Solar cell electrode structure and preparation method thereof

Abstract

The invention discloses a solar cell electrode structure and a preparation method thereof, and the method comprises the steps: printing a layer of conductive polymer on an original electrode through a screen printing mode; and the conductive polymer is selected from PEDOT: PSS, Fe2O3 is adjustably added, or polyphenylene sulfide arsenic hexafluoride is selected and AsF5 is adjustably added, so that the conductive polymer layer is blue, the influence of ultraviolet light on a metal electrode can be prevented, the influence of the ultraviolet light on the polymer is relatively small, and in addition, the color integration of the front surface of the battery can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of solar cell electrodes, and in particular to a solar cell electrode structure and a preparation method thereof. Background Art

[0002] Solar cells have metal electrodes for collecting the current generated by photoelectric conversion and inputting it into an external circuit. The preparation method of solar cells with metal electrodes is usually to print the slurry on the front and back of the solar cell sheet by screen printing.

[0003] The slurry used in solar cells contains metal powder, glass, organic carrier, additives and other ingredients. When solar cells are exposed to ultraviolet light in sunlight for a long time, the composition and structure of the electrode will change, resulting in increased resistance, thereby reducing the photoelectric conversion efficiency of the cell. Therefore, it is necessary to improve the slurry formula or design a new electrode structure to solve the problem of increased resistance of metal electrodes caused by ultraviolet light.

[0004] Therefore, it is necessary to develop a solar cell electrode structure and a preparation method thereof to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to design a solar cell electrode structure and a preparation method thereof in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: A solar cell electrode structure comprises a first silicon nitride layer, a second silicon nitride layer, and a first silver electrode, a doped polysilicon layer, a silicon oxide layer, a silicon substrate, an aluminum oxide layer, and a second silver electrode which are sequentially connected from one end to the other end; the first silicon nitride layer covers the surface of the doped polysilicon layer, the second silicon nitride layer covers the surface of the aluminum oxide layer, and a conductive polymer layer is arranged on the surface of the second silver electrode.

[0007] As a preference, the conductive polymer layer is PEDOT:PSS.

[0008] Furthermore, Fe2O3 is added into the conductive polymer layer.

[0009] As another preference, the conductive polymer layer is polyphenylene sulfide arsenic hexafluoride.

[0010] Furthermore, AsF5 is added to polyphenylene sulfide arsenic hexafluoride.

[0011] Preferably, the conductive polymer layer is provided on the fine grid of the second silver electrode.

[0012] A method for preparing a solar cell electrode structure comprises the following steps: S1, the silicon substrate uses N-type single crystal silicon wafer; S2, performing double-sided alkaline polishing on the silicon wafer; S3, texturing the front side of the silicon wafer; S4, diffusing boron on the textured silicon wafer at high temperature to form a shallowly doped region; S5, printing boron paste on the front side of the silicon wafer according to the electrode pattern, printing masks on the rest of the front side, and performing high temperature treatment to form a heavily doped area; S6. Perform single-sided acid polishing on the back of the silicon wafer, and evenly cover the borosilicate glass layer BSG on the front of the silicon wafer with a water film; S7, based on the previous step, growing tunneling silicon oxide and n-doped amorphous silicon, and then performing annealing to form an n-poly silicon layer; S8, using HF to clean the front borosilicate glass layer and the back phosphosilicate glass layer; S9, based on the previous step, depositing aluminum oxide on the front side; S10, based on the previous step, coating the front and back surfaces with a silicon nitride film or a silicon nitride oxide film or a silicon oxide film or a combination film as a passivation layer and an anti-reflection layer; S11, printing silver paste, printing silver aluminum paste or silver paste in the front laser doped area, printing the main grid and fine grid separately, and printing silver paste on the main grid; S12, screen-printing a conductive polymer layer on the front side of the battery, and annealing at 100-150° C. for 10-20 minutes after printing.

[0013] Preferably, in step S1, the silicon substrate is an N-type single crystal silicon wafer with a resistivity of 1Ω·cm.

[0014] Preferably, in step S7, tunneling silicon oxide and n-doped amorphous silicon are grown by PECVD, PEALD or PVD.

[0015] Preferably, in step S9, aluminum oxide is deposited by ALD or PEALD, and the thickness of aluminum oxide is 5 nm.

