Abstract
Photochemical solar cells operating on the principle of dye sensitization have demonstrated to be highly efficient in converting light energy into electricity. A frequently asked question is {open_quotes}What makes these nanocryastalline semiconductor based solar cells so efficient?{close_quotes} The present study addresses several important issues related to kinetics and mechanisms of photosensitization of SnO{sub 2}, TiO{sub 2} and ZnO thin films with Ruthenium(II) complexes. Fast kinetic spectroscopy and spectroelectrochemical measurements have been carried out to reveal the mysteries of these photochemical solar cells. Efforts are also underway to improve the efficiency of photocurrent generation with composite semiconductor thin films (e.g., SnO{sub 2}/TiO{sub 2}; SnO{sub 2}/CdSe). The efficient charge separation achieved in such composite semiconductor films is useful for suppressing reverse electron transfer between dye cation and electron injected into the particle.