D-A-π-A Carbazole Dyes Bearing Fluorenone Acceptor for Dye Sensitized Solar Cells

Abstract

Three novel D-A-π-A carbazole sensitizing dyes were synthesized with fluorenone as the auxiliary acceptor, benzene, furan and thiophene as π bridge and cyanoacrylic acid as the anchoring acceptor. Compared with the similar D-π-A carbazole dye, the incorporation of fluorenone improved markedly the molar extinction coefficients of carbazole dyes, which increased the short-circuit current density and accordingly the photoelectric conversion efficiency. The presence of thiophene or furan bridge favors the short-circuit current density while the introduction of benzene bridge benefits the open-circuit voltage. Among three carbazole dyes, dye with benzene bridge exhibited the optimal efficiency 4.88% due to its highest open-circuit voltage and factor fill (VOC = 690 mV, JSC = 8.30 mA/cm2, and FF = 0.86).