Fluorescence and photoelectrochemical behavior of chlorophyll a adsorbed on a nanocrystalline SnO2 film

Abstract

Fluorescence and photoeletrochemical studies of chlorophyll a (Chl a) adsorbed on nanocrystalline SnO2 film were carried out. The results of fluorescence and incident photon to current conversion efficiency (IPCE) as a function of applied bias suggest that the fluorescence quenching and the photocarrier generation are interrelated. Fluorescence quenching has thus been utilized to determine the photogeneration efficiency, η(e), of charges in a SnO2/Chl a based photoelectrochemical cell. A value of 0.75 was obtained for η(e) for unbiased cells. With an IPCE of 13%, η(e) of 75%, and a light harvesting efficiency of 70%, the charge collection efficiency of ∼23% was evaluated. These results suggest that the losses due to the charge recombination are a major factor that limit the efficiency of the cells. © 1996 American Institute of Physics.