Electronic and optical properties of halide perovskite quantum dots: a DFT and TDDFT study.

Perovskite quantum dots (QDs) constitute a novel and rapidly developing field of nanotechnology with promising potential for optoelectronic applications. However, few perovskite materials for QDs and other nanostructures have been theoretically explored. In this study, we present a wide spectrum of different hybrid halide perovskite cuboid-like QDs with the general formula of ABX₃ (A = Cs, CH₃NH₃; B = Pb, Sn, Ge, Ca, Sr and X = Cl, Br, I) with varying sizes below and near the Bohr exciton radius. Density functional theory (DFT) and time-dependent DFT calculations were employed to determine their structural, electronic, and optical properties. Our calculations include both stoichiometric and non-stoichiometric QDs, and our results reveal several materials with high optical absorption and application-suitable electronic and optical gaps. Our results also reveal whether the stoichiometric or non-stoichiometric model is closer to experiment. Finally, we explore a computational approach for the study of resonance energy transfer between 2 nanostructures of different sizes. Our study highlights the potential as well as the challenges and issues regarding nanostructured halide perovskite materials, laying the background for future theoretical and experimental work.