WO-2026091195-A1 - BACK-CONTACT SOLAR CELL AND MANUFACTURING METHOD THEREFOR

WO2026091195A1WO 2026091195 A1WO2026091195 A1WO 2026091195A1WO-2026091195-A1

Abstract

The present invention relates to a back-contact solar cell and a manufacturing method therefor. The back-contact solar cell comprises a monocrystalline silicon substrate, a tunnel oxide layer, a first doped type polycrystalline silicon layer, a second doped type polycrystalline silicon layer, an intrinsic amorphous silicon layer, a first electrode and a second electrode; the tunnel oxide layer is arranged on one side of the monocrystalline silicon substrate; the first doped type polycrystalline silicon layer, the second doped type polycrystalline silicon layer and the intrinsic amorphous silicon layer are separately arranged on the tunnel oxide layer, the intrinsic amorphous silicon layer being arranged between the first doped type polycrystalline silicon layer and the second doped type polycrystalline silicon layer; the first electrode is connected to the first doped type polycrystalline silicon layer, and the second electrode is connected to the second doped type polycrystalline silicon layer.

Inventors

OU, Wenkai
ZHANG, PENG
ZHANG, Dongwei
SHEN, Pinwen
ZHANG, LIN
HAN, Jiqiang
HU, Shan

Assignees

江门普乐开瑞太阳能科技有限公司

Dates

Publication Date: 20260507
Application Date: 20241119
Priority Date: 20241029

Claims (19)

