EP-4742863-A1 - HETEROJUNCTION SOLAR CELL AND PREPARATION METHOD THEREFOR

EP4742863A1EP 4742863 A1EP4742863 A1EP 4742863A1EP-4742863-A1

Abstract

Embodiments of the present disclosure provide a heterojunction solar cell and a preparation method therefor. The heterojunction solar cell comprises: a silicon substrate, wherein at least one of the front and back surfaces of the silicon substrate is a textured surface of a pyramid structure; silicon-based thin films provided on the front and back surfaces of the silicon substrate, wherein each silicon-based thin film comprises an intrinsic layer and a doped layer provided on the side of the intrinsic layer facing away from the silicon substrate, the doping types of the doped layers provided on the front and back surfaces of the silicon substrate are opposite, and the thickness of the silicon-based thin film covering the pyramid structure decreases as the silicon-based thin film covering the pyramid structure gets closer the silicon substrate; and a transparent conductive layer and grid electrodes provided on the side of each silicon-based thin film facing away from the silicon substrate. The apex of the pyramid structure is a stress concentration point, and the stress gradually decreases in a downward direction. In the coating process of the transparent conductive layer, because the silicon-based thin film at the apex is thick, the transparent conductive material in an apex area can be prevented from being bombarded into an interface of the silicon substrate, thereby preventing interface recombination and improving the efficiency of heterojunction solar cells.

Inventors

GAO, Jifan
MENG, Zibo
BAI, Yanhui
LI, HONGWEI
Huo, Tingting
HOU, CHENGLI
YANG, Guangtao
CHEN, Daming

Assignees

Trina Solar Co., Ltd
Trina Solar (Changzhou) Science & Technology Co., Ltd

Dates

Publication Date: 20260513
Application Date: 20240730

Claims (20)

