Transparent crystalline silicon solar cell and preparation method thereof

Abstract

The invention discloses a transparent crystalline silicon solar cell and a preparation method thereof, and relates to the technical field of photoelectric conversion. The preparation method is based on half-cell preparation, the half-cell comprises a crystal silicon wafer and a positive electrode located on one side of the crystal silicon wafer, and the preparation method comprises the following steps: performing reverse micropore etching on the crystal silicon wafer by using a reactive ion etching process to form a microporous cell comprising a plurality of micropores; pretreating the microporous battery to form a protective layer covering the positive electrode on one side of the microporous battery; sequentially carrying out acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition on the microporous battery to sequentially form a silicon oxide passivation layer, an organic molecule modification layer and a magnesium oxide passivation layer on the side wall of the micropore of the microporous battery; and depositing a back electrode on one side, far away from the positive electrode, of the microporous cell to prepare the transparent crystalline silicon solar cell. The transparent crystalline silicon solar cell prepared by the invention has relatively high photoelectric conversion efficiency, light transmittance and preparation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric conversion, and in particular to a transparent crystalline silicon solar cell and a preparation method thereof. Background Art

[0002] In the prior art, the preparation of transparent crystalline silicon solar cells is usually based on preparing micron-sized through holes in crystalline silicon and then preparing the positive electrode. This preparation method not only leads to a significant increase in the specific surface area of ​​the battery, but also causes the composite loss caused by surface defects to cause low photoelectric conversion efficiency. The setting of the through hole also complicates the preparation process of the positive electrode, affecting the preparation efficiency of the transparent crystalline silicon solar cell. In addition, although the acid solution chemical treatment in the prior art can smooth the microporous side wall surface of the transparent crystalline silicon solar cell, the side wall still has a certain degree of roughness. In addition, the smoothing treatment only deals with macroscopic defects, and there will still be microscopic defects and a large number of dangling bonds on the side wall surface, which affects the photoelectric conversion efficiency of the transparent crystalline silicon solar cell. Summary of the invention

[0003] An object of the first aspect of the present invention is to provide a method for preparing a transparent crystalline silicon solar cell, so as to solve the technical problems in the prior art that the preparation process of the transparent crystalline silicon solar cell is complicated and the photoelectric conversion efficiency is low.

[0004] Another object of the first aspect of the present invention is to further improve the photoelectric conversion efficiency of transparent crystalline silicon solar cells.

[0005] The second aspect of the present invention aims to provide a transparent crystalline silicon solar cell prepared according to the above preparation method.

[0006] According to the purpose of the first aspect of the present invention, the present invention provides a method for preparing a transparent crystalline silicon solar cell, the preparation method is based on half-cell preparation, the half-cell includes a crystalline silicon wafer and a positive electrode located on one side of the crystalline silicon wafer, the preparation method includes the following steps: Performing reverse micropore etching on the crystalline silicon wafer by using a reactive ion etching process to form a microporous battery including a plurality of micropores; Pre-treating the microporous battery to form a protective layer covering the positive electrode on one side of the microporous battery; The microporous battery is sequentially subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition to sequentially form a silicon oxide passivation layer, an organic molecule chemical modification layer, and a magnesium oxide passivation layer on the sidewalls of the micropores of the microporous battery; A back electrode is deposited on a side of the microporous battery away from the positive electrode, and the protective layer is removed to prepare a transparent crystalline silicon solar cell; wherein, when the silicon oxide layer is deposited, the ozone concentration is any value between 10ppm and 100ppm, the volume fraction of the reaction atmosphere is any value between 90% and 95%, the flow rate of the reaction atmosphere is any value between 0.2L / min and 1.0L / min, and the evaporation rate of the magnesium oxide during deposition is any value between 0.1Å / s and 0.5Å / s.

[0007] Optionally, the acid-treated solution is an HNA solution, and the volume ratio of nitric acid:hydrofluoric acid:acetic acid in the HNA solution is any value in the range of 2.5-3.5:1:1.

[0008] Optionally, the relative humidity of the reaction atmosphere in the silicon oxide deposition is any value between 15% and 30%, and the processing time is any value between 5 min and 15 min.

[0009] Optionally, the thickness of the magnesium oxide passivation layer is any value between 0.5 nm and 5 nm.

[0010] Optionally, the angle between the incident directions of two adjacent magnesium oxide vapors in the magnesium oxide deposition is a preset angle.

[0011] Optionally, the back electrode is made of aluminum or indium tin oxide.

[0012] Optionally, the material of the protective layer is polymethyl methacrylate, and the step of removing the protective layer includes: The microporous battery is soaked in an acetone solution.

[0013] Optionally, the material of the organic molecule modification layer can be any one of APTES and APTMS.

