Tunable white light generation by modified oligothiophenes blends

Fully tunable binary blends have been fabricated by combining a new class of modified oligothiophenes with photoluminescence efficiency up to 70 %. The blends cover the entire spectrum of colors according to the standards of the Commission International de l'Eclairage (CIE), including white and purple. We demonstrate that the emission spectrum of the blend is determined by the Forster transfer when the energy separation between the HOMO-