Monolithic Perovskite/Silicon-Heterojunction Tandem Solar Cells with Open-Circuit Voltage of over 1.8 V

Perovskite/silicon tandem solar cells with high theoretical efficiency, low cost, and the potential for simple mass production have received significant attention. To maintain the current matching, increasing the open-circuit voltage (VOC) of the top and bottom subcells is an effective route to enhance the efficiency of tandem solar cells (TSCs). In this paper, we focus on a strategy for increasing the VOC and simultaneously maintaining a high efficiency of over 20%. Perovskite thin films with added Cs in traditional FAMA cations have shown a large grain, smooth surface morphology, wider band gap, and reduced defects, which together bring about a TSC VOC of 1.78 V. In addition, the high minority carrier lifetime (τeff) of bottom silicon solar cells resulting from the good passivation of a-Si:H/c-Si interface enhance the VOC values to as high as 1.83 V, which is the highest value for perovskite/silicon TSCs.