DEVELOPMENT OF LARGE AREA, LOW-COST, SOLAR CELL PROCESSING SEQUENCE.

Abstract

The work upon which this report is based was directed toward the development of low-cost, large area, polysilicon solar cells. Every process selected is state-of-the-art technology. Process optimization for production oriented yields and reproducibility of conversion efficiency for various kinds of available poly-silicon were performed and a cost effective process was defined using IPEG analyses. Innovative processes such as gettering, spray-on polymer dopants and a hybrid nickel/ copper system were used in conjunction with texturizing and spray-on antireflection coating. Comparisons were made among: spray-on dopants and POC1//3 diffusions; LPCVD Si//3N//4 and spray-on titanium isopropoxide; evaporated, printed and sprayed-on aluminum for back surface field formation; electroless nickel, printed silver and the hybrid nickel/copper metallization. In all cases analyses were made based on both performance and cost effectiveness. The influence of crystal grains on solar cell efficiency was studied. Grid line spacing sensitivity analysis for minimal fractional power loss with respect to statistically averaged grain size was used for optimized pattern definition.