Intercalating-Organic-Cation-Induced Stability Bowing in Quasi-2D Metal-Halide Perovskites

Quasi-2D metal-halide perovskites with Ruddlesden−Popper structures have shown promising stability due to the protectiveeffects of the intercalating organic cations. However, a systematic studyof the effect of intercalating organic cations on stability has rarely beenreported. Here we use a high-throughput-robot platform to fabricateover 300 perovskite films and study the effect of cations and theirconcentrations on the thermal stability of perovskite films. We find thatapproximately 20−25 mol % of intercalating organic cations intoMAPbI3 (nominal n = 4/5) can maximize the film stability, whilehigher/lower concentrations lead to inferior stability, which is termedstability bowing in analogy to band-gap bowing. A model with twocompetitive effects of the intercalating organic cation (better protectionvs more defects) is proposed to rationalize this behavior. We anticipatethis work to provide new insights into the stability of quasi-2Dperovskites.