We are interested in the study of photo-induced processes in molecular systems and materials. We study the dynamics and spectroscopy of short-lived species employing femtosecond-nanosecond time-resolved pump-probe and fluorescence upconversion and single photon counting techniques. We also investigate the behavior of photo-excited species at the single molecule/particle level using fluorescence correlation spectroscopy technique. Some of the problems of our current interest are ultrafast charge separation dynamics in perovskite and metal semiconductor nanocrystals, fluorescence blinking behavior in different materials, photo-processes in biomolecules, translational and rotational diffusion in ionic liquids.