Development and comparison of n+pn+ and n+pp+ solar cells in multicrystalline silicon

Abstract

The goal of this paper is to present the development and comparison of p-type multicrystalline silicon solar cells with screen printed metallization. Industrial processes were developed to manufacture the n+pn+and n+pp+ solar cells. The n+pn+ structure was obtained with single phosphorus diffusion. The n+pp+ solar cell was developed and the p+ region was optimized experimentally by using one single high temperature step for phosphorus and aluminum diffusion. The results showed that the average efficiency of n+pn+ solar cells with no texturing was 12.3%. The efficiency increased 1.5% (absolute) with the implementation of acidic solution texturing. The highest efficiency achieved for solar cell without (n+pn+) and with (n+pp+) back surface field (BSF) was 13.8% and 14.1%, respectively. The BSF does not result in a significant improvement in the efficiency when the diffusion is carried out in a single step thermal diffusion in industrial process with screen printed metallization.