A transparent crystalline silicon solar cell and a preparation method thereof

Abstract

The present invention discloses a transparent crystalline silicon solar cell and a preparation method thereof, relating to the technical field of photoelectric conversion. The preparation method is based on the preparation of half-cells. The half-cell includes a crystalline silicon wafer and a positive electrode located on one side of the crystalline silicon wafer. The preparation method comprises the following steps: performing reverse microporous etching on the crystalline silicon wafer by using a reactive ion etching process to form a microporous cell including a plurality of micropores; pre-treating the microporous cell to form a protective layer covering the positive electrode on one side of the microporous cell; successively performing acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition on the microporous cell to successively form a silicon oxide passivation layer, an organic molecule modification layer, and a magnesium oxide passivation layer on the side walls of the micropores of the microporous cell; depositing a back electrode on the side of the microporous cell away from the positive electrode to prepare a transparent crystalline silicon solar cell. The transparent crystalline silicon solar cell prepared by the present invention has high photoelectric conversion efficiency, light transmittance, and preparation efficiency.

Description

Technical Field

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

[0002] In the prior art, the preparation of a transparent crystalline silicon solar cell is usually based on preparing micron-sized through holes in crystalline silicon and then preparing a positive electrode. This preparation method not only causes a significant increase in the specific surface area of the cell, and the recombination loss caused by surface defects results in a low photoelectric conversion efficiency, but also complicates the preparation process of the positive electrode due to the setting of the through holes, affecting the preparation efficiency of the transparent crystalline silicon solar cell. Moreover, although chemical treatment with an acid solution can smooth the surface of the microporous sidewalls of the transparent crystalline silicon solar cell in the prior art, there is still a certain roughness on the sidewalls. In addition, the smoothing treatment only deals with macroscopic defects, and there are still microscopic defects and a large number of dangling bonds on the sidewall surface, affecting 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 preparation method of a transparent crystalline silicon solar cell, so as to solve the technical problems of complex preparation process and low photoelectric conversion efficiency of the transparent crystalline silicon solar cell in the prior art.

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

[0005] An object of the second aspect of the present invention is to provide a transparent crystalline silicon solar cell obtained by the above preparation method.

[0006] According to the object of the first aspect of the present invention, the present invention provides a preparation method of 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:

[0007] Performing reverse microporous etching on the crystalline silicon wafer in the half-cell with the positive electrode already prepared by using a reactive ion etching process to form a microporous cell including a plurality of micropores;

[0008] Performing pretreatment on the microporous cell to form a protective layer covering the positive electrode on one side of the microporous cell;

[0009] Performing acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition on the microporous cell in sequence to 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 cell in sequence;

[0010] Deposit a back electrode on the side of the microporous battery away from the positive electrode, and remove the protective layer to obtain a transparent crystalline silicon solar cell; wherein, when depositing the silicon oxide layer, the ozone concentration is any value from 10 ppm to 100 ppm, the volume fraction of the reaction atmosphere is any value from 90% to 95%, the flow rate of the reaction atmosphere is any value from 0.2 L / min to 1.0 L / min, and the evaporation rate when depositing the magnesium oxide is any value therein.

[0011] Optionally, the solution for acid treatment is an HNA solution, and the volume ratio of nitric acid: hydrofluoric acid: acetic acid in the HNA solution is any value from 2.5 - 3.5:1:1.

[0012] Optionally, the relative humidity of the reaction atmosphere during the silicon oxide deposition is any value from 15% to 30%, and the treatment time is any value from 5 min to 15 min.

[0013] Optionally, the thickness of the magnesium oxide passivation layer is any value from 0.5 nm to 5 nm.

[0014] Optionally, the included angle between the incident directions of adjacent magnesium oxide vapors during the magnesium oxide deposition is a preset angle.

[0015] Optionally, the material of the back electrode is any one of aluminum or indium tin oxide.

[0016] Optionally, the material of the protective layer is polymethyl methacrylate, and the step of removing the protective layer includes:

[0017] Soak the microporous battery with an acetone solution.

[0018] Optionally, the material of the organic molecular modification layer can be any one of APTES or APTMS.

