Electronic structure calculations and optical properties of a new organic–inorganic luminescent perovskite: (C9H19NH3)2PbI2Br2

(C9H19NH3)2PbI2Br2 compound is a new crystal belonging to the large hybrid organic–inorganic perovskites compounds family. Optical properties are investigated by optical absorption UV–visible and photoluminescence (PL) techniques. Bands to band absorption peak at 2.44 eV as well as an extremely strong yellow–green photoluminescence emission at 2.17 eV is observed at room temperature. First principle calculations based on the DFT and FLAPW methods combined with LDA approximation are performed as well. Density of state close to the gap is presented and discussed in terms of optical absorption and photoluminescence experimental results. The perfect agreement between experimental data and electronic structure calculations is highlighted.