Method for manufacturing carbon electrode-based solar cell comprising perovskite thin film surface-treated through polishing, and carbon electrode-based solar cell manufactured thereby

Abstract

The present invention relates to a method for manufacturing a carbon electrode-based solar cell comprising a perovskite thin film surface-treated through polishing, and a carbon electrode-based solar cell manufactured by the method. According to the present invention, the surface of the perovskite thin film can be smoothed through polishing. Accordingly, the performance and stability of the solar cell are improved by inducing the formation of an effective interface with a hole transport material due to reduced surface roughness. Additionally, the present invention is effective for a carbon electrode-based solar cell, and exhibits improved thermal stability due to the non-use of a metal electrode that is unstable at high temperatures.

Description

Method for manufacturing a carbon electrode-based solar cell including a perovskite thin film surface-treated by polishing, and a carbon electrode-based solar cell manufactured by the method

[0001] The present invention relates to a method for manufacturing a carbon electrode-based solar cell including a perovskite thin film surface-treated through polishing, and a carbon electrode-based solar cell manufactured by the method.

[0002] This invention is the result of research conducted with the support of the National Research Foundation of Korea (NRF) through funding from the government (Ministry of Science and ICT) (No. RS-2024-00345042).

[0003]

[0004] A solar cell is a device that converts sunlight into electrical energy. It typically has a structure with a photoactive layer between an anode and a cathode, and generates electrical energy by utilizing the photovoltaic effect, which absorbs solar energy and generates electrons and holes.

[0005] Perovskite solar cells are a type of solar cell that utilizes a perovskite-structured material as a light-absorbing layer. Perovskite is a mineral with a unique, regular three-dimensional structure composed of two cations and one anion. When exposed to sunlight, it generates electrons and holes, which conduct electricity. Compared to commercially available silicon solar cells, perovskite solar cells utilize inexpensive materials and can be manufactured at low temperatures using a solution process. Therefore, they are attracting attention as a next-generation solar cell material that could replace existing solar cells.

[0006] Traditionally, precious metals such as gold and silver were used as the top electrodes of perovskite solar cells. While these precious metal electrodes offer high conductivity and can be applied thinly and uniformly, they are very expensive and react with the underlying perovskite, negatively impacting the long-term stability of the solar cell.

[0007] Carbon-based materials are attracting attention as electrode materials that can overcome the limitations of conventional noble metal electrodes. One common method for introducing carbon electrodes is to transfer a porous carbon electrode fabricated through a dry process onto a perovskite thin film, followed by infiltrating the carbon electrode with a hole-transport material. However, if the surface roughness of the perovskite thin film is high, non-radiative recombination can occur at the perovskite-carbon interface, reducing device performance, even though the hole-transport material can infiltrate after direct contact with the carbon electrode. Furthermore, even when coating the hole-transport material onto the perovskite thin film and attaching the carbon electrode, a thick hole-transport layer is required to fully cover the rough perovskite thin film. This increases the series resistance of the cell, negatively impacting the photovoltaic efficiency.

[0008] Accordingly, there is a need to develop a technology that can control the roughness of the surface of perovskite thin films to improve the efficiency and stability of perovskite solar cells.

[0009]

[0010] The present invention provides a method for manufacturing a carbon electrode-based solar cell with improved performance and stability by controlling the roughness of a perovskite thin film surface through polishing, and a carbon electrode-based solar cell manufactured by the method.

[0011]

[0012] The method for manufacturing a carbon electrode-based solar cell including a surface-treated perovskite thin film through polishing of the present invention may include the steps of S1) stacking and surface-treating a perovskite thin film on a substrate having a transparent electrode layer formed thereon; and S2) forming an upper layer on the surface-treated perovskite thin film.

[0013] The above step S1) may include a step S1-1) of forming a transparent electrode layer by laminating a conductive material on a substrate; a step S1-2) of forming an electron transport layer by coating an electron transport material on the transparent electrode layer; and a step S1-3) of laminating a perovskite thin film on the electron transport layer and performing surface treatment.

[0014] The above perovskite thin film may be a three-dimensional perovskite thin film having an ABX3 structure (A is a monovalent cation, B is a divalent cation, and X is a halogen anion).

[0015] The above ABX3 structure is FA x MA y Cs z PbI 3-a Br a can have the composition of (x+y+z is 1, and a is 0 to 3).

[0016] A perovskite precursor having the ABX3 structure can be dissolved in an organic solvent and coated on the electron transport layer, and then heat treated at 100 to 150°C to form a perovskite thin film having the ABX3 structure.

[0017] The above organic solvent may be a mixture of dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) in a volume ratio of 1 to 2:5 to 10.

[0018] The thickness of the perovskite thin film having the above ABX3 structure may be 100 to 1000 nm.

[0019] In the above step S1-3), the surface treatment of the perovskite thin film can be performed by physically or chemically polishing the surface of the perovskite thin film.

[0020] The perovskite thin film can be physically polished by contacting a polishing material and applying pressure in one direction.

[0021] The above polishing material may be a polishing cloth having a particle size of 0.02 to 10 μm.

[0022] Roughness (R) of the perovskite thin film after the above polishing RMS ) can be 10 to 55 nm.

[0023] In the above polishing, the following equation 2 can be satisfied for the thickness (t0) of the perovskite thin film before polishing and the thickness (t1) of the perovskite thin film after polishing.

[0024] [Formula 2]

[0025] 20 nm ≤ t0- t1≤ 80 nm

[0026] The surface of the above polished perovskite thin film can be coated with a solution of FABr (Formamidinium Bromide) or MeO-PEAI (4-methoxy-phenethylammonium iodide) dissolved in IPA.

[0027] The concentration of the above FABr solution may be 1 to 60 mM.

[0028] The concentration of the above MeO-PEAI solution may be 1 to 20 mM.

[0029] The perovskite thin film surface-treated with the above MeO-PEAI solution forms a quasi-2D perovskite structure on the surface, which can be an upper 2D and lower 3D perovskite heterostructure.

