Dye mixture promoted light harvesting for organic dye-sensitized solar cells using triphenylamine dyes with various numbers of anchoring groups

Three sensitizers with triphenylamine as an electron donor, thiophene as a bridge and various numbers of acceptors/anchors cyanoacetic acid (TPA3T1A, TPA3T2A and TPA3T3A) are synthesized and TPA3T1A, TPA3T2A were used as co-adsorbents with TPA3T3A. The results show that, with co-adsorption ratio on TiO2 surface with TPA3T3A 73%, TPA3T1A 17% and TPA3T2A 10%, the photovoltaic performance of DSSCs increased from 5.27% to 5.83% compared with a single TPA3T3A sensitizer due to the increasing both of JSC and VOC. This enhancement may attribute to improved light absorption, diffusion length, and decreased recombination by fulfilling all of empty place on TPA3T3A-adsorbed TiO2.215