DFT and TD-DFT studies of new triphenylamine-based (D-A-D) donor materials for high-efficiency organic solar cells

The DFT approach of Becke's three-parameter compound (B3LYP) was employed in all studies of triphenylamine (TPA) molecules as a donor (D) for solar cell applications in this work. We created three donor molecules (D-A-D) with a strong donor moiety of triphenylamine (TPA) connected to three distinct acceptor (A) units, including benzo[c][1,2,5]thiadiazole, [1,2,5]thiadiazolo[3,4-c]pyridine, and [1,2,5]thiadiazolo[3,4-d]pyridazine. DFT and TD-DFT methods were used to examine the photophysical properties, frontier molecular orbitals (FMOs), density of states (DOS), and open-circuit voltages (V-OC). The designed molecule D3 has been proven to be the best candidate for solar cell applications over the others due to its promising photovoltaic properties, which include the lowest bandgap (1.53 eV) and excitation energy (1.21 eV), a low binding energy (E-b = 0.31 eV), and the highest max values of 964.01 nm and 1017.00 nm in the gas and solvent phases, respectively. This theoretically developed model indicates that D-A-D unit modifications are a viable alternative to achieve the desired optoelectronic properties. As a result, the developed D1, D2, and D3 molecules are exceptional and strongly suggested to experimentalists for the future creation of highly efficient solar cell systems.