Publication

Abstract : A new series of dibenzothiophene-based oligomers with dibenzothiophene serving as the central framework and various aromatic groups as substituents was designed, synthesized and characterized. Theoretical studies were carried out using Time-Dependent Density Functional Theory with the PBEPBE/6–311+G(d) basis set to optimize molecular geometry, calculate band gaps and identify the chemical reactivity indices. The synthesis of these oligomers was achieved via Suzuki coupling, enabling detailed characterization of their optical and electrochemical properties. All the oligomers exhibited strong UV–Vis absorption in the range of 295 - 400 nm in solution, with a red shift observed in the film state. Bluish-violet emission was observed in solution, which shifted to longer wavelengths in the solid state. Excited state dynamics were studied using Time Correlated Single Photon Counting, revealing average lifetimes between 0.55 ns and 1.69 ns. The electrochemical studies showed the band gap of the oligomers ranging from 2.68 eV to 3.20 eV. Theoretical calculations of chemical reactivity indices were performed, and electrophilic and nucleophilic sites were identified through molecular electrostatic potential simulations. Quantum chemical parameters and the open circuit voltage of the oligomers were also calculated. Atomic Force Microscopy analysis of film surfaces indicated nanoscale roughness, with a smooth morphology conducive to device fabrication. The excellent optical properties, tunable band gaps and favorable surface features of these dibenzothiophene-based materials make them promising candidates for advancing organic electronic technologies.