Halide Perovskite-Derived Compounds RbTeX (X = Cl, Br, and I): Electronic Structure of the Ground and First Excited States.

Herein, we report a study of the electronic structure of the ground and first excited states of RbTeCl, RbTeBr, and RbTeI halide-perovskite-derived crystals. Using X-ray photoelectron spectroscopy (XPS) measurements and density functional theory and multiconfiguration self-consistent field (MCSCF) calculations, the experimental and theoretical XPS spectra of the valence region were obtained. In addition, the effects of the cations and halogen atoms on the electronic structure were determined, and the classification of the excited states in double point group representation was carried out.