Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

Abstract All-inorganic CsPbI3 perovskite quantum dots (QDs) have received intense research interest for photovoltaic applications because of the recently demonstrated higher power conversion efficiency compared to solar cells using other QD materials. These QD devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. In this work, through developing a hybrid interfacial architecture consisting of CsPbI3 QD/PCBM heterojunctions, we report the formation of an energy cascade for efficient charge transfer at both QD heterointerfaces and QD/electron transport layer interfaces. The champion CsPbI3 QD solar cell has a best power conversion efficiency of 15.1%, which is among the highest report to date. Building on this strategy, we demonstrate the very first perovskite QD flexible solar cell with a record efficiency of 12.3%. A detailed morphological characterization reveals that the perovskite QD film can better retain structure integrity than perovskite bulk thin-film under external mechanical stress. This work is the first to demonstrate higher mechanical endurance of QD film compared to bulk thin-film, and highlights the importance of further research on high‐performance and flexible optoelectronic devices using solution-processed QDs.