D–A–π–A featured sensitizers containing an auxiliary acceptor of benzoxadiazole: molecular engineering and co-sensitization

Abstract

Two novel D–A–π–A organic sensitizers (WS-24 and WS-26) incorporating a benzoxadiazole (BOD) unit are synthesized for dye sensitized solar cells. An additional n-hexylthiophene unit is incorporated into WS-26 to decrease unfavourable dye aggregation, thus suppressing charge recombination and increasing the solubility. Incorporating an auxiliary acceptor of benzoxadiazole (BOD) into the π-bridge can red shift absorption bands, and sharply decrease the LUMO level. In virtue of co-sensitization, the WS-26 based DSSC device can achieve photovoltaic efficiency as high as 9.72%.