[0019] Optionally, in the step of performing reverse microporous etching on the crystalline silicon wafer using a reactive ion etching process, the following steps are further included:

[0020] Implement a single etching process for anisotropic etching of the silicon substrate and sidewall protection using an etching gas and a passivation gas;

[0021] Repeat the single etching process for a preset number of times to obtain the microporous battery; wherein, the etching gas is sulfur hexafluoride, and the gas flow rate is any value from 420 sccm to 450 sccm, and the passivation gas is perfluorocyclobutane, and the gas flow rate is any value from 180 sccm to 200 sccm.

[0022] According to the object of the second aspect of the present invention, the present invention also provides a transparent crystalline silicon solar cell prepared by the preparation method according to any one of the above.

[0023] In the present invention, the crystalline silicon wafer in the half cell with the positive electrode already prepared is subjected to reverse microporous etching to improve the light transmittance of the microporous cell. After a protective layer is provided on the peripheral side of the positive electrode of the microporous cell, the microporous cell is sequentially subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition by means of multi-means collaborative passivation treatment to prevent the cell grid lines and the front pn junction in the positive electrode from being corroded by the acid treatment solution and causing device damage. At the same time, by setting the 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 deposited on the back surface and the side walls of the micropores of the microporous cell simultaneously to form a high-stability composite passivation structure, reduce the surface defect state density, improve 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.

[0024] Further, by setting the volume ratio of nitric acid, hydrofluoric acid, and acetic acid in the HNA solution within the above range, the present invention can remove the etching residual impurities and the oxide layer, smooth the side walls of the micropores, improve the adhesion and continuity of the passivation layer deposition, and thus further improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell.

[0025] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and describes them in detail in conjunction with the drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the drawings in an exemplary rather than restrictive manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0027] 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;

[0028] Figure 2 is a schematic structural diagram of a transparent crystalline silicon solar cell according to an embodiment of the present invention;

[0029] Figure 3 is a schematic cross-sectional view of a transparent crystalline silicon solar cell according to an embodiment of the present invention;

[0030] Figure 4is the SEM image of a crystalline silicon wafer according to an embodiment of the present invention;

[0031] Figure 5 is a schematic flowchart of a preparation method of a microporous battery according to an embodiment of the present invention;

[0032] Figure 6 is a schematic current-voltage curve graph of a transparent crystalline silicon solar cell prepared according to Example 1 and Comparative Example 1 of the present invention;

[0033] Figure 7 is the SEM image of a transparent crystalline silicon solar cell prepared according to Comparative Example 1 of the present invention;

[0034] Figure 8 is the SEM image of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention;

[0035] Figure 9 is a physical diagram of a transparent crystalline silicon solar cell prepared according to Example 1 of the present invention.

[0036] Reference numerals:

[0037] 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 embodiments

[0038] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0039] To make the above objects, features, and advantages of the present application more obvious and understandable, the following combines the drawings to make a detailed description of the specific embodiments of the present application. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the convenience of description, only the parts related to the present application are shown in the drawings, rather than all the structures. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0040] The terms "including" and "having" in the present application and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0041] References to "embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0042] 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 an 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 graph of a transparent crystalline silicon solar cell prepared according to Embodiment 1 and Comparative Example 1 of the present invention, Figure 7 is an SEM image of a transparent crystalline silicon solar cell prepared according to Comparative Example 1 of the present invention, Figure 8 is an SEM image of a transparent crystalline silicon solar cell prepared according to Embodiment 1 of the present invention, Figure 9 is a physical diagram of a transparent crystalline silicon solar cell prepared according to Embodiment 1 of the present invention.

[0043] As Figure 2 shown, the present invention provides a method for preparing a transparent crystalline silicon solar cell. The preparation method is based on the preparation of half-cells. 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 the semi-finished half-cell with the positive electrode 20 already prepared on one side of the crystalline silicon wafer 10 to prepare the transparent crystalline silicon solar cell 100.

