Gradient doped amorphous silicon passivation structure of TOPCon battery and preparation method of gradient doped amorphous silicon passivation structure

Abstract

The invention discloses a gradient doped amorphous silicon passivation structure of a TOPCon battery, at least two layers of doped amorphous silicon films are deposited on one side of a tunneling oxide layer of a silicon wafer, and the doping concentration of the multiple layers of doped amorphous silicon films is increased in a gradient manner from one side in contact with the tunneling oxide layer. The thickness of each layer of doped amorphous silicon thin film is 10-40nm, and the total thickness of the plurality of layers of doped amorphous silicon thin films is 60-80nm. According to the gradient doped amorphous silicon passivation structure provided by the invention, the doping concentration of the doped amorphous silicon layer is increased in a gradient manner from the innermost layer in contact with the tunneling oxide layer to the outermost layer in contact with the silver paste, the doped amorphous silicon layer with low film thickness and high passivation property is finally obtained, and the total thickness is reduced to about 60-80 nm from the conventional more than 100 nm; and not only is the near-infrared light loss of the back surface of the cell caused by doped amorphous silicon effectively reduced, but also the light utilization rate is improved, and meanwhile, the coating process cost is reduced.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a TOPCon battery gradient doped amorphous silicon passivation structure and a preparation method. Background technique [0002] TOPCon is a tunneling oxide layer passivation contact solar cell technology based on the principle of selective carriers. Its cell structure is mainly an N-type silicon substrate cell. A layer of ultra-thin silicon oxide is prepared on the back surface of the cell, and then deposited A layer of phosphorus-doped amorphous silicon film, the two together form a passivation contact structure, in which the phosphorus-doped amorphous silicon layer provides a good field passivation effect and selectively permeates carriers, which is helpful for improving the battery current. and fill factor play a crucial role. However, the doped amorphous silicon layer will absorb near-infrared light, reduce the effective reflection of near-infrared light on the back surf...

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Problems solved by technology

[0006] 2. Prepare a doped amorphous silicon layer with a low film thickness and use back surface busbar paste with weakened burn-through performance to avoid burn-through phenomenon, and reduce the burn-through performance by reducing the content of auxiliary additives in the silver paste. However, the decrease in the burn-through performance of the slurry will also cause a substantial increase in the contact resistance, which will reduce the FF of the battery and reduce the efficiency of the battery.

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