Efficiency difference between furan- and thiophene-based D–π–A dyes in DSSCs explained by theoretical calculations

The performance of two donor–π-bridge–acceptor type phenothiazine dyes bearing different π-bridges (furan and thiophene) was investigated by density functional theory and time-dependent density functional theory to explore the reasons for the differences in DSSC efficiency. It was revealed that dye1 with furan showed higher short-circuit photocurrent density due to its larger driving force and better light harvesting efficiency compared with dye2. Moreover, a larger number of photo-injected electrons into TiO(2) for dye1 leads to higher open-circuit photovoltage. Our results indicate that furan could be used as a promising π-bridge to improve the efficiency of PTZ dyes. We hope that our work can provide a theoretical basis and view for designing efficient dyes in dye-sensitized solar cells (DSSCs).