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CN-224218755-U - Passivation contact battery structure

CN224218755UCN 224218755 UCN224218755 UCN 224218755UCN-224218755-U

Abstract

The utility model discloses a passivation contact battery structure which comprises a silicon substrate, wherein the back surface of the silicon substrate comprises a metal contact area and a non-metal contact area, the metal contact area on the back surface of the silicon substrate is of a suede structure, a back surface first tunneling oxide layer, a back surface first doped polysilicon layer, a back surface second tunneling oxide layer, a back surface second doped polysilicon layer, a back surface aluminum oxide layer, a back surface silicon nitride layer and a back electrode are sequentially stacked from inside to outside in the metal contact area on the back surface of the silicon substrate, the non-metal contact area on the back surface of the silicon substrate is of a polished surface structure, and a back surface first tunneling oxide layer, a back surface first doped polysilicon layer, a back surface aluminum oxide layer and a back surface silicon nitride layer are sequentially stacked from inside to outside in the non-metal contact area on the back surface of the silicon substrate. The battery structure of the utility model can reduce parasitic absorption and inhibit silver ion diffusion, bring current gain, improve metal recombination, improve interface contact resistance and be beneficial to improving the battery efficiency.

Inventors

  • Du Zheren
  • NIU SIQI
  • SHEN DONGDONG
  • QUAN CHENG
  • JI GENHUA

Assignees

  • 江苏林洋太阳能有限公司

Dates

Publication Date
20260508
Application Date
20250527

Claims (10)

  1. 1. The passivation contact battery structure comprises a silicon substrate (1), wherein the back surface of the silicon substrate (1) comprises a metal contact area and a non-metal contact area, and the passivation contact battery structure is characterized in that the metal contact area on the back surface of the silicon substrate (1) is of a suede structure, and a back surface first tunneling oxide layer (2), a back surface first doped polysilicon layer (3), a back surface second tunneling oxide layer (4), a back surface second doped polysilicon layer (5), a back surface aluminum oxide layer (6), a back surface silicon nitride layer (7) and a back surface electrode (8) are sequentially laminated from inside to outside; The non-metal contact area on the back of the silicon substrate (1) is of a polished surface structure, and a back first tunneling oxide layer (2), a back first doped polysilicon layer (3), a back aluminum oxide layer (6) and a back silicon nitride layer (7) are sequentially laminated from inside to outside in the non-metal contact area on the back of the silicon substrate (1).
  2. 2. The passivation contact cell structure according to claim 1, characterized in that a front emitter (9), a front aluminum oxide layer (10), a front silicon nitride layer (11) and a front electrode (12) are sequentially stacked from inside to outside on the front surface of the silicon substrate (1).
  3. 3. The passivation contact cell structure according to claim 1, characterized in that the height of the pyramid formed in the textured structure of the back metal contact area of the silicon substrate (1) is 0.5-2 μm.
  4. 4. The passivated contact cell structure of claim 1 wherein the back first tunneling oxide layer has a thickness of 1-2 nm.
  5. 5. The passivation contact battery structure according to claim 1, characterized in that the back first doped polysilicon layer (3) is a first in-situ phosphorus doped amorphous silicon layer with a thickness of 50-80 nm and a phosphorus atom doping concentration of 1.0-2.5 x 10 20 /cm 3 .
  6. 6. The passivated contact cell structure of claim 1 wherein the thickness of the backside second tunneling oxide layer is 1-2 nm.
  7. 7. The passivation contact battery structure according to claim 1, characterized in that the back second doped polysilicon layer (5) is a second in-situ phosphorus doped amorphous silicon layer with a thickness of 40-70 nm and a phosphorus atom doping concentration of 3.0-4.0 x 10 20 /cm 3 .
  8. 8. The passivated contact cell structure according to claim 1, characterized in that the thickness of the back aluminum oxide layer (6) is 2-10 nm.
  9. 9. The passivation contact cell structure according to claim 1, characterized in that the thickness of the back side silicon nitride layer (7) is 70-80 nm, and the refractive index of silicon nitride is 2.1-2.2.
  10. 10. The passivation contact cell structure according to claim 2, characterized in that the front-side emitter (9) is a boron doped emitter, and the thickness of the front-side emitter is 0.7-1.0 μm, the thickness of the front-side aluminum oxide layer (10) is 2-10 nm, and the thickness of the front-side silicon nitride layer (11) is 70-80 nm.