[0014] Optionally, the step of performing reverse micropore etching on the crystalline silicon wafer using a reactive ion etching process further includes the following steps: A single etching process for anisotropic etching of silicon substrate and sidewall protection using etching gas and passivation gas; The single etching procedure is cycled for a preset number of times to prepare the microporous battery; wherein the etching gas is sulfur hexafluoride, and the gas flow rate is any value between 420sccm and 450sccm; the passivation gas is octafluorocyclobutane, and the gas flow rate is any value between 180sccm and 200sccm.

[0015] According to the purpose of the second aspect of the present invention, the present invention also provides a transparent crystalline silicon solar cell prepared according to any one of the preparation methods described above.

[0016] The present invention performs reverse micropore etching on a crystalline silicon wafer in a half-cell with a prepared positive electrode to improve the light transmittance of the microporous battery, and after setting a protective layer on the side of the positive electrode of the microporous battery, the microporous battery is sequentially subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition in a multi-means coordinated passivation treatment manner to prevent the battery grid line and the front pn junction in the positive electrode from being corroded by the acid treatment solution to cause device damage. At the same time, by setting corresponding parameter ranges during the silicon oxide deposition and magnesium oxide deposition processes, the silicon oxide passivation layer and the magnesium oxide passivation layer can be respectively and simultaneously deposited on the back of the microporous battery and the sidewalls of the micropores to form a high-stability composite passivation structure, reduce the surface defect state density, increase the minority carrier lifetime and enhance the long-term stability, thereby effectively improving the photoelectric conversion efficiency and reliability of the transparent crystalline silicon solar cell, and at the same time improving the preparation efficiency of the transparent crystalline silicon solar cell.

[0017] Furthermore, the present invention can remove etching residual impurities and oxide layers, smooth the side walls of the micropores, improve the conformability and continuity of the passivation layer deposition, and further improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell by setting the volume ratio of nitric acid, hydrofluoric acid and acetic acid in the HNA solution within the above range.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings: Figure 1 is a schematic flow chart of a method for preparing a transparent crystalline silicon solar cell according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of a transparent crystalline silicon solar cell according to an embodiment of the present invention; Figure 3 is a schematic cross-sectional view of a transparent crystalline silicon solar cell according to an embodiment of the present invention; Figure 4 is a SEM image of a crystalline silicon wafer according to an embodiment of the present invention; Figure 5 is a schematic flow chart of a method for preparing a microporous battery according to an embodiment of the present invention; Figure 6 is a schematic current-voltage curve diagram of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention and Comparative Example 1; Figure 7 is a SEM image of a transparent crystalline silicon solar cell prepared according to Comparative Example 1 of the present invention; Figure 8 is a SEM image of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention; Fig. 9 This is a physical picture of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention.

[0020] Reference numerals: 100-solar cell, 10-crystalline silicon wafer, 20-positive electrode, 11-micropore, 12-silicon oxide passivation layer, 13-organic molecule modification layer, 14-magnesium oxide passivation layer, 30-back electrode. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0023] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] Figure 1 is a schematic flow chart of a method for preparing a transparent crystalline silicon solar cell according to an embodiment of the present invention. Figure 2 is a schematic structural diagram of a transparent crystalline silicon solar cell according to an embodiment of the present invention, Figure 3 is a schematic cross-sectional view of a transparent crystalline silicon solar cell according to an embodiment of the present invention, Figure 4 is a SEM image of a crystalline silicon wafer according to an embodiment of the present invention, Figure 5 is a schematic flow chart of a method for preparing a microporous battery according to an embodiment of the present invention, Figure 6 is a schematic current-voltage curve diagram of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention and Comparative Example 1, Figure 7 is a SEM image of a transparent crystalline silicon solar cell prepared according to Comparative Example 1 of the present invention, Figure 8 is a SEM image of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention, Fig. 9 This is a physical picture of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention.

[0026] like Figure 2 As shown, the present invention provides a method for preparing a transparent crystalline silicon solar cell. The preparation method is based on half-cell preparation. The half-cell includes a crystalline silicon wafer 10 and a positive electrode 20 located on one side of the crystalline silicon wafer 10. That is, the preparation method of the present invention is based on a semi-finished half-cell in which a positive electrode 20 has been prepared on one side of the crystalline silicon wafer 10 to prepare a transparent crystalline silicon solar cell 100.

