Dft/Tddft Studies on Carbazole-Antipyrine Schiff Base Organic Dyes Containing Different Πi-Spacer for Dsscs Applications

Abstract

A series of organic dyes (W1-W12) with D-πi-D’-π-A configuration with antipyrine and carbazole moieties as donor unit, thiophene derivatives (πi) and phenyl (π) as π-spacer and carboxyl group as acceptor unit were investigated theoretically based on the synthetic compounds WLE1 and WLE2. The purpose of this work was to reveal the effect of insertion and modification thiophene-based πi-spacers between antipyrine (D) and carbazole (D’) on the photoelectric properties and photovoltaic performance of the twelve designed dyes in dye-sensitized solar cells (DSSCs) application with the assist of density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The calculated results revealed that the introduction of πi-spacers between antipyrine and carbazole moieties can significantly reduce the HOMO and LUMO energy gap, and leading to the absorption maximum (λmax) red-shift and the oscillator strengths (ƒ) significantly increased. The designed dyes exhibit good photovoltaic performance, such as higher VOC (1.742 to 2.257 eV), good LHE performance (0.8517 to 0.9962), negative values of ΔGinj (-1.7784 to -1.1628 eV), and smaller values of ΔGreg (0.428 to 0.946 eV), which can lead to a higher JSC and hence a greater photon-to-electron conversion efficiency (PCE). Especially, the dyes W9 and W12 could be the excellent candidate for high efficiency DSSCs applications. We further used (TiO2)6 as model semiconductor to evaluate the overall optoelectronic properties and transport parameters of the dye/TiO2 assembly after anchoring the dyes on the model TiO2 cluster.

Keywords: Dye-sensitized solar cells, Carbazole-antipyrine Schiff base dye, Photovoltaic properties, DFT, TD-DFT