Phenothiazine dyes containing a 4-phenyl-2-(thiophen-2-yl) thiazole bridge for dye-sensitized solar cells

Abstract

Two novel phenothiazine dyes bearing a single or double cyanoacrylic acid acceptors, which share the same electron donor phenothiazine and the same 4-phenyl-2-(thiophen-2-yl)thiazole π-bridge, were synthesized. Thus, phenothiazine dyes with D-π-A and A-D-π-A framework were configured, and their photophysical properties and photovoltaic performance were investigated. The incorporation of another cyanoacrylic acid acceptor was found to benefit the loading amount on TiO2, the light-harvesting ability, and the electron-injection efficiency. Dye with double cyanoacrylic acid acceptors showed a double short-circuit current compared with dye with a single acceptor. Therefore, dye with double cyanoacrylic acid acceptors achieved improved photoelectric conversion efficiency 4.35% (JSC = 10.29 mA cm−2, VOC = 0.65 V, FF = 0.65) under standard global AM 1.5 G solar condition with dye N719 (7.19%) as a reference.