Preparation method of casting polysilicon with large crystal grains in single crystal direction

Abstract

The invention discloses a preparation method for casting columnar multi-crystal silicon with large crystal grains in the same crystal direction, which comprises the following steps: (1) sequentially putting single-crystal silicon blocks, silicon raw materials and doped elements in a crucible; (2) heating the crucible to melt the silicon raw materials and the doped elements on the single-crystal silicon blocks, wherein all single-crystal silicon block can not be completely melted; and (3) starting heat exchange from the bottom of the crucible, and using the single-crystal silicon blocks as seed crystals for induced growth and directional solidification to form the multi-crystal silicon. The columnar multi-crystal silicon with large crystal grains can effectively reduce the crystal boundarydensity in the materials and basically solves the problem of the reduction of the battery efficiency caused by the existence of a large number of crystal boundaries in the prior common process of casting the multi-crystal silicon; and meanwhile, the crystal grains in the multi-crystal silicon prepared by the invention have the same crystal direction, so that the high-efficiency alkaline wool making technology in the preparation process of batteries can be used, thereby improving the absorption efficiency of batteries for light.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and in particular relates to cast polysilicon with single crystal orientation and columnar large crystal grains. Background technique [0002] Solar photovoltaic power generation is currently one of the cleanest, environmentally friendly forms of sustainable energy utilization, and it has developed rapidly around the world in recent years. According to statistics, in the past 10 years, the average annual growth rate of the global photovoltaic industry was 41.3%, and in the past 5 years it was 49.5%. In 2008, it increased by about 60% compared with 2007, and the growth rate increased year by year. Currently commercial solar cells are mainly made of crystalline silicon materials, including single crystal silicon and polycrystalline silicon. Monocrystalline silicon is obtained by the Czochralski method, while polycrystalline silicon is mainly obtained by the casting meth...

AI Technical Summary

Problems solved by technology

On the other hand, due to the disordered grain orientation of cast polysilicon, the highly efficient anisotropic alkali etching technology cannot be applied to cast polysilicon wafers in the battery manufacturing process to obtain a uniform texture. Therefore, isotropic acid etching is generally used A textured structure is formed on the surface of the polycrystalline silicon wafer. However, the acid-etched silicon wafer has a limited trapping effect on sunlight, and it is difficult to improve the photoelectric conversion efficiency of the cell.