[0030] The thickness of the quasi-2D perovskite structure formed on the perovskite surface may be 10 to 150 nm.

[0031] The thickness of the surface-treated perovskite thin film may be 80 to 900 nm.

[0032] The upper layer may include a hole-carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the surface-treated perovskite thin film and infiltrating a hole transport material.

[0033] The upper layer may include a hole transport layer formed by coating a hole transport material on the surface-treated perovskite thin film; and a carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the hole transport layer.

[0034] The above hole transport material and cobalt salt mixture can be mixed in a weight ratio of 1800 to 2000:1, dissolved in chlorobenzene, and coated on the perovskite thin film to form a hole transport layer.

[0035] The above cobalt salt mixture may include 20 to 30 wt% of bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI), 65 to 75 wt% of tri-butyl phosphate (tBP), and 5 to 10 wt% of cobalt salt (tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide]).

[0036] The carbon electrode-based solar cell of the present invention has a roughness (R) of the perovskite thin film after the polishing. RMS ) can be 10 to 55 nm.

[0037] The carbon electrode-based solar cell of the present invention can satisfy the following equation 2 for the thickness (t0) of the perovskite thin film before polishing and the thickness (t1) of the perovskite thin film after polishing.

[0038] [Formula 2]

[0039] 20 nm ≤ t0- t1≤ 80 nm

[0040] In the carbon electrode-based solar cell of the present invention, the thickness of the surface-treated perovskite thin film may be 80 to 900 nm.

[0041]

[0042] According to the present invention, the surface of a perovskite thin film can be smoothed through polishing. Consequently, the reduced surface roughness leads to effective interface formation with the hole transport material, thereby improving the performance and stability of the solar cell.

[0043] In addition, the present invention is effective for carbon electrode-based solar cells, and has improved thermal stability by not using a metal electrode that is unstable at high temperatures.

[0044]

[0045] FIG. 1 schematically illustrates a carbon electrode-based solar cell according to one embodiment of the present invention.

[0046] FIG. 2 schematically illustrates a carbon electrode-based solar cell according to another embodiment of the present invention.

[0047] Figure 3 shows a surface image of a perovskite thin film before polishing according to the present invention.

[0048] Figure 4 shows a surface image of a perovskite thin film after polishing according to the present invention.

[0049] Figure 5 shows the surface roughness of a perovskite thin film before polishing according to the present invention.

[0050] Figure 6 shows the surface roughness of a perovskite thin film after polishing according to the present invention.

[0051] Figure 7 shows a cross-sectional image of a perovskite thin film before polishing according to the present invention.

[0052] Figure 8 shows a cross-sectional image of a perovskite thin film after polishing according to the present invention.

[0053] Figure 9 shows the grazing-incidence XRD results of a perovskite thin film before and after polishing according to the present invention.

[0054] Figure 10 shows the current density-voltage measurement results of Example 1 and Comparative Example 1 according to the present invention.

[0055] Figure 11 shows the current density-voltage measurement results of Example 2 and Comparative Example 2 according to the present invention.

[0056] Figure 12 shows the current density-voltage measurement results of Example 3 and Comparative Example 3 according to the present invention.

[0057]

[0058] The embodiments described herein may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. In addition, the embodiments of one embodiment are provided to more completely explain the present disclosure to a person with average knowledge in the relevant technical field. In this case, unless there is a different definition for the technical and scientific terms used, they have the meaning commonly understood by a person with ordinary skill in the technical field to which this invention belongs, and in the following description and the attached drawings, descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted.

[0059] Additionally, the singular forms used in this specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0060] Additionally, in this specification and the appended claims, the terms first, second, etc. are not used in a limiting sense but are used for the purpose of distinguishing one component from another.

[0061] Additionally, in this specification and the appended claims, when a part such as a film (layer), region or component is said to be located “on,” “above,” “upper,” “below,” “lower,” or “lower” another part, this includes not only cases where one part is in contact with another part, but also cases where another part exists between the two parts.

[0062] In addition, the terms "about," "substantially," and the like used in this specification and the appended claims are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly utilizing the disclosure in which exact or absolute values ​​are stated to aid in the understanding of this specification and the appended claims.

[0063] Additionally, the numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes.

[0064] Furthermore, in this specification and the appended claims, terms such as “include” or “have” mean that a feature or component described in the specification is present, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

[0065] Hereinafter, a method for manufacturing a carbon electrode-based solar cell including a surface-treated perovskite thin film through polishing according to the present invention and a carbon electrode-based solar cell manufactured by the method will be described in detail with reference to the attached drawings.

[0066]

[0067] Perovskite solar cells are a type of solar cell that utilizes a perovskite-structured material as a light-absorbing layer. Perovskite is a mineral with a unique, regular three-dimensional structure composed of two cations and one anion. When exposed to sunlight, it generates electrons and holes, which conduct electricity. Compared to commercially available silicon solar cells, perovskite solar cells utilize inexpensive materials and can be manufactured at low temperatures using a solution process. Therefore, they are attracting attention as a next-generation solar cell material that could replace existing solar cells.

[0068] Traditionally, precious metals such as gold and silver were used as the top electrodes of perovskite solar cells. While these precious metal electrodes offer high conductivity and can be applied thinly and uniformly, they are very expensive and react with the underlying perovskite, negatively impacting the long-term stability of the solar cell.

[0069] Carbon-based materials are attracting attention as electrode materials that can overcome the limitations of conventional noble metal electrodes. One common method for introducing carbon electrodes is to transfer a porous carbon electrode fabricated through a dry process onto a perovskite thin film, followed by infiltrating the carbon electrode with a hole-transport material. However, if the surface roughness of the perovskite thin film is high, non-radiative recombination can occur at the perovskite-carbon interface, reducing device performance, even though the hole-transport material can infiltrate after direct contact with the carbon electrode. Furthermore, even when coating the hole-transport material onto the perovskite thin film and attaching the carbon electrode, a thick hole-transport layer is required to fully cover the rough perovskite thin film. This increases the series resistance of the cell, negatively impacting the photovoltaic efficiency.

