In Situ Formation of High-p<i>K</i><sub>a</sub> Cations for Perovskite Solar Cells
Pengfei Wu, Jin Hyuck Heo, Yating Shi, Shirong Wang, Minghui Li, Chuanxiao Xiao, Xianggao Li, Fei Zhang
Abstract
Surface passivation is one of the most promising strategies for improving the illumination stability at high temperatures for perovskite solar cells. However, commonly used surface agents should be presynthesized and were usually located at the perovskite surface or interfaces, making it challenging to suppress bulk defects simultaneously. Here, we present an approach for the in situ formation of high-p K a cations ([N(Z)]-N-(Aminomethylene)guanidinium) to eliminate charge defects in bulk and interfacial sites simultaneously. Consequently, the performance is enhanced for both n-i-p and p-i-n structures, with the highest reaching ∼25.4% and 20.1% (64 cm 2 aperture area). Additionally, the treatment can be applied to extensive perovskite compositions, including triple cations, double cations, and single cation-based perovskites. The devices retain 94% of their initial efficiency after 2000 h continuous light illumination under the maximum power point tracking (ISOS-L-1), representing the best photostability among n-i-p structured devices(>25%)reported to date.