<p>Organic solar cells (OSCs) are the future of traditional photovoltaics in that they are lightweight, flexible and can be fabricated at a very low cost, but the challenge is to enhance their efficiency. This research will focus on improving the optoelectronic behavior of thiophene-based OSC materials by adjusting terminal acceptor groups in a donor-acceptor (D-A) system. The calculations were carried out on a reference molecule (<b>R</b>) and seven designed derivatives (<b>DA1-DA7</b>) using the WB97XD functional on a 6-31G(d, p) basis set in chloroform (IEFPCM model). Important properties, such as frontier molecular orbitals (FMOs), bandgap energies, natural bond orbital (NBO) parameters, absorption spectra, transition density matrices (TDMs), dipole moments and open-circuit voltage (V_OC) were systematically assessed. The results demonstrate that the designed molecules exhibit improved optoelectronic properties compared to the reference. DA4 exhibited the lowest bandgap (3.0069&#xa0;eV), suggesting enhanced charge-transfer characteristics, while DA6 and DA7 showed comparatively greater stability. Optical analysis revealed strong absorption in the visible to near-infrared region, with DA6 displaying the highest absorption maximum (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{\lambda\:}_{\text{m}\text{a}\text{x}}\)</EquationSource> </InlineEquation>) at 863&#xa0;nm. The calculated V_OC values were comparatively high due to the frontier molecular orbital energy differences obtained from theoretical calculations under idealized conditions. TDM and natural bond orbital (NBO) analyses further supported efficient intramolecular charge transfer within the designed systems. Overall, the incorporation of strong electron-withdrawing acceptor groups significantly influenced the optoelectronic properties of the studied molecules. These findings provide useful theoretical insights for the future design of thiophene-based materials for organic solar cell applications.</p> Graphical abstract <p></p>