Overcoming the Heterointerface Energetics Changes in Perovskite Photovoltaics With Nondestructive Halide Exchange

ABSTRACT Surface passivation is essential for high‐performance perovskite solar cells (PSCs). However, passivator‐induced carrier accumulation in potential wells and the reduction of ion migration activation energy caused by heterointerface energy changes pose significant challenges to device stability. Herein, we demonstrate a nondestructive halide exchange strategy with IBr‐treatment to pre‐construct a positive work function change without incorporating exogenous impurities. By simply varying concentration, this strategy enables continuous adjustment of the heterointerface energetics to suit various perovskites and passivators. The pre‐constructed positive work function change avoids the generation of the potential well during perovskite surface passivation, preventing the electron accumulation and facilitating interfacial hole extraction. Upon the IBr‐treatment, the PSCs achieve outstanding power conversion efficiency of 24.70% with PEAI passivation, 26.19% for small‐area device and 24.48% for 1‐cm 2 device with CHEAI passivation. The devices retain 94% of their initial efficiency after 1500 h continuous light illumination under maximum power point tracking. Our study provides a promising and practical strategy to overcome the passivator‐induced heterointerface energetics changes, avoiding the deteriorated efficiency and stability for the iodine‐containing perovskite photovoltaics.