Effect of furan pi-spacer and triethylene oxide methyl ether substituents on performance of phenothiazine sensitizers in dye-sensitized solar cells

Conjugated pi-spacers are used to improve the light harvesting properties of sensitizers for dye-sensitized solar cells. In several recent works, furan has outperformed other popular pi-spacers such as thiophene and phenyl. One of the best performing phenothiazine dyes in the literature has no pi-spacer, and two polar triethylene oxide methyl ether (TEOME) chains. Herein we report the synthesis and evaluation of three novel sensitizers based on EO3, investigating the effect of introducing a furan linker and stepwise removal of the TEOME chains. The furan linker redshifted the onsets in the IPCE spectra by 50 nm and improved the PCE by up to 29% compared to EO3, despite lowering the V-OC by more than 60 mV. The best sensitizer of the study was AFB-30, with an average PCE of 5.86% (J(SC) = 10.41 mA cm(-2), V-OC = 783 mV, FF = 0.73) under 1 sun AM 1.5G illumination.