Design of the efficient, tunable T-shaped Metal-Free Organic Dyes for TiO 2 Dye-Sensitized Solar Cells—A TD-DFT study analysis

Abstract Dye sensitized-solar cells (DSSCs) have drawn much attention as being a low cost, in simple fabrication and as a high power conversion alternative to photovoltaic cells. In this study, small meta-free sensitizers comprising of Triphenylamine (TPA) as a donor moiety, double bond as a л-linker and cyanoacrylic acid as an acceptor (anchoring group) having different substitutions at donner sides were designed and analysis by Time-dependent Density Functional theory (TD-DFT). The substitution effects at different positions (R1, R2, R3 and R4) with different a variety of electron-withdrawing and electron-donating groups at donor moiety has been demonstrated to investigate the optoelectronic properties, absorption energy. For the proposed structures, molecular orbitals, HOMO, LUMO energy levels, and absorption spectra were calculated on DFT and TD-DFT level of theory by employing CAM-B3LYP methods and LANL2DZ /6-31G basis set using Gaussian 9.0 software. Eight dye-sensitizers (D1-D8) posing different substitutions (-CH3, -F, -NH2, -C (CH3)3, -NO2, -C6H5) on donor sides are capable of lowering the Egap (HOMO-LUMO), however, a few sensitizers show much lower Egap than to the conduction band edge value (4.0 eV). Nevertheless, the calculated properties inferred that three (D1, D4, and D6) studied sensitizers are supposed to be the good candidates for use and observe experimentally and eventually provide a guideline to design new sensitizers for dye-sensitized solar cells.