Single excited molecular orbitals’ contribution in Uv-Vis absorption of dichloride-bis(5,7-dichloroquinolin-8-olato)tin(IV)

The absorption spectrum of dichloride-bis(5,7-dichloroquinolin-8-olato)tin(IV) of the chemical formula Q2SnCl2 is calculated making use of first-principles methods and is compared with the experimental data. The energy correction terms for the excitation energies are computed by considering the single excited molecular orbitals (SEMO) from ground state to excited states of the molecule. By this approach, the contributions of the Columbic interaction between an excited electron and the remained hole in the absorption spectrum during the process of optical excitation are estimated. The MO energy difference and MO wave functions calculated by the density functional theory (DFT) and SEMO energy contribution are calculated. The results show that the corrections in energies by considering the contributions of the SEMO improve significantly the theoretical optical absorption spectrum. The calculations are based on DFT and necessary parameters and integrals for the computation of SEMO are obtained in DFT scheme. This method proves to be preferred compared to other ab-initio methods for calculating excited states, due to its ability in specifying MOs for any excitation energy, and also its lower computational cost. The method is applied for the first time to the calculation of the energy of transitions and specifies the electronic transition between MOs, especially in the absorption machinery of the OLED. Taking into account the contribution of the electron-hole interaction in the optical mechanism of absorption in the molecule makes the theoretical spectrum closer to that of the experiment. As a result, the crucial role of the electron-hole interaction, i.e. the interaction between the excited electron and the remained hole, in the absorption mechanism cannot be ignored..