Efficient energy storage and uvioresistant perovskite solar cells through insulating Y2O2S-based long-lasting phosphor layer

Abstract Perovskite solar cells (PSCs) attract widespread attention owing to its extremely high power conversion efficiency (PCE) and low-price fabrication processing. However, the high-power output is merely limited under sunlight illumination and nearly zero at a dark atmosphere, which may potentially hinder the commercial development and outdoor applications. In this work, we introduce an efficient and stable long-lasting phosphor layer, Y2O2S: Eu3+, Ti4+, Mg2+ enabling PSCs to achieve energy-storage function owing to its persistent photoelectric conversion. When sunlight illumination is turned off, the modified devices can still keep current output for 2 h. Besides, the modified devices demonstrate a considerable improvement of PCE, suppressed hysteretic effects, and highly prolonged light stability. The optimized PCE of 20.9% is obtained through elevated light-harvesting, optimized bandgap alignment, and depressed charge recombination provided by the YOS layer. The modified PSCs maintain 83% of their original PCE after aging in UV light for 100 h and retain 78% of their original PCE after 90 days in the oxygen and humid condition. This work represents a novel strategy on obtaining energy storage and uvioresistant PSCs.