[0044] It should be noted that the preparation method of the present invention is based on a half-cell with a prepared positive electrode 20 for the preparation of the transparent crystalline silicon solar cell 100. It 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 micropores 11. In addition, since the surface of the half-cell used in the present invention already includes the positive electrode 20, direct acid treatment will damage the structure of the positive electrode 20, resulting in damage to the optoelectronic performance of the prepared transparent crystalline silicon solar cell 100. Moreover, since multiple micropores 11 arranged at intervals have been prepared on the surface of the micropore cell, when silicon oxide deposition or magnesium oxide deposition is carried out on the side wall of the micropore 11 and the back surface of the crystalline silicon wafer 10 simultaneously, due to each micropore 11 having a preset depth-width ratio, directly using a conventional silicon oxide deposition or magnesium oxide deposition process to deposit the silicon oxide passivation layer 12 or magnesium oxide passivation layer 14 on the back surface of the crystalline silicon wafer 10 and the side wall of the micropore 11 cannot deposit a corresponding uniformly covered passivation layer on the back surface of the crystalline silicon wafer 10 and the side wall of the micropore simultaneously.

[0045] In order to solve the above-mentioned multiple technical problems simultaneously, the present invention provides a preparation method of a transparent crystalline silicon solar cell 100 (refer to Figure 1 ), which includes the following steps:

[0046] Step S100: Using a reactive ion etching process to perform reverse micropore 11 etching on the crystalline silicon wafer 10 in the half-cell with a prepared positive electrode to form a micropore cell including multiple micropores 11 (refer to Figure 4 );

[0047] Step S200: Pretreating the micropore cell to form a protective layer covering the positive electrode 20 on one side of the micropore cell;

[0048] Step S300: Sequentially performing acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition on the micropore cell to sequentially form a silicon oxide passivation layer 12, an organic molecule modification layer 13, and a magnesium oxide passivation layer 14 on the side wall of the micropore 11 in the micropore cell (refer to Figure 3 );

[0049] Step S400: Depositing a back electrode 30 on the side of the micropore cell away from the positive electrode 20 and removing the protective layer to prepare the transparent crystalline silicon solar cell 100; wherein, when depositing the silicon oxide layer, the ozone concentration is any value in 10 ppm - 100 ppm, the volume fraction of the reaction atmosphere is any value in 90% - 95%, the flow rate of the reaction atmosphere is any value in 0.2 L / min - 1.0 L / min, and the evaporation rate during magnesium oxide deposition is any value.

[0050] In this embodiment, during the preparation of the transparent crystalline silicon solar cell 100, first, a reactive ion etching process is used to etch reverse micropores 11 on the crystalline silicon wafer 10 to form a plurality of spaced micropores 11 on the back surface of the crystalline silicon wafer 10 of the half-cell, so as to prepare a micropore cell. Then, the micropore cell is pretreated to form a protective layer covering the positive electrode 20 on one side of the micropore cell. After that, the micropore cell is successively subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition to successively 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 micropore cell. Finally, a back electrode 30 is deposited on the side of the micropore cell away from the positive electrode 20 and the protective layer is removed to obtain the transparent crystalline silicon solar cell 100. Here, the ozone concentration during the silicon oxide layer deposition can be 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, or 100 ppm, or any value in the range of 10 ppm - 100 ppm. The volume fraction of the reaction atmosphere can be 90%, 91%, 92%, 93%, 94%, or 95%, or any value in the range of 90% - 95%. The flow rate of the reaction atmosphere can be 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, or 1.0 L / min, or any value in the range of 0.2 L / min - 1.0 L / min. The evaporation rate during the magnesium oxide deposition can be Or it can also be any value within

[0051] In this embodiment, by performing reverse micropore 11 etching on the crystalline silicon wafer 10 in the half-cell with the positive electrode 20 already prepared, the light transmittance of the micropore cell is improved. After setting a protective layer on the periphery of the positive electrode 20 of the micropore cell, the micropore cell is successively subjected to acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition by means of multi-means collaborative passivation treatment, preventing the cell grid lines 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 respectively deposited on the back surface of the micropore cell and the side walls of the micropores 11 simultaneously to form a high-stability composite passivation structure, reducing the density of interface defect states, increasing the minority carrier lifetime, and enhancing 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.

[0052] In this embodiment, step S200 includes the following steps:

[0053] Prepare a polymethyl methacrylate solution with a preset concentration;

[0054] Spin-coat the polymethyl methacrylate solution on the surface of the glass slide, and attach the positive electrode 20 of the half-cell to the polymethyl methacrylate solution on the glass slide.

