US-20260130002-A1 - SOLAR CELL, METHOD FOR PREPARING SOLAR CELL, AND SOLAR CELL PRODUCTION LINE

US20260130002A1US 20260130002 A1US20260130002 A1US 20260130002A1US-20260130002-A1

Abstract

Embodiments of the present disclosure relate to a solar cell, a method for preparing the solar cell, and a solar cell production line. The method includes providing a stack including an N-type silicon substrate having a boron-doped polysilicon layer near a first surface, with a tunneling oxide layer, a phosphorus-doped polysilicon layer, and a mask layer sequentially stacked as stated on an opposite second surface; forming through holes in the mask layer to expose the phosphorus-doped polysilicon layer; forming grooves at the through holes that extend through the phosphorus-doped polysilicon layer and the tunneling oxide layer and partially extend into the N-type silicon substrate, thereby separating a surface of the stack provided with the phosphorus-doped polysilicon layer into spaced emitter regions, and removing the mask layer.

Inventors

Wei Fan
Wu Zhang
Qun Liu

Assignees

LAPLACE RENEWABLE ENERGY TECHNOLOGY CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251230
Priority Date: 20250808

Claims (20)

1 . A method of preparing a solar cell comprising: providing a stack comprising an N-type silicon substrate, a tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer, and a mask layer; wherein the N-type silicon substrate comprises a first surface and a second surface opposite to the first surface, a boron-doped polycrystalline silicon layer is formed in the N-type silicon substrate at a depth close to the first surface; and the tunnel oxide layer, the phosphorus-doped polycrystalline silicon layer, and the mask layer are stacked as stated on the second surface along a direction away from the N-type silicon substrate; forming through holes exposing the phosphorus-doped polycrystalline silicon layer in the mask layer; forming grooves one-to-one corresponding to the through holes, wherein each of the grooves extends through the phosphorus-doped polycrystalline silicon layer and the tunnel oxide layer and partially extends into the N-type silicon substrate, and a surface of the stack provided with the phosphorus-doped polycrystalline silicon layer comprises emitter regions separated by the grooves; and removing the mask layer.
2 . The method as claimed in claim 1 , wherein forming the through holes comprises performing laser ablation on the mask layer using a green laser source with a laser power between 80 W and 200 W, a laser pulse frequency between 400 kHz and 1000 kHz, a peak energy between 1 μJ and 1 mJ, and a laser spot side length between 100 μm and 600 μm.
3 . The method as claimed in claim 1 , wherein forming the grooves comprises: placing the stack into an alkaline solution, and etching the stack with the alkaline solution to remove the phosphorus-doped polycrystalline silicon layer, the tunnel oxide layer, and part of the N-type silicon substrate corresponding to the through holes, thereby forming the grooves.
4 . The method as claimed in claim 3 , wherein a depth of each of the grooves is controlled in a range from 1 μm to 3μm by adjusting a pH value of the alkaline solution and an etching time of the stack.
5 . The method as claimed in claim 3 , wherein forming the grooves further comprises: selecting the alkaline solution with a PH value between 11.8 and 13, and etching the stack for 4 min to 10 min.
6 . The method as claimed in claim 1 , wherein removing the mask layer comprises at least partially immersing the stack in a hydrofluoric acid solution, and removing the mask layer with the hydrofluoric acid solution.
7 . The method as claimed in claim 1 , after removing the mask layer, further comprising: performing double-sided deposition on the N-type silicon substrate to form a front passivation layer on the first surface and a back passivation layer on the second surface, wherein the back passivation layer covers the phosphorus-doped polycrystalline silicon layer and inner walls of the grooves.
8 . The method as claimed in claim 1 , after removing the mask layer, further comprising: arranging front grid lines in contact with the boron-doped polycrystalline silicon layer and arranging back grid lines in contact with the phosphorus-doped polycrystalline silicon layer in the emitter regions.
9 . The method as claimed in claim 8 , wherein the solar cell has a front side corresponding to the first surface and a back side corresponding to the second surface; forming the front grid lines comprises printing a first conductive metal paste on the front side, and curing the first conductive metal paste by laser-assisted sintering to form the front grid lines; forming the back grid lines comprise printing a second conductive metal paste on the back side, and curing the second conductive metal paste by laser-assisted sintering to form the back grid lines.
10 . A solar cell comprising: an N-type silicon substrate comprising a first surface and a second surface opposite to the first surface, wherein a boron-doped polycrystalline silicon layer is in the N-type silicon substrate at a depth close to the first surface; a tunnel oxide layer in contact with the second surface; a phosphorus-doped polycrystalline silicon layer on a surface of the tunnel oxide layer away from the N-type silicon substrate; grooves extending through the phosphorus-doped polycrystalline silicon layer and the tunnel oxide layer and partially extending into the N-type silicon substrate; front grid lines in contact with the boron-doped polycrystalline silicon layer; and back grid lines in contact with the phosphorus-doped polycrystalline silicon layer, wherein in a thickness direction of the N-type silicon substrate, projections of contact regions between the back grid lines and the phosphorus-doped polycrystalline silicon layer do not overlap with projections of the grooves.
11 . The solar cell according to claim 10 , further comprising a back passivation layer covering the phosphorus-doped polycrystalline silicon layer and inner walls of the grooves.
12 . The solar cell according to claim 10 , wherein a depth of each of the grooves ranges from 1 μm to 3 μm.
13 . The solar cell according to claim 11 , further comprising a back anti-reflection layer covering the back passivation layer and extending into the grooves to cover the inner walls.
14 . The solar cell according to claim 13 , further comprising a front passivation layer on the first surface.
15 . The solar cell according to claim 14 , further comprising a front anti-reflection layer on the front passivation layer.
16 . A solar cell production line comprising sequentially connected: a texturing equipment configured for texturing an N-type silicon substrate; a boron doping equipment configured for boron doping the N-type silicon substrate to form a boron-doped polycrystalline silicon layer in the N-type silicon substrate close to a first surface; a first chain-type acid polishing equipment configured for removing a borosilicate glass layer on a second surface of the N-type silicon substrate, the second surface being opposite to the first surface; a first tank-type polishing equipment configured for polishing the second surface of the N-type silicon substrate; a phosphorus doping equipment configured for forming a tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer, and a mask layer on the second surface of the N-type silicon substrate; a first laser equipment configured for performing laser ablation on the mask layer to form through holes each exposing the phosphorus-doped polycrystalline silicon layer; a second chain-type acid polishing equipment configured for removing a phosphosilicate glass layer on the first surface of the N-type silicon substrate; a second tank-type polishing equipment comprising an alkaline solution tank configured for containing an alkaline solution and a hydrofluoric acid tank configured for containing a hydrofluoric acid solution, so as to etch and remove the phosphorus-doped polycrystalline silicon layer, the tunnel oxide layer, and part of the N-type silicon substrate corresponding to the through holes using the alkaline solution, thereby forming grooves extending through the phosphorus-doped polycrystalline silicon layer and the tunnel oxide layer and partially extending into the N-type silicon substrate, and to remove the mask layer using the hydrofluoric acid solution; a deposition equipment configured for forming a front passivation layer and/or a front anti-reflection layer on the first surface of the N-type silicon substrate, and/or forming a back passivation layer and/or a back anti-reflection layer on the second surface of the N-type silicon substrate; a printing equipment configured for forming front grid lines on the first surface of the N-type silicon substrate and forming back grid lines on the second surface of the N-type silicon substrate; and a second laser equipment configured for assisting sintering of the front grid lines and the back grid lines.
17 . The solar cell production line according to claim 16 , wherein the first laser equipment is a green laser source.
18 . The solar cell production line according to claim 16 , wherein the boron doping equipment comprises a single boron diffusion station, or a combination of a boron diffusion station and an oxidation station.
19 . The solar cell production line according to claim 16 , wherein the phosphorus doping equipment is a low-pressure chemical vapor deposition equipment; or the phosphorus doping equipment comprises a low-pressure chemical vapor deposition equipment and a phosphorus diffusion equipment; o the phosphorus doping equipment comprises a first plasma-enhanced chemical vapor deposition equipment and an annealing equipment; or the phosphorus doping equipment comprises a physical vapor deposition equipment and an annealing equipment.
20 . The solar cell production line according to claim 16 , wherein the deposition equipment comprises an atomic layer deposition equipment, or a second plasma-enhanced chemical vapor deposition equipment.

