen element I contained in one surface of the light-absorbing layer is less than the content of the second halogen element I contained in the other surface of the light-absorbing layer. The light-absorbing layer includes a first layer with the smallest optical band gap, a second layer with an intermediate optical band gap, a third layer with the largest optical band gap, a fourth layer between the first and second layers, and a fifth layer between the second and third layers. The first layer is adjacent to the other surface of the light-absorbing layer, and the third layer is adjacent to the one surface of the light-absorbing layer. The optical band gaps of the first layer, the second layer, and the third layer are constant. The optical band gap of the fourth layer gradually increases from the optical band gap of the first layer to the optical band gap of the second layer. The optical band gap of the fifth layer gradually increases from the optical band gap of the second layer to the optical band gap of the third layer. A method for manufacturing a solar cell, wherein the content of the third halogen element, Br, is uniform in the first layer, the second layer, and the third layer.

7. The hydrogen halogen comprises a first hydrogen halogen and a second hydrogen halogen, The first hydrogen halide contains the first halogen element, Cl. The aforementioned second hydrogen halide contains the aforementioned second halogen element, I. The amount of the first hydrogen halide introduced when forming one surface of the light-absorbing layer is greater than the amount of the first hydrogen halide introduced when forming the other surface of the light-absorbing layer. The method for manufacturing a solar cell according to claim 6, wherein the amount of the second hydrogen halide introduced when forming one surface of the light-absorbing layer is less than the amount of the second hydrogen halide introduced when forming the other surface of the light-absorbing layer.

8. The hydrogen halogen comprises a first hydrogen halogen and a second hydrogen halogen, The first hydrogen halide contains the first halogen element, Cl. The aforementioned second hydrogen halide contains the aforementioned second halogen element, I. The amount of the first hydrogen halide introduced when forming the one surface of the light-absorbing layer is greater than the amount of the second hydrogen halide introduced when forming the one surface of the light-absorbing layer. The method for manufacturing a solar cell according to claim 6, wherein the amount of the first hydrogen halide introduced when forming the other surface of the light-absorbing layer is less than the amount of the second hydrogen halide introduced when forming the other surface of the light-absorbing layer.

9. The process further includes forming a substrate-type solar cell and forming a buffer layer on the substrate-type solar cell before forming the light-absorbing layer and the conductive charge transfer layer. A method for manufacturing a solar cell according to claim 6, wherein the light-absorbing layer and the conductive charge transfer layer are formed on the buffer layer.

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