[0055] In this embodiment, by attaching the positive electrode 20 of the half-cell to the polymethyl methacrylate solution on the glass slide, a protective layer is formed on the periphery of the positive electrode 20 to prevent damage to the structure of the positive electrode 20 during subsequent acid treatment, thereby reducing the impact of 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 in the range of 180 mg / mL - 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 in the range of 180 mg / mL - 200 mg / mL. Here, the polymethyl methacrylate solution can also be replaced by a polyethylene solution or a polypropylene solution.

[0056] In this embodiment, the method of depositing silicon oxide is an ultraviolet ozone oxidation process. By setting the ozone concentration, reaction atmosphere and gas flow rate of silicon oxide deposition within the above ranges, a silicon oxide passivation layer 12 can be formed simultaneously on the back surface of the microcell and the side walls of the micropores 11, improving the deposition uniformity of the side walls and the bottom of the micropores 11, improving the coverage consistency of the silicon oxide layer, and also being able to increase the penetration depth and passivation integrity of ozone in the micropores 11 with a high aspect ratio, which is beneficial to improving the interfacial recombination characteristics of the device and obtaining a silicon oxide passivation layer 12 with low defects and good adhesion. That is, by in-situ growing the silicon oxide passivation layer 12, the interfacial state density can be effectively reduced, the carrier recombination loss can be reduced, and at the same time, the silicon oxide passivation layer 12 can be used as a buffer layer to optimize the film-forming quality of the subsequent magnesium oxide passivation layer 14. In other embodiments, the silicon oxide passivation layer 12 can also be prepared by a thermal oxidation method.

[0057] In this embodiment, the magnesium oxide is deposited by a thermal evaporation process. By setting the evaporation rate and evaporation temperature during the deposition of magnesium oxide within the above ranges, it helps to form a dense, continuous, and completely covered magnesium oxide passivation layer 14, enhancing the passivation effect and improving the interface stability. Moreover, since the magnesium oxide passivation layer 14 is formed before the deposition of the back electrode 30, it reduces the diffusion of the back electrode 30 metal into the holes, improving the electrical insulation and environmental stability of the hole region. Additionally, it can also enhance the interfacial adhesion between magnesium oxide and silicon oxide, avoiding delamination, voids, and pinholes at the interface caused by high stress or high defect density, while improving the growth foundation of the magnesium oxide passivation layer 14 surface for the back electrode 30. Here, the evaporation temperature for the magnesium oxide deposition is any value within 100°C - 150°C. The evaporation temperature can be 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C, or any value within 100°C - 150°C.

[0058] In this embodiment, the reaction time of the acid treatment is any value within 40s - 60s, that is, the reaction time of the acid treatment can be 40s, 45s, 50s, 55s, or 60s, or any value within 40s - 60s. By setting the reaction time of the acid treatment within the above ranges, it can moderately etch away the nanoscale burrs and residues generated by etching, reducing the serrated structure on the sidewalls, which helps the dense adhesion and uniform coating of the subsequent silicon oxide passivation layer 12 and magnesium oxide passivation layer 14, further reducing the surface trap state density and enhancing the interface passivation ability.

[0059] In a further embodiment, the material of the organic molecular modification layer can be any one of APTES ((3 - Aminopropyl)triethoxysilane) or APTMS ((3 - Aminopropyl)trimethoxysilane). In this embodiment, the volume fraction of the organic molecular solution used for the organic molecular chemical modification is any value within 0.5% - 1.5%, that is, the volume fraction of APTES or APTMS in the organic molecular 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 within 0.5% - 1.5%. By setting the volume fraction of the organic molecular solution used for the organic molecular chemical modification within the above ranges, it can accurately regulate the amino functionalization of the micropores 11 and the sidewalls, improve the interfacial adhesion of the passivation layer and the subsequent transparent electrode, reduce the interface recombination and stress failure, and enhance the performance and stability of the solar cell 100.