[0027] It should be noted that the preparation method of the present invention is based on the preparation of the transparent crystalline silicon solar cell 100 based on the half-cell with the positive electrode 20 prepared, which can not only reduce the time cost of preparing the transparent crystalline silicon solar cell 100, but also reduce the process cost of the transparent crystalline silicon solar cell 100, and reduce the process difficulty of directly preparing the positive electrode 20 with a complex structure on the surface of the etched micropore 11. In addition, since the surface of the half-cell used in the present invention already includes the positive electrode 20, directly using acid treatment will damage the structure of the positive electrode 20, resulting in the photoelectric performance of the prepared transparent crystalline silicon solar cell 100 being damaged, and a plurality of spaced micropores 11 have been prepared on the surface of the micropore cell, when silicon oxide deposition or magnesium oxide deposition is performed simultaneously on the side wall of the micropore 11 and the back of the crystalline silicon wafer 10, since each micropore 11 has a preset aspect ratio, the conventional silicon oxide deposition or magnesium oxide deposition process is directly used to deposit the silicon oxide passivation layer 12 or the magnesium oxide passivation layer 14 on the back of the crystalline silicon wafer 10 and the side wall of the micropore 11, and the corresponding uniformly covered passivation layer cannot be deposited on the back of the crystalline silicon wafer 10 and the side wall of the micropore at the same time.

[0028] In order to solve the above-mentioned multiple technical problems at the same time, the present invention provides a method for preparing a transparent crystalline silicon solar cell 100 (refer to Figure 1 ), including the following steps: Step S100: Reversely etch the micropores 11 on the crystalline silicon wafer 10 using a reactive ion etching process to form a microporous battery including a plurality of micropores 11 (refer to Figure 4 ); Step S200: pre-treating the microporous battery to form a protective layer covering the positive electrode 20 on one side of the microporous battery; Step S300: The microporous battery is subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition in sequence to form a silicon oxide passivation layer 12, an organic molecule modification layer 13 and a magnesium oxide passivation layer 14 on the sidewalls of the micropores 11 of the microporous battery in sequence (refer to Figure 3 ); Step S400: depositing a back electrode 30 on a side of the microporous battery away from the positive electrode 20, and removing the protective layer to prepare a transparent crystalline silicon solar cell 100; wherein, the ozone concentration during the deposition of the silicon oxide layer is any value between 10ppm and 100ppm, the volume fraction of the reaction atmosphere is any value between 90% and 95%, the flow rate of the reaction atmosphere is any value between 0.2L / min and 1.0L / min, and the evaporation rate during the deposition of magnesium oxide is any value between 0.1Å / s and 0.5Å / s.

[0029] In the present embodiment, during the preparation process of the transparent crystalline silicon solar cell 100, the crystalline silicon wafer 10 is firstly etched with reverse micropores 11 by using a reactive ion etching process to form a plurality of spaced micropores 11 on the back side of the crystalline silicon wafer 10 of the half-cell to prepare a microporous battery. The microporous battery is then pretreated to form a protective layer coated on the positive electrode 20 on one side of the microporous battery. The microporous battery is then subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition in sequence to form a silicon oxide passivation layer 12, an organic molecule modification layer 13 and a magnesium oxide passivation layer 14 on the side walls of the micropores 11 of the microporous battery in sequence. Finally, a back electrode 30 is deposited on the side of the microporous battery away from the positive electrode 20 and the protective layer is removed to prepare the transparent crystalline silicon solar cell 100. Here, the ozone concentration during the deposition of the silicon oxide layer can be 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm or 100ppm, or any value between 10ppm and 100ppm, the volume fraction of the reaction atmosphere can be 90%, 91%, 92%, 93%, 94% or 95%, or any value between 90% and 95%, and the flow rate of the reaction atmosphere can be 0.2L / min , 0.3L / min, 0.4L / min, 0.5L / min, 0.6L / min, 0.7L / min, 0.8L / min, 0.9L / min or 1.0L / min, and can also be any value from 0.2L / min to 1.0L / min. The evaporation rate during magnesium oxide deposition can be 0.1Å / s, 0.2Å / s, 0.3Å / s, 0.4Å / s or 0.5Å / s, and can also be any value from 0.1Å / s to 0.5Å / s.

[0030] In this embodiment, the crystalline silicon wafer 10 in the half-cell with the positive electrode 20 prepared is reversely etched to the micropores 11 to improve the transmittance of the microporous battery, and after a protective layer is set around the positive electrode 20 of the microporous battery, the microporous battery is sequentially subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition in a multi-means coordinated passivation treatment manner to prevent the battery grid line and the front pn junction in the positive electrode 20 from being corroded by the acid treatment solution and causing device damage. At the same time, by setting corresponding parameter ranges during the silicon oxide deposition and magnesium oxide deposition processes, the silicon oxide passivation layer 12 and the magnesium oxide passivation layer 14 can be deposited on the back of the microporous battery and the sidewalls of the micropores 11 respectively, so as to form a high-stability composite passivation structure, reduce the interface defect state density, increase the minority carrier lifetime and enhance the long-term stability, thereby effectively improving the photoelectric conversion efficiency and reliability of the transparent crystalline silicon solar cell 100, and at the same time improving the preparation efficiency of the transparent crystalline silicon solar cell 100.