Description

Passivation contact battery structure Technical Field The utility model belongs to the field of passivation contact batteries, and particularly relates to a passivation contact battery structure. Background The tunneling oxide passivation contact (Tunnel Oxide Passivated Contact, TOPCon for short) battery is one of the mainstream solar batteries at present, and the battery is characterized in that an ultrathin tunneling oxide layer and a doped polysilicon layer are sequentially prepared on the back surface of the battery, and the ultrathin tunneling oxide layer and the doped polysilicon layer form a passivation contact structure together, so that good interface passivation is provided for the back surface of a silicon wafer. The doped polysilicon has fermi energy level difference with the silicon substrate, causes energy band bending on the silicon substrate surface, can enable electrons to pass through to block holes, plays a field passivation role, and realizes selective collection of carriers, thereby reducing current loss caused by metal contact recombination and improving the conversion efficiency of the battery. However, doped polysilicon has parasitic absorption to light, resulting in short-circuit current loss, so the thinner the doped polysilicon is, the better from the perspective of increasing the short-circuit current. However, silver paste has more serious corrosion damage to thinner doped polysilicon, so that metal recombination is obviously increased, open pressure loss is larger, and meanwhile, excessive corrosion of the polysilicon film layer by the paste can cause failure of an interface tunneling contact mechanism, thereby influencing interface contact resistance. Therefore, it is a key to further improve the battery efficiency how to achieve lower metal recombination and better interface contact while reducing parasitic absorption. In order to overcome the above-mentioned drawbacks, for example, publication No. CN106449800a provides a passivation contact structure of a selective polysilicon film, a silicon dioxide layer with a thickness of <2nm is prepared on the surface of the crystalline silicon, a doped polysilicon film is prepared on the surface of the silicon dioxide layer, the doped polysilicon film has a first thickness in a metal-free contact area and a second thickness in a metal-free contact area, and the first thickness is smaller than the second thickness, and a metal electrode is formed on the surface of the second thickness area of the polysilicon film. Meanwhile, the invention also discloses a method for preparing the passivation contact structure of the selective polysilicon film, so that the traditional screen printing technology and the passivation contact technology can be effectively combined together, the passivation contact technology can be pushed to yield, and meanwhile, the efficiency of the solar cell is effectively improved. The method comprises the steps of printing a mask on the surface of polycrystalline silicon, and then thinning the polycrystalline silicon in a mask-free area by adopting an etching method to form a first thickness area. And removing the mask layer, wherein an unetched polycrystalline silicon film region below the mask layer is a second thickness region, and the metal electrode is printed on the second thickness region. However, the above-mentioned battery structure has the technical defects that in the contact area of the metal electrode, the polysilicon film is a single layer, the longitudinal diffusion and corrosion of silver ions cannot be effectively inhibited, and thus the metal recombination cannot be inhibited, and secondly, as the reflection angle is reduced, the surface recombination of the tunneling oxide layer/doped polysilicon passivation contact is gradually reduced, the hidden open-circuit voltage (iVoc) is gradually increased, however, the interface contact resistivity of the electrode paste and the tunneling oxide layer/doped polysilicon passivation contact structure is gradually increased. Disclosure of Invention The utility model aims to overcome the defects in the prior art and provide a passivation contact battery structure based on the prior art. The aim of the utility model can be achieved by the following measures: a passivation contact cell structure comprises a silicon substrate, a metal contact region and a non-metal contact region on the back surface of the silicon substrate, wherein The metal contact area on the back of the silicon substrate is of a suede structure, and a first tunneling oxide layer on the back, a first doped polysilicon layer on the back, a second tunneling oxide layer on the back, a second doped polysilicon layer on the back, a back aluminum oxide layer, a back silicon nitride layer and a back electrode are sequentially laminated from inside to outside; The non-metal contact area on the back of the silicon substrate is of a polished surface structure, and a back first tunneling oxide layer, a