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CN-122002950-A - Back contact solar cell and preparation method thereof

CN122002950ACN 122002950 ACN122002950 ACN 122002950ACN-122002950-A

Abstract

Providing a back contact solar cell and a preparation method thereof, preparing a functional layer and a mask layer on the back of a silicon wafer, performing laser patterning processing on the back of the silicon wafer, and removing part of the mask layer or modifying; the method comprises the steps of scanning a main body of a patterning processing area by using film opening laser, processing the edge of the laser scanning area by using the edge, superposing light spots of the edge processing laser in the scanning direction to form a straight laser processing line, merging the film opening laser scanning area and the edge processing laser scanning area into the patterning processing area, removing a functional layer corresponding to the laser patterning processing area by wet cleaning, wherein the obtained side surface is an inclined surface, and the laser patterning processing area is an N area, a P area, an N area and a GAP area or positions corresponding to the P area and the GAP area. And the edge laser is adopted for modification to form a straight laser processing line, and after wet cleaning, the inclined plane formed by the edge can reduce the surface recombination rate of the silicon wafer and improve the conversion efficiency of the solar cell.

Inventors

  • LU HONGYAN
  • ZHANG SONG
  • ZHU FAN
  • YAN TINGTING
  • CHENG XIAOWEI

Assignees

  • 帝尔激光科技(无锡)有限公司

Dates

Publication Date
20260508
Application Date
20260131

Claims (17)

