Ferrocenyl benzimidazole with carboxylic and nitro anchors as potential sensitizers in dye-sensitized solar cells

Abstract

Two ferrocenyl benzimidazoles with carboxylic (1) and nitro (2) anchors have been synthesized and characterized using microanalyses, IR, ¹H and ¹³C NMR spectroscopy, and in one case using single crystal X-ray diffraction. UV-Vis spectroscopic studies indicate that in comparison to ferrocene the electronic absorption bands of the synthesized 1 and 2 dyes are bathochromically shifted up to 530 nm with concomitant enhancement in their intensities. The synthesized dyes have been exploited as a photosensitizer in TiO₂-based dye-sensitized solar cells (DSSCs). The photovoltaic performances and charge transport properties (EIS spectra) were studied to evaluate the synthesized dye performance in DSSCs. Amongst both the dyes, the one with the carboxylic anchor showed relatively superior photovoltaic performance in comparison to the dye with a nitro anchor. The superior performance of 1 is probably due to the better anchorage and superior dye loading capability on the TiO₂ surface, which suppresses charge recombination, prolongs electron lifetime, and decreases the total resistance of the DSSC. The assembly fabricated using 1 showed the best performance with an overall conversion efficiency η of 5.81%, J_sc of 12.74 mA cm⁻², and V_oc of −0.648 V. The obtained efficiency is ∼84% of the cell efficiency compared with the state-of-the-art N719 dye in similar conditions.