[0031] In this embodiment, step S200 includes the following steps: Prepare a polymethyl methacrylate solution of a preset concentration; The polymethyl methacrylate solution is spin-coated on the surface of a glass slide, and the positive electrode 20 of the half-cell is attached to the polymethyl methacrylate solution on the glass slide.

[0032] In this embodiment, the positive electrode 20 of the half-cell is attached to the polymethyl methacrylate solution of the slide glass to form a protective layer around the positive electrode 20 to prevent damage to the structure of the positive electrode 20 during subsequent acid treatment, thereby reducing the effect of the acid treatment on the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100. Here, the concentration of the polymethyl methacrylate solution is any value between 180 mg / mL and 200 mg / mL, that is, the concentration of the polymethyl methacrylate solution can be 180 mg / mL, 185 mg / mL, 190 mg / mL, 195 mg / mL or 200 mg / mL, or any value between 180 mg / mL and 200 mg / mL. Here, the polymethyl methacrylate solution can also be replaced by a polyethylene solution or a polypropylene solution.

[0033] In this embodiment, the silicon oxide deposition method is an ultraviolet ozone oxidation process. By setting the ozone concentration, reaction atmosphere and gas flow rate of silicon oxide deposition within the above range, a silicon oxide passivation layer 12 can be formed on the back of the microporous battery and the side wall of the micropore 11 at the same time, thereby improving the deposition uniformity of the side wall and the bottom of the micropore 11, improving the coverage consistency of the silicon oxide layer, and improving the penetration depth and passivation integrity of ozone in the high aspect ratio micropore 11, which is beneficial to improving the device interface recombination characteristics and obtaining a silicon oxide passivation layer 12 with low defects and good adhesion. That is, by in-situ growth of the silicon oxide passivation layer 12, the interface state density can be effectively reduced, the carrier recombination loss can be reduced, and the silicon oxide passivation layer 12 can be used as a buffer layer to optimize the film quality of the subsequent magnesium oxide passivation layer 14. In other embodiments, the silicon oxide passivation layer 12 can also be prepared by thermal oxidation.

[0034] In this embodiment, the magnesium oxide is deposited by a thermal evaporation process. By setting the evaporation rate and evaporation temperature during magnesium oxide deposition within the above range, it is helpful to form a dense, continuous, and fully covered magnesium oxide passivation layer 14, enhance the passivation effect and improve the interface stability. In addition, since the magnesium oxide passivation layer 14 is formed before the back electrode 30 is deposited, the metal diffusion into the hole of the back electrode 30 is reduced, and the electrical insulation and environmental stability of the hole area are improved. In addition, the interface adhesion between magnesium oxide and silicon oxide can be improved, and interface delamination, voids, and pinholes caused by high stress or high defect density can be avoided, and the growth basis of the magnesium oxide passivation layer 14 surface to the back electrode 30 can be improved. Here, the evaporation temperature of magnesium oxide deposition is any value between 100°C and 150°C, and the evaporation temperature can be 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, or any value between 100°C and 150°C.

[0035] In this embodiment, the reaction time of the acid treatment is any value between 40s and 60s, that is, the reaction time of the acid treatment can be 40s, 45s, 50s, 55s or 60s, or any value between 40s and 60s. By setting the reaction time of the acid treatment within the above range, the nano-scale burrs and residues generated by etching can be properly etched away, the jagged structure of the side wall can be reduced, and the dense adhesion and uniform coating of the subsequent silicon oxide passivation layer 12 and the magnesium oxide passivation layer 14 can be facilitated, the surface trap state density can be further reduced, and the interface passivation ability can be enhanced.

[0036] In a further embodiment, the material of the organic molecule modification layer can be any one of APTES ((3-Aminopropyl)triethoxysilane, 3-aminopropyltriethoxysilane) or APTMS ((3-Aminopropyl)trimethoxysilane, 3-aminopropyltrimethoxysilane). In this embodiment, the volume fraction of the organic molecule solution used for chemical modification of organic molecules is any value from 0.5% to 1.5%, that is, the volume fraction of APTES or APTMS in the organic molecule solution can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%, or any value from 0.5% to 1.5%. By setting the volume fraction of the organic molecule solution used for chemical modification of organic molecules within the above range, the amino functionalization of the micropores 11 and the side walls can be precisely controlled, the interfacial adhesion of the passivation layer and the subsequent transparent electrode can be improved, the interfacial recombination and stress failure can be reduced, and the performance and stability of the solar cell 100 can be improved.

