A kind of double-sided selective emitter high-efficiency crystalline silicon cell and preparation method thereof

Abstract

The invention belongs to the field of solar photovoltaic industry, and specifically provides a double-sided selective emitter high-efficiency crystalline silicon battery and a preparation method thereof; the double-sided selective emitter structure is adopted, and the boron-doped heavily doped region is aluminum oxide Instead of silicon oxide as the polysilicon structure of the tunneling layer, it can reach >1E20atom / cm 3 The constant surface concentration improves the fill factor (FF), while the light expansion area is pure boron doping, and the boron doping process of re-expansion and light expansion can be realized in one step, which simplifies the process. Silicon oxide is used as the tunneling layer for the phosphorous-doped region, the heavily doped region is a double-layer polysilicon (poly) structure with high surface concentration, which improves the metallization contact, and the lightly expanded region is a single-layer lightly doped poly structure, thereby improving the open circuit Voltage (Voc). The formation of double-sided selective emitter effectively utilizes the method of mask etching. This structure can effectively improve battery efficiency and is suitable for mass production.

Description

technical field [0001] The invention belongs to the field of solar crystal silicon cells, in particular to a double-sided selective emitter high-efficiency crystal silicon cell and a preparation method thereof. Background technique [0002] The pursuit of high-efficiency cells is a development trend in the photovoltaic industry. The solution that takes into account both cost and process is the n-TOPCon cell, which uses an ultra-thin oxide layer and doped thin-film silicon to passivate the back of the cell. Among them, the backside oxide layer has a thickness of 1.4nm and is grown by wet chemical method. Then on the oxide layer, 20nm phosphorous-doped amorphous silicon is deposited, and then annealed to recrystallize and strengthen the passivation effect. It will become the next-generation mainstream product after PERC. For the existing n-TOPCon battery mass production process, its efficiency has not widened the gap with PERC batteries, and the efficiency difference is only...

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Problems solved by technology

However, the efficiency of the existing mass production process of n-TOPCon batteries has not widened the gap with PERC batteries, and the efficiency difference is only 0.5%. Therefore, how to improve the efficiency of batteries with this structure has become a top priority.

[0003] The conventional boron-doped selective emitter on the front side is difficult to realize by conventional etching and laser or APCVD, and the current technology is immature

However, the use of silicon oxide as the tunneling layer cannot passivate boron-doped

The conventional selective emitter on the back side is the existing technical solution of etching and laser, but the laser method cannot be used for phosphorus-doped polysilicon, because the laser will damage the tunnel oxide layer, and the simple etching solution is suitable for polysilicon with uniform doping concentration The structure is also infeasible

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