Insights into end-capped modifications effect on the photovoltaic and optoelectronic properties of S-shaped fullerene-free acceptor molecules: A density functional theory computational study for organic solar cells

Non-fused ring electron acceptors with different end-capped substituents were designed to construct efficient organic solar cells (OSCs). End-capped modification of acceptor materials is an efficient approach for developing high performance OSCs. In this report, five new S-shaped fullerene-free acceptor molecules (3P1 to 3P5) have been designed and examined through density function and time-dependent density functional theories (TD-DFTs). Designed molecules have twisted backbone with different out-of-plane rings that cause high solubility in dilute solvent. Different optoelectronic and photovoltaic properties of newly designed S-shape molecules have been examined and explored through DFT tools. Orientation of frontier molecular orbitals (FMOs), light absorption range, exciton binding energy (E_b), oscillating strength (f), open circuit voltage (V_oc), and transition density matrix (TDM) analysis have been performed for 3P1 to 3P5 molecules. Further, electron and hole reorganization energies are also estimated with excitation energy. Results of different computed parameters have recommended that these designed molecules are effective contributors for possible applications in the field of OSCs.