  1. 1. The preparation method of the back contact solar cell comprises the steps of preparing a functional layer and a mask layer on the back surface of a silicon wafer, and is characterized in that: The method comprises the steps of carrying out laser patterning processing on the back surface of a silicon wafer, removing part of the mask layer or modifying the mask layer, wherein a main body of a patterning processing area is scanned by using an opening film laser, the edge of the patterning processing area is scanned by using an edge processing laser, and the union of the opening film laser scanning area and the edge processing laser scanning area is the patterning processing area; Wherein, the facula of the edge processing laser is overlapped in the scanning direction to form a straight laser processing line; wet cleaning to remove the functional layer corresponding to the laser patterning processing region; The laser patterning processing area is an N area corresponding position, a P area corresponding position, an N area corresponding position and a GAP area corresponding position, or a P area corresponding position and a GAP area corresponding position.
  2. 2. The method for manufacturing a back contact solar cell according to claim 1, wherein the functional layer is a tunneling oxide layer and a doped polysilicon layer or a boron diffusion layer, which are sequentially arranged, and the doped polysilicon layer is a phosphorus doped polysilicon layer or a boron doped polysilicon layer.
  3. 3. The method of claim 1, wherein the edge processing laser is nanosecond or picosecond pulse laser.
  4. 4. The method for manufacturing a back contact solar cell according to claim 1, wherein the wet cleaning is cleaning with an alkali solution.
  5. 5. The method of manufacturing a back contact solar cell of claim 1, wherein the side surface of the patterned processing region after wet cleaning is an inclined surface, and the width of the top contour line of the side surface is less than 10 μm.
  6. 6. The method for manufacturing a back contact solar cell according to claim 1, wherein the spot width of the edge processing laser is 2-50 μm.
  7. 7. The method for manufacturing the back contact solar cell according to claim 1, wherein the edge processing laser is single-pulse laser, the light spot overlapping rate in the scanning direction is 50% -99% when the laser light spot is a Gaussian light spot, the light spot overlapping rate in the scanning direction is 50% -99% when the laser light spot is a flat-top circular light spot, the light spot overlapping rate in the scanning direction is 1% -99% when the laser light spot is a flat-top square light spot, the light spot overlapping rate in the scanning direction is 50% -99% when the laser light spot is an annular light spot, and the light spot overlapping rate in the scanning direction is 1% -99% when the laser light spot is a linear light spot; Or the edge processing laser is pulse train laser, the line connecting direction and the scanning direction of the sub-pulses of each pulse train are not parallel, the projection parts of the adjacent sub-pulses in the vertical scanning direction are overlapped, when the laser light spot is a Gaussian light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 50% -99%, when the laser light spot is a flat-top round light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 50% -99%, when the laser light spot is a flat-top square light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 1% -99%, when the laser light spot is a ring light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 1% -99%.
  8. 8. The method for manufacturing the back contact solar cell according to claim 1, wherein the edge processing laser is single-pulse laser, the light spot overlapping rate in the scanning direction is 75% -95% when the laser light spot is a Gaussian light spot, the light spot overlapping rate in the scanning direction is 75% -95% when the laser light is a flat-top round light spot, the light spot overlapping rate in the scanning direction is 1% -75% when the laser light spot is a flat-top square light spot, the light spot overlapping rate in the scanning direction is 75% -95% when the light spot is a circular light spot, and the light spot overlapping rate in the scanning direction is 1% -75% when the light spot is a linear light spot; Or the edge processing laser is pulse train laser, the line connecting direction and the scanning direction of the sub-pulses of each pulse train are not parallel, the projection parts of the adjacent sub-pulses in the vertical scanning direction are overlapped, when the laser light spot is a Gaussian light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 75% -95%, when the laser light spot is a flat-top round light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 75% -95%, when the laser light spot is a flat-top square light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 1% -75%, when the laser light spot is a ring light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 75% -95%.
  9. 9. The method for producing a back contact solar cell according to any one of claims 1 to 8, comprising the steps of, S10, preprocessing a silicon wafer; S20, preparing a first functional layer on the back surface of the silicon wafer, wherein the first functional layer is provided with a first doping layer, and a first mask layer is formed on the first functional layer; S30, performing first laser patterning processing on the back surface of the silicon wafer; the first laser patterning processing area is an area corresponding to the N area and the GAP area; S40, wet cleaning is carried out to remove the first functional layer of the first laser patterning processing area; s50, preparing a second functional layer on the back of the silicon wafer, wherein the second functional layer is provided with a second doping layer, and a second mask layer is formed on the second functional layer; S60, performing second laser patterning processing on the back surface of the silicon wafer; the second patterning processing area is a corresponding area of the P area and the GAP area; S70, wet cleaning is carried out to remove a second functional layer of the second laser patterning processing region, and a GAP region with a certain depth is formed between the adjacent P region and N region; S80, pickling to remove a first doped layer and a second doped layer which are plated around the front edge, performing double-sided texturing by alkali solution, forming textured surfaces on the front surface and the back GAP area of the silicon wafer, and then pickling by hydrofluoric acid to remove the remaining first mask layer and the second mask layer on the back surface; s90, preparing a front passivation layer and a back passivation layer on the silicon wafer, S100, metalizing the back of the silicon wafer to finish the preparation of the back contact solar cell; Wherein the conductivity types of the first functional layer and the second functional layer are opposite.
  10. 10. The method for manufacturing a back contact solar cell according to claim 9, wherein: s10, preprocessing the silicon wafer, namely polishing the two sides of the silicon wafer; the first functional layer is a tunneling oxide layer and a boron doped polysilicon layer, and the second functional layer is a tunneling oxide layer and a phosphorus doped polysilicon layer.
  11. 11. The method for manufacturing a back contact solar cell according to claim 9, wherein: s10, preprocessing the silicon wafer, namely performing double-sided texturing on the silicon wafer; the first functional layer is a boron diffusion layer, and the second functional layer is a tunneling oxide layer and a phosphorus doped polysilicon layer.
  12. 12. The method of manufacturing a back contact solar cell according to claim 9, wherein the side surface of the GAP region is an inclined surface, and the width of the top contour line of the side surface is less than 10 μm.
  13. 13. The method of claim 9, wherein the GAP region has a depth of 1-10 μm and a width of 20-500 μm.
  14. 14. The method for producing a back contact solar cell according to any one of claims 1 to 8, comprising the steps of, S01, polishing the two sides of the silicon wafer; s02, preparing a tunneling oxide layer and a phosphorus doped polysilicon layer on the back surface of the silicon wafer, wherein a third mask layer is formed on the phosphorus doped polysilicon layer; S03, performing first laser patterning processing on the back surface of the silicon wafer; The first laser patterning processing area is a P area corresponding area; S04, wet cleaning is carried out to remove the phosphorus doped polysilicon layer and the tunneling oxide layer of the first laser patterning processing area, and simultaneously, the first laser processing area on the back and the texturing on the front are completed to form a pyramid structure; S05, preparing an intrinsic amorphous silicon layer, a boron-doped microcrystalline silicon layer or a combination layer thereof on the back surface of the silicon wafer; S06, opening an N-region conductive channel; processing an N region on the back of the silicon wafer, and removing the boron-doped amorphous silicon layer, the boron-doped microcrystalline silicon layer or a combination layer thereof, the intrinsic amorphous silicon layer and the third mask layer to form a conductive channel reaching the phosphorus-doped polycrystalline silicon layer of the N region; S07, preparing a TCO layer on the back surface of the silicon wafer; s08, preparing a front passivation layer on the front side of the silicon wafer; s09, removing the TCO layer between the P area and the N area to complete PN area isolation; s010 prepares the electrode on the back of the silicon chip, finish the preparation of the back contact solar cell.
  15. 15. The method of claim 14, wherein the width of the top contour line of the boundary bevel of the P region and the N region is less than 10 μm.
  16. 16. A back contact solar cell characterized in that it is produced by the method of any one of claims 9 to 13, The N-type silicon substrate comprises an N-type silicon substrate, wherein a front passivation layer is arranged on the front surface of the N-type silicon substrate, an N-region functional layer and a P-region functional layer are arranged on the back surface of the N-type silicon substrate at intervals, a GAP region is arranged between the N-region functional layer and the P-region functional layer, wherein the GAP region is a groove opposite to the arrangement of the P-region functional layer and the N-region functional layer, the depth of the GAP region reaches the silicon substrate, passivation layers are arranged above the P-region functional layer, the N-region functional layer and the GAP region, electrodes are further arranged above the P-region functional layer and above the N-region functional layer, the side surface of the GAP region is an inclined plane, and the width of the top contour line of the side surface is smaller than 10 mu m.
  17. 17. A back contact solar cell is characterized by comprising an N-type silicon substrate, wherein a front passivation layer is arranged on the front surface of the N-type silicon substrate, an N-region functional layer and a P-region functional layer are arranged on the back surface of the N-type silicon substrate at intervals, TCO films are arranged above the N-region functional layer and the P-region functional layer, electrodes are arranged on the TCO films, the TCO films between the P-region functional layer and the N-region functional layer are removed, and the width of the top contour line position of the boundary inclined plane of the N-region functional layer and the P-region functional layer is smaller than 10 mu m.

