Ambient-aging process enables enhanced efficiency for wide-bandgap perovskite solar cells

Wide-bandgap perovskite is considered an ideal absorber for the top component cell of a tandem configuration, in addition to having proven advantageous for indoor light conversion and semitransparent solar cells. In this work, we demonstrate an ambient aging process that appears to further raise the performance of wide-bandgap perovskite solar cells. Systematic study shows that that secondary recrystallization arises during the aging process. The defect density is further attenuated by air passivation and the self-healing effect induced by halogen redistribution. As such, the nonradiative recombination in the perovskite films is suppressed, and the carrier lifetime is prolonged during the ambient aging. The champion wide-bandgap (Eg=1.74 eV) perovskite solar cell delivered a power-conversion efficiency as high as 20.12%, coupled with a high open-circuit voltage of 1.27 V, which is among the highest values reported for this type of wide-bandgap solar cells. This work reveals the impact of the air aging process on the properties of perovskite films from various aspects and demonstrates a scalable post-treatment strategy capable of producing state-of-the-art semiconducting films.