[0070] Accordingly, the present invention provides a method for manufacturing a carbon electrode-based solar cell with improved performance and stability by controlling the roughness of a perovskite thin film surface through polishing, and a carbon electrode-based solar cell manufactured by the method.

[0071]

[0072] FIG. 1 schematically illustrates a carbon electrode-based solar cell according to one embodiment of the present invention.

[0073] A method for manufacturing a carbon electrode-based solar cell including a surface-treated perovskite thin film through polishing according to the present invention may include the steps of S1) stacking and surface-treating a perovskite thin film on a substrate having a transparent electrode layer formed thereon; and S2) forming an upper layer on the surface-treated perovskite thin film.

[0074] The above step S1) may include a step S1-1) of forming a transparent electrode layer by laminating a conductive material on a substrate; a step S1-2) of forming an electron transport layer by coating an electron transport material on the transparent electrode layer; and a step S1-3) of laminating a perovskite thin film on the electron transport layer and performing surface treatment.

[0075] The above step S1-1) is a step of forming a transparent electrode layer by laminating a conductive material on a substrate, and the substrate includes at least one selected from a flexible substrate including glass, plastic, or polymer, and may be, for example, a glass substrate 1.1t, a glass substrate 2.2t, or a flexible substrate 0.1t, but is not limited thereto.

[0076] The conductive material includes at least one selected from transparent conductive oxides including indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO). The conductive material may preferably be FTO, but is not limited thereto.

[0077] In the step S1-1), the lamination of the conductive material can be performed using any method that can form a transparent electrode layer by depositing the conductive material on the substrate without limitation. For example, methods such as sputtering, physical vapor deposition (PVD), and chemical vapor deposition (CVD) can be selected, and sputtering is preferred, but is not limited thereto.

[0078] As an example, the thickness of the transparent electrode layer may be 50 to 1000 nm, preferably 75 to 800 nm, and more preferably 100 to 700 nm.

[0079] The above step S1-2) is a step of forming an electron transport layer by coating an electron transport material on the transparent electrode layer, wherein the electron transport material includes at least one selected from n-type oxides including TiO2 and SnO2. The n-type oxide is a material that conducts electricity via electrons, and the minimum of the material's conduction band is formed at 3.9 to 4.3 eV, and the maximum of the valence band is formed at 6.5 eV or less. The electron transport material may preferably be TiO2 or SnO2, but is not limited thereto.

[0080] In the above step S1-2), the coating of the electron transport material can be done without limitation by any method that can form an electron transport layer by coating the electron transport material on the transparent electrode layer. For example, methods such as spin coating, spray coating, and dip coating can be selected, and spin coating is preferred, but is not limited thereto.

[0081] As an example, the step S1-2) may form an electron transport layer by coating the electron transport material dissolved in water on the transparent electrode layer washed with alcohol.

[0082] As an example, the thickness of the electron transport layer may be 10 to 1000 nm, preferably 20 to 500 nm, and more preferably 30 to 250 nm.

[0083] The above step S1-3) is a step of laminating a perovskite thin film on the electron transport layer and performing surface treatment, and the perovskite thin film may be a three-dimensional perovskite thin film having an ABX3 structure. (A is a monovalent cation, B is a divalent cation, and X is a halogen anion.)

[0084] In the above ABX3 structure, A may include a formamidinium (FA) cation, a methylammonium (MA) cation, or a mixture thereof, B may include at least one selected from metal cations including Pb and Sn, and X may include at least one selected from halogen anions including Cl, Br, and I. For example, FA x MA y Cs z PbI 3-a Br a It may have a composition of (x+y+z is 1, a is 0 to 3), preferably FAPbI3 or FA 0.97 MA 0.03 PbI 2.91 Br 0.09 It may be, but is not limited to,

[0085] As an example, the perovskite precursor having the ABX3 structure is dissolved in a solution of dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) in a volume ratio of 1 to 2:5 to 10, and then coated on the electron transport layer, and the substrate is 2.5×2.5 cm. 2Based on this, 0.1 to 1 mL of diethyl ether or ethyl acetate is dropped onto the substrate coated with the perovskite precursor, and then heat treatment is performed at 100 to 150° C. to form a perovskite thin film having an ABX3 structure and a dark brown color.

[0086] As an example, the thickness of the perovskite thin film having the ABX3 structure may be 100 to 1000 nm, preferably 300 to 900 nm, and more preferably 500 to 800 nm.

[0087] In the above step S1-3), the surface treatment of the perovskite thin film can be performed using any method capable of physically or chemically polishing the surface of the perovskite thin film without limitation. Physical polishing is a method of applying physical force to the surface of a material using an abrasive, and chemical polishing is a method of selectively removing a surface material using a chemical agent.

[0088] As an example, a polishing tool having a size larger than the substrate may be fixed and brought into contact with the perovskite thin film, and pressure may be applied to repeatedly push the tool in one direction to physically polish the surface of the perovskite thin film.

[0089] The above polishing material is not particularly limited, but may be, for example, a polishing cloth having a particle size of 0.02 to 10 μm, preferably Chemomet (1 to 0.02 μm), MicroCloth (5 to 0.02 μm), or VelTex (9 to 1 μm), but is not limited thereto.

[0090] According to the present invention, the roughness of the surface of a perovskite thin film can be reduced through polishing to create a smooth surface. The surface roughness is not particularly limited, but can be measured using, for example, atomic force microscopy, and R can be obtained from a topographic image of the perovskite thin film. RMS can be derived. R RMS (Root-mean-square roughness) is one of the indices used to measure the irregularity or roughness of a surface, and is particularly useful for measuring roughness on uneven surfaces.

[0091] R in the present invention RMS It represents the square root of the average of the squares of the measurements of the curvature formed on the surface of the perovskite thin film and is calculated using the formula in Equation 1 below.

[0092] [Formula 1]

[0093]

[0094] The above N is the number of height data, and h i are the respective height values, and R RMS The higher the value, the rougher the surface appears.

