Effect of donor and acceptor on optoelectronic properties of benzo[1,2-b:4,5-b′]dithiophene

A series of acceptor and donor groups anchored to benzo[1,2-b:4,5-b′]dithiophene (BDT) molecule have been systematically investigated at the density functional theory (DFT) time-dependent (TDDFT) level reveal structure–property relationships, charge transfer, fluorescence lifetimes. The DFT optimization shows that hetero atom in ring induces polarity from central both ends thiophene ring, participating conjugation. were terminals BDT two different positions fine-tune properties according requirement study push–pull effect. All models studied this work retain their aromaticity as estimated NICS(0) NICS(1) index ground excited states. results show hardness, softness, HOMO–LUMO gaps, ionization potentials (IP), electron affinities (EA) BDTs are significantly affected by electron-withdrawing electron-donating groups. 1H 13C NMR chemical shift values computed quantify Further, transfer these explored based on reorganization energies diagnostic descriptors derived hole–electron present excitation behavior. relationship between variables such highest occupied molecular orbital, lowest unoccupied oscillator strength, dipole moment, absorption, energy correlates system with one another also extend possible applications optical devices. Structure–property various that, upon excitation, resonance effect plays an important role changing bonding character substituent unit, enabling efficient delocalization. examination TDDFT indicates among work, nitro-substituted model is better candidate for optoelectronic relatively large absorption wavelength long lifetime.