CdZnTe (cadmium zinc telluride) thin film solar cell with gradient band gap structure

Abstract

The invention discloses a CdZnTe (cadmium zinc telluride) thin film solar cell with a gradient band gap structure, comprising a glass substrate, wherein a front electrode layer of transparent conducting oxides, an n-type CdS (cadmium sulfide) window layer, a p-type Cd1-xZnxTe absorption layer and a back electrode layer are deposited on the glass substrate in sequence; the p-type Cd1-xZnxTe absorption layer comprises three areas; the band gap in an intermediate area is not changed and mainly used for strengthening the absorption of sun peak spectrums; and the two areas at two sides are of a gradient band gap structure and used for broadening the absorption range of the solar spectrums. The structure is used to reduce the back surface recombination rate of a cell carrier, improve the ohmic contact of a back electrode of the cell and increase the open-circuit voltage and the short-circuit current of the cell, thus improving the performances of the cell.

Description

technical field [0001] The present invention relates to thin-film solar cells, in particular to a cadmium zinc telluride (Cd 1-x Zn x Te) thin film solar cells. Background technique [0002] A solar cell is a device that directly converts light energy into electrical energy. If you want to obtain high conversion efficiency, you should fully consider the matching between the light absorption of the cell and the solar spectrum. Under normal conditions, the best band gap of the absorbing material is about 1.45eV. The band gap of CdTe is 1.45eV, and it is a direct transition material. The absorption coefficient increases sharply near the band gap. A thin film with a thickness of 1um is enough to absorb more than 99% of the radiation energy greater than the energy of the CdTe band gap. Therefore, CdTe can Made very thin. However, since it is difficult to form a good ohmic contact between P-type CdTe and the back electrode, it has become a key technical problem that needs to be...

AI Technical Summary

Problems solved by technology

[0004] Cd proposed by Chinese patent CN 101276854A 1-x Zn x Te film has a graded bandgap structure, and the bandgap is a triangular structure. Although this graded bandgap structure can be used to broaden the response band of solar cells and solve the problem of ohmic contact with the back electrode layer, it is close to the solar radiation spectrum. The optimal bandgap width of the peak is 1.45eV. The bandgap width of this triangular structure cannot fully absorb sunlight in the peak range of the solar radiation spectrum, thereby reducing the short-circuit current of the battery.

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