[0037] In this embodiment, during the organic molecule chemical modification process, the microporous battery is soaked in the organic molecule solution and deionized water for a first preset time and a second preset time in sequence, wherein the first preset time is any value from 20min to 30min, and the second preset time is any value from 1.5h to 2h, so as to achieve the modification of the siloxane molecules on the side walls of the micropores 11. That is, through the above-mentioned organic molecule chemical modification treatment, the side walls of the micropores 11 are uniformly amino-modified, which is convenient for the stable curing mode of the silane structure, improves the interface bonding ability, prevents the pores of the micropores 11 from being blocked, and provides a clean and stable interface for the subsequent deposition of transparent electrodes or functional layers, thereby improving the device performance and long-term reliability. Here, the first preset time can be 20min, 22min, 24min, 26min, 28min or 30min, or any value from 20min to 30min, and the second preset time can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, or any value from 1.5h to 2h.

[0038] In this embodiment, the plurality of micropores 11 in the microporous battery are arranged at intervals to maintain electrical connection and mechanical strength while improving the light transmittance of the transparent crystalline silicon solar cell 100. Here, the diameter of the micropore 11 is any value in the range of 5μm-20μm, that is, the diameter of the micropore 11 can be 5μm, 10μm, 15μm or 20μm, or any value in the range of 5μm-20μm, and the spacing between adjacent micropores 11 is any value in the range of 10μm-50μm, that is, the spacing between adjacent micropores 11 can be 10μm, 20μm, 30μm, 40μm or 50μm, or any value in the range of 10μm-50μm. By setting the diameter of the micropore 11 and the spacing between the micropores 11 within the above range, transparency can be ensured while maintaining electrical and mechanical stability. Here, the diameter of the micropore 11 and the spacing between adjacent micropores 11 can be selectively prepared according to the light transmittance and photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0039] In a further embodiment, the acid-treated solution is an HNA solution, and the volume ratio of nitric acid: hydrofluoric acid: acetic acid in the HNA solution is any value in 2.5-3.5: 1: 1, that is, the volume ratio of nitric acid: hydrofluoric acid: acetic acid in the HNA solution can be 2.5: 1: 1, 2.7: 1: 1, 2.9: 1: 1, 3.0: 1: 1, 3.1: 1: 1, 3.3: 1: 1 or 3.5: 1: 1, or any value in 2.5-3.5: 1: 1. By setting the volume ratio of nitric acid, hydrofluoric acid and acetic acid in the HNA solution within the above range, it is possible to remove etching residual impurities and oxide layers, smoothen the sidewalls of the micropores 11, and improve the conformability and continuity of the deposition of the passivation layer, thereby further improving the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100. Here, when the HNA solution is prepared, the mass concentration of the added nitric acid is 68wt%, the mass concentration of the hydrofluoric acid is 40wt%, and the mass concentration of the acetic acid is 99.5wt%.

[0040] In a further embodiment, the relative humidity of the reaction atmosphere during silicon oxide deposition is any value between 15% and 30%, and the processing time is any value between 5 min and 15 min, that is, the relative humidity during silicon oxide deposition can be 15%, 20%, 25% or 30%, or any value between 15% and 30%, and the processing time can be 5 min, 7 min, 9 min, 10 min, 12 min or 15 min, or any value between 5 min and 15 min. By setting the relative humidity and processing time of the silicon oxide deposition process within the above range, it is beneficial to control the surface quality and distribution uniformity of the silicon oxide passivation layer 12, and prepare a silicon oxide passivation layer 12 with moderate thickness and stability. Here, the reaction atmosphere can be air or oxygen.

[0041] In a further embodiment, the thickness of the magnesium oxide passivation layer 14 is any value in the range of 0.5 nm to 5 nm, that is, the thickness of the magnesium oxide passivation layer 14 can be 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm or 5 nm, or any value in the range of 5 nm to 15 nm. By setting the thickness of the magnesium oxide passivation layer 14 within the above range, the side walls of the micropores 11 of the microporous battery and the back surface are further covered, the surface roughness of the side walls of the micropores 11 is reduced, and a low resistance is maintained, thereby optimizing the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0042] In a further embodiment, the angle between the incident directions of the magnesium oxide vapors deposited two times in the magnesium oxide deposition is a preset angle. That is, in the magnesium oxide deposition process, by adjusting the incident direction of the magnesium oxide vapor, the magnesium oxide vapor can act on the side wall of the micropore 11 in different directions, realizing multi-directional and co-form deposition, effectively covering the side wall area that is difficult to deposit directly, thereby improving the deposition uniformity of the magnesium oxide passivation layer 14 on the side wall surface of the micropore 11, avoiding the uneven film thickness that may be caused by one-time long-term deposition at the same position, reducing the film stress during the deposition process, preventing the magnesium oxide passivation layer 14 from being too thick and affecting the performance of the transparent crystalline silicon solar cell 100, thereby improving the deposition quality of the magnesium oxide passivation layer 14, reducing thermal stress, and reducing the rupture or shedding of the magnesium oxide passivation layer 14.