[0060] In this embodiment, during the organic molecule chemical modification process, the microporous battery is immersed in an organic molecule solution and deionized water for a first preset time and a second preset time respectively, where the first preset time is any value within 20 min - 30 min, and the second preset time is any value within 1.5 h - 2 h, so as to achieve the modification of the side walls of the micropores 11 with siloxane molecules. That is, through the above organic molecule chemical modification process, a uniform amino modification is formed on the side walls of the micropores 11, which is convenient for the stable curing method of the silane structure, improves the interfacial bonding ability, prevents the blockage of the pores 11 of the micropores, provides a clean and stable interface for the subsequent deposition of the transparent electrode or the functional layer, and improves the device performance and long-term reliability. Here, the first preset time can be 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, or any value within 20 min - 30 min, and the second preset time can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h, or any value within 1.5 h - 2 h.

[0061] In this embodiment, the multiple micropores 11 in the microporous battery are arranged at intervals to improve the light transmittance of the transparent crystalline silicon solar cell 100 while maintaining electrical connection and mechanical strength. Here, the diameter of the micropores 11 is any value within 5 μm - 20 μm, that is, the diameter of the micropores 11 can be 5 μm, 10 μm, 15 μm or 20 μm, or any value within 5 μm - 20 μm, and the distance between adjacent micropores 11 is any value within 10 μm - 50 μm, that is, the distance between adjacent micropores 11 can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, or any value within 10 μm - 50 μm. By setting the diameter of the micropores 11 and the distance between adjacent micropores 11 within the above ranges, the transparency can be ensured while maintaining electrical and mechanical stability. Here, the diameter of the micropores 11 and the distance 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.

[0062] In a further embodiment, the acid treatment 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, 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 can also be any value in the range of 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 the oxide layer, smooth the sidewalls of the micropores 11, improve the adhesion and continuity of the passivation layer deposition, and thus further improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100. Here, when preparing the HNA solution, the mass concentration of the added nitric acid is 68 wt%, the mass concentration of hydrofluoric acid is 40 wt%, and the mass concentration of acetic acid is 99.5 wt%.

[0063] In a further embodiment, the relative humidity of the reaction atmosphere during silicon oxide deposition is any value in the range of 15% - 30%, and the treatment time is any value in the range of 5 min - 15 min, that is, the relative humidity during silicon oxide deposition can be 15%, 20%, 25% or 30%, or can also be any value in the range of 15% - 30%, and the treatment time can be 5 min, 7 min, 9 min, 10 min, 12 min or 15 min, or can also be any value in the range of 5 min - 15 min. By setting the relative humidity and treatment time during 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 a moderate and stable thickness. Here, the reaction atmosphere can be air or oxygen.

[0064] In a further embodiment, the thickness of the magnesium oxide passivation layer 14 is any value in the range of 0.5 nm - 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 can also be any value in the range of 5 nm - 15 nm. By setting the thickness of the magnesium oxide passivation layer 14 within the above range, it is possible to further complete the coverage of the sidewalls and the back surface of the micropores of the micropore battery, reduce the surface roughness of the sidewalls of the micropores 11 while maintaining a low resistance, and optimize the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0065] In a further embodiment, the angle between the incident directions of the magnesium oxide vapor in two adjacent depositions during the magnesium oxide deposition is a preset angle. That is, during the magnesium oxide deposition process, by adjusting the incident direction of the magnesium oxide vapor, the magnesium oxide vapor can act on the sidewall of the micropore 11 in different directions, realizing multi-directional and co-form deposition, effectively covering the sidewall area that is difficult to directly deposit, thereby improving the deposition uniformity of the magnesium oxide passivation layer 14 on the surface of the sidewall of the micropore 11, avoiding uneven film thickness that may be caused by depositing at the same position for a long time at one time, 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 the thermal stress, and reducing the cracking or peeling off of the magnesium oxide passivation layer 14.

[0066] In this embodiment, the preset angle is any value between 15° and 30°. That is, during the magnesium oxide deposition process, the angle between the incident directions of the magnesium oxide vapor on two adjacent sides can be 15°, 18°, 20°, 25°, or 30°, or any value between 15° and 30°. By setting the preset angle within the above range, the microstructure coverage of the magnesium oxide passivation layer 14 can be improved, preventing poor coverage of the sidewall or back surface caused by single-direction deposition due to the shielding effect of the micropore 11 or the surface structure. That is, by adjusting the incident direction of the magnesium oxide vapor, the vapor beam can be sprayed from multiple directions to effectively enter the sidewall or concave area, thereby improving the overall coverage rate and uniformity of the magnesium oxide passivation layer 14. At the same time, the vapor with different incident angles promotes the multi-directional growth of grains, which is beneficial to the formation of a continuous and dense magnesium oxide passivation layer 14, reducing defects such as voids and cracks.

