CN-122028537-A - Battery back partition preparation process

CN122028537ACN 122028537 ACN122028537 ACN 122028537ACN-122028537-A

Abstract

The invention relates to the technical field of batteries and discloses a battery back partition preparation process which is characterized by comprising the following steps of controlling partition thickness of a back polysilicon layer in a battery structure of passivation contact of a tunneling oxide layer, so that the polysilicon layer below a metal electrode contact area keeps a first thickness, and the polysilicon layer of a non-electrode contact area is thinned to a second thickness, thereby forming a polysilicon finger structure, wherein the first thickness is larger than the second thickness, parasitic light absorption is effectively reduced by reducing the thickness of the polysilicon layer of the non-electrode area, and particularly, the utilization of infrared light is increased, so that the photoelectric conversion efficiency of the battery is absolutely improved by 0.3-0.45%. The thicker polysilicon layer under the electrode ensures low contact resistance and good passivation, while the thin layer structure of the non-electrode region reduces optical shielding and carrier recombination, achieving the best balance of passivation, contact and optical performance.

Inventors

GAO BEI
DONG SHUQUAN
XIAO BIN
XU WENZHOU
WAN YIMAO

Assignees

正奇光能科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260202

Claims (7)

1. A process for preparing a cell back surface partition is characterized by comprising the following steps of controlling partition thickness of a back surface polycrystalline silicon layer in a cell structure with a tunneling oxide layer in passivation contact mode, enabling the polycrystalline silicon layer below a metal electrode contact area to keep a first thickness, and enabling the polycrystalline silicon layer below a non-electrode contact area to be thinned to a second thickness, so that a polycrystalline silicon finger-shaped structure is formed, wherein the first thickness is larger than the second thickness.
2. The process of claim 1, wherein the first thickness is 75nm to 85nm and the second thickness is 35nm to 45nm.
3. The cell backside segment fabrication process of claim 1, wherein the segment thickness control is achieved by a laser mask in combination with a chemical etching process.
4. A cell backside partition preparation process according to claim 3, wherein the chemical etching process is an alkaline etching process.
5. The cell backside partitioned fabrication process of claim 1, wherein the thinned polysilicon finger structure is used to reduce optical parasitic absorption at the non-electrode contact region.
6. The cell backside zoned fabrication process of claim 1, wherein the thicker metal contact region polysilicon layer is used to optimize passivation and reduce metal contact resistance.
7. A TOPCon solar cell, characterized in that the back polysilicon layer is a polysilicon finger structure produced by the process of any one of claims 1 to 6.

Description

Battery back partition preparation process Technical Field The invention relates to the technical field of batteries, in particular to a battery back partition preparation process. Background In Topcon (tunnel oxide passivation contact) cell structures, the Poly layer (polysilicon) acts primarily as a passivation layer and a dielectric layer. The effect is not only to reduce the recombination probability of carriers. And good ohmic contact can be provided for the silicon base and the metal electrode, so that carrier output is effectively promoted. However, POLY layers present serious parasitic light absorption problems due to the nature of the polysilicon material itself and its doping concentration. Although it absorbs photons, these photons cannot be converted into efficient electron-hole pairs, resulting in a loss of cell efficiency. In order to balance passivation effect, contact resistance and optical loss, the prior art proposes a backside polysilicon thinning technique. However, the conventional uniform thinning process is difficult to meet the contradictory requirements of low contact resistance at the electrode and low parasitic absorption at the non-electrode area. Therefore, a preparation process capable of realizing regional and differential thickness control of the polysilicon layer is urgently needed to further improve the conversion efficiency of TOPCon batteries. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide a battery back partition preparation worker. The process realizes the zonal thickness control on the polysilicon layer, aims to optimize passivation effect, reduce contact resistance and obviously reduce parasitic light absorption, thereby improving the photoelectric conversion efficiency of the battery. Technical proposal In order to achieve the aim, the preparation process of the TOPCon back side polycrystalline silicon finger structure of the battery adopts the following technical scheme that in the battery structure with passivation contact of a tunneling oxide layer, the back side polycrystalline silicon layer is subjected to zone thickness control, so that the polycrystalline silicon layer below a metal electrode contact area keeps a first thickness, and the polycrystalline silicon layer of a non-electrode contact area is thinned to a second thickness, so that the polycrystalline silicon finger structure is formed, wherein the first thickness is larger than the second thickness. Preferably, the first thickness is 75nm-85nm, and the second thickness is 35nm-45nm. Preferably, the zoned thickness control is achieved by a laser mask in combination with a chemical etching process. Preferably, the chemical etching process is an alkaline etching process. Preferably, the thinned polysilicon finger structure is used to reduce optical parasitic absorption of the non-electrode contact region. Preferably, the thicker metal contact region polysilicon layer is used to optimize passivation effect and reduce metal contact resistance. A TOPCon solar cell includes a polysilicon finger structure made by the fabrication process. Advantageous effects By reducing the thickness of the polysilicon layer in the non-electrode region, parasitic light absorption is effectively reduced, particularly, the utilization of infrared light is increased, and the photoelectric conversion efficiency of the battery can be absolutely improved by 0.3-0.45%. The thicker polysilicon layer under the electrode ensures low contact resistance and good passivation, while the thin layer structure of the non-electrode region reduces optical shielding and carrier recombination, achieving the best balance of passivation, contact and optical performance. Drawings Fig. 1 is a schematic diagram of the overall structure of the present invention. Detailed Description In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings are merely for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. In the description of the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "configured," "engaged," "connected," and the like are to be construed broadly, and include, for example, "connected," either permanently or