Effect of aromatic linkers on thermally activated delayed fluorescence of selected organic molecules

[Display omitted] •DFT studies of D-L-A framework molecules with aromatic linkers are carried out.•TADF properties of the designed molecules are assessed based on the energy gap ΔEST.•Less ΔEST for molecules with six membered linkers than five membered linkers.•The spatial separation between HOMO and LUMO of the molecules is analysed w.r.t the linkers used. The effect of aromatic linkers on the energy gap between the lowest excited singlet and triplet states (ΔEST) of molecules with D-L-A framework having carbazole as donor and benzonitrile as acceptor is investigated using density functional method. The study revealed that molecules with six membered linkers have less ΔEST than those of five membered linkers. The molecule in which benzene acts as the linker is suggested as the ideal candidate for the up-conversion of excitons from the excited triplet to excited singlet state due to the smallest value of ΔEST. All the molecules designed are of high exciton binding energies.