[0095] Roughness (R) of perovskite thin films after polishing RMS ) may be 10 to 55 nm, preferably 30 to 45 nm, more preferably 35 to 45 nm.

[0096] In addition, in the above polishing, the following equation 2 may be satisfied for the thickness (t0) of the perovskite thin film before polishing and the thickness (t1) of the perovskite thin film after polishing.

[0097] [Formula 2]

[0098] 20 nm ≤ t0- t1≤ 80 nm

[0099] The surface of the polished perovskite thin film can be surface-treated by coating with a solution of FABr (Formamidinium Bromide) or MeO-PEAI (4-methoxy-phenethylammonium iodide) dissolved in IPA. FABr or MeO-PEAI is a material introduced as a post-treatment to improve the quality of perovskite. The concentration of the FABr solution may be 1 to 60 mM, preferably 10 to 50 mM, more preferably 20 to 40 mM, and the concentration of the MeO-PEAI solution may be 1 to 20 mM, preferably 5 to 15 mM, more preferably 8 to 12 mM. In addition, the coating method is not particularly limited, and for example, a method such as spin coating, spray coating, or dip coating may be selected, and spin coating may be used, but is not limited thereto.

[0100] As an example, when the surface of the polished perovskite thin film is surface-treated with the FABr solution and heat-treated, FA and Br penetrate and diffuse into the perovskite, thereby improving crystallinity.

[0101] As an example, when the surface of the polished perovskite thin film is surface-treated with the MeO-PEAI solution and heat-treated, a quasi-2D perovskite structure of several tens of nm is formed on the perovskite surface, thereby forming an upper two-dimensional and lower three-dimensional perovskite heterostructure. The thickness of the quasi-2D perovskite structure formed on the perovskite surface may be 10 to 150 nm, preferably 10 to 100 nm, and more preferably 20 to 80 nm.

[0102] As an example, the heat treatment may be, but is not limited to, 100°C for 5 to 10 minutes, 150°C for 1 to 5 minutes, or any value therebetween.

[0103] As an example, the thickness of the surface-treated perovskite thin film may be 80 to 900 nm, preferably 270 to 850 nm, and more preferably 450 to 780 nm.

[0104] The above step S2) is a step of forming an upper layer on the surface-treated perovskite thin film.

[0105] As an example, the upper layer may include a hole-carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the surface-treated perovskite thin film and infiltrating a hole transport material.

[0106] The carbon-based electrode may be a carbon paste in the form of a slurry containing at least one carbon material selected from carbon nanotubes (CNTs), graphite, carbon black, and a polymeric binder, and may be a carbon nanotube solidified through a dry process. The thickness of the carbon-based electrode may be 30 to 5000 nm, preferably 100 to 3500 nm, and more preferably 250 to 2500 nm.

[0107] The lamination of the carbon-based electrode can be performed by any method that can laminate the carbon-based electrode on the surface-treated perovskite thin film. For example, after laminating the carbon-based electrode on the surface-treated perovskite thin film, a pressure of several MPa can be applied through a device at the level of simply pressing with a hand, or a method such as spin coating, spray coating, or dip coating can be selected, and spin coating is preferred, but is not limited thereto.

[0108] The hole transport material is spiro-OMeTAD (2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene), DM(N2,N2',N7,N7'-tetrakis(9,9-dimethyl-9H-fluoren-2-yl)-N2,N2',N7,N7'-tetrakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine), EC(N2,N2',N7,N7'-tetrakis(9-ethyl-9H-carbazol-2-yl)-N2,N2',N7,N7'-tetrakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine), It comprises at least one hole transport material selected from PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) and CuPC (copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine). The hole transport material may preferably be spiro-OMeTAD, but is not limited thereto.

[0109] The infiltration of the above-mentioned hole transport material can be performed by any method that allows the hole transport material to permeate the laminated carbon-based electrode without limitation. For example, methods such as drop casting, spin coating, spray coating, and dip coating can be selected, and drop casting is preferred, but is not limited thereto.

[0110] As an example, the hole transport material may be dissolved in chlorobenzene, drop-casted onto a carbon-based electrode laminated on the surface-treated perovskite thin film to allow it to permeate, and then spin-coated to form a hole / carbon electrode layer.

[0111] As an example, the thickness of the hole / carbon electrode layer may be 0.1 to 100 μm. In the case of carbon paste, the thickness may be 2 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm, and in the case of solidified carbon nanotubes, the thickness may be 0.1 to 50 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

[0112] FIG. 2 schematically illustrates a carbon electrode-based solar cell according to another embodiment of the present invention.

[0113] As another example, the upper layer may include a hole transport layer formed by coating a hole transport material on the surface-treated perovskite thin film; and a carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the hole transport layer.

[0114] The coating of the above hole transport material can be used without limitation as long as it is a method that can form a hole transport layer by coating the hole transport material on the surface-treated perovskite thin film, and is preferably spin coating, but is not limited thereto.

[0115] As an example, the hole transport material and cobalt salt mixture may be mixed at a weight ratio of 1800 to 2000:1, dissolved in chlorobenzene, and coated on the surface-treated perovskite thin film to form a hole transport layer. The cobalt salt mixture may include 20 to 30 wt% of bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI), 65 to 75 wt% of tri-butyl phosphate (tBP), and 5 to 10 wt% of cobalt salt (tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide]).

[0116] As an example, the thickness of the hole transport layer may be 10 to 1000 nm, preferably 20 to 500 nm, and more preferably 20 to 300 nm.

[0117] The lamination of the carbon-based electrode can be performed using any method that can laminate the carbon-based electrode on the hole transport layer without limitation. For example, after laminating the carbon-based electrode on the hole transport layer, a pressure of several MPa can be applied through a device at the level of simply pressing with a hand, or a method such as spin coating, spray coating, or dip coating can be selected, and spin coating is preferred, but is not limited thereto.

