Cell piece possessing back reflection layer and manufacturing method thereof

Abstract

The invention discloses a cell piece possessing a back reflection layer. A back side of a silicon substrate of the cell piece is provided with a SiOx reflecting layer, an Al metal layer and a local aluminum back field. The SiOx reflecting layer is directly connected to the back side of the silicon substrate. The Al metal layer is arranged on an external surface of the SiOx reflecting layer. The local aluminum back field passes through the SiOx reflecting layer so that the silicon substrate is connected with the Al metal layer. The cell piece of the invention can generate above 95% extremely strong reflex to long wave light with a 900-1100 wavelength. Absorption of cell to the long wave light can be increased. Composite of a cell back surface can be reduced. Cell efficiency can be increased. The cell piece is beneficial to thinning of a crystalline silicon solar cell. Simultaneously, a production technology is simple and easy. The production can be achieved by using a current cell production line. The method is very suitable for industrialization development.

Description

technical field [0001] The invention relates to a battery sheet with a back reflection layer and a preparation method thereof. Background technique [0002] In recent years, in order to reduce the cost of solar cells, the thickness of silicon wafers has been continuously reduced, from the initial 350 μm to 270, 240, 220, and 180 μm, and even thinner in the future. As the thickness of the silicon wafer is reduced, the diffusion length of minority carriers may be close to or greater than the thickness of the silicon wafer, and some minority carriers will diffuse to the back of the cell and recombine, which will have a great impact on cell efficiency. At the same time, when the thickness of the silicon wafer is reduced to less than 200μm, the absorption of long-wave light (wavelength 900-1100nm) decreases, which not only reduces the battery efficiency, but also increases the temperature of the back electrode contact point, which affects the battery life. Therefore, the battery ...

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Problems solved by technology

Someone has also developed a three-dimensional back reflection layer, which is a photonic crystal doped with aluminum and zinc oxide with three-dimensional macropores, which can achieve a reflectivity of 80% or more in the 600-1000nm visible light band, thereby increasing the photoelectric conversion efficiency. , the three-dimensional back reflection layer requires more raw materials, and the production process is more complicated, which increases the production cost and is not conducive to mass production

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