Description

Back contact solar cell and preparation method thereof Technical Field The invention belongs to the technical field of solar cell processing, and particularly relates to a back contact solar cell and a preparation method thereof. Background In the production process of the crystalline silicon solar cell, laser patterning is one of important ways for realizing the localization of PN junctions, NN+ and PP+ of the solar cell. And performing auxiliary chemical corrosion after laser processing, and performing corrosion removal on the laser processing area or the non-laser processing area to complete specific graphical processing. The preparation of the prior art Back Contact (BC) solar cell, a number of processes, such as GAP region preparation, may be accomplished by patterning processes. The applicant finds that the silicon surface recombination rate index of the BC solar cell cannot be effectively improved all the time through research. Disclosure of Invention In order to meet the above defects or improvement demands of the prior art, the invention provides a back contact solar cell and a preparation method thereof. In order to achieve the above object, according to a first aspect of the present invention, there is provided a method for manufacturing a back contact solar cell, comprising preparing a functional layer and a mask layer on a back surface of a silicon wafer, performing laser patterning processing on the back surface of the silicon wafer, removing a part of the mask layer or modifying the mask layer, wherein a main body of a patterning processing region is scanned by an open film laser, an edge of the patterning processing region is scanned by an edge processing laser, and a union of the open film laser scanning region and the edge processing laser scanning region is a patterning processing region; Wherein, the facula of the edge processing laser is overlapped in the scanning direction to form a straight laser processing line; wet cleaning to remove the functional layer corresponding to the laser patterning processing region; The laser patterning processing area is an N area corresponding position, a P area corresponding position, an N area corresponding position and a GAP area corresponding position, or a P area corresponding position and a GAP area corresponding position. According to the scheme, the functional layer is a tunneling oxide layer and a doped polysilicon layer or a boron diffusion layer which are sequentially arranged, and the doped polysilicon layer is a phosphorus doped polysilicon layer or a boron doped polysilicon layer. According to the scheme, the edge processing laser is nanosecond or picosecond pulse laser. According to the scheme, the wet cleaning is carried out by adopting alkali solution. According to the scheme, the side surface of the patterning processing area after wet cleaning is an inclined surface, and the width of the top contour line position of the side surface is smaller than 10 mu m. According to the scheme, the light spot width of the edge processing laser is 2-50 mu m. According to the scheme, the edge processing laser is single-pulse laser, when the laser light spot is a Gaussian light spot, the light spot overlapping rate in the scanning direction is 50% -99%, when the laser light spot is a flat-top round light spot, the light spot overlapping rate in the scanning direction is 50% -99%, when the laser light spot is a flat-top square light spot, the light spot overlapping rate in the scanning direction is 1% -99%, when the laser light spot is an annular light spot, the light spot overlapping rate in the scanning direction is 50% -99%, and when the laser light spot is a linear light spot, the light spot overlapping rate in the scanning direction is 1% -99%; Or the edge processing laser is pulse train laser, the line connecting direction and the scanning direction of the sub-pulses of each pulse train are not parallel, the projection parts of the adjacent sub-pulses in the vertical scanning direction are overlapped, when the laser light spot is a Gaussian light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 50% -99%, when the laser light spot is a flat-top round light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 50% -99%, when the laser light spot is a flat-top square light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 1% -99%, when the laser light spot is a ring light spot, the light spot overlapping rate of the corresponding sub-pulse of the adjacent pulse train in the scanning direction is 1% -99%. According to the scheme, the edge processing laser is single-pulse laser, when a laser spot is a Gaussian spot, the spot overlapping rate in the scanning direction is 75% -95%, when a laser flat-top circular spot is a flat-top