Back contact solar cell with various tunnel junction structures and preparation method thereof

Abstract

The invention relates to a back contact solar cell with various tunnel junction structures and a preparation method thereof. The solar cell comprises an N-type crystalline silicon substrate; the frontsurface of the N-type crystalline silicon substrate comprises a lightly-doped n+ surface field and a passivation antireflection film, and the back surface of the N-type crystalline silicon substratecomprises a P-type emitter region, an N-type back surface field region and a groove structure; the P-type emitter region is located in the groove structure, and the N-type back surface field region islocated above the groove structure; the N-type back surface field region sequentially comprises a tunneling SiOX layer, an n+poly layer, an oxide layer, an n+poly layer, a tunneling SiOX layer and ap+poly layer from inside to outside; the SiOX layer and the n+poly layer form a c-Si / SiOX / n+poly tunnel junction; the oxide layer and the n+poly layer form an n+poly / Oxide / n+poly tunnel junction, andthe tunneling SiOX layer and the p+poly layer form an n+poly / SiOX / p+poly tunnel junction; the P-type emitter region sequentially comprises a tunneling SiOx layer and a p+poly layer from inside to outside, and the SiOx layer and the p+poly layer form a c-Si / SiOX / p+poly tunnel junction; the P-type emitter region is provided with a P-type metal electrode, and the N-type back surface field region is provided with an N-type metal electrode.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a back-contact solar cell with multiple tunnel junction structures and a preparation method thereof. Background technique [0002] In crystalline silicon solar cells, the efficiency loss of the cell can be divided into two aspects: electrical loss and optical loss. Shielding of surface metal grid lines. [0003] In the current commercialized crystalline silicon solar cells, such as p-type all-aluminum back field cells, p-type PERC cells or n-type PERT cells, the metal shielding area of ​​the light-receiving surface is about 5%; in the case of ensuring low contact resistivity , the dark saturation current density (J0, metal) of the n+ emission on the front surface of the p-PERC battery and the metal contact area is 800-1000fA / cm 2 ; For n-type batteries, the recombination loss is higher, and the dark saturation current density (J0, metal) of the p+ emitter and metal contact ...

AI Technical Summary

Problems solved by technology

In 2017, Feldmann et al. from the Fraunhofer Institute for Solar Energy Systems in Germany increased the conversion efficiency of solar cells with tunnel oxide layer passivation metal contact structures to 25.8%, and the grid lines on the front surface of the cells caused ~0.2% efficiency loss

[0006] In addition, the most commonly used metallization method in the industrialization of crystalline silicon solar cells is screen printing plus sintering, which is different from mild metallization methods such as PVD. Polysilicon, which is in direct contact with the silicon substrate, causes recombination surges under metal regions and poor contact

For silver-aluminum paste, metal penetration through oxide layer / doped polysilicon will be more serious

Images