Design, Synthesis and Photophysical Analysis of New Unsymmetrical Carbazole-Based Dyes for Dye-Sensitized Solar Cells

Abstract

The molecular design, synthesis, and characterization of di-anchoring carbazole-based dyes (Car-Cy, Car-Amin, and Car-Mal) with A-π-D-π-A-π-A structure as materials for dye-sensitized solar cells applications (DSSCs) are reported. The electron-rich carbazole moiety in the structure of synthesized dyes is connected with acceptor/ or anchoring groups (cyanoacetic acid, 4-aminobenzoic acid, and malonic acid) and π-spacers (vinylene and cynovinyl thiophene). Electronic characteristics and molecular geometry of the sensitizers were optimized using Density Functional Theory (DFT), and the influence of dye structure on their photovoltaic performances was studied. Among the synthesized dyes in this research, Car-Amin dye presents a better photovoltaic performance as a sensitizer in the constructed device, with a power conversion efficiency (PCE) of 2.27%, JSC of 5.95 mAcm−2, VOC of 0.54 V and FF of 71%. The enhanced performance of this dye could be related to the powerful electron-withdrawing characteristic of the 4-aminobenzoic acid as an acceptor group in the dye structure. Consequently, the impact of various acceptor groups on the constructed DSSC devices was examined, and the results indicated that the improvement of DSSC performance is due to the presence of 4-aminobenzoic acid as acceptor on the carbazole-based dyes.