A back-contact solar cell, characterized in that it comprises a monocrystalline silicon substrate, a tunneling oxide layer, a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, an intrinsic amorphous silicon layer, a first electrode, and a second electrode; the tunneling oxide layer is disposed on a first side of the monocrystalline silicon substrate, the first-doped polycrystalline silicon layer, the second-doped polycrystalline silicon layer, and the intrinsic amorphous silicon layer are respectively disposed on the tunneling oxide layer, the intrinsic amorphous silicon layer is disposed between the first-doped polycrystalline silicon layer and the second-doped polycrystalline silicon layer, the first electrode is connected to the first-doped polycrystalline silicon layer, and the second electrode is connected to the second-doped polycrystalline silicon layer.
The back-contact solar cell according to claim 1, wherein the thickness of the tunneling oxide layer is 1 nm to 3 nm.
The back-contact solar cell as described in claim 1 is characterized in that the thickness of the first doped polycrystalline silicon layer is 80 nm to 300 nm.
The back-contact solar cell as described in claim 1 is characterized in that the thickness of the second doped polycrystalline silicon layer is 80 nm to 300 nm.
The back-contact solar cell according to claim 1, wherein the thickness of the intrinsic amorphous silicon layer is 80 nm to 300 nm.
The back-contact solar cell according to claim 1, wherein the back-contact solar cell includes a front passivation antireflection layer, the front passivation antireflection layer being disposed on a second side of the monocrystalline silicon substrate.
The back-contact solar cell according to any one of claims 1 to 6 is characterized in that the back-contact solar cell includes a back passivation antireflection layer, the back passivation antireflection layer being integrally covered on the first doped polycrystalline silicon layer, the second doped polycrystalline silicon layer and the intrinsic amorphous silicon layer.
A method for fabricating a back-contact solar cell, characterized by comprising the following steps: A tunneling oxide layer is prepared on a first side of a single-crystal silicon substrate, and a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, and an intrinsic amorphous silicon layer are prepared on the tunneling oxide layer, wherein the intrinsic amorphous silicon layer is located between the first-doped polycrystalline silicon layer and the second-doped polycrystalline silicon layer. A first electrode is fabricated and connected to the first doped type polycrystalline silicon layer; A second electrode is prepared and connected to the second type of doped polycrystalline silicon layer.
The preparation method according to claim 8, characterized in that the step of preparing a tunneling oxide layer on a first side of a single-crystal silicon substrate, and preparing a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, and an intrinsic amorphous silicon layer on the tunneling oxide layer, wherein the intrinsic amorphous silicon layer is located between the first-doped polycrystalline silicon layer and the second-doped polycrystalline silicon layer, comprises: A first tunneling oxide layer is prepared on a first side of a single-crystal silicon substrate; A first intrinsic amorphous silicon layer is prepared on the first tunneling oxide layer; Remove the first intrinsic amorphous silicon layer in the first region to expose the first tunneling oxide layer in the first region; A first-doped polycrystalline silicon layer is prepared on the first tunneling oxide layer in the first region; The first tunneling oxide layer and the first intrinsic amorphous silicon layer in the second region are removed, while the first tunneling oxide layer and the first intrinsic amorphous silicon layer in the third region are retained. The third region is located between the first region and the second region. A second tunneling oxide layer and a second doped polycrystalline silicon layer are prepared on the single-crystal silicon substrate in the second region.
The preparation method according to claim 9, wherein the step of removing the first intrinsic amorphous silicon layer in the first region includes: An etching protective film is prepared on the first intrinsic amorphous silicon layer, the etching protective film exposing the first intrinsic amorphous silicon layer in the first region; The first intrinsic amorphous silicon layer in the first region is removed by etching.
The preparation method according to claim 10, characterized in that the step of preparing a first doped polycrystalline silicon layer on the first tunneling oxide layer in the first region includes: A second intrinsic amorphous silicon layer is prepared on the first tunneling oxide layer in the first region; A first doping diffusion process is performed to transform the second intrinsic amorphous silicon layer into a first doped polycrystalline silicon layer, the etching protective film is transformed into a doped protective film, and a first doped oxide layer is formed on the surface of the doped protective film.
The preparation method according to claim 11, characterized in that the step of removing the first tunneling oxide layer and the first intrinsic amorphous silicon layer in the second region includes: Remove the doped protective film and the first doped oxide layer in the second region, and retain the doped protective film and the first doped oxide layer in the third region; Under the protection of the first doped oxide layer and the doped protective film, the first tunneling oxide layer and the first intrinsic amorphous silicon layer in the second region are etched away.
The preparation method according to claim 12, characterized in that the step of preparing the second tunneling oxide layer and the second doped polycrystalline silicon layer on the single-crystal silicon substrate in the second region includes: A second tunneling oxide layer is prepared by deposition on the entire surface of the first side; A third intrinsic amorphous silicon layer is prepared on the second tunneling oxide layer; A second doping diffusion process is performed to transform the third intrinsic amorphous silicon layer into a second doped polycrystalline silicon layer, and a second doped oxide layer is formed on the surface of the second doped polycrystalline silicon layer. Remove the second doped oxide layer on the first and third regions; Under the protection of the first doped oxide layer, the doped protective film and the second doped oxide layer, the second tunneling oxide layer and the second doped polysilicon layer on the first region and the third region are etched away. Remove the first doped oxide layer, the doped protective film, and the second doped oxide layer in the second region.
The preparation method according to any one of claims 8 to 13, wherein the thickness of the tunneling oxide layer is 1 nm to 3 nm.
The preparation method according to any one of claims 8 to 13 is characterized in that the thickness of the first doped polycrystalline silicon layer is 80 nm to 300 nm.
The preparation method according to any one of claims 8 to 13 is characterized in that the thickness of the second doped polycrystalline silicon layer is 80 nm to 300 nm.
The preparation method according to any one of claims 8 to 13, wherein the thickness of the intrinsic amorphous silicon layer is 80 nm to 300 nm.
The preparation method according to any one of claims 8 to 13 is characterized in that the preparation method further includes the step of preparing a front passivation antireflection layer, wherein the front passivation antireflection layer is disposed on the second side of the single crystal silicon substrate.
The preparation method according to any one of claims 8 to 13 is characterized in that the preparation method further includes the step of preparing a back passivation antireflection layer, wherein the back passivation antireflection layer is integrally covered on the first doped polycrystalline silicon layer, the second doped polycrystalline silicon layer and the intrinsic amorphous silicon layer.

