Search

CN-122002961-A - Back contact solar cell, preparation method thereof and photovoltaic module

CN122002961ACN 122002961 ACN122002961 ACN 122002961ACN-122002961-A

Abstract

The invention discloses a back contact solar cell, a preparation method thereof and a photovoltaic module, and relates to the technical field of photovoltaics. According to the back contact solar cell provided by the invention, the doped region is formed on the isolation region between the first region and the second region, the doped region is utilized to form the reverse bypass channel, and the equal concentration profile shape of the depth of the doped region is controlled at the same time, so that the off-state impedance and the on-state impedance of the bypass channel are balanced, the leakage current of the back contact cell under the normal working condition is reduced on the premise of ensuring the hot spot resistance, and the negative influence on the open-circuit voltage and the parallel resistance of the back contact cell is reduced.

Inventors

  • GUAN TONGZHOU
  • SONG NAN

Assignees

  • TCL中环新能源科技股份有限公司

Dates

Publication Date
20260508
Application Date
20260211

Claims (10)

  1. 1. A back contact solar cell, comprising: The substrate comprises a backlight surface, wherein first areas and second areas are alternately arranged on the backlight surface, the first areas are provided with first doping layers, and the second areas are provided with second doping layers; the substrate comprises a first area, a second area, an isolation area, a first surface layer, a second surface layer, a first surface layer and a second surface layer, wherein the isolation area is arranged between the first area and the second area and comprises a first platform area and a second platform area; The doping region is arranged in the substrate corresponding to the region where the isolation region is located, the equal concentration profile of the doping region comprises a first sub-profile and a second sub-profile, the doping concentration of the first sub-profile is the same as that of the second sub-profile, the first sub-profile corresponds to the first platform region, and the second sub-profile corresponds to the second platform region, so that the shape of the equal concentration profile corresponds to the shape of the isolation region.
  2. 2. The back contact solar cell of claim 1, wherein the first sub-profile is parallel to the first mesa region and the second sub-profile is parallel to the second mesa region; And/or, in the thickness direction of the substrate, the distance between the first sub-profile and the first platform region is a first distance, the distance between the second sub-profile and the second platform region is a second distance, and the difference between the first distance and the second distance is less than 200nm; and/or, in the thickness direction of the substrate, the distance from the first sub-profile to the substrate surface of the first region is L1, the distance from the second sub-profile to the substrate surface of the first region is L2, and L1 and L2 satisfy that L2-L1 is less than or equal to 0.1 μm and less than or equal to 2 μm; and/or, the first platform region and the second platform region are both arranged in parallel with the backlight surface of the substrate.
  3. 3. The back contact solar cell of claim 1 or 2, wherein the first doped layer has a highest doping concentration of A1 and the second doped layer has a highest doping concentration of A2; When A1 is more than or equal to A2, the highest doping concentration A1 of the first doping layer meets 1 multiplied by 10 20 atoms/cm 3 ≤A1≤1×10 21 atoms/cm 3 , and the highest doping concentration A2 of the second doping layer meets 1 multiplied by 10 19 atoms/cm 3 ≤A2≤1×10 20 atoms/cm 3 ; When A1 is less than or equal to A2, the highest doping concentration A1 of the first doping layer meets 1 multiplied by 10 19 atoms/cm 3 ≤A1≤1×10 20 atoms/cm 3 , and the highest doping concentration A2 of the second doping layer meets 1 multiplied by 10 20 atoms/cm 3 ≤A2≤1×10 21 atoms/cm 3 .
  4. 4. The back contact solar cell of claim 3, wherein the doping type of the doped region is the same as the doping type of the first doped layer or the second doped layer; the highest doping concentration of the doped region is A3, and the highest doping concentration of the first doped layer or the second doped layer with the same doping type as the doped region is A, so that the condition that A3/A is more than or equal to 0.9 and less than or equal to 1.1 is satisfied; and/or the equal concentration profile refers to a set of curved surfaces formed by points in the doped region where the doping concentration is equal to 1/100 of the highest doping concentration.
  5. 5. The back contact solar cell of claim 1, wherein a transition region is disposed between the first and second mesa regions, the transition region being disposed obliquely, and an angle between the transition region and the second mesa region being greater than 90 °.
  6. 6. The back contact solar cell of claim 1, wherein the first region is provided with a first dielectric layer disposed between the first doped layer and the substrate; the second region is provided with a second dielectric layer disposed between the second doped layer and the substrate.
  7. 7. A method for manufacturing a back contact solar cell according to any one of claims 1 to 6, comprising depositing a multi-layer dielectric film layer on a back light surface of a substrate, the multi-layer dielectric film layer comprising an intrinsic semiconductor layer; removing the multi-layer dielectric film layer on the corresponding region of the isolation region, and etching the substrate to form a recessed isolation region between the first region and the second region; And in the process of doping the intrinsic semiconductor layer on the first region or the second region to form a first doping layer or a second doping layer, synchronously performing diffusion doping on the isolation region to form a doped region.
  8. 8. The method of claim 7, wherein the multi-layer dielectric film further comprises a dielectric layer and a mask functional layer, the intrinsic semiconductor layer being located between the dielectric layer and the mask functional layer; Removing the mask functional layer on the region corresponding to the isolation region, and then removing the intrinsic semiconductor layer, the dielectric layer and part of the substrate on the region corresponding to the isolation region to form an isolation region between the first region and the second region; the regions of the first region and the second region, which have the same doping type as the doping regions, are regions of the same type, and the other region is a region of a different type; Removing the mask functional layer on the surface of the same type region, depositing an impurity source layer, doping the intrinsic semiconductor layer in the same type region through a heat treatment process, and synchronously performing diffusion doping on the isolation region to form a doped region; and removing the impurity source layers and the mask functional layers on the surfaces of the different types of regions, reserving the impurity source layers on the surfaces of the different types of regions and the isolation region as diffusion barrier layers, and doping the intrinsic semiconductor layers on the different types of regions.
  9. 9. The method according to claim 8, wherein the impurity source layer contains a silicon oxide layer of a corresponding doping element; And/or the treatment temperature of the heat treatment process is 800-1000 ℃ and the treatment time is 1-3 h; and/or doping the intrinsic semiconductor layer on the different types of regions with a gaseous doping source or a solid doping source.
  10. 10. A photovoltaic module comprising the back contact solar cell of any one of claims 1 to 6 or the back contact solar cell prepared by the preparation method of any one of claims 7 to 9.

