Highly passivated TOPCon bottom cells for perovskite/silicon tandem solar cells

Abstract Tunnel oxide passivating contact (TOPCon) silicon solar cells are rising as a competitive photovoltaic technology, seamlessly blending high efficiency with cost-effectiveness and mass production capabilities. However, the numerous defects from the fragile silicon oxide/c-Si interface and the low field-effect passivation due to the inadequate boron in-diffusion in p-type TOPCon (p-TOPCon) reduce their open-circuit voltages (VOCs), impeding their widespread application in the promising perovskite/silicon tandem solar cells (TSCs) that hold a potential to break 30% module efficiency. To address this, we develop highly passivated p-TOPCon structure by optimizing the oxidation conditions, boron in-diffusion and aluminium oxide hydrogenation, thus pronouncedly improving the implied VOC (iVOC) of p-TOPCon to 715 mV and the VOC of double-sided TOPCon bottom cells to 710 mV. Consequently, integrating with perovskite top cells, our proof of concept 1 cm2 n-i-p perovskite/silicon TSCs exhibit VOCs exceeding 1.9 V and a highest reported efficiency of 28.20%, which paves a way for TOPCon cells in the commercialization of future tandems.