Theoretical study elucidates deep surface structure of emerging perovskite material

The results of a new theoretical study into the surfaces of CsPbI₃, an emerging perovskite material with potential for photovoltaic applications, highlights both the complexity of such surfaces and paves the way for future surface science and interface studies.

Cesium lead triiodide is an emerging all-inorganic perovskite material which has remarkable stability in ambient conditions. These properties make it particularly suitable for use in photovoltaic applications.

A recent article authored by Azimatu Seidu unravels the (001) surface of cesium lead triiodide (CsPbI3) using a first principles method. In particular, Seidu and co-workers investigated the atomic and electronic structure of the cubic (α) and orthorhombic (γ) phases of CsPbI3 surfaces. For both phases, Seidu studied surfaces with CsI- (CsI-T) and PbI₂-terminations (PbI₂-T) and found CsI-T to be more stable than PbI₂-T.

In addition, the work explored surface reconstructions of CsI-T by adding and removing Cs, Pb, I, CsI, PbI and PbI₂ units. Interestingly, adding or removing units of nonpolar CsI and PbI₂ turned out the most stable.

These results now offer concrete guidance for growing favourable CsPbI₃ surfaces for use in photovoltaics. Seidu now plans to combine her recent work and previous search on suitable coating materials for perovskites to model stable and robust perovskites for solar applications. The current research combines a machine learning based Bayesian optimization structural search (BOSS) and density functional theory (DFT) to obtain stable coating-perovskite interfaces. 

This article was published in the Journal of Chemical Physics (https://doi.org/10.1063/5.0035448).