Novel D-π-A dye as a co-sensitizer of indoline and benzothiadiazole dyes to enhance photovoltaic performance of dye-sensitized solar cells

A novel D-it-A type of dye (BIM33) comprising diphenylamine as electron donor, diphenylacridine as a it-bridge and cyanoacrylic acid as an anchoring unit has been synthesized and used as sensitizer and co-sensitizer in dyesensitized solar cells (DSSCs). The DSSC based on BIM33 achieved a power conversion efficiency (PCE) of 3.19 % under one sun (AM 1.5G). To improve the photovoltaic performance of the DSSCs, this orange dye was also cosensitized with red benzothiadiazole (C1) and purple indoline (D205) organic dyes. The DSSCs based on cosensitizers BIM33/D205 and BIM33/C1 showed superior PCEs of 6.57 % (JSC = 13.69 mA cm- 2, VOC = 0.766 V, and FF = 0.63) and 6.82 % (JSC = 14.47 mA cm- 2, VOC = 0.722 V, and FF = 0.65), respectively, exhibiting significant improvements of 28 % and 36 % compared to the DSSCs based on D205 and C1, respectively. The high photovoltaic performance of the co-sensitized DSSCs may be explained by the broader visible light absorption and a denser packing of the dyes on the TiO2 surface.