[0016] The beneficial effects of the present invention are: The present invention prints a layer of conductive polymer on the original electrode by screen printing; and the conductive polymer is selected as PEDOT:PSS, and Fe2O3 can be adjusted to be added, or polyphenylene sulfide arsenic hexafluoride is selected, and AsF5 can be adjusted to be added, so the conductive polymer layer is formed in blue, which can prevent the influence of ultraviolet light on the metal electrode, and the polymer itself is less affected by ultraviolet rays. In addition, the front side of the battery can also be made uniform in color. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of the solar cell electrode structure in this application (cross-section view); Figure 2Schematic diagram of the structure of the electrode in this application (top view); Figure 3 The figure is a schematic diagram of the process of preparing the solar cell electrode structure in this application.

[0018] Legend: 1-first silver electrode; 2-first silicon nitride layer; 3-doped polysilicon layer; 4-silicon oxide layer; 5-silicon substrate; 6-aluminum oxide layer; 7-second silicon nitride layer; 8-second silver electrode; 9-conductive polymer layer; 10-main gate; 11-fine gate. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0023] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, a solar cell electrode structure includes a first silicon nitride layer 2, a second silicon nitride layer 7, and a first silver electrode 1, a doped polysilicon layer 3, a silicon oxide layer 4, a silicon substrate 5, an aluminum oxide layer 6, and a second silver electrode 8 that are sequentially connected from one end to the other end; the first silicon nitride layer 2 covers the surface of the doped polysilicon layer 3, the second silicon nitride layer 7 covers the surface of the aluminum oxide layer 6, and a conductive polymer layer 9 is arranged on the surface of the second silver electrode 8.

[0027] As a preference, the conductive polymer layer is PEDOT:PSS; Fe2O3 is added to the conductive polymer layer.

[0028] As another preferred embodiment, the conductive polymer layer is polyphenylene sulfide arsenic hexafluoride; AsF5 is added to the polyphenylene sulfide arsenic hexafluoride.

[0029] like Figure 2 As shown, in some embodiments, the conductive polymer layer is disposed on the fine grid 11 of the second silver electrode. It is only printed on the fine grid 11, and not on the main grid 10 of the second silver electrode, because the main grid 10 needs to be connected to a metal wire, which originally shields the main grid below from being affected by ultraviolet light.

[0030] PEDOT:PSS and polyphenylene sulfide arsenic hexafluoride are both blue conductive liquids that can be deposited on solids by printing or spraying and cured at high temperatures.

[0031] Covering the metal electrode of the solar cell with a layer of blue conductive polymer material can prevent the metal electrode from being irradiated by ultraviolet light, and the blue conductive polymer material itself is less affected by ultraviolet light. In addition, the blue conductive polymer material also has conductive properties, and it also combines with the metal electrode and enhances conductivity. For PEDOT:PSS, under the irradiation of ultraviolet light, it will increase the connection between polystyrene sulfonic acid (PSS) particles and enhance conductivity.

[0032] The surface color of solar cells is blue, which is generally divided into light blue, blue and dark blue according to the color depth. The metal electrode is white. After covering the metal electrode with blue conductive polymer material, the color of the battery surface can be unified and more beautiful. The color depth of the blue conductive polymer can also be adjusted.

[0033] In the original solar cell production process, after screen printing, cells of different colors can be sorted out in the test and analysis automation equipment; this application selects the blue conductive polymer liquid of the corresponding color for printing according to the sorted cells of different colors. Optional blue conductive polymer liquid 1: PEDOT:PSS solution color configuration: In the original PEDOT:PSS solution, add an appropriate amount of Fe2O3 to adjust the depth of blue. Optional blue conductive polymer liquid 2: Adding an appropriate amount of AsF5 to polyphenylene sulfide arsenic hexafluoride can adjust the blue depth of the liquid, and the adjustable range is blue to black; then print the conductive polymer. After printing, annealing at high temperature for a certain period of time can achieve the curing of the conductive polymer.

[0034] In addition to this embodiment, this method can be used on the front electrode of TOPCon cells, perc cells, and heterojunction cells.

[0035] like Figure 3 As shown, a method for preparing a solar cell electrode structure comprises the following steps: S1. Silicon wafer: Use N-type single crystal silicon wafer with a resistivity of 1Ω·cm.