[0043] In this embodiment, the preset angle is any value in the range of 15°-30°, that is, during the magnesium oxide deposition process, the angle of the incident direction of the magnesium oxide vapor on the adjacent two sides can be 15°, 18°, 20°, 25° or 30°, or any value in the range of 15°-30°. By setting the preset angle within the above range, the microstructure coverage of the magnesium oxide passivation layer 14 can be improved, and the poor sidewall or back coverage caused by the shielding effect of the micropores 11 or the surface structure caused by the single-direction deposition can be prevented, that is, by adjusting the incident direction of the magnesium oxide vapor, the steam beam can be sprayed from multiple directions to effectively enter the sidewall or recessed area, thereby improving the overall coverage and uniformity of the magnesium oxide passivation layer 14. At the same time, steam with different incident angles promotes the multi-directional growth of grains, which is conducive to the formation of a continuous and dense magnesium oxide passivation layer 14, reducing defects such as voids and cracks.

[0044] In a further embodiment, the material of the back electrode 30 is any one of aluminum or indium tin oxide. That is, aluminum or indium tin oxide can be used as the back electrode 30 and deposited on the back of the crystalline silicon wafer 10. Aluminum has the characteristics of low cost, good conductivity, and low reflectivity, and is suitable for preparing low-cost and high-demand transparent crystalline silicon solar cells 100. Indium tin oxide has a high photoelectric conversion efficiency and is suitable for preparing transparent or semi-transparent crystalline silicon solar cells 100. Here, the corresponding back electrode material can be selected according to the required characteristics of the transparent crystalline silicon solar cell 100.

[0045] In a further embodiment, the step of removing the protective layer includes: The microporous battery was soaked in acetone solution.

[0046] In this embodiment, the microporous battery is soaked in an acetone solution to dissolve the polymethyl methacrylate around the positive electrode 20 in the microporous battery, thereby exposing the positive electrode 20 of the microporous battery. The acetone solution can effectively remove the polymethyl methacrylate without generating other pollutants, thereby avoiding the influence of surface residues on the electrode structure, thereby reducing the contact resistance or performance degradation caused by contamination. Here, after being treated with the acetone solution, the battery is repeatedly cleaned with an ethanol solution until the surface is clean, and finally dried with nitrogen.

[0047] like Figure 5 As shown, in a further embodiment, step S100 further includes the following steps: Step S110: using etching gas and passivation gas to implement a single etching process of anisotropic etching of the silicon substrate and sidewall protection; Step S120: Repeat the single etching procedure for a preset number of times to prepare a microporous battery.

[0048] In step S100, when the crystalline silicon wafer 10 is etched in reverse micropores 11 by reactive ion etching, the etching gas is first used to achieve anisotropic etching of the silicon substrate, and then the passivation gas is used to perform preliminary passivation on the etched sidewalls to achieve preliminary passivation protection of the sidewalls by the passivation gas, thereby completing a single etching procedure, and repeating the single etching procedure according to a preset number of cycles, thereby preparing a microporous battery. That is, the preparation of a microporous structure with a preset aspect ratio is achieved through precise timing control, which not only can achieve the formation of a high anisotropic microporous structure, but also can utilize the alternate injection of the passivation gas to form a layer of polymerized fluorocarbon passivation film in the etching gap, perform preliminary passivation protection on the sidewalls of the micropores 11, and prevent them from being lateral eroded by the etching gas, thereby reducing the roughness of the sidewalls, avoiding the formation of collapsed edges or jagged irregular morphologies in the sidewalls of the micropores 11, and facilitating the deposition uniformity of subsequent passivation layers, modification layers or transparent electrodes. Here, the preset aspect ratio is any value in the range of 5-20, that is, the aspect ratio of a single microhole 11 can be 5, 10, 15 or 20, or any value in the range of 5-20.

[0049] In this embodiment, the etching time of the etching gas in the single etching procedure is any value from 8s to 9s, the etching time of the passivation gas is any value from 2s to 3s, and the total etching time of the reverse micropore 11 is any value from 30min to 35min, so as to prepare the micropore 11 with a preset aspect ratio. Here, the etching time of the etching gas can be 8s, 8.2s, 8.4s, 8.6s, 8.8s or 9s, or any value from 8s to 9s, the etching time of the passivation gas can be 2s, 2.2s, 2.4s, 2.6, 2.8s or 3s, or any value from 2s to 3s, and the total etching time of the reverse micropore 11 can be 30min, 31min, 32min, 33min, 34min or 35min, or any value from 30min to 35min.

