Oligomer molecules: first-principles investigation of the optical properties and applications to luminescent devices

Oligomer molecules offer a number of advantages for the study of their photo-physical properties and for the application to optoelectronic devices. We investigated the optical properties of a substituted quinquethiophene by first-principles calculations, determining the absorption and the emission energies, and compared these to the experimental data. The optical gain properties of the oligomer were exploited for the realization of a solid-state laser device exhibiting single-mode emission at 637 nm, with a full-width half-maximum of about 0.7 nm and a pump fluence threshold as low as 220 μJ/cm2.