[0036] S2, rough polishing: double-sided alkaline polishing with KOH, NaOH or TMAH, thinning one side by 2μm; S3, front texturing: Use KOH, NaOH or TMAH with texturing additives to texturing the front side, and the size of the front texturing pyramid is 2um; S4, shallow boron doping on the front side: Boron is diffused on the silicon wafer after texturing at high temperature to form a shallow doping area; S5, front boron expansion and heavy doping: Boron paste is printed on the front side of the silicon wafer according to the electrode pattern, and a mask is printed on the rest of the front side, and high temperature treatment is performed to form a heavily doped area; S6, cleaning: use HF / HNO3 to perform single-sided acid polishing on the back side, and evenly cover the front borosilicate glass layer BSG with a water film; S7, preparation of back tunneling oxide layer + doped polysilicon layer: growing tunneling oxide silicon and n-doped amorphous silicon by PECVD or PEALD or PVD, and then performing annealing to form an n-poly silicon layer; S8, secondary cleaning: using HF to clean the front borosilicate glass layer and the back phosphosilicate glass layer; S9, front deposition of aluminum oxide: front ALD or PEALD method to deposit aluminum oxide with a thickness of 5 nm; S10, anti-reflection coating on the front and back: Silicon nitride film or silicon oxynitride film or silicon oxide or combination film is coated on the front and back as passivation layer and anti-reflection layer, with a thickness of 75nm on the front and back S11, Printing and sintering: Print silver paste, print silver-aluminum paste or silver paste on the front laser-doped area, print the main grid and fine grid separately on the front, and use silver paste for the main grid.

[0037] S12, light injection and laser-assisted sintering.

[0038] S13, secondary printing: printing a conductive polymer layer on the front side of the battery, and annealing at 100-150°C for 10-20 minutes after printing.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A solar cell electrode structure, characterized in that: The invention comprises a first silicon nitride layer, a second silicon nitride layer, and a first silver electrode, a doped polysilicon layer, a silicon oxide layer, a silicon substrate, an aluminum oxide layer, and a second silver electrode which are sequentially connected from one end to the other end; the first silicon nitride layer covers the surface of the doped polysilicon layer, the second silicon nitride layer covers the surface of the aluminum oxide layer, and a conductive polymer layer is arranged on the surface of the second silver electrode.

2. A solar cell electrode structure according to claim 1, characterized in that: The conductive polymer layer is PEDOT:PSS.

3. A solar cell electrode structure according to claim 2, characterized in that: Fe2O3 is added to the conductive polymer layer.

4. A solar cell electrode structure according to claim 1, characterized in that: The conductive polymer layer is polyphenylene sulfide arsenic hexafluoride.

5. A solar cell electrode structure according to claim 4, characterized in that: AsF5 is added to polyphenylene sulfide arsenic hexafluoride.

6. A solar cell electrode structure according to claim 1, characterized in that: A conductive polymer layer is disposed on the fine grid of the second silver electrode.

7. A method for preparing a solar cell electrode structure according to claims 1-6, characterized in that: The following steps are involved: S1, silicon substrate uses N-type single crystal silicon wafer; S2, performing double-sided alkaline polishing on the silicon wafer; S3, texturing the front side of the silicon wafer; S4, diffusing boron on the textured silicon wafer at high temperature to form a shallowly doped region; S5, printing boron paste on the front side of the silicon wafer according to the electrode pattern, printing masks on the rest of the front side, and performing high temperature treatment to form a heavily doped area; S6. Perform single-sided acid polishing on the back of the silicon wafer, and evenly cover the borosilicate glass layer BSG on the front of the silicon wafer with a water film; S7, based on the previous step, growing tunneling silicon oxide and n-doped amorphous silicon, and then performing annealing to form an n-poly silicon layer; S8, using HF to clean the front borosilicate glass layer and the back phosphosilicate glass layer; S9, based on the previous step, depositing aluminum oxide on the front side; S10, based on the previous step, coating the front and back surfaces with a silicon nitride film or a silicon nitride oxide film or a silicon oxide film or a combination film as a passivation layer and an anti-reflection layer; S11, printing silver paste, printing silver aluminum paste or silver paste in the front laser doped area, printing the main grid and fine grid separately, and printing silver paste on the main grid; S12, screen-printing a conductive polymer layer on the front side of the battery, and annealing at 100-150° C. for 10-20 minutes after printing.

8. The method for preparing a solar cell electrode structure according to claim 7, characterized in that: In step S1, the silicon substrate is an N-type single crystal silicon wafer with a resistivity of 1Ω·cm.

9. The method for preparing a solar cell electrode structure according to claim 7, characterized in that: In step S7, tunneling silicon oxide and n-doped amorphous silicon are grown by PECVD, PEALD or PVD.

10. The method for preparing a solar cell electrode structure according to claim 7, characterized in that: In step S9, aluminum oxide is deposited by ALD or PEALD, and the thickness of aluminum oxide is 5 nm.

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