[0118] As an example, the thickness of the carbon electrode layer may be 0.1 to 100 μm. In the case of carbon paste, the thickness may be 2 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm, and in the case of solidified carbon nanotubes, the thickness may be 0.1 to 50 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

[0119] The thickness of a carbon electrode-based solar cell including a perovskite thin film surface-treated through polishing according to the present invention may be 50 μm to 10 mm, preferably 200 μm to 5 mm, and more preferably 1 mm to 3 mm.

[0120]

[0121] A carbon electrode-based solar cell including a perovskite thin film surface-treated through polishing according to the present invention comprises: a transparent electrode layer disposed on a substrate; an electron transport layer disposed on the transparent electrode layer; a perovskite thin film disposed on the electron transport layer; and an upper layer disposed on the perovskite thin film.

[0122] The substrate includes at least one selected from a flexible substrate including glass, plastic, or polymer, and may be, for example, a glass substrate 1.1t, a glass substrate 2.2t, or a flexible substrate 0.1t, but is not limited thereto.

[0123] A transparent electrode layer is disposed on the substrate. The transparent electrode layer includes at least one selected from transparent conductive oxides including indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO). The transparent conductive oxide may preferably be an FTO electrode, but is not limited thereto.

[0124] As an example, the thickness of the transparent electrode layer may be 50 to 1000 nm, preferably 75 to 800 nm, and more preferably 100 to 700 nm.

[0125] An electron transport layer is disposed on the transparent electrode layer. The electron transport layer includes at least one selected from n-type oxides including TiO2 and SnO2. The n-type oxide is a material that conducts electricity via electrons, and the minimum of the material's conduction band is formed at 3.9 to 4.3 eV, and the maximum of the valence band is formed at 6.5 eV or less. The n-type oxide may preferably be TiO2 or SnO2, but is not limited thereto.

[0126] As an example, the thickness of the electron transport layer may be 10 to 1000 nm, preferably 20 to 500 nm, and more preferably 30 to 250 nm.

[0127] A perovskite thin film is disposed on the electron transport layer. The perovskite thin film may be a three-dimensional perovskite thin film having an ABX3 structure (A is a monovalent cation, B is a divalent cation, and X is a halogen anion).

[0128] In the above ABX3 structure, A may include a formamidinium (FA) cation, a methylammonium (MA) cation, or a mixture thereof, B may include at least one selected from metal cations including Pb and Sn, and X may include at least one selected from halogen anions including Cl, Br, and I. For example, FA x MA y Cs z PbI 3-a Br aIt may have a composition of (x+y+z is 1, a is 0 to 3), preferably FAPbI3 or FA 0.97 MA 0.03 PbI 2.91 Br 0.09 It may be, but is not limited to,

[0129] As an example, the thickness of the perovskite thin film having the ABX3 structure may be 100 to 1000 nm, preferably 300 to 900 nm, and more preferably 500 to 800 nm.

[0130] The perovskite thin film has many defects on its surface. Accordingly, the surface of the perovskite thin film can be physically or chemically polished.

[0131] As an example, a polishing tool having a size larger than the substrate may be fixed and brought into contact with the perovskite thin film, and pressure may be applied to repeatedly push the tool in one direction to physically polish the surface of the perovskite thin film.

[0132] The above polishing material is not particularly limited, but may be, for example, a polishing cloth having a particle size of 0.02 to 10 μm, preferably Chemomet (1 to 0.02 μm), MicroCloth (5 to 0.02 μm), or VelTex (9 to 1 μm), but is not limited thereto.

[0133] Roughness (R) of the perovskite thin film after polishing according to the present invention RMS ) may be 10 to 55 nm, preferably 30 to 45 nm, more preferably 35 to 45 nm.

[0134] In addition, in the above polishing, the following equation 2 may be satisfied for the thickness (t0) of the perovskite thin film before polishing and the thickness (t1) of the perovskite thin film after polishing.

[0135] [Formula 2]

[0136] 20 nm ≤ t0- t1≤ 80 nm

[0137] The surface of the polished perovskite thin film can be surface-treated by coating with a solution of FABr (Formamidinium Bromide) or MeO-PEAI (4-methoxy-phenethylammonium iodide) dissolved in IPA. FABr or MeO-PEAI is a material introduced as a post-treatment to improve the quality of perovskite. The concentration of the FABr solution may be 1 to 60 mM, preferably 10 to 50 mM, and more preferably 20 to 40 mM, and the concentration of the MeO-PEAI solution may be 1 to 20 mM, preferably 5 to 15 mM, and more preferably 8 to 12 mM.

[0138] As an example, when the surface of the polished perovskite thin film is surface-treated with the FABr solution, FA and Br penetrate and diffuse into the perovskite, thereby improving crystallinity.

[0139] As an example, when the surface of the polished perovskite thin film is surface-treated with the MeO-PEAI solution, a quasi-2D perovskite structure of several tens of nm is formed on the perovskite surface, thereby forming an upper two-dimensional and lower three-dimensional perovskite heterostructure. The thickness of the quasi-2D perovskite structure formed on the perovskite surface may be 10 to 150 nm, preferably 10 to 100 nm, and more preferably 20 to 80 nm.

[0140] As an example, the thickness of the surface-treated perovskite thin film may be 80 to 900 nm, preferably 270 to 850 nm, and more preferably 450 to 780 nm.

[0141] An upper layer is placed on the perovskite layer thin film.

[0142] As an example, the upper layer may include a hole-carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the surface-treated perovskite thin film and infiltrating a hole transport material.

[0143] The carbon-based electrode may be a carbon paste in the form of a slurry containing at least one carbon material selected from carbon nanotubes (CNTs), graphite, carbon black, and a polymeric binder, and may be a carbon nanotube solidified through a dry process. The thickness of the carbon-based electrode may be 30 to 5000 nm, preferably 100 to 3500 nm, and more preferably 250 to 2500 nm.

[0144] The hole transport material is spiro-OMeTAD (2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene), DM(N2,N2',N7,N7'-tetrakis(9,9-dimethyl-9H-fluoren-2-yl)-N2,N2',N7,N7'-tetrakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine), EC(N2,N2',N7,N7'-tetrakis(9-ethyl-9H-carbazol-2-yl)-N2,N2',N7,N7'-tetrakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine), It comprises at least one hole transport material selected from PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) and CuPC (copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine). The hole transport material may preferably be spiro-OMeTAD, but is not limited thereto.

