Photophysical Studies on D-π-A Imidazole Derivative for Organic Dye Sensitized Solar Cell Application

In present study, a new organic dye 2-(4-chlorophenyl)-1-(4-methoxyphenyl)-4,5-diphenyl-1Himidazole (CMI) containing phenyl donor with imidazole ring as π-linker and chlorophenyl group as acceptor have been synthesized. The photophysical properties like solvato-chromism, optical band gap and fluorescence lifetime are estimated using experimental as well as quantum chemical computational techniques. Further, photosensitization of TiO2 nanoparticles from CMI dye has been investigated using absorption, steady-state and time resolved fluorescence methods. The increase in absorbance and a decrease in fluorescence spectra with different concentrations of TiO2 nanoparticles confirmed the possibility of interactions between dye and TiO2 nanoparticles. Rehm-Weller relation suggests that a decrease in fluorescence of CMI dye was due to photo-induced electron transfer process and the Stern-Volmer studies suggest that the fluorescence quenching mechanism was due to combined dynamic and static quenching process. Further, dye-sensitized solar cell using this newly synthesized CMI dye has been fabricated and characterized for their photovoltaic performance under illumination. Photovoltaic energy conversion efficiency and fill factor of the CMI dye were found to be 1.76% and 0.56, respectively.