Description

Back contact solar cells and their fabrication methods This application claims priority to Chinese Patent Application No. 202411525775.0, filed on October 29, 2024, entitled “Back Contact Solar Cell and Method for Preparing the Same”, the entire contents of which are incorporated herein by reference. Technical Field This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell and its fabrication method. Background Technology Energy is the foundation of world economic and social development. Future energy demand will increase with the development of the world economy. Photovoltaic power generation, as a sustainable energy alternative, has developed rapidly in recent years. Currently, the solar cells used in photovoltaic power plants are mainly crystalline silicon solar cells. With improvements in front-side light trapping, metallization performance, and silicon wafer quality, the cells have evolved from aluminum back-field cells to the TOPCon cells of today. In order to pursue the theoretical conversion efficiency of crystalline silicon solar cells to the extreme, full back-electrode contact crystalline silicon solar cells (BC cells) are gradually being considered as the most likely cells to become mass-produced cells with high conversion efficiency. All-back contact crystalline silicon solar cells (BC cells) place all metal electrodes on the back of the cell. Since there are no metal electrodes obstructing the front, this maximizes the area of the cell that absorbs sunlight, reduces optical losses, and thus improves photoelectric conversion efficiency. However, these cells also have both P-regions and N-regions on the back, which can easily create leakage paths between them, reducing cell efficiency. Therefore, the formation of these leakage paths is a key technological challenge limiting maximum efficiency. Summary of the Invention Therefore, it is necessary to provide a back-contact solar cell and its fabrication method to solve the problem of leakage current channels forming between the P-region and N-region of a BC cell. The first aspect of the present invention is to provide a back-contact solar cell, the solution of which is as follows: A back-contact solar cell includes a monocrystalline silicon substrate, a tunneling oxide layer, a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, an intrinsic amorphous silicon layer, a first electrode, and a second electrode. The tunneling oxide layer is disposed on one side of the monocrystalline silicon substrate. The first-doped polycrystalline silicon layer, the second-doped polycrystalline silicon layer, and the intrinsic amorphous silicon layer are respectively disposed on the tunneling oxide layer. The intrinsic amorphous silicon layer is disposed between the first-doped polycrystalline silicon layer and the second-doped polycrystalline silicon layer. The first electrode is connected to the first-doped polycrystalline silicon layer, and the second electrode is connected to the second-doped polycrystalline silicon layer. In one embodiment, the thickness of the tunneling oxide layer is 1 nm to 3 nm. In one embodiment, the thickness of the first doped polysilicon layer is 80 nm to 300 nm. In one embodiment, the thickness of the second doped polysilicon layer is 80 nm to 300 nm. In one embodiment, the thickness of the intrinsic amorphous silicon layer is 80 nm to 300 nm. In one embodiment, the back-contact solar cell includes a front passivation antireflection layer disposed on a second side of the monocrystalline silicon substrate. In one embodiment, the back-contact solar cell includes a back passivation antireflection layer that covers the first doped polycrystalline silicon layer, the second doped polycrystalline silicon layer, and the intrinsic amorphous silicon layer. A second aspect of the present invention is to provide a method for fabricating a back-contact solar cell, the scheme of which is as follows: A method for fabricating a back-contact solar cell includes the following steps: A tunneling oxide layer is prepared on one side of a single-crystal silicon substrate, and a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, and an intrinsic amorphous silicon layer are prepared on the tunneling oxide layer, wherein the intrinsic amorphous silicon layer is located between the first-doped polycrystalline silicon layer and the second-doped polycrystalline silicon layer. A first electrode is fabricated and connected to the first doped type polycrystalline silicon layer; A second electrode is prepared and connected to the second type of doped polycrystalline silicon layer. In one embodiment, the step of fabricating a tunneling oxide layer on a first side of a single-crystal silicon substrate, and fabricating a first-doped polycrystalline silicon layer, a second-doped polycrystalline silicon layer, and an intrinsic amorphous silicon l