DFT and TD-DFT Calculations of Some Metal Free Phthalonitrile Derivatives for Enhancement of the Dye Sensitized Solar Cells
Résumé
The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizers
3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile were studied
based on density functional theory using the hybrid functional B3LYP. Ultraviolet-visible spectra were investigated
by time dependent density functional theory. The features of electronic absorption spectra in the visible and
near-UV regions were assigned based on time dependent density functional theory calculations. The absorption
bands are assigned to π → π transitions. Calculated results suggest that the three lowest energy excited states
of 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile are due to
photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode
and dye sensitizers 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and 4-methylphthalonitrile is due to an electron injection process from excited dyes to the semiconductor’s conduction band. The role
of amide and methyl groups in phthalonitrile in geometries, electronic structures, and spectral properties were
analyzed in a comparative study of 3,4-pyridinedicarbonitrile, 3-aminophthalonitrile, 4-aminophthalonitrile and
4-methylphthalonitrile for the improvement of dye sensitized solar cells.
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