How methoxy groups change nature of the thiophene based heterocyclic chalcones from p-channel to ambipolar transport semiconducting materials

Abstract

Chalcone derivatives gained significant consideration from scientific community due to their potential applications ranging from better biological activity to the efficient semiconducting properties. Present investigation deals with the in-depth study of three chalcone derivatives (2E)-1-(2,5-Dimethyl-3-thienyl)-3-(2-methoxyphenyl)prop-2-en-1-one (1), (2E)-3-(3,4-Dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one (2), and (E)-1-(2,5-Dimethyl-3-thienyl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one (3) highlighting their optoelectronic, charge transport (CT) and nonlinear optical (NLO) response. The ground and excited state geometries are optimized by applying density functional theory (DFT) and time dependent DFT, respectively. The effect of electron donating groups on the frontier molecular orbitals, absorption and emission wavelengths are investigated and discussed thoroughly using the quantum chemical calculations. The comprehensive intra-molecular charge transfer (ICT) is perceived from the occupied orbitals to the unoccupied molecular orbitals. A novel structure-property relationship is established on the basis of their calculated electronic structures, frontier orbitals and density of states. The electro-optical and nonlinear optical (NLO) properties are finely tuned in the chalcone derivatives comprising of di- and tri-methoxy groups at peripheral. The nature of the p-type and ambipolar charge transport behavior of the compounds 1–3 is limelighted on the basis of their ionization potentials, electron affinities, reorganization energies, transfer integrals and intrinsic mobility. The mono- and di-substituted methoxy chalcone derivatives show the ambipolar performance owing to the better transfer integral and intrinsic mobility values for hole and electron. Whilst tri-methoxy at peripheral would lead the p-channel characteristics due to the balanced reorganization energy (hole and electron) and superior hole transfer integrals leads to higher hole intrinsic mobility.