[0050] In a further embodiment, the etching gas is sulfur hexafluoride, and the gas flow rate is any value between 420sccm and 450sccm; the passivation gas is octafluorocyclobutane, and the gas flow rate is any value between 180sccm and 200sccm. That is, the gas flow rate of the etching gas can be 420sccm, 425sccm, 430sccm, 435sccm, 440sccm, 445sccm or 450sccm, or any value between 420sccm and 450sccm, and the gas flow rate of the passivation gas can be 180sccm, 185sccm, 190sccm, 195sccm or 200sccm, or any value between 180sccm and 200sccm. By setting the etching gas to sulfur hexafluoride, the passivation gas to octafluorocyclobutane, and setting the gas flow rates of the etching gas and the passivation gas within the above range, a higher reactive atmosphere density can be provided, ensuring a stable etching process and a moderate etching rate, while maintaining a suitable etching rate. At the same time, it is avoided that etching too fast causes the hole shape to be out of control or the silicon structure to be damaged, which is conducive to achieving high aspect ratio etching in the vertical direction. At the same time, the passivation gas has uniform coverage and controllable thickness, which can effectively inhibit lateral etching, protect the side walls, and improve the verticality and flatness of the micropores 11.

[0051] The present invention also provides a transparent crystalline silicon solar cell 100 prepared according to any one of the above preparation methods. The preparation method of the transparent crystalline silicon solar cell 100 will not be described in detail here.

[0052] The present application will be further described in detail below with reference to specific embodiments.

[0053] Example 1 In this embodiment, the crystalline silicon wafer 10 is firstly etched with reverse micropores 11 by using a reactive ion etching process. The etching time of sulfur hexafluoride in each etching procedure in the reactive ion etching process is 9s, the gas flow rate is 430sccm, the etching time of octafluorocyclobutane is 2s, the gas flow rate is 190sccm, and the total etching time of the reactive ion etching process is 32min, so as to form a microporous battery including a plurality of micropores 11, the diameter of the micropore 11 is 15μm, and the aspect ratio is 5. Then, a polymethyl methacrylate solution with a concentration of 190mg / mL is spin-coated on the surface of a glass slide, and the positive electrode 20 of the half-cell is attached to the polymethyl methacrylate solution on the glass slide to form a protective layer covering the side of the positive electrode 20. Then, the microporous battery is acid-treated with a HNA solution with a volume ratio of nitric acid: hydrofluoric acid: acetic acid of 3.0:1:1, and a silicon oxide layer is deposited by an ultraviolet ozone oxidation process to form a microporous battery. A silicon oxide passivation layer 12 is formed, and then the microporous battery is immersed in an APTES solution with a volume fraction of 1% for APTES modification, and magnesium oxide is deposited by a thermal evaporation process to sequentially form an APTES modification layer 13 and a magnesium oxide passivation layer 14 with a thickness of 2 nm on the side walls of the micropores 11 of the microporous battery, and then an aluminum back electrode 30 is deposited on the side of the microporous battery away from the positive electrode 20, and finally the microporous battery is immersed in an acetone solution to remove the protective layer to prepare a transparent crystalline silicon solar cell 100, the reaction time of the acid treatment is 50s, the ozone concentration during silicon oxide deposition is 70ppm, the relative humidity of the reaction atmosphere is 20%, the reaction time is 10min, the volume fraction of the reaction atmosphere is 92%, the flow rate of the reaction atmosphere is 0.5L / min, the evaporation rate during magnesium oxide deposition is 0.1Å / s, the evaporation temperature is 120℃, and the angle of the incident direction of magnesium oxide vapor is 15°.

[0054] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the magnesium oxide passivation layer 14 is not prepared for the microporous battery.

[0055] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the microporous battery is not subjected to the preparation of the magnesium oxide passivation layer 14 and the APTES modification.

[0056] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the microporous battery is not subjected to the preparation of the magnesium oxide passivation layer 14, the APTES modification and the preparation of the silicon oxide passivation layer 12.

[0057] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the microporous battery is not subjected to the steps of preparing the magnesium oxide passivation layer 14, APTES modification, preparing the silicon oxide passivation layer 12, and acid treatment.

[0058] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that only the microporous battery is modified with APTES.

[0059] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that only the magnesium oxide passivation layer 14 is prepared for the microporous battery.

[0060] First, the photoelectric conversion efficiency of the transparent crystalline silicon solar cells 100 prepared in Example 1 and Comparative Examples 1-6 was tested, and the test results shown in Table 1 were obtained.

[0061]

[0062] As shown in Table 1, the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100 prepared in Example 1 is significantly higher than that of Comparative Examples 1-6, indicating that the synergistic passivation treatment using acid treatment, silicon oxide layer deposition, organic molecule chemical modification and magnesium oxide deposition can significantly improve the interface state density of the side wall of the transparent crystalline silicon solar cell 100, reduce carrier recombination losses, effectively reduce surface recombination, and improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0063] Then, the electrical performance of the transparent crystalline silicon solar cell 100 prepared in Example 1 and Comparative Example 3 was tested, and the following results were obtained: Figure 6 The current-voltage curve is shown in FIG. 2 and the electrical performance test results are shown in FIG.