[0067] In a further embodiment, the material of the back electrode 30 is any one of aluminum or indium tin oxide. That is, both aluminum and indium tin oxide can be deposited as the back electrode 30 on the back surface of the crystalline silicon wafer 10. Aluminum has the characteristics of low cost, good electrical conductivity, and low reflectivity, and is suitable for preparing transparent crystalline silicon solar cells 100 with low cost and large demand. 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 demand characteristics of the transparent crystalline silicon solar cell 100.

[0068] In a further embodiment, in the step of removing the protective layer, it includes:

[0069] Soaking the microporous battery with an acetone solution.

[0070] In this embodiment, the microporous battery is soaked in an acetone solution to dissolve the polymethyl methacrylate on the side of the positive electrode 20 of 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, avoiding the influence of surface residues on the electrode structure, and thus reducing the contact resistance or performance degradation caused by contamination. Here, after treatment with the acetone solution, the battery is repeatedly washed with an ethanol solution until the surface is clean, and finally dried with nitrogen gas.

[0071] As Figure 5 shown, in a further embodiment, step S100 further includes the following steps:

[0072] Step S110: Implement a single etching process for anisotropic etching of the silicon substrate and sidewall protection using etching gas and passivation gas;

[0073] Step S120: Repeat the single etching process a preset number of times to prepare a microporous battery.

[0074] In step S100, when performing reverse micropore 11 etching on the crystalline silicon wafer 10 using reactive ion etching, first, anisotropic etching of the silicon substrate is achieved using etching gas, and then the etched sidewalls are preliminarily passivated using passivation gas to achieve preliminary passivation protection of the sidewalls by the passivation gas, thereby completing the single etching process. The single etching process is repeated according to the preset number of cycles to prepare a microporous battery. That is, by precise timing control, the preparation of a microporous structure with a preset aspect ratio is achieved. This not only enables the formation of a highly anisotropic microporous structure but also allows the alternating injection of passivation gas to form a layer of polymeric fluorocarbon passivation film layer during the etching gap, providing preliminary passivation protection for the sidewalls of the micropores 11, preventing lateral erosion by the etching gas, thereby reducing the sidewall roughness and avoiding the formation of edge collapse or serrated irregular morphologies in the sidewalls of the micropores 11, which is beneficial to the deposition uniformity of subsequent passivation layers, modification layers, or transparent electrodes. Here, the preset aspect ratio is any value between 5 and 20, that is, the aspect ratio of a single micropore 11 can be 5, 10, 15, or 20, or any value between 5 and 20.

[0075] In this embodiment, the etching time of the etching gas in a single etching process is any value between 8 s and 9 s, the etching time of the passivation gas is any value between 2 s and 3 s, and the total etching duration of the reverse micropores 11 is any value between 30 min and 35 min, so as to prepare micropores 11 with a preset aspect ratio. Here, the etching time of the etching gas can be 8 s, 8.2 s, 8.4 s, 8.6 s, 8.8 s or 9 s, or any value between 8 s and 9 s. The etching time of the passivation gas can be 2 s, 2.2 s, 2.4 s, 2.6 s, 2.8 s or 3 s, or any value between 2 s and 3 s. The total etching duration of the reverse micropores 11 can be 30 min, 31 min, 32 min, 33 min, 34 min or 35 min, or any value between 30 min and 35 min.

