Local passivation contact structure battery and preparation method thereof

Abstract

The invention discloses a local passivation contact structure battery and a preparation method thereof. The key points of the technical scheme are that the local passivation contact structure battery comprises an N-type silicon substrate, the front surface of the N-type silicon substrate is provided with a positive electrode, the front surface of the N-type silicon substrate is covered with an AlOx passivation layer or a SiNx anti-reflection layer, the positive electrode passes through the AlOx passivation layer or the SiNx anti-reflection layer and is in contact with an emitter, a negative electrode is arranged on the back surface of the N-type silicon substrate, a tunneling oxide layer is prepared on the back surface of the N-type silicon substrate, a contact area of the N-type silicon substrate and the negative electrode is not etched to form a heavily doped n + + poly layer, and the n + + poly layer in a non-electrode contact area is etched and thinned to form a lightly doped n + poly layer. According to the invention, light doping is carried out in the non-metal area, so that the parasitic absorption effect of the n + poly layer is reduced, and the short-circuit current is improved; and heavy doping is carried out in the metal area, metal contact recombination and contact resistance are reduced, open-circuit voltage and filling factors are improved, and cell efficiency is further improved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a battery with a local passivation contact structure and a preparation method thereof. Background technique [0002] The TOPCon structure consists of an ultra-thin tunnel oxide layer and a doped polysilicon layer, which can significantly reduce metal contact recombination, and at the same time have good contact performance, which can greatly improve the efficiency of photovoltaic cells. This technology uses an n-type silicon wafer as a substrate, deposits a tunneling layer on the front and back of the silicon wafer, and then covers a doped polysilicon (n+poly) layer to form a tunneling oxide passivation contact. The tunneling oxide layer passivation technology can isolate the contact between the metal electrode and the substrate, reduce the contact recombination loss, and the electrons can tunnel through the film without affecting the current tra...

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Problems solved by technology

[0003] However, although the n+poly layer on the tunneling oxide layer can play a good field passivation effect, it has a strong parasitic absorption effect on light, which will reduce the current density of the battery, thereby affecting the solar cell. Conversion Efficiency and Cell Efficiency on the Back

The more heavily doped n+poly layer, the more significant the parasitic absorption effect, but the light doping will affect the contact resistance with the metal electrode, and it is difficult to balance the two

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