Simultaneously enhancing moisture and mechanical stability of flexible perovskite solar cells via a polyimide interfacial layer

Perovskite solar cells (PSCs) have aroused tremendous attention due to the high power conversion efficiency (PCE) and flexibility of the organic-inorganic hybrid perovskite films. However, the commercialization of perovskite solar cells is still impeded due to the instability issue induced by moisture and mechanical stress. Herein, we introduce soluble hydrophobic polyimide (PI) as an interfacial layer on top of the perovskite film to block the infiltration of moisture into the perovskite film. The MAPbI 3 -based solar cell with the insertion of PI layer exhibited an impressive stability, maintaining 87% of the initial PCE even after exposing to 50% relative humidity for 550 h and presenting a decent PCE of 21.22% due to its ability to extract holes and reduce trap-assisted recombination. Moreover, the high tolerance of PI to the mechanical stress gives a more stable flexibility to the PSCs under