A heterojunction solar cell, characterized by comprising: a silicon substrate comprising a front side and a back side, wherein at least one of the front surface and the back surface is provided as a textured surface having a pyramid structure; a silicon-based thin film disposed on the front surface and the back surface of the silicon substrate, the silicon-based thin film comprising an intrinsic layer and a doped layer disposed on a side of the intrinsic layer away from the silicon substrate; wherein a doping type of the doped layer on the front surface is opposite to a doping type of the doped layer on the back surface, and a thickness of the silicon-based thin film covering the pyramid structure decreases closer to the silicon substrate; and a transparent conductive layer and grid electrodes disposed on a side of each silicon-based thin film away from the silicon substrate.
The heterojunction solar cell according to claim 1, wherein the intrinsic layer is a double-layer structure; the intrinsic layer comprises: an intrinsic hydrogenated amorphous silicon oxide layer and an intrinsic hydrogenated nanocrystalline silicon layer; and the intrinsic hydrogenated amorphous silicon oxide layer is closer to the silicon substrate than the intrinsic hydrogenated nanocrystalline silicon layer.
The heterojunction solar cell according to claim 2, wherein a thickness of the intrinsic hydrogenated amorphous silicon oxide layer is 4-8 nm.
The heterojunction solar cell according to claim 2, wherein a thickness of the intrinsic hydrogenated nanocrystalline silicon layer is 5-10 nm.
The heterojunction solar cell according to claim 1, wherein the doped layer is a doped microcrystalline silicon oxycarbide layer.
The heterojunction solar cell according to claim 5, wherein the doped microcrystalline silicon oxycarbide layer located on the front surface of the silicon substrate has N-type dopant, an activation concentration of N-type dopant is not less than 1E+17/cm 3 ; and the doped microcrystalline silicon oxycarbide layer located on the back surface of the silicon substrate has P-type dopant, an activation concentration of P-type dopant is not less than 1E+16/cm 3 .
The heterojunction solar cell according to claim 1, wherein a doping concentration of the doped layer increases in a direction from the silicon substrate toward the grid electrodes.
The heterojunction solar cell according to claim 1, wherein the doped layer disposed on the front surface of the silicon substrate has N-type dopant, the doped layer disposed on the back surface of the silicon substrate has P-type dopant; and a grid density of the grid electrodes located on the front surface of the silicon substrate is greater than a grid density of the grid electrodes located on the back surface of the silicon substrate.
The heterojunction solar cell according to claim 1, wherein the heterojunction solar cell further comprises: an anti-reflection layer, disposed on a side of the transparent conductive layer on the front surface of the silicon substrate away from the silicon substrate; and a light transmittance of the anti-reflection layer is greater than a light transmittance of the transparent conductive layer on the front surface of the silicon substrate.
The heterojunction solar cell according to claim 1, wherein the intrinsic layer is a single-layer structure, and the intrinsic layer comprises: a single intrinsic amorphous silicon layer.
The heterojunction solar cell according to claim 1, wherein, the front surface and the back surface of the silicon substrate are both provided as textured surfaces having a pyramid structure; the silicon-based thin film disposed on the front surface of the silicon substrate is a first silicon-based thin film, and the silicon-based thin film disposed on the back surface of the silicon substrate is a second silicon-based thin film; the first silicon-based thin film comprises a first intrinsic layer and a first doped layer disposed on a side of the first intrinsic layer away from the silicon substrate; and the second silicon-based thin film comprises a second intrinsic layer and a second doped layer disposed on a side of the second intrinsic layer away from the silicon substrate.
The heterojunction solar cell according to claim 11, wherein, the silicon substrate is an N-type silicon substrate; a doping type of the first doped layer is N-type doping, and a doping element is phosphorus; and a doping type of the second doped layer is P-type doping, and a doping element is boron or aluminum.
The heterojunction solar cell according to claim 11, wherein a thickness of the first doped layer is 60-80 nm, and a thickness of the second doped layer is 60-80 nm.
A method for preparing a heterojunction solar cell, characterized by comprising: texturing at least one of a front surface and a back surface of a silicon substrate, to obtain a textured surface having a pyramid structure; forming a silicon-based thin film on the front surface and the back surface of the silicon substrate, the silicon-based thin film comprising an intrinsic layer and a doped layer disposed on a side of the intrinsic layer away from the silicon substrate, wherein a thickness of the silicon-based thin film covering the pyramid structure decreases closer to the silicon substrate; and forming a transparent conductive layer and grid electrodes on a side of each silicon-based thin film away from the silicon substrate.
The method for preparing a heterojunction solar cell according to claim 14, wherein the intrinsic layer is a double-layer structure; the intrinsic layer comprises: an intrinsic hydrogenated amorphous silicon oxide layer and an intrinsic hydrogenated nanocrystalline silicon layer; and the intrinsic hydrogenated amorphous silicon oxide layer is closer to the silicon substrate than the intrinsic hydrogenated nanocrystalline silicon layer.
The method for preparing a heterojunction solar cell according to claim 15, wherein a thickness of the intrinsic hydrogenated amorphous silicon oxide layer is 4-8 nm, and a thickness of the intrinsic hydrogenated nanocrystalline silicon layer is 5-10 nm.
The method for preparing a heterojunction solar cell according to claim 14, wherein the doped layer is a doped microcrystalline silicon oxycarbide layer.
The method for preparing a heterojunction solar cell according to claim 17, wherein the doped microcrystalline silicon oxycarbide layer located on the front surface of the silicon substrate has N-type dopant, an activation concentration of N-type dopant is not less than 1E+17/cm 3 ; and the doped microcrystalline silicon oxycarbide layer located on the back surface of the silicon substrate has P-type dopant, an activation concentration of P-type dopant is not less than 1E+16/cm 3 .
The method for preparing a heterojunction solar cell according to claim 14, wherein a doping concentration of the doped layer increases in a direction from the silicon substrate toward the grid electrodes.
The method for preparing a heterojunction solar cell according to claim 14, wherein the doped layer disposed on the front surface of the silicon substrate has N-type dopant, and the doped layer disposed on the back surface of the silicon substrate has P-type dopant; and a grid density of the grid electrodes located on the front surface of the silicon substrate is greater than a grid density of the grid electrodes located on the back surface of the silicon substrate.

