A combination of fluorine-induced effect and co-sensitization for highly efficient and stable dye-sensitized solar cells

Developing dyes with high open-circuit photovoltage (Voc) is a vital strategy to improve the power conversion efficiency (PCE) of co-sensitized solar cells (co-DSSCs). Herein, three organic fluorine-containing dyes [YY-ThP(3F), YY-ThP(2F), and YY-ThP(26F)] are designed and synthesized for investigating the fluorine-induced effect on photophysical and photovoltaic performances. Consequently, this effect can significantly broaden the UV-vis absorption spectra of dyes but fail to improve the light-harvesting capability of DSSCs. Strikingly, YY-ThP(3F), featuring 3-position fluorine substitution to cyanoacrylic acid, yields a relatively high Voc compared to the corresponding fluorine-free dye (YY-ThP). Furthermore, the co-sensitization of YY-ThP+YY-ThP(3F) achieves a remarkably high PCE and long-term stability. This work implies that the combination of judicious molecular engineering and co-sensitization is a promising strategy for highly efficient and stable DSSCs.