[0145] As an example, the thickness of the hole / carbon electrode layer may be 0.1 to 100 μm. In the case of carbon paste, the thickness may be 2 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm, and in the case of solidified carbon nanotubes, the thickness may be 0.1 to 50 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

[0146] As another example, the upper layer may include a hole transport layer formed by coating a hole transport material on the surface-treated perovskite thin film; and a carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the hole transport layer.

[0147] As an example, the thickness of the hole transport layer may be 10 to 1000 nm, preferably 20 to 500 nm, and more preferably 20 to 300 nm.

[0148] As an example, the thickness of the carbon electrode layer may be 0.1 to 100 μm. In the case of carbon paste, the thickness may be 2 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm, and in the case of solidified carbon nanotubes, the thickness may be 0.1 to 50 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

[0149] The thickness of a carbon electrode-based solar cell including a perovskite thin film surface-treated through polishing according to the present invention may be 50 μm to 10 mm, preferably 200 μm to 5 mm, and more preferably 1 mm to 3 mm.

[0150]

[0151] According to the present invention, the surface of a perovskite thin film can be smoothed through polishing. Consequently, the reduced surface roughness leads to effective interface formation with the hole transport material, thereby improving the performance and stability of the solar cell.

[0152] In addition, the present invention is effective for carbon electrode-based solar cells, and has improved thermal stability by not using a metal electrode that is unstable at high temperatures.

[0153]

[0154] Hereinafter, specific examples and experimental examples will be described. However, the examples and experimental examples described below are only illustrative, and the technology described in this specification is not limited thereto.

[0155]

[0156] <Example 1>

[0157] 2.5×2.5 cm 2A transparent electrode layer 800 nm thick was formed by sputtering fluorine-doped tin oxide (FTO) on a plastic substrate. TiO2 (b-TiO2, mp-TiO2) nanoparticles dissolved in water were spin-coated on the transparent electrode layer washed with ethanol to form a 30 nm thick electron transport layer.

[0158] Perovskite FAPbI3 was dissolved in a solution of 1 mL of DMSO and 8 mL of DMF and spin-coated on the electron transport layer. 1 mL of diethyl ether was dropped onto the perovskite-coated rotating substrate, and heat treatment was performed at 150°C to form an 850 nm thick perovskite thin film with a dark brown color.

[0159] 3×3 cm 2 After fixing a polishing cloth Chemomet (1-0.02 μm) on a flat surface with a handle, it was brought into contact with the perovskite thin film, and the perovskite thin film was polished by repeatedly pushing it in one direction 30 times under a pressure of 1 MPa. Formamidinium Bromide (FABr) dissolved in IPA at a concentration of 40 mM was spin-coated on the polished perovskite thin film, and then heat-treated at 150°C to form a surface-treated perovskite thin film with a thickness of 800 nm.

[0160] Carbon nanotubes with a thickness of 500 to 2500 nm were stacked on the surface-treated perovskite thin film, and 26596 g of spiro-OMeTAD, 3.3 g of bis(trifluoromethane) sulfonimide lithium salt, 9.6 g of tri-butyl phosphate, and 1 g of tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide] were mixed and dissolved in chlorobenzene to prepare a hole transport material solution. The hole transport material solution was drop-casted on the stacked carbon nanotubes, left for 1 minute to allow sufficient permeation, and then spin-coated at 3000 rpm for 30 seconds to form a 30 μm thick hole / carbon electrode layer, thereby manufacturing a carbon electrode-based solar cell.

[0161]

[0162] <Example 2>

[0163] A carbon electrode-based solar cell was manufactured in the same manner as in Example 1, except that a 720 nm perovskite thin film was formed and polished to form a 670 nm surface-treated perovskite thin film.

[0164]

[0165] <Example 3>

[0166] 2.5×2.5 cm 2 A transparent electrode layer 800 nm thick was formed by sputtering fluorine-doped tin oxide (FTO) on a plastic substrate. SnO2 nanoparticles dissolved in water were spin-coated on the transparent electrode layer, which was washed with ethanol, to form an electron transport layer 30 nm thick.

[0167] Perovskite FA 0.97 MA 0.03 PbI 2.91 Br 0.09was dissolved in a solution of 1 mL of DMSO and 8 mL of DMF and spin-coated on the electron transport layer. 1 mL of diethyl ether was dropped on the rotating substrate coated with the perovskite, and heat treatment was performed at 150°C to form a 750 nm thick perovskite thin film with a dark brown color.

[0168] 3×3 cm 2 After fixing a polishing cloth Chemomet (1-0.02 μm) on a flat surface with a handle, it was brought into contact with the perovskite thin film, and the perovskite thin film was polished by repeatedly pushing it in one direction 30 times under a pressure of 1 MPa. MeO-PEAI (4-methoxy-phenethylammonium iodide) dissolved in IPA at a concentration of 10 mM was spin-coated on the polished perovskite thin film, and then heat-treated at 150°C to form a surface-treated perovskite thin film with a thickness of 700 nm.

[0169] 26596 g of spiro-OMeTAD, 3.3 g of bis(trifluoromethane) sulfonimide lithium salt, 9.6 g of tri-butyl phosphate, and 1 g of tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide] were mixed and dissolved in chlorobenzene, and then spin-coated on the surface-treated perovskite thin film to form a 200 nm thick hole transport layer. Solidified carbon nanotubes with a thickness of 500 to 2500 nm were laminated on the hole transport layer, and a 2 μm thick carbon electrode layer was formed to manufacture a carbon electrode-based solar cell.

[0170]

[0171] <Comparative Example 1>

[0172] A carbon electrode-based solar cell was manufactured in the same manner as in Example 1, except that polishing was not performed.

