Search

CN-122028546-A - Back contact battery, battery assembly and photovoltaic system

CN122028546ACN 122028546 ACN122028546 ACN 122028546ACN-122028546-A

Abstract

The application relates to the technical field of solar cells and provides a back contact cell, a cell assembly and a photovoltaic system, wherein in the back contact cell, the middle part of a separation part is doped with a third main group element and a fifth main group element, the average doping concentration of the fifth main group element in the middle part is larger than that of the third main group element in the middle part, the average doping concentration of the fifth main group element in the middle part is smaller than 2E17/cm 3 , or the average doping concentration of the third main group element in the middle part is larger than that of the fifth main group element in the middle part, and the average doping concentration of the third main group element in the middle part is smaller than 5E17/cm 3 . Therefore, effective isolation of the p-type doped part and the n-type doped part can be realized without forming a groove, the field passivation effect is improved, the electric field distribution is optimized, and the collection efficiency of carriers is further improved, so that the conversion efficiency of the back contact battery is improved.

Inventors

  • ZHANG SHENGLI
  • LI ZHONGYU
  • JIANG SHENG
  • ZOU CAN
  • LIU RUIMIN
  • WANG YONGQIAN

Assignees

  • 浙江爱旭太阳能科技有限公司

Dates

Publication Date
20260512
Application Date
20260416

Claims (20)

