Enhancement of power conversion efficiency of dye-sensitized solar cells by co-sensitization of Phloxine B and Bromophenol blue dyes on ZnO photoanode

A single dye usually absorbs light only in a limited range of solar spectrum. In order to widen the absorption range, a combination of dyes, namely, Phloxine B and Bromophenol blue have been used as sensitizers in ZnO based dye sensitized solar cell (DSSC). It has been found that the DSSC sensitized by mixed dyes exhibited better photovoltaic performance than those observed with the DSSCs using test dyes individually. It has been ascribed to the enhanced absorption of light particularly in higher energy region (λ=400-550 nm) when both dyes were used together as was evident from the absorption spectra of dyes adsorbed onto ZnO electrode. The DSSC using ZnO electrode sensitized by mixed dyes provided JSC=5.6 mA cm−2, VOC=0.606 V, FF=0.53 and maximum energy conversion efficiency (η) of 1.35% on illuminating the cell with visible light of 150 mW cm−2 intensity.