[0173]

[0174] <Comparative Example 2>

[0175] A carbon electrode-based solar cell was manufactured in the same manner as in Example 2, except that polishing was not performed.

[0176]

[0177] <Comparative Example 3>

[0178] A carbon electrode-based solar cell was manufactured in the same manner as in Example 3, except that polishing was not performed.

[0179]

[0180] Experimental Example 1

[0181] The surface, surface roughness, and cross-section of the perovskite thin film according to the polishing according to the present invention were compared. The surface roughness was measured using atomic force microscopy, and R was calculated from the topographic image of the perovskite thin film. RMS was derived.

[0182] Fig. 3 shows a surface image of a perovskite thin film before polishing according to the present invention, and Fig. 4 shows a surface image of a perovskite thin film after polishing according to the present invention. It was confirmed that the grain boundaries of the perovskite thin film after polishing were smaller than before polishing.

[0183] Figure 5 shows the surface roughness of a perovskite thin film before polishing according to the present invention, and Figure 6 shows the surface roughness of a perovskite thin film after polishing according to the present invention. Surface roughness (R) before polishing RMS ) is 48.6 nm, surface roughness (R) after polishing RMS) was measured as 44.0 nm, and it was confirmed that the surface roughness of the perovskite thin film decreased after polishing compared to before polishing.

[0184] Fig. 7 shows a cross-sectional image of a perovskite thin film before polishing according to the present invention, and Fig. 8 shows a cross-sectional image of a perovskite thin film after polishing according to the present invention. The thickness before polishing was measured to be 798±46 nm, and the thickness after polishing was measured to be 755±23 nm. It was confirmed that the thickness of the perovskite thin film after polishing was reduced compared to before polishing, and the upper part was relatively flattened.

[0185] Figure 9 shows the grazing-incidence XRD results of a perovskite thin film before and after polishing according to the present invention. It was confirmed that the peak (PbI2 peak) around 12.4° decreased and the peak (perovskite peak) around 14° increased in the polished thin film (Polished) compared to the one before polishing (Control). This indicates that the polishing process removed the PbI2 remaining on the surface, and at the same time, it indicates that the crystallinity of the perovskite in the upper layer was improved.

[0186]

[0187] Experimental Example 2

[0188] To check the performance in the example (polishing performed) and comparative example (non-polishing performed), the open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF), and power conversion efficiency (PCE) were measured. V OC Wow J SC is a value determined by the intrinsic properties of the electron donor and acceptor, and FF is an external variable that depends on the shape of the solar cell and the structure of the device. PCE refers to the ratio of the output energy to the incident energy from the sun.

[0189] Measurement conditions were 100 mWcm using a standard Si solar cell (RC1000-TC-KG5-N, VLSI Standards). -2 Solar simulations were performed with AM 1.5G sunlight generated by an Oriel Sol3A solar simulator calibrated to .

[0190]

[0191] Table 1, Figures 10 and 11 show the current density-voltage measurement results of examples and comparative examples of the present invention.

[0192]

[0193] J SC (mA cm -2 )V OC (V)FF (%)PCE (%)Example 123.61.1279.320.9Comparative Example 123.51.1177.520.2Example 223.51.1080.720.9Comparative Example 223.21.1278.520.4

[0194]

[0195] Example 1 (Polishing) is J SC 23.6 mA cm -2 , V OC The measured values ​​were 1.12 V, FF 79.3%, and PCE 20.9%, and Comparative Example 1 (non-polished) was J SC 23.5 mA cm -2 , V OC The measured voltage was 1.11 V, FF was 77.5%, and PCE was 20.2%.

[0196] Example 2 (Polishing) is J SC 23.5 mA cm -2 , V OC The measured values ​​were 1.10 V, FF 80.7%, and PCE 20.9%, and Comparative Example 2 (non-polished) was J SC 23.2 mA cm -2 , V OC The measured voltage was 1.12 V, FF was 78.5%, and PCE was 20.4%.

[0197] It was confirmed that FF was improved in the example in which polishing was performed compared to the comparative example in which polishing was not performed.

[0198] In addition, when comparing Example 1 (thickness of perovskite thin film: 850 nm) and Example 2 (thickness of perovskite thin film: 720 nm), it can be confirmed that the effect of polishing is more prominent as the perovskite thin film is thicker under the same structure.

[0199]

[0200] Table 2, Figures 10 and 12 show the current density-voltage measurement results of examples and comparative examples of the present invention.

[0201]

[0202] J SC (mA cm -2 )V OC (V)FF (%)PCE (%)Example 123.61.1279.320.9Comparative Example 123.51.1177.520.2Example 324.31.1479.422.0Comparative Example 324.11.1475.120.6

[0203]

[0204] Example 1 (Polishing) is J SC 23.6 mA cm -2 , V OC The measured values ​​were 1.12 V, FF 79.3%, and PCE 20.9%, and Comparative Example 1 (non-polished) was J SC 23.5 mA cm -2 , V OC The measured voltage was 1.11 V, FF was 77.5%, and PCE was 20.2%.

[0205] Example 3 (Polishing) is J SC 24.3 mA cm -2 , V OC The measured values ​​were 1.14 V, FF 79.4%, and PCE 22.0%, and Comparative Example 3 (non-polished) was J SC 24.1 mA cm -2, V OC The measured voltage was 1.14 V, FF was 75.1%, and PCE was 20.6%.

[0206] It was confirmed that FF was improved in Example 1 (polishing) compared to Comparative Example 1 (no polishing). In addition, it was confirmed that FF and PCE were improved in Example 3 (polishing) compared to Comparative Example 3 (no polishing).

[0207]

[0208] Although the present invention has been described in this specification with specific details and limited examples, these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on these descriptions. Therefore, the ideas described in this specification should not be limited to the described examples, and all things that are equivalent or equivalent to the claims below, as well as the claims, are considered to fall within the scope of the ideas described in this specification.