Description

FIELD The subject matter herein generally relates to the field of photovoltaic technology, specifically solar cells, methods for preparing solar cells, and solar cell production lines. BACKGROUND In conventional tunnel oxide passivated contact (TOPCon) solar cells, a back side optical utilization efficiency of the TOPCon solar cells is low, and a bifacial utilization of the TOPCon solar cells needs to be improved. Therefore, there is room for improvement in the art. BRIEF DESCRIPTION OF THE DRAWINGS Implementations of the present disclosure will now be described, by way of embodiment, with reference to the attached figures. FIG. 1 is a flowchart of a method for preparing a solar cell according to an embodiment of the present disclosure. FIG. 2 is a schematic structural diagram of an N-type silicon substrate provided in the method showing in FIG. 1. FIG. 3 is a schematic diagram showing a structure obtained after texturing the N-type silicon substrate in FIG. 2. FIG. 4 is a schematic diagram showing a structure obtained after boron doping the N-type silicon substrate in FIG. 3. FIG. 5 is a schematic diagram showing a structure obtained after removing a borosilicate glass layer from a second surface of the N-type silicon substrate in FIG. 4 and polishing the second surface. FIG. 6 is a schematic diagram showing a structure obtained after forming a tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer, and a mask layer on the second surface of the N-type silicon substrate in FIG. 5. FIG. 7 is a schematic diagram showing a structure obtained after forming through holes in the mask layer in FIG. 6. FIG. 8 is a schematic diagram showing a structure obtained after forming grooves at the through holes in FIG. 7 and removing the mask layer. FIG. 9 is a schematic diagram showing a structure obtained after forming a front passivation layer, a back passivation layer, a front anti-reflection layer, and a back anti-reflection layer on the structure in FIG. 8. FIG. 10 is a schematic structural diagram showing a solar cell obtained after forming front grid lines and back grid lines on the structure in FIG. 9. FIG. 11 is a schematic diagram of a solar cell production line according to an embodiment of the present disclosure. DETAILED DESCRIPTION It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the exemplary embodiments described herein may be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the exemplary embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. The term “comprising” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references can mean “at least one”. FIG. 1 is a flowchart of a method for preparing a solar cell according to an embodiment of the present disclosure. The method is provided by way of embodiment, as there are a variety of ways to carry out the method. The method described below can be carried out using the configurations illustrated in FIG. 1 through FIG. 10 for example, and various elements of these figures are referenced in explaining the method. Each block in this method represents one or more processes, methods, or subroutines, carried out in the method. Additionally, the illustrated order of blocks is by example only and the order of the blocks can change. The method can begin at block S1 of FIG. 1. In block S1, a stack is provided, wherein the stack includes an N-type silicon substrate, a tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer, and a mask layer. In some embodiments, the block S1 includes the following steps S11 to S15. Step S11: providing an N-type silicon substrate. As shown in FIG. 2, the N-type silicon substrate 11 has a first surface 11a, a second surface 11b, and a side surface 11c. The second surface 11b is opposite to the first surface 11a. The side surface 11c connects the secon