How to achieve efficiencies exceeding 22% with multicrystalline n-type silicon solar cells

In this contribution, we demonstrate a route for efficiencies exceeding 22% with n-type multicrystalline (mc) silicon solar cells based on the TOPCon cell concept featuring a boron-diffused front side emitter and a full-area passivating rear contact. By applying a high-performance (HP) crystallization process with an adapted seed structure in order to obtain an optimized grain boundary area fraction, we reduce recombination losses in the HP mc-Si material to a minimum. We discuss the electrical properties of the optimized n-type HP mc-Si, which features very low material-related efficiency losses of approximately 0.5%(abs) and, thus, enables an efficiency potential of 22.6% with regard to a cell limit of 23.1% of the TOPCon cell concept adapted for multicrystalline silicon. Results at the device level reveal a record efficiency of 21.9%, which is the highest efficiency reported for a multicrystalline silicon solar cell. Finally, we discuss the deviations between the predicted efficiency potential and the solar cell results. (C) 2017 The Authors. Published by Elsevier Ltd.