Synthesis, Characterization, Optical, Electrochemical and Current-Voltage Characteristics of Coumarin Dyes.

A series of coumarin dyes having common acceptor and pi spacer with different donors were synthesized and characterized by spectroscopic techniques. The TiO2 nanoparticle has been synthesized by sol-gel method and characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Photophysical and electrochemical properties have been investigated. The band gap, molar absorption coefficient and energies of frontier molecular orbitals (FMO) have been calculated. The results showed that an electron releasing group helps in tuning the band gap. The geometry optimization and energies of FMO were obtained by density functional theory calculations. The calculated global chemical parameters help in understanding the intrinsic donor-acceptor properties of the synthesized dye molecules. The result of current-voltage characteristics showed good photocurrent response under illumination condition.