[0064]

[0065] like Figure 6 As shown, the black curve is the current-voltage curve of the transparent crystalline silicon solar cell 100 prepared in comparative example 3, and the green curve is the current-voltage curve of the transparent crystalline silicon solar cell 100 prepared in Example 1. As shown in Table 2, the open circuit voltage, short circuit current density and fill factor of the transparent crystalline silicon solar cell 100 prepared in Example 1 are greater than those of the transparent crystalline silicon solar cell 100 prepared in comparative example 3, and the photoelectric conversion efficiency of Example 1 is significantly higher than that of comparative example 3, indicating that the synergistic effect of multiple passivation means can significantly improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0066] Finally, the transparent crystalline silicon solar cell 100 prepared in Example 1 and Comparative Example 3 was characterized by scanning electron microscopy, and the following results were obtained: Figure 7 and Figure 8 The SEM image shown. Figure 7 As shown in FIG. 1 , the surface roughness of the sidewalls of the micropores 11 of the transparent crystalline silicon solar cell 100 that has only been subjected to acid treatment is relatively high, and the surface flatness is relatively low. Figure 8As shown, after the synergistic effect of multiple passivation methods, the side walls of the micropores 11 of the transparent crystalline silicon solar cells 100 prepared in Example 1 and Comparative Example 3 are smooth.

[0067] like Fig. 9 As shown, the transparent crystalline silicon solar cell 100 prepared in Example 1 was subjected to a light transmittance test, indicating that the transparent crystalline silicon solar cell 100 prepared in Example 1 has a high light transmittance.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a transparent crystalline silicon solar cell, characterized in that: The preparation method is based on half-cell preparation, wherein the half-cell comprises a crystalline silicon wafer and a positive electrode located on one side of the crystalline silicon wafer, and the preparation method comprises the following steps: Performing reverse micropore etching on the crystalline silicon wafer by using a reactive ion etching process to form a microporous battery including a plurality of micropores; Pre-treating the microporous battery to form a protective layer covering the positive electrode on one side of the microporous battery; The microporous battery is sequentially subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition to sequentially form a silicon oxide passivation layer, an organic chemical modification layer, and a magnesium oxide passivation layer on the sidewalls of the micropores of the microporous battery; A back electrode is deposited on a side of the microporous battery away from the positive electrode, and the protective layer is removed to prepare a transparent crystalline silicon solar cell; wherein, when the silicon oxide layer is deposited, the ozone concentration is any value between 10ppm and 100ppm, the volume fraction of the reaction atmosphere is any value between 90% and 95%, the flow rate of the reaction atmosphere is any value between 0.2L / min and 1.0L / min, and the evaporation rate of the magnesium oxide during deposition is any value between 0.1Å / s and 0.5Å / s.

2. The preparation method according to claim 1, characterized in that: The acid-treated solution is an HNA solution, and the volume ratio of nitric acid:hydrofluoric acid:acetic acid in the HNA solution is any value in the range of 2.5-3.5:1:

1.

3. The preparation method according to claim 2, characterized in that: The relative humidity of the reaction atmosphere during the deposition of the silicon oxide layer is any value between 15% and 30%, and the processing time is any value between 5 minutes and 15 minutes.

4. The preparation method according to claim 3, characterized in that: The thickness of the magnesium oxide passivation layer is any value between 0.5 nm and 5 nm.

5. The preparation method according to claim 4, characterized in that: The included angle between two adjacent incident directions of magnesium oxide vapor in the magnesium oxide deposition is a preset angle.

6. The preparation method according to claim 5, characterized in that: The material of the back electrode is any one of aluminum and indium tin oxide.

7. The preparation method according to any one of claims 1 to 6, characterized in that The material of the protective layer is polymethyl methacrylate, and the step of removing the protective layer includes: The microporous battery is soaked in an acetone solution.

8. The preparation method according to claim 7, characterized in that: The material of the organic molecule modification layer can be any one of APTES and APTMS.

9. The preparation method according to claim 8, characterized in that: The step of performing reverse micropore etching on the crystalline silicon wafer using a reactive ion etching process also includes the following steps: A single etching process for anisotropic etching of silicon substrate and sidewall protection using etching gas and passivation gas; The single etching procedure is cycled for a preset number of times to prepare the microporous battery; wherein the etching gas is sulfur hexafluoride, and the gas flow rate is any value between 420sccm and 450sccm; the passivation gas is octafluorocyclobutane, and the gas flow rate is any value between 180sccm and 200sccm.

10. A transparent crystalline silicon solar cell, characterized in that: Prepared according to the preparation method described in any one of claims 1 to 9.

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