Light emitting diodes (LEDs) are one of the many possible applications for metal halide perovskites. Despite their many advantages, the well-known instability issue persists in these devices, with the ion migration being a major cause of degradation. Inspired by the research in 2D perovskites, our group together with researchers from group of Ni Zhao at the Chinese University of Hong Kong achieved record operational lifetime perovskite LEDs, by treating the perovskite surface with phenylalkylammonium iodides (PAAIs), molecules consisting of a benzene ring, an alkyl chain and an amine tail. This is not the first time PAAIs are employed for the purpose of stabilizing perovskites. What makes all the difference here is the utilization of molecules with longer chains than usual, which proved to improve the stability dramatically.

Sofia contributed to the understanding of the physicochemical processes behind the improved stability. Density functional theory calculations showed that molecules with larger chains form stronger bonds with the perovskite surface. Moreover, an appropriate model was developed to study the effect of the molecular surface treatment on the iodine ion migration. This migration is effectively suppressed with the surface treatment and it turns out that the longer the molecular chain, the stronger the suppression.

This work, which was recently published in Nature Communications, is an important step towards the stabilization and succeeding commercialization of perovskite devices. Read more at behind the paper at Nature’s device materials community.

An illustration of PeLED device and the perovskite emitter modified with a long-chain passivation molecule (n=3).