[0209]

[0210] [Explanation of symbols]

[0211] 100, 101: Carbon electrode-based solar cells

[0212] 110: Substrate

[0213] 120: Transmissive electrode layer

[0214] 130: Electron transport layer

[0215] 140: Perovskite thin film

[0216] 150: Hole and carbon electrode layer

[0217] 160: Hole transport layer

[0218] 170: Carbon electrode layer

Claims

1. S1) A step of laminating and surface treating a perovskite thin film on a substrate on which a transparent electrode layer is formed; and S2) A step of forming an upper layer on the surface-treated perovskite thin film; A method for manufacturing a carbon electrode-based solar cell including:

2. In paragraph 1, The above step S1) is a step S1-1) of forming a transparent electrode layer by laminating a conductive material on a substrate; S1-2) A step of forming an electron transport layer by coating an electron transport material on the transparent electrode layer; and S1-3) Step of depositing a perovskite thin film on the electron transport layer and performing surface treatment; A method for manufacturing a carbon electrode-based solar cell including:

3. In paragraph 1, A method for manufacturing a carbon electrode-based solar cell, wherein the above perovskite thin film is a three-dimensional perovskite thin film having an ABX3 structure. (A is a monovalent cation, B is a divalent cation, and X is a halogen anion.) 4. In paragraph 3, The above ABX3 structure is FA x MA y Cs z PbI 3-a Br a A method for manufacturing a carbon electrode-based solar cell having a composition of . (x+y+z is 1, and a is 0 to 3.) 5. In paragraph 3, A method for manufacturing a carbon electrode-based solar cell, comprising dissolving a perovskite precursor having the ABX3 structure in an organic solvent, coating the perovskite precursor on the electron transport layer, and then performing heat treatment at 100 to 150°C to form a perovskite thin film having the ABX3 structure.

6. In paragraph 5, A method for manufacturing a carbon electrode-based solar cell, wherein the organic solvent is a solution of dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) mixed in a volume ratio of 1 to 2:5 to 10.

7. In paragraph 3, A method for manufacturing a carbon electrode-based solar cell, wherein the thickness of the perovskite thin film having the ABX3 structure is 100 to 1000 nm.

8. In paragraph 2, A method for manufacturing a carbon electrode-based solar cell, wherein the surface treatment of the perovskite thin film in the above step S1-3) is to physically or chemically polish the surface of the perovskite thin film.

9. In paragraph 8, A method for manufacturing a carbon electrode-based solar cell, which comprises physically polishing the perovskite thin film by contacting a polishing material with the perovskite thin film and applying pressure in one direction.

10. In paragraph 9, A method for manufacturing a carbon electrode-based solar cell, wherein the above polishing material is a polishing cloth having a particle size of 0.02 to 10 μm.

11. In paragraph 8, Roughness (R) of the perovskite thin film after the above polishing RMS ) A method for manufacturing a carbon electrode-based solar cell having a thickness of 10 to 55 nm.

12. In paragraph 8, A method for manufacturing a carbon electrode-based solar cell that satisfies the following equation 2 for the thickness (t0) of the perovskite thin film before polishing and the thickness (t1) of the perovskite thin film after polishing in the above polishing. [Formula 2] 20 nm ≤ t0- t1≤ 80 nm 13. In paragraph 8, A method for manufacturing a carbon electrode-based solar cell in which the surface of the polished perovskite thin film is treated by coating it with a solution of FABr (Formamidinium Bromide) or MeO-PEAI (4-methoxy-phenethylammonium iodide) dissolved in IPA.

14. In paragraph 13, A method for manufacturing a carbon electrode-based solar cell, wherein the concentration of the above FABr solution is 1 to 60 mM.

15. In paragraph 13, A method for manufacturing a carbon electrode-based solar cell, wherein the concentration of the MeO-PEAI solution is 1 to 20 mM.

16. In paragraph 13, A method for manufacturing a carbon electrode-based solar cell having a perovskite heterostructure of upper two dimensions and lower three dimensions by forming a quasi-2D perovskite structure on the surface of a perovskite thin film surface-treated with the above MeO-PEAI solution.

17. In paragraph 16, A method for manufacturing a carbon electrode-based solar cell, wherein the thickness of the quasi-2D perovskite structure formed on the perovskite surface is 10 to 150 nm.

18. In paragraph 1, A method for manufacturing a carbon electrode-based solar cell, wherein the surface-treated perovskite thin film has a thickness of 80 to 900 nm.

19. In paragraph 1, A method for manufacturing a carbon electrode-based solar cell, wherein the upper layer comprises a carbon-based electrode as an electrode material, which is formed by laminating the carbon-based electrode on the surface-treated perovskite thin film and infiltrating a hole transport material.

20. In paragraph 1, A method for manufacturing a carbon electrode-based solar cell, comprising: a hole transport layer formed by coating a hole transport material on the surface-treated perovskite thin film; and a carbon electrode layer formed by laminating a carbon-based electrode as an electrode material on the hole transport layer.

21. In paragraph 20, A method for manufacturing a carbon electrode-based solar cell, comprising mixing the above-mentioned hole transport material and cobalt salt mixture in a weight ratio of 1800 to 2000:1, dissolving it in chlorobenzene, and coating it on the perovskite thin film to form a hole transport layer.

22. In paragraph 21, A method for manufacturing a carbon electrode-based solar cell, wherein the cobalt salt mixture comprises 20 to 30 wt% of bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI), 65 to 75 wt% of tri-butyl phosphate (tBP), and 5 to 10 wt% of cobalt salt (tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide]).

23. A carbon electrode-based solar cell manufactured by the method of any one of claims 1 to 22.

24. In paragraph 23, Roughness (R) of the perovskite thin film after the above polishing RMS ) A carbon electrode-based solar cell having a thickness of 10 to 55 nm.

25. In paragraph 23, A carbon electrode-based solar cell satisfying the following equation 2 for the thickness of the perovskite film before polishing (t0) and the thickness of the perovskite film after polishing (t1). [Formula 2] 20 nm ≤ t0- t1≤ 80 nm 26. In paragraph 23, A carbon electrode-based solar cell having a thickness of the surface-treated perovskite thin film of 80 to 900 nm.

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