  1. 1. A back contact battery, comprising: a silicon substrate having opposite front and back sides; a first dielectric layer laminated on the back surface, and The doped layer is stacked on the first dielectric layer and comprises p-type doped parts and n-type doped parts which are arranged at intervals, and isolation parts which are positioned between the p-type doped parts and the n-type doped parts, wherein third main group elements are doped in the p-type doped parts, and fifth main group elements are doped in the n-type doped parts; the isolation part comprises a middle part, a first contact part and a second contact part, wherein the first contact part and the second contact part are respectively connected to two sides of the middle part, the first contact part is positioned between the p-type doping part and the middle part, and the second contact part is positioned between the n-type doping part and the middle part; The conductivity type of the middle part is the same as that of the silicon substrate, and the middle part is doped with a third main group element and a fifth main group element; Wherein the average doping concentration of the fifth main group element in the middle part is larger than the average doping concentration of the third main group element in the middle part, the average doping concentration of the fifth main group element in the middle part is smaller than 2E17/cm 3 , or the average doping concentration of the third main group element in the middle part is larger than the average doping concentration of the fifth main group element in the middle part, and the average doping concentration of the third main group element in the middle part is smaller than 5E17/cm 3 .
  2. 2. The back contact battery of claim 1, wherein the average doping concentration of the fifth main group element in the middle portion is greater than the average doping concentration of the third main group element in the middle portion, the average doping concentration of the fifth main group element in the middle portion is 1E14/cm 3 -1E17/cm 3 , or the average doping concentration of the third main group element in the middle portion is greater than the average doping concentration of the fifth main group element in the middle portion, the average doping concentration of the third main group element in the middle portion is 1E13/cm 3 -1E15/cm 3 .
  3. 3. The back contact cell of claim 1, wherein the silicon substrate is an n-type silicon substrate, the average doping concentration of the fifth main group element in the intermediate portion is 0.01-0.9 times the average doping concentration of the fifth main group element within the silicon substrate, or The silicon substrate is a p-type silicon substrate, and the average doping concentration of the third main group element in the middle part is 0.01-0.9 times of the average doping concentration of the third main group element in the silicon substrate.
  4. 4. The back contact battery of claim 1, wherein the silicon substrate is an n-type silicon substrate, the average doping concentration of the fifth main group element in the middle portion is 10-10000 times that of the third main group element in the middle portion, or The silicon substrate is a p-type silicon substrate, and the average doping concentration of the third main group element in the middle part is 2-1000 times of the average doping concentration of the fifth main group element in the middle part.
  5. 5. The back contact battery of claim 1, wherein the average doping concentration of the third main group element in the first contact portion is greater than the average doping concentration of the fifth main group element in the first contact portion, and the average doping concentration of the third main group element in the first contact portion is greater than the average doping concentrations of the third main group element and the fifth main group element in the middle portion; The average doping concentration of the fifth main group element in the second contact portion is greater than the average doping concentration of the third main group element in the second contact portion, and the average doping concentration of the fifth main group element in the second contact portion is greater than the average doping concentrations of the third main group element and the fifth main group element in the intermediate portion.
  6. 6. The back contact battery of claim 5, wherein the average doping concentration of the third main group element in the first contact portion is 1E16/cm 3 -3E19/cm 3 , and/or The average doping concentration of the fifth main group element in the second contact portion is 1E17/cm 3 -2E20/cm 3 .
  7. 7. The back contact battery of claim 5, wherein the doping concentration of the third main group element of the intermediate portion is less than or equal to 0.1 times the doping concentration of the third main group element in the first contact portion, and/or The doping concentration of the fifth main group element in the intermediate portion is less than or equal to 0.1 times that in the second contact portion.
  8. 8. The back contact battery of claim 1, wherein a ratio between a width of the first contact portion and an entire width of the separator is 0.005-0.2, a ratio between a width of the second contact portion and an entire width of the separator is 0.01-0.2, and a ratio between a width of the intermediate portion and an entire width of the separator is 0.7-0.99.
  9. 9. The back contact battery of any one of claims 1-8, wherein the width of the middle portion is 50 μιη -700 μιη.
  10. 10. The back contact battery of claim 1, wherein the thickness of the spacer is greater than the thickness of the p-type doped portion, which is greater than the thickness of the n-type doped portion.
  11. 11. The back contact battery of claim 1, wherein the doping concentration of the third main group element in the p-type doping is 1.2E19/cm 3 -1.2E20/cm 3 ; The doping concentration of the fifth main group element in the n-type doping portion was 8E19/cm 3 -9.8E20/cm 3 .
  12. 12. The back contact battery of claim 1, wherein the doping concentration of the third main group element in the p-type doping portion is in an upward trend in a direction toward the side where the silicon substrate is located.
  13. 13. The back contact battery of claim 12, wherein the p-type doping comprises a first low-doped portion located within 20nm from a surface of the p-type doping facing away from the silicon substrate and a first high-doped portion located within 20nm from the first dielectric layer, the doping concentration of the third main group element in the first low-doped portion being 60% -98% of the doping concentration of the third main group element in the first high-doped portion.
  14. 14. The back contact battery of claim 1, wherein the first dielectric layer comprises a first portion corresponding to the p-type doping, a doping concentration of a third main group element at an interface of the first portion and the p-type doping is greater than an average doping concentration of a third main group element in the p-type doping, and a doping concentration of a third main group element at an interface of the first portion and the silicon substrate is less than or equal to 10% of a doping concentration of a third main group element at an interface of the first portion and the p-type doping.
  15. 15. The back contact battery of claim 1, wherein a first inner diffusion layer is formed at the interface of the p-type doped portion of the silicon substrate covered by the p-type doped portion and the first dielectric layer, the first inner diffusion layer having a thickness of less than or equal to 100nm.
  16. 16. The back contact battery of claim 15, wherein the doping concentration of the third main group element in the first inner diffusion layer is less than or equal to 5E18/cm 3 .
  17. 17. The back contact battery of claim 1, wherein the doping concentration of the fifth main group element in the n-type doping section is in a decreasing trend in a direction toward the side where the silicon substrate is located.
  18. 18. The back contact battery of claim 17, wherein the n-type doping comprises a second highly doped portion located within 20nm from a surface of the n-type doping facing away from the silicon substrate and a second highly doped portion located within 20nm from the first dielectric layer, the doping concentration of the fifth main group element in the second highly doped portion being 1-6 times the doping concentration of the fifth main group element in the second highly doped portion.
  19. 19. The back contact battery of claim 1, wherein the first dielectric layer comprises a second portion corresponding to the n-type doping, the doping concentration of the fifth main group element at the interface of the second portion and the silicon substrate being less than the doping concentration of the fifth main group element at the interface of the second portion and the n-type doping.
  20. 20. The back contact battery of claim 19, wherein a doping concentration of a fifth main group element at an interface of the second portion and the silicon substrate is less than or equal to 10% of a doping concentration of a fifth main group element at an interface of the second portion and the n-type doped portion.

