Insight into the effects of the donors and pi-spacers on the photovoltaic performance of quinoline and pyridocarbazole based DSSCs

Abstract

Four novel D-pi-A organic dyes containing quinoline (5a, 5b) and pyridocarbazole (5c, 5d) as the pi-spacers have been synthesized for dye-sensitized solar cells (DSSCs). The experimental and theoretical results confirmed that the incorporation of pyridocarbazole in the dyes could be favorable for the long wavelength light-harvesting as compared to quinoline based dyes. Upon coadsorption with chenodeoxycholic acid (CDCA), the DSSC based on 5d exhibited the power conversion efficiency of 3.35%, which is better than those of 2.39%, 2.62% and 3.25% for 5a-c, respectively. However, these efficiencies present only 8-15% of enhancement compared to that in the absence of coadsorbent, which suggests dyes 5a-d suppress the intermolecular aggregation and restrain charge recombination. In other words, this work suggests that the introduction of quinoline or pyridocarbazole as the pi-spacers into D-pi-A organic dyes is a promising way for coadsorbent-free DSSCs.