Effects of heterocycles containing different atoms as π-bridges on the performance of dye-sensitized solar cells†
Two new D–π–A zinc porphyrin dyes with thiophene and furan π-bridges have been synthesized and employed in dye-sensitized solar cells (DSSCs). Here, the triphenylamine (TPA) moiety was used as the electron donor, and the hexylthiophene chromophores were introduced onto the donor groups, which effectively extended the π-conjugation system. Although the two dyes had similar molecular structures, there was a significant difference between their optical and photoelectric properties. The EIS analysis suggested that the dye with the thiophene π-bridge had a lower charge recombination rate compared to the dye with the furan π-bridge. Based on their light-harvesting abilities, the power conversion efficiency (PCE) of dye JP-S was higher than that of dye JP-O. The JP-S-based DSSC showed a PCE of 5.84%, whereas the PCE of the JP-O-based DSSC was 4.68%. Moreover, using the dye TTR1 as a co-sensitizer made up for the poor absorption of porphyrin dyes in the 480–600 nm range and reduced the charge recombination. The JP-S + TTR1-based DSSCs showed a higher PCE of 6.71%, and the Jsc and Voc values of the device were both increased using this strategy.