Description

Cross-reference to related applications The present disclosure claims the priority to Chinese Patent Application No. 202310970322.8, filed on August 02, 2023, and entitled "Heterojunction Solar Cell and Preparation Method therefor", the entire contents of which are incorporated herein by reference. Technical field The present disclosure relates to the field of solar cell technologies, and in particular, to a heterojunction solar cell and a preparation method therefor. Background Heterojunction with Intrinsic Thin layer (HJT) solar cells are receiving increasing attention in the industry. The heterojunction cell structure typically takes a silicon substrate as the center, and an intrinsic amorphous silicon thin film is deposited between the doped amorphous silicon on both sides of the silicon substrate and the silicon substrate. After adopting this process measure, the performance of the PN junction is improved, thereby increasing the conversion efficiency of the heterojunction solar cell. How to improve the cell efficiency of heterojunction solar cells is a topic considered by the industry. Summary of the invention In view of the disadvantages of the related art described above, the present disclosure aims to provide a heterojunction solar cell and a preparation method therefor, so as to solve the technical problem of low efficiency of heterojunction solar cells in the related art. A first aspect of the present disclosure provides a heterojunction solar cell, comprising: a silicon substrate comprising a front side and a back side, wherein at least one of the front surface and the back surface is provided as a textured surface having a pyramid structure;a silicon-based thin film disposed on the front surface and the back surface of the silicon substrate, the silicon-based thin film comprising an intrinsic layer and a doped layer disposed on a side of the intrinsic layer away from the silicon substrate; wherein a doping type of the doped layer on the front surface is opposite to a doping type of the doped layer on the back surface, and a thickness of the silicon-based thin film covering the pyramid structure decreases closer to the silicon substrate; anda transparent conductive layer and grid electrodes disposed on a side of each silicon-based thin film away from the silicon substrate. In some embodiments, the intrinsic layer is a double-layer structure, the intrinsic layer comprises: an intrinsic hydrogenated amorphous silicon oxide layer and an intrinsic hydrogenated nanocrystalline silicon layer; andthe intrinsic hydrogenated amorphous silicon oxide layer is closer to the silicon substrate than the intrinsic hydrogenated nanocrystalline silicon layer. In some embodiments, a thickness of the intrinsic hydrogenated amorphous silicon oxide layer is 4-8 nm. In some embodiments, a thickness of the intrinsic hydrogenated nanocrystalline silicon layer is 5-10 nm. In some embodiments, the doped layer is a doped microcrystalline silicon oxycarbide layer. In some embodiments, the doped microcrystalline silicon oxycarbide layer located on the front surface of the silicon substrate has N-type dopant, an activation concentration of N-type dopant is not less than 1E+17/cm3; and the doped microcrystalline silicon oxycarbide layer located on the back surface of the silicon substrate has P-type dopant, an activation concentration of P-type dopant is not less than 1E+16/cm3. In some embodiments, a doping concentration of the doped layer increases in a direction from the silicon substrate toward the grid electrodes. In some embodiments, the doped layer disposed on the front surface of the silicon substrate has N-type dopant, the doped layer disposed on the back surface of the silicon substrate has P-type dopant; anda grid density of the grid electrodes located on the front surface of the silicon substrate is greater than a grid density of the grid electrodes located on the back surface of the silicon substrate. In some embodiments, the heterojunction solar cell further comprises: an anti-reflection layer, disposed on a side of the transparent conductive layer on the front surface of the silicon substrate away from the silicon substrate; and a light transmittance of the anti-reflection layer is greater than a light transmittance of the transparent conductive layer on the front surface of the silicon substrate. A second aspect of the present disclosure further provides a method for preparing a heterojunction solar cell, wherein the method for preparing a heterojunction solar cell comprises: texturing at least one of a front surface and a back surface of a silicon substrate, to obtain a textured surface having a pyramid structure;forming a silicon-based thin film on the front surface and the back surface of the silicon substrate, the silicon-based thin film comprising an intrinsic layer and a doped layer disposed on a side of the intrinsic layer away from the silicon substrate, wherein a thickness of the silicon-based thin film