Description

Back contact battery, battery assembly and photovoltaic system Technical Field The application relates to the technical field of solar cells, in particular to a back contact cell, a cell assembly and a photovoltaic system. Background The back contact solar cell enables the light receiving surface to completely avoid shielding of the metal electrode by integrating the emitter electrode and the base electrode contact electrode on the back of the cell, thereby improving light capturing capacity and short circuit current output. In the prior art, a process scheme of etching a deep trench on a silicon substrate is commonly adopted by a back contact battery to realize physical and electrical isolation between a p-type doped layer and an n-type doped layer. However, the mechanical strength of the silicon substrate is significantly impaired by the opening of the grooves, and cracking problems are easily caused during manufacturing, transportation and use, resulting in reduced yield and reliability of the product. If the trench process is omitted, the structural integrity of the silicon wafer can be enhanced, but the p-type doped layer and the n-type doped layer lack effective isolation, so that carrier recombination loss is easy to generate. Therefore, how to ensure the electrical isolation performance and the carrier transmission efficiency of the p-type and n-type regions without depending on deep trenches is a core challenge faced by the current back contact battery technology. Disclosure of Invention The application provides a back contact battery, a battery assembly and a photovoltaic system. The application is realized in such a way that the back contact battery of the embodiment of the application comprises: a silicon substrate having opposite front and back sides; a first dielectric layer laminated on the back surface, and The doped layer is stacked on the first dielectric layer and comprises p-type doped parts and n-type doped parts which are arranged at intervals, and isolation parts which are positioned between the p-type doped parts and the n-type doped parts, wherein third main group elements are doped in the p-type doped parts, and fifth main group elements are doped in the n-type doped parts; the isolation part comprises a middle part, a first contact part and a second contact part, wherein the first contact part and the second contact part are respectively connected to two sides of the middle part, the first contact part is positioned between the p-type doping part and the middle part, and the second contact part is positioned between the n-type doping part and the middle part; The conductivity type of the middle part is the same as that of the silicon substrate, and the middle part is doped with a third main group element and a fifth main group element; Wherein the average doping concentration of the fifth main group element in the middle part is larger than the average doping concentration of the third main group element in the middle part, the average doping concentration of the fifth main group element in the middle part is smaller than 2E17/cm 3, or the average doping concentration of the third main group element in the middle part is larger than the average doping concentration of the fifth main group element in the middle part, and the average doping concentration of the third main group element in the middle part is smaller than 5E17/cm 3. In some embodiments, the average doping concentration of the fifth main group element in the middle portion is greater than the average doping concentration of the third main group element in the middle portion, the average doping concentration of the fifth main group element in the middle portion is 1E14/cm 3-1E17/cm3, or the average doping concentration of the third main group element in the middle portion is greater than the average doping concentration of the fifth main group element in the middle portion, the average doping concentration of the third main group element in the middle portion is 1E13/cm 3-1E15/cm3. In some embodiments, the silicon substrate is an n-type silicon substrate, the average doping concentration of the fifth main group element in the intermediate portion is 0.01-0.9 times the average doping concentration of the fifth main group element within the silicon substrate, or The silicon substrate is a p-type silicon substrate, and the average doping concentration of the third main group element in the middle part is 0.01-0.9 times of the average doping concentration of the third main group element in the silicon substrate. In some embodiments, the silicon substrate is an n-type silicon substrate, the average doping concentration of the fifth main group element in the intermediate portion is 10-10000 times the average doping concentration of the third main group element in the intermediate portion, or The silicon substrate is a p-type silicon substrate, and the average doping concentration of the third main group element in the middle