CN-121985625-A - Back contact solar cell and preparation method and application thereof

CN121985625ACN 121985625 ACN121985625 ACN 121985625ACN-121985625-A

Abstract

The invention provides a back contact solar cell, a preparation method and application thereof. The back contact solar cell comprises a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface which are opposite, the front surface is of a suede structure, the back surface comprises a first type region and a second type region which are alternately arranged in a first direction, the adjacent first type region and second type region are separated by a separation region, the surfaces of the silicon substrate corresponding to the first type region, the second type region and the separation region are of a plane structure, the first type region comprises a first dielectric layer, a first doping layer, a first passivation layer and a first anti-reflection layer, the second type region comprises a second dielectric layer, a second doping layer, a second passivation layer and a second anti-reflection layer, the front surface is provided with a front surface floating emitter, and the back surface is provided with a metal electrode. The invention not only fully utilizes the optical secondary internal refraction of the back surface, but also reduces the recombination loss caused by the transverse transmission process of minority carriers and reduces the influence of electric shielding.

Inventors

CHEN JIE
YANG PAN
LI XIAOLONG
HE SHENG
HE CHENXU

Assignees

正泰新能科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260203

Claims (10)

1. The back contact solar cell is characterized by comprising a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface which are opposite, and the front surface is of a suede structure; The back surface comprises first type areas and second type areas which are alternately arranged in a first direction, and the adjacent first type areas and second type areas are separated by a separation area, wherein the first direction is a direction perpendicular to the thickness of the silicon substrate; The surfaces of the silicon substrate corresponding to the first type region, the second type region and the interval region are all planar structures; the second type region comprises a second dielectric layer, a second doping layer, a second passivation layer and a second anti-reflection layer along the direction away from the thickness of the silicon substrate; the front side has a front surface floating emitter and the back side is provided with a metal electrode.
2. The back contact solar cell of claim 1, wherein the first type region is a P-type doped region and the second type region is an N-type doped region; And the P-type doped region, the N-type doped region and the isolation region respectively correspond to the back surface of the silicon substrate, and the vertical distances from the P-type doped region, the N-type doped region and the isolation region to the front surface of the silicon substrate are sequentially reduced.
3. The back contact solar cell of claim 1, wherein the spacer comprises a third passivation layer and a third anti-reflection layer in a direction away from the thickness of the silicon substrate; And/or the surface roughness Ra of the back surface of the silicon substrate corresponding to the spacing region is less than 2 mu m; and/or the width of the spacing region in the first direction is 20-70 μm.
4. The back contact solar cell of claim 1, wherein the silicon substrate is an N-type silicon wafer or a P-type silicon wafer; And/or, the first dielectric layer and the second dielectric layer each independently comprise a silicon oxide layer; And/or, the thickness of the first dielectric layer and the second dielectric layer is 1nm-2nm independently; and/or the first doped layer is a P-type doped polysilicon layer, and the second doped layer is an N-type doped polysilicon layer; and/or the thickness of the first doped layer is 90nm-400nm; and/or the thickness of the second doped layer is 90nm-400nm.
5. The back contact solar cell of claim 3, wherein the first passivation layer, the second passivation layer, and the third passivation layer each independently comprise any one or a combination of at least two of an aluminum oxide layer, a silicon nitride layer, or a silicon oxynitride layer; and/or the thicknesses of the first passivation layer, the second passivation layer and the third passivation layer are each independently 3nm to 45nm; and/or, the first, second and third anti-reflection layers each independently comprise at least one silicon nitride layer and/or at least one silicon oxynitride layer; and/or the thicknesses of the first, second and third anti-reflection layers are each independently 10nm to 130nm; and/or the first type region and the second type region are respectively provided with the metal electrode; and/or the front side of the silicon substrate comprises a front side passivation layer and a front side anti-reflection layer along a direction far away from the thickness of the silicon substrate.
