Simple Thiophene Based Organic Dyes as Active Photosensitizers for DSSC Application: from Molecular Design to Structure Property Relationship.

The main objective of our present investigation includes the design synthesis and characterization of two novel D-π-A configured carbazole based dyes C_1-2, carrying two different anchors and the same donor system. In the new design, a simple O-alkylated phenyl group as a donor scaffold, cyanovinylene and thiophene group serve as a π-spacer, while cyanoacetic acid, barbituric acid units function as electron acceptor/ anchoring units. The newly synthesized compounds were characterized by FTIR, NMR spectroscopic techniques including the elemental analysis. Further, their optical properties were investigated by using UV-visible, fluorescence spectrophotometer. In addition, the Density functional theory (DFT) calculations were performed to get their electron distribution in FMO levels. In order to investigate their photovoltaic characteristics, the synthesized dyes were employed as sensitizers towards the fabrication of DSSC's. The device fabricated with dye C₁ displayed better PCE of 1.2 % with JSC of 3.64 mA·cm^-2, VOC of 0.50 V and FF of 65 % than other dye C₂. These experimental results provide a better understanding and deeper insight into the intricacies involved in the design of superior sensitizers to further improve the performance of DSSCs. [ABSTRACT FROM AUTHOR]