Density-Functional Theory Study of the Optoelectronic Properties of {π}-Conjugated Copolymers for Organic Light-Emitting Diodes

Novel low-band-gap copolymer oligomers are proposed on the basis of density functional theory (DFT) quantum chemical calculations of photophysical properties. These molecules have an electron donor-accepter (D-A) architecture involving poly(3-hexylthiophene-2,5-diyl) (P3HT) as D units and furan, aniline, or hydroquinone as A units. Structural parameters, electronic properties, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps and molecular orbital densities are predicted. The charge transfer process between the D unit and the A unit one is supported by analyzing the optical absorption spectra of the compounds and the localization of the HOMO and LUMO.