6. The back contact solar cell of claim 5, wherein the first, second, and third anti-reflective layers each independently comprise a first silicon nitride back layer, a second silicon nitride back layer, a third silicon nitride back layer, a first silicon oxynitride back layer, a second silicon oxynitride back layer, and a third silicon oxynitride back layer; The thickness of the first silicon nitride rear layer is 10-20nm, the thickness of the second silicon nitride rear layer is 15-30nm, the thickness of the third silicon nitride rear layer is 20-35nm, the thickness of the first silicon oxynitride rear layer is 8-15nm, the thickness of the second silicon oxynitride rear layer is 6-15nm, and the thickness of the third silicon oxynitride rear layer is 5-15nm; And/or, the front passivation layer comprises an aluminum oxide layer; and/or the front side anti-reflection layer comprises a first silicon nitride front layer, a second silicon nitride front layer, a third silicon nitride front layer, a first silicon oxynitride front layer, a second silicon oxynitride front layer and a third silicon oxynitride front layer; The thickness of the first silicon nitride front layer is 10-20nm, the thickness of the second silicon nitride front layer is 10-20nm, the thickness of the third silicon nitride front layer is 15-30m, the thickness of the first silicon oxynitride front layer is 6-15nm, the thickness of the second silicon oxynitride front layer is 6-15nm, and the thickness of the third silicon oxynitride front layer is 5-10nm.
7. A method of manufacturing a back contact solar cell according to any one of claims 1-6, comprising the steps of: Providing a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface which are opposite, and the front surface and the back surface are textured structures; performing double-sided boron expansion on the silicon substrate, and then removing a first BSG layer formed on the back surface; adopting a polishing method to thin a first BSG layer on the front surface of the silicon substrate, and polishing the back surface of the silicon substrate to form a planar structure; Sequentially depositing a first dielectric layer and a first doping layer on the whole back surface of the silicon substrate, removing the second BSG layer, the first doping layer and the first dielectric layer in a preset area of a second type area and a spacer, and removing the formed second BSG layer and poly layer on the front surface of the silicon substrate; Continuously depositing a second dielectric layer and a second doped layer on the whole back surface of the silicon substrate, then removing the PSG layer, the second doped layer and the second dielectric layer in a preset area of a first type area and a spacer area, and removing the formed PSG layer and poly layer on the front surface of the silicon substrate; And sequentially depositing a passivation layer and an anti-reflection layer on the back surface of the silicon substrate, and then preparing a metal electrode.
8. The method according to claim 7, wherein the polishing method comprises the specific steps of: firstly, polishing the back surface of the silicon substrate by adopting polishing solution until the back surface of the silicon substrate is polished to the silicon substrate, and then removing part of the first BSG layer on the front surface of the silicon substrate by adopting cleaning solution to finish thinning treatment; The polishing solution comprises alkali and a polishing additive, wherein the polishing additive comprises a silicon-GPT 01V01 additive, and the cleaning solution comprises hydrofluoric acid and hydrogen peroxide, wherein the concentration of the hydrofluoric acid is 0.01-1.25 wt%; And/or, the method for removing the second BSG layer, the first doping layer and the first dielectric layer in the preset area of the second type area and the spacer area and removing the formed second BSG layer and the formed poly layer on the front surface of the silicon substrate comprises the following steps: Removing the second BSG layer of the preset area of the second type area and the interval area and the second BSG layer formed on the front surface of the silicon substrate, and polishing to remove the poly layer formed on the front surface and the first doping layer and the first dielectric layer of the preset area of the second type area and the interval area; wherein, in the polishing removal process, the polishing solution used comprises alkali and a polishing additive, and the polishing additive comprises a silicon-GPT 01V01 additive; and/or, the method for removing the PSG layer, the second doping layer and the second dielectric layer in the preset area of the first type area and the spacer area and removing the formed PSG layer and poly layer on the front surface of the silicon substrate comprises the following steps: Firstly removing the PSG layer of the preset area of the first type area and the interval area and the PSG layer on the front surface of the silicon substrate, then polishing and removing the second doped layer and the second dielectric layer of the preset area of the first type area and the interval area and the front surface poly layer of the silicon substrate, and then carrying out secondary polishing treatment on the preset area of the interval area; the polishing solution used in the polishing removal process comprises alkali and a polishing additive, wherein the polishing additive comprises a Tuoban additive, and the polishing solution used in the secondary polishing treatment process comprises alkali and a polishing additive, and the secondary polishing additive comprises a Tuoban additive.
