Density Functional Theory Study of Surface Stability and Phase Diagram of Orthorhombic CsPbI3

TL;DR

This study uses density functional theory to analyze the surface stability of orthorhombic CsPbI3, identifying the most stable surface terminations and their implications for optoelectronic device performance.

Contribution

It provides a detailed theoretical analysis of surface stability and reconstructions of CsPbI3, highlighting the most stable surface terminations and their electronic properties.

Findings

CsI-terminated (110) surface has lowest surface energy

(001) and (110) surfaces are stable with CsI termination

(110) surface has no mid-gap states, favoring charge transport

Abstract

CsPbI3 has been recognized as a promising candidate for optoelectronic device applications. To further improve the efficiency of the devices, it is imperative to better understand the surface properties of CsPbI3, which affect charge carrier transport and defect formation properties. In this study, we perform density functional theory calculations to explore the stability of the (001), (110), and (100) surfaces of orthorhombic CsPbI3, considering different stoichiometries and surface reconstructions. Our results show that, under the chemical potentials confined by the thermodynamically stable region of bulk CsPbI3, the CsI-terminated surfaces of (001) and (110) and the stoichiometric surface of (100) are stable. Among these three surfaces, the CsI-terminated (110) surface has the lowest surface energy and no mid-gap states, which benefits the transport properties of the material.