First principles study of ferroelastic twins in halide perovskites

Abstract

We present an ab initio simulation of $90^{\circ }$ ferroelastic twins that were recently observed in methyl ammonium lead iodide. There are two inequivalent types of $90^{\circ }$ walls that we calculate to act as either electron or hole sinks which suggests a possible route to enhancing charge carrier separation in photovoltaic devices. Despite separating non-polar domains, we show these walls to have a substantial in-plane polarisation of $\sim 6\mu \text{C}{\text{cm}}^{-2}$, due in part to flexoelectricity. We suggest this in turn could allow for the photoferroic effect and create efficient pathways for photocurrents within the wall.

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Cited by in corpus (1)

• Decoupled molecular and inorganic framework dynamics in CH${}_3$NH${}_3$PbCl${}_3$