Description

Back contact solar cell, preparation method thereof and photovoltaic module Technical Field The invention relates to the technical field of photovoltaics, in particular to a back contact solar cell, a preparation method thereof and a photovoltaic module. Background The hot spot effect is a very dangerous phenomenon in a solar power generation system, the packaging material is burnt by the high Wen Zuyi generated by the hot spot effect, even a large fire disaster is caused, and the structure of the conventional double-sided battery ensures that when a certain battery piece is shielded, reverse current can be discharged through a welding strip and a metallization network of the battery to a certain extent, and the effect is not as good as that of an independent diode, but the effect is relieved to a certain extent. More importantly, the PN junction area is large, heat generated during reverse breakdown is relatively dispersed, and the generation of a hot spot effect can be avoided by additionally arranging a bypass diode during packaging. The front surface of the back contact battery is not provided with grid lines, the P area and the N area of the battery are alternately arranged and distributed on the back surface of the battery, the back contact battery is very dense, each main grid is only connected with the metal grid lines of the corresponding areas, the metal electrodes with the same polarity in different areas are not connected into a whole, and the reverse current does not have the condition of discharging through a metal electrode network. If one of the small cells (or a portion of the entire battery) is blocked, the reverse voltage will be concentrated on this small, isolated PN junction, and if there is no preset bleed path, the reverse voltage of the blocked cell will rise rapidly until avalanche breakdown of the PN junction occurs. All energy is concentrated at that tiny breakdown point and released, creating extremely high local temperatures (hot spots), which are very likely to burn the battery, damage the packaging material, and even cause a fire. The existing researches at present show that the arrangement of a reverse bypass channel in the battery of the back contact battery is an effective method for avoiding the hot spot effect when the battery is shielded. In the related art, an overlap region is generally provided at a predetermined region between two polarity semiconductor layers alternately distributed, and the two semiconductor layers are contacted through a thin dielectric layer at the overlap region, thereby forming a reverse bypass channel. However, the reverse bypass channel is subjected to multiple thin film deposition, laser and wet chemical etching in the preparation process, so that the overlapped film layer structure is easily damaged, and the off-state and on-state characteristics of the bypass channel in different areas distributed on the battery are greatly different, so that the integral hot spot effect resistance of the back contact battery and the conversion efficiency of the back contact battery are affected. Therefore, the reverse bypass channel prepared by the prior art has a complex structure, and complicated preparation steps and methods, so that the performance of the reverse bypass channel is inconsistent, and the overall performance of the back contact battery is further affected. At present, the structure of the reverse bypass channel needs to be optimized so as to simplify the preparation process, improve the consistency of the performance of the reverse bypass channel and improve the overall performance of the back contact battery. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a back contact solar cell, a preparation method thereof and a photovoltaic module, and aims to provide a simple reverse bypass channel structure, wherein the reverse bypass channel has better performance consistency, and is beneficial to improving the overall performance of the cell. The invention is realized in the following way: in a first aspect, the present invention provides a back contact solar cell comprising: The substrate comprises a backlight surface, wherein first areas and second areas are alternately arranged on the backlight surface, the first areas are provided with first doping layers, and the second areas are provided with second doping layers; Along the thickness direction of the substrate, at least part of the substrate of the isolation region is sunken relative to the surface of the substrate of the first region or the second region to a direction far away from the surface of the substrate so as to form a second platform region, and the first platform region is arranged between the second platform region and the first region and the second region; The doping region is arranged in the substrate corresponding to the region where the isolation region is located, the equal concentration profile of the doping