Over 14% efficiency on RST-ribbon solar cells

Abstract

In solar cell production silicon wafer material still has a large impact on the total costs. Material losses due to slicing wafers from ingots are one of the main reasons. Ribbon technologies can avoid these problems by producing wafers directly out of the silicon melt. We focus on the Ribbon on Sacrificial Template (RST) method which uses carbon-based substrates to cast silicon wafers. RST wafers have effective minority charge carrier diffusion lengths in the range of ~120 m. Thus, the potential for good cell performances is given. A high efficiency solar cell process developed for defect-rich multicrystalline silicon materials at the University of Konstanz was applied on RST wafers. The goal was to gain insight into the material quality and properties to provide feedback for the wafer production. With over 14%, we can present the so far highest obtained solar cell efficiency for this material.