(512a) Role of Redox Electrolyte on the Performance of CdSe Based Quantum Dot Solar Cell

Inorganic quantum dots with their well defined properties such as size-tunable band gaps, high luminescence quantum efficiency, and excellent photostability, have been successfully used as sensitizers in the photoelectrochemical solar cells.  The efficiency in a such device is determined by the intricate balance achieved between the various charge separation and recombination reactions.  Large differences in the timescales of electron injection (femto- second) and transport (milli second) processes, amplifies the rate of recombination.  Improvement in the performance requires precise estimation and tuning of rate constants for all the charge injection and recombination processes.  Here, we report the charge injection and recombination dynamics of CdSe quantum dots anchored on TiO₂ and SiO₂ in the presence of various liquid electrolytes and its influence on the light conversion efficiency.  The ability to alter the energy gap between CdSe and TiO₂ as well as CdSe and redox couple has profound influence on the interfacial charge transfer kinetics.  Femto second absorption spectroscopy and photoluminescence lifetime measurements have been carried out to monitor the charge injection kinetics in various electrolytes as a function of redox couple with different redox potential, concentration and pH of the medium.  Various strategies to maximize photoinduced charge separation and electron transfer processes for improving the overall efficiency of light energy conversion will be discussed.