[0076] In a further embodiment, the etching gas is sulfur hexafluoride and the gas flow rate is any value between 420 sccm and 450 sccm, and the passivation gas is perfluorocyclobutane and the gas flow rate is any value between 180 sccm and 200 sccm. That is, the gas flow rate of the etching gas can be 420 sccm, 425 sccm, 430 sccm, 435 sccm, 440 sccm, 445 sccm or 450 sccm, or any value between 420 sccm and 450 sccm. The gas flow rate of the passivation gas can be 180 sccm, 185 sccm, 190 sccm, 195 sccm or 200 sccm, or any value between 180 sccm and 200 sccm. By setting the etching gas as sulfur hexafluoride, the passivation gas as perfluorocyclobutane, and setting the gas flow rates of the etching gas and the passivation gas within the above ranges, a higher reactive atmosphere density can be provided, ensuring a stable etching process, a moderate etching rate, maintaining a suitable etching rate, while avoiding out-of-control hole shape or damage to the silicon structure caused by too fast etching, which is beneficial 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 sidewalls, and improve the perpendicularity and flatness of the micropores 11.

[0077] The present invention also provides a transparent crystalline silicon solar cell 100 prepared by the preparation method according to any one of the above. Regarding the preparation method of the transparent crystalline silicon solar cell 100, it will not be elaborated here one by one.

[0078] The following will further illustrate the present application in detail with specific embodiments.

[0079] Example 1

[0080] In this embodiment, first, a reactive ion etching process is used to etch reverse microholes 11 in the crystalline silicon wafer 10. In the reactive ion etching process, the etching time of sulfur hexafluoride in each etching program is 9 s, the gas flow rate is 430 sccm, the etching time of octafluorocyclobutane is 2 s, and the gas flow rate is 190 sccm. The total etching duration of the reactive ion etching process is 32 min to form a microhole battery including a plurality of microholes 11. The diameter of the microholes 11 is 15 μm, and the aspect ratio is 5. Then, a polymethyl methacrylate solution with a concentration of 190 mg / mL is spin-coated on the surface of the glass slide, and the positive electrode 20 of the half-cell is attached to the polymethyl methacrylate solution on the glass slide, and then a protective layer covering the peripheral side of the positive electrode 20 is formed. After that, the microhole battery is acid-treated with an 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 silicon oxide passivation layer 12. Then, the microhole 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 microholes 11 of the microhole battery. After that, an aluminum back electrode 30 is deposited on the side of the microhole battery away from the positive electrode 20. Finally, the microhole battery is immersed in an acetone solution to remove the protective layer, and a transparent crystalline silicon solar cell 100 is prepared. The reaction time of the acid treatment is 50 s, the ozone concentration during the silicon oxide deposition is 70 ppm, the relative humidity of the reaction atmosphere is 20%, the reaction time is 10 min, the volume fraction of the reaction atmosphere is 92%, the flow rate of the reaction atmosphere is 0.5 L / min, and the evaporation rate during the magnesium oxide deposition is The evaporation temperature is 120 °C, and the angle between the incident direction of the magnesium oxide vapor is 15°.

[0081] Comparative Example 1

[0082] The difference between Comparative Example 1 and Example 1 is only that the preparation of the magnesium oxide passivation layer 14 for the microhole battery is not carried out.

[0083] Comparative Example 2

[0084] The difference between Comparative Example 2 and Example 1 is only that the preparation of the magnesium oxide passivation layer 14 and APTES modification for the microhole battery are not carried out.

[0085] Comparative Example 3

[0086] The difference between Comparative Example 3 and Example 1 is only that the preparation of the magnesium oxide passivation layer 14, APTES modification, and silicon oxide passivation layer 12 for the microhole battery are not carried out.

[0087] Comparative Example 4

[0088] The difference between Comparative Example 4 and Example 1 is only that the preparation of the magnesium oxide passivation layer 14, APTES modification, the preparation of the silicon oxide passivation layer 12, and acid treatment are not carried out on the microporous battery.

[0089] Comparative Example 5

[0090] The difference between Comparative Example 5 and Example 1 is only that only APTES modification is carried out on the microporous battery.

[0091] Comparative Example 6

[0092] The difference between Comparative Example 6 and Example 1 is only that only the preparation of the magnesium oxide passivation layer 14 is carried out on the microporous battery.

[0093] 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.

[0094] Table 1. Performance test results of the solar cells in Example 1 and Comparative Examples 1-6

[0095] Comparative Example Photoelectric Conversion Efficiency Example 1 16.12％ Comparative Example 1 15.45％ Comparative Example 2 14.68％ Comparative Example 3 15.2％ Comparative Example 4 14.31％ Comparative Example 5 14.56％ Comparative Example 6 15.60％

[0096] 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 use of acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition for synergistic passivation treatment can significantly improve the interface state density of the sidewalls of the transparent crystalline silicon solar cell 100, reduce carrier recombination loss, effectively reduce surface recombination, and improve the photoelectric conversion efficiency of the transparent crystalline silicon solar cell 100.

