Quantum chemical modelling of "green" luminescence in ABO₃ perovskites

The origin of the intrinsic excitonic ("green") luminescence in ABO₃ perovskites remains a hot topic over the last quarter of a century. We suggest as a theoretical interpretation for the "green" luminescence in these crystals, the recombination of electron and hole polarons forming a charge transfer vibronic exciton. In order to check quantitatively the proposed model, we performed quantum chemical calculations using the Intermediate Neglect of Differential Overlap (INDO) method combined with the periodic defect model. The luminescence energies calculated for four perovskite crystals are found to be in good agreement with experimental data.