Theoretical studies of optoelectronic and photovoltaic properties of D–A polymer monomers by Density Functional Theory (DFT)

In this research article, the new donor–acceptor (D–A) monomers developed using 4-methoxy-9-methyl-9 H-carbazole (MMCB) as electron donors and various electron acceptors. DFT and TD-DFT methods at the level of B3LYP with a 6–311 G basis set in a gas and chloroform solvent were used to calculate electronic and optoelectronic properties. To dissect the relationship between the molecular and optoelectronic structures, the impacts of specific acceptors on the geometry of molecules and optoelectronic properties of these D–A monomers were discussed. The calculations are also carried out on HOMO–LUMO, atomic orbital densities. The calculated band gap E(g) of the monomers considered increases 3,6-MMCB-OCP ≈ 3,6-MMCB-BCO < 3,6-MMCB-SDP < 3,6-MMCB-SCP < 3,6-MMCB-TCP < 3,6-MMCB-TDP < 3,6-MMCB-BCS < 3,6-MMCB-BCT in both in the gas and solvent phases. Subsequently, the optoelectrical properties of E(HOMO), E(LUMO), E(opt), and E(B) energies were critically updated. Compared to different monomers, the far lower E(g) of the 3,6-MMCB-OCP and 3,6-CB-BCO has shown optoelectronic applications in organic solar cells like BHJ.