Enhanced charge transport properties in heteroatomic (NH, O, Se) analogs of benzotrithiophene (BTT) isomers: a DFT insight

Abstract

ABSTRACTA comprehensive comparative study of the geometry, optoelectronic and charge transport properties in benzotrithiophene (BTT), benzotripyrrole (BTP), benzotrifuran (BTF) and benzotriselenophene (BTSe) and their possible isomers are reported by employing density functional theory (DFT). The motive of this work is to examine the role of different heteroatoms (NH, O and Se) on optical and charge transport properties. The optimised molecules display planar geometry, which is ideal for organic semiconductor applications. The absorption properties of all the molecules are calculated using time-dependent density functional theory (TDDFT). Nucleus independent chemical shift (NICS) calculations are performed to see the stability and aromatic character in these molecules. The calculated hole and electron reorganisation energies (λh and λe) for majority of the isomers in each series are smaller than that of typical hole and electron transport material (TPD and Alq3). BTP series isomers are with exceptionally small λe values (10–60 meV), which means these isomers are better for electron transport materials. The quantum chemical results show that HOMO, LUMO, HOMO–LUMO gap, and reorganisation energies along with ionisation potentials and electron affinities are significantly affected by changing the heteroatoms. The smaller hole and electron reorganisation energies of these molecules suggest possible use in OLEDs.