Geometries, electronic structures and vibrational spectral studies of 4-aminophthalonitrile using quantum chemical calculations for dye sensitized solar cells

Abstract

The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizer 4-Aminophthalonitrile were studied based on Hartee-Fock (HF) and Density Functional Theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectrum was investigated by Time Dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TD-DFT calculations. The absorption bands have been assigned to n → π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in 4-Aminophthalonitrile is due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer is due to an electron injection process from excited dye to the semiconductor’s conduction band. The role of cyanide and amine group in 4-Aminophthalonitrile geometries, electronic structures, and vibrational spectra were compared with experimental values and in view of these results, it was concluded that 4-Aminophthalonitrile used in Dye Sensitized Solar Cells (DSSC) gives a good conversion efficiency.