9. The preparation method according to claim 7, characterized in that the preparation method comprises the steps of: (1) Providing a textured silicon substrate, wherein the front and back surfaces of the silicon substrate are textured structures; (2) Performing double-sided boron expansion on the silicon substrate, and then removing a first BSG layer formed on the back surface; (3) The polishing method is characterized in that a polishing method is adopted to thin a first BSG layer on the front side of the silicon substrate, and meanwhile the back side of the silicon substrate is polished to the silicon substrate to form a planar structure, and the polishing method comprises the following specific steps: firstly, pre-cleaning the silicon substrate, then polishing by adopting polishing solution, and then post-cleaning; Adopting cleaning liquid to carry out tail cleaning so as to remove part of the first BSG layer on the front surface of the silicon substrate and finish thinning treatment; The polishing solution comprises alkali and a polishing additive, wherein the polishing additive comprises a silicon-GPT 01V01 additive, and the cleaning solution comprises hydrofluoric acid and hydrogen peroxide, wherein the concentration of the hydrofluoric acid is 0.1-1.25 wt%; (4) Sequentially depositing a first dielectric layer and a first amorphous silicon layer on the whole back surface of the silicon substrate, and then performing boron diffusion to form a first doped layer; (5) Removing the formed second BSG layer in the second type region and the predetermined region of the spacer, and removing the second BSG layer formed on the front surface of the silicon substrate; (6) Pre-cleaning the silicon substrate treated in the step (5), then polishing and removing the P-poly layer formed on the front surface of the silicon substrate by adopting a polishing solution, simultaneously polishing and removing the first doped layer and the first dielectric layer of the second type region and the preset region of the spacer region, and then post-cleaning; Adopting cleaning liquid to thin the second BSG layer in a preset area of a first type area on the back surface of the silicon substrate, and then adopting acid liquor to carry out surface dehydration and metal ion removal and drying; The polishing solution comprises alkali and a polishing additive, wherein the polishing additive comprises a silicon-GPT 01V01 additive, and the cleaning solution comprises hydrofluoric acid and hydrogen peroxide; (7) Sequentially depositing a second dielectric layer and a second amorphous silicon layer on the back surface of the silicon substrate, and then performing phosphorus diffusion to form a second doped layer; (8) Removing the PSG layer in a first type region on the back surface of the silicon substrate and a preset region of the spacer, and removing the PSG layer on the front surface of the silicon substrate; (9) Removing the second doping layer and part of the second dielectric layer in a preset area of the first type area and the spacer area on the back surface of the silicon substrate by adopting a polishing method, and simultaneously removing the N-poly layer on the front surface of the silicon substrate; performing secondary polishing treatment on the preset area of the interval area until the silicon substrate is polished; removing the residual second dielectric layer in the preset area of the first type area by adopting cleaning liquid, and simultaneously removing the residual second BSG layer, PSG layer and first BSG layer on the silicon substrate; the polishing method comprises a polishing method, a polishing method and a cleaning method, wherein the polishing method comprises the steps of using polishing solution comprising alkali and polishing additive, wherein the polishing additive comprises a Tuoban additive, and the polishing solution comprises alkali and a secondary polishing additive in the secondary polishing treatment process, wherein the secondary polishing additive comprises a Tuoban additive; (10) Respectively depositing a passivation layer and an antireflection layer on the front surface and the back surface of the silicon substrate; and carrying out metallization treatment on the back surface of the silicon substrate, and then carrying out sintering and light injection treatment to obtain the back contact solar cell.
10. Use of a back contact solar cell according to any of claims 1-6 in the photovoltaic field.

