The effect of substituent groups on D-A organic molecule system for organic solar cells (OSCs) technology: “A Computational Approach”

Abstract In this work, the density functional theory (DFT) method of Becke’s three-parameter (B3LYP) was used for entirely investigations of D-A organic molecules as a donor (D) designed for organic solar cell (OSC) uses. We designed three D-A molecules with three different substituent groups (H, OCH3, and F) in the donor (D) unit, linked to a strong acceptor moiety. We investigated the open-circuit voltages (VOC), frontier molecular orbitals (FMOs), and photophysical characteristics using DFT and TD-DFT methodologies. A low binding energy (Eb = 2.2061 eV), the smallest bandgap (2.7484 eV) as well as excitation energy (2.5423 eV), and the highest maximum absorption wavelength (λmax) values of 467.07 and 487.69 nm in both the gas phase and acetonitrile solvent, respectively, are just a few of the promising photovoltaic characteristics that have demonstrated that the designed molecule M2 is the best nominee intended for solar cell applications compared to the others. According to this theoretical model, D-A unit alterations of substituent groups in the position of donor unit are a workable substitute for achieving the required optoelectronic characteristics. Consequently, the M1, M2, and M3 molecules that have been produced are remarkable and highly recommended to experimenters for the development of future solar cell systems with great efficiency.