Process for preparing back point-contact crystalline-silicon solar cells

Abstract

The invention discloses a process for preparing back point-contact crystalline-silicon solar cells. The process comprises the following steps: coating the back surface of a silicon wafer with a silicon dioxide and silicon nitride compound passivating film; screen-printing a silicon slurry layer with a point-contact pattern on the compound passivating film with silicon slurry; then, etching off the area which is not covered by the silicon slurry layer with a chemical etching solution; further screen-printing an aluminum slurry layer on the back surface of the silicon wafer; allowing the contact surface of the aluminum slurry layer and the silicon slurry layer to form a silicon-aluminum alloy layer by sintering; and finally, allowing the aluminum slurry and the silicon substrate on the back surface of the silicon wafer to form the local ohmic contact and the local aluminum back-surface field. The process can reduce the preparation cost and realize the industrial mass production more easily; and the prepared back point-contact electrode crystalline-silicon solar cell can form good back ohmic contact and local aluminum back-surface field, solve the problem that the resistance increases when the cells are connected in series caused by the point contact to a certain extent and maintain the good back-passivating effect and the optical back-reflecting property.

Description

technical field [0001] The invention belongs to the technical field of solar cells, and in particular relates to a preparation process of back point-contact crystalline silicon solar cells. Background technique [0002] In recent years, the output of crystalline silicon solar cells has grown rapidly, resulting in tight supply of silicon materials. For this reason, it is necessary to find a new process for preparing solar cells, which can reduce the cost on the one hand and improve the efficiency of the cell on the other hand. As the thickness of silicon wafers continues to decrease, the influence of the recombination rate on the back surface of silicon wafers on the efficiency of solar cells will become more and more prominent. The traditional aluminum back field process cannot meet the requirements of thin silicon wafer solar cells. However, point contact electrodes are considered to be a way to reduce the area of ​​the metal-semiconductor contact region and effectively r...

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Problems solved by technology

There are also reports on the opening of corrosive pastes by screen printing, but the effect of corrosive pastes on the opening of thick passivation layers is not very good; there are also direct printing of dotted metal pastes (such as aluminum pastes) On the passivation layer, and then through high-temperature sintering to make point-like metal paste burn through the passivation layer to make point contact on the back, but it is difficult to form a good ohmic contact, and there are also problems such as difficulty in mass production

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