文摘
Natural dye sensitizers from Ixora coccinea (anthocyanin) and Bougainvillea glabra (betalain) flowers were prepared in five different ratios of ethanol to water (0, 30, 50, 70, and 90 % ethanol), and the effect of dye aggregation toward dye sensitized solar cell (DSSC) performance was evaluated. As the concentration of ethanol increases, the tendency of dye molecules to aggregate increased in Ixora dye extracts while no definite trend was observed in Bougainvillea dye extracts. The best DSSC performances of Ixora and Bougainvillea dyes exhibited by extracts in 70 % ethanol and 0 % ethanol are 0.58 ± 0.02 and 0.25 ± 0.02 %, respectively. Both high conversion efficiencies were ascribed to high electron density and low charge transfer resistance. From this study, it was revealed that the performances of DSSC could be affected by the formulation of dye aggregation on the TiO2 surface.