Enhanced Photocurrent via π-Bridge Extension of Perylenemonoimide-Based Dyes for p-Type Dye-Sensitized Solar Cells and Photoelectrochemical Cells

[Image: see text] Two dyes TB and TSB containing triphenylamine as the donor and perylenemonoimide as the acceptor, with and without bithiophene as π-bridge, respectively, were successfully prepared and characterized for p-type dye-sensitized solar cells (p-DSSCs) and dye-sensitized photoelectrochemical cells (DS-PECs). As a result, TSB with bithiophene π-bridge exhibited a broader absorption spectrum and a higher molar extinction coefficient than TB. Furthermore, the photocurrents of p-DSSCs and DS-PECs for the dye TSB were increased by 26.9 and 32.9%, respectively, compared with those of the dye TB. Meanwhile, the electrochemical impedance spectroscopy of the TSB-based p-DSSC showed the smaller charge-transfer resistance and larger hole lifetime because the longer π-bridge facilitated charge transfer and separation within the dye molecule and effectively prevented the hole recombination process at the NiO/dye interface, resulting in improvement of photoelectric performance. Hence, these results show that the π-bridge extension of dyes has a promising effect on the photocurrent improvement of p-DSSCs and DS-PECs.