Description

Back contact solar cell and preparation method and application thereof Technical Field The invention belongs to the technical field of photovoltaics, and particularly relates to a back contact solar cell, and a preparation method and application thereof. Background The full back electrode contact (INTERDIGITATED BACK CONTACT, IBC) is proposed by Schwartz and Lammert in 1975 for the first time, the IBC is prepared by preparing p-region and n-region which are arranged in an interdigital interval manner on the back of the battery, and forming metallization contact and grid lines on the p-region and the n-region respectively, the anode and the cathode of the IBC battery are both arranged on the back of the battery, the front of the IBC battery is free from metal grid line shading, the metal electrode shading loss is avoided, the optical absorption of the battery is greatly improved, good short-circuit current is realized, the emitter on the front surface of the IBC battery is eliminated, and the front surface recombination loss is reduced. The tunneling oxide passivation contact solar cell (Tunnel Oxide Passivated Contact solar cell, TOPCon) is a novel passivation contact solar cell proposed by Fraunhofer solar institute of Germany in the 28 th European PVSEC photovoltaic society in 2013 for the first time, firstly, a layer of tunneling oxide layer of 1-2nm is prepared on the back of the cell, then, a layer of doped polysilicon is deposited, and the tunneling oxide layer and the doped polysilicon form a passivation contact structure together, so that good interface passivation is provided for the back of a silicon wafer. The ultrathin oxide layer can enable electrons to tunnel into the polycrystalline silicon layer and simultaneously block the transportation of holes, so that the recombination current is reduced. The lateral transport characteristics of the doped polysilicon layer reduce the series resistance. The two characteristics improve the open circuit voltage, the filling factor and the conversion efficiency of the battery together. The IBC battery has excellent process superposition capability, and can be organically combined with TOPCon, heterojunction WITH INTRINSIC THIN LAYER, HJT, perovskite and other technologies, so that the battery conversion efficiency is further improved. A brand new battery based on IBC battery structure superposition is called an "XBC battery", which is expected to become the next generation mainstream technology choice in the future. However, for XBC batteries, the following defects and defects still exist that 1) in the process of forming a p region and an n region on the back surface, a Gap region between the p region and the n region always presents a suede shape due to technological influence, the reflectivity of the Gap region is lower, the optical loss of the back surface is increased, meanwhile, the suede structure has larger specific surface area, dangling bonds and surface defect states are more, interface passivation difficulty is increased, and effective collection of carriers is not facilitated, and 2) as the p region and the n region of the XBC battery are concentrated on the back surface, minority carriers can be collected by an emitter only by transverse transmission through a base region, and the movement distance of the minority carriers is increased when the base region is wider, so that the collection effect is weakened. Therefore, how to better utilize the optical secondary internal refraction of the back surface of the silicon substrate and reduce the recombination loss caused by the lateral transmission process of minority carriers is a technical problem to be solved. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a back contact solar cell and a preparation method and application thereof. The invention designs the surfaces of the silicon substrate corresponding to the first type region, the second type region and the interval region respectively into a planar structure, thereby better utilizing optical secondary internal refraction and absorption paths on the back surface of the silicon substrate, effectively reducing optical loss on the back surface, laying a foundation for improving short-circuit current of the battery, simultaneously, in the structural design of integrating all metal electrodes on the back surface, leading in a front surface floating emitter on the front surface of the silicon substrate, thereby constructing a strong longitudinal built-in electric field in the battery body, effectively reducing composite loss caused by the transverse transmission process of minority carriers, reducing electric shielding influence and remarkably improving photoelectric conversion efficiency of the battery. In order to achieve the aim of the invention, the invention adopts the following technical scheme: in a first aspect, the present invention provides a back contact solar cell comprising a silicon substr