Sensitization of nanoporous TiO2 electrodes using the naturally occurring chromophores: stentorin and hypericin

Abstract This paper compares hypericin and stentorin as possible photosensitizers for transparent, nanoporous, TiO 2 -based photovoltaic cells. The absolute photon conversion efficiency (APCE) of stentorin-sensitized nanoporous TiO 2 electrodes was 2%, 20 times greater than that of electrodes sensitized by the structural analog, hypericin (0.1%). We attribute the greater efficiency of the stentorin electrode to the decreased tendency of stentorin to aggregate on the electrode surface. These results suggest that controlling aggregation by making a slight structural modification to the chromophore could be a viable and generalizable method for improving the performance of dye-sensitized electrodes.