Multicrystalline silicon solar cells from RST ribbon process

Abstract

AbstractThe aim of Solarforce is the achievement of high efficiency solar cells made out of ≤100 µm thick multicrystalline silicon wafers produced by the Ribbon on Sacrificial Template (RST) process. For a first evaluation of the RST material, solar cells were fabricated on p‐type RST wafers with different processes. The first conclusion is that the density of silicon carbide inclusions has to be lowered to obtain better FF values, and in turn a better homogeneity in cell performances. Secondly, conversion efficiency is found to be limited around 14% by low bulk minority carrier lifetime values, limiting both Voc and Leff. ICP‐MS analyses on RST material show that this lifetime may be improved with the possible achievement of low metallic impurity content in the wafers, under 1 ppb wt. Further enhancement is also shown to be possible with the n doping of RST material, a well controlled process in ribbon growth (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)