Diffusion technology for reducing dark current of metallurgical silicon solar battery

Abstract

The invention discloses a diffusion technology for reducing dark current of a metallurgical silicon solar battery, which includes the steps of firstly, carrying out concentrated phosphorus diffusion at the low temperature: feeding from a high-concentration phosphorus source for diffusion at the low temperature so as to form high-concentration phosphor doping; secondly, performing phosphorus gettering for a long time at the high temperature: releasing impurities such as deposited impurities, displacement impurities or other impurity complexes of iron, carbon, boron, oxygen and the like into interstitial impurities at the high temperature, so that the interstitial impurities quickly release into a phosphorosilicate glass layer with high solid solubility, high-temperature phosphorus gettering is completed, and the minority carrier lifetime of a body is prolonged; and thirdly, propelling at the lower temperature: at the lower temperature, propelling the junction depth, adjusting to square resistance meeting technological requirements, and lowering the solid solubility of the impurities in a surface concentrated area along with the temperature, so that the interstitial impurities turn to the deposited impurities, the complex impurities and the like. A metallurgical crystal silicon wafer is diffused by means of the diffusion technology, so that the dark current of the solar battery can be effectively reduced, and the conversion efficiency of the solar battery is improved.

Description

technical field [0001] The invention belongs to the technical field of solar cells, and in particular relates to a diffusion process for reducing the dark current of metallurgical-grade silicon solar cells. Background technique [0002] The basic manufacturing process of conventional solar cells: cleaning and making suede, diffusion sheet resistance, edge etching, dephosphorous silicon glass, anti-reflection coating, screen printing grid lines, electrical performance testing, sorting and packaging. The diffusion process plays a very important role in the solar cell manufacturing process and is the core process of solar cell manufacturing. The purpose of diffusion is to form the heart PN junction of the solar cell, and the structure of the PN junction directly affects the electrical performance parameters such as short-circuit current, open-circuit voltage, and dark current of the solar cell. [0003] Metallurgical grade silicon is generally produced by purification by physi...

AI Technical Summary

Problems solved by technology

At present, the industry generally uses the diffusion process of solar-grade silicon to produce metallurgical-grade silicon solar cells. The presence of such a large amount of impurities such as iron, carbon, boron, and oxygen will increase the recombination probability of photocarriers, and the manufactured solar cells generally have lower efficiency. Low, large dark current