Impeded degradation of perovskite solar cells via the dual interfacial modification of siloxane

It is challenging to improve the long-term stability of perovskite solar cells (PSCs) without sacrificing efficiency. The perovskite absorbers degrade from the film surface/interfaces, which follows entangled mechanisms that have not been fully revealed yet. Herein, we decouple and elaborate two distinctive pathways regarding film degradation based on FACsPbI(3) perovskites. Moreover, a dual interfacial modification strategy has been developed for improving the material's intrinsic stability, thus leading to the film degrading in a more retardant pathway. The corresponding PSCs achieve a stable power output efficiency of 23.75%. More importantly, the unencapsulated PSCs devices retain over 93% of their initial PCE after the maximum power point (MPP) tracking under the continuous 1-sun illumination and show significantly improved stability after aged under the thermal treatment or stored in ambient atmosphere for over 1500 hours without obvious PCE decay. This work shows the importance of modulating the degradation pathway on stability improvement, and at the same time, proposes a strategy for designing perovskite-based optoelectronics with excellent performance and stability.