[0097] Then, the electrical properties of the transparent crystalline silicon solar cells 100 prepared in Example 1 and Comparative Example 3 were tested, and the current-voltage curves as Figure 6 shown and the electrical property test results shown in Table 2 were obtained.

[0098] Table 2. Electrical property test results of the solar cells prepared in Example 1 and Comparative Example 1

[0099]

[0100] As Figure 6As 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 all 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.

[0101] Finally, the transparent crystalline silicon solar cells 100 prepared in Example 1 and Comparative Example 3 were characterized by scanning electron microscopy, and the SEM images shown in Figure 7 and Figure 8 were obtained. As shown in Figure 7 , the surface roughness of the side wall of the micropore 11 of the transparent crystalline silicon solar cell 100 treated only with acid is relatively high, and the surface flatness is relatively low. As shown in Figure 8 , after the synergistic effect of multiple passivation means, 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.

[0102] As shown in Figure 9 , the transmittance test was carried out on the transparent crystalline silicon solar cell 100 prepared in Example 1, indicating that the transparent crystalline silicon solar cell 100 prepared in Example 1 has a relatively high light transmittance.

[0103] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0104] The above-described embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A preparation method of a transparent crystalline silicon solar cell, characterized in that, The preparation method is based on the preparation of a half-cell, the half-cell includes a crystalline silicon wafer and a positive electrode located on one side of the crystalline silicon wafer, and the preparation method includes the following steps: Use a reactive ion etching process to perform reverse microporous etching on the crystalline silicon wafer in the half-cell with the positive electrode already prepared to form a microporous cell including a plurality of micropores; Pretreat the microporous cell to form a protective layer covering the positive electrode on one side of the microporous cell; Successively perform acid treatment, silicon oxide layer deposition, organic molecule chemical modification, and magnesium oxide deposition on the microporous cell to successively form a silicon oxide passivation layer, an organic chemical modification layer, and a magnesium oxide passivation layer on the side walls of the micropores of the microporous cell; Deposit a back electrode on the side of the microcell away from the positive electrode and remove the protective layer to obtain a transparent crystalline silicon solar cell; wherein, when the silicon oxide layer is deposited, the ozone concentration is any value from 10 ppm to 100 ppm, the volume fraction of the reaction atmosphere is any value from 90% to 95%, the flow rate of the reaction atmosphere is any value from 0.2 L / min to 1.0 L / min, and the evaporation rate during the deposition of magnesium oxide is any value.

2. The preparation method according to claim 1, wherein The solution for the acid treatment 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, wherein In the silicon oxide layer deposition, the relative humidity of the reaction atmosphere is any value in the range of 15%-30%, and the treatment time is any value in the range of 5 min-15 min.

4. The preparation method according to claim 3, wherein The thickness of the magnesium oxide passivation layer is any value in the range of 0.5 nm-5 nm.

5. The preparation method according to claim 4, wherein In the magnesium oxide deposition, the included angle between the incident directions of two adjacent magnesium oxide vapors is a preset angle.

6. The preparation method according to claim 5, wherein The material of the back electrode is any one of aluminum or indium tin oxide.

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

8. The preparation method according to claim 1, wherein The material of the organic chemical modification layer can be any one of APTES or APTMS.

9. The preparation method according to claim 8, wherein In the step of performing reverse microporous etching on the crystalline silicon wafer using the reactive ion etching process, the following steps are further included: Use an etching gas and a passivation gas to implement a single etching process for anisotropic etching of the silicon substrate and side wall protection; Repeat the single etching process a preset number of times to prepare the microporous cell; wherein, the etching gas is sulfur hexafluoride, and the gas flow rate is any value in the range of 420 sccm-450 sccm, and the passivation gas is octafluorocyclobutane, and the gas flow rate is any value in the range of 180 sccm-200 sccm.

10. A transparent crystalline silicon solar cell, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

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