Atomic and electronic structure of cesium lead triiodide surfaces

The (001) surface of the emerging photovoltaic material cesium lead triiodide (CsPbI3) is studied. Using first-principles methods, we investigate the atomic and electronic structure of cubic (alpha) and orthorhombic (gamma) CsPbI3. For both phases, we find that CsI-termination is more stable than PbI2-termination. For the CsI-terminated surface, we then compute and analyze the surface phase diagram. We observe that surfaces with added or removed units of nonpolar CsI and PbI2 are most stable. The corresponding band structures reveal that the alpha phase exhibits surface states that derive from the conduction band. The surface reconstructions do not introduce new states in the bandgap of CsPbI3, but for the alpha phase, we find additional surface states at the conduction band edge.

Automated summary

The (001) surface of the emerging photovoltaic material cesium lead triiodide (CsPbI3) is studied using first-principles methods to investigate its atomic and electronic structure. It is found that CsI-termination is more stable than PbI2-termination on both cubic (alpha) and orthorhombic (gamma) CsPbI3 phases. Surface phase diagrams show that surfaces with added or removed units of nonpolar CsI and PbI2 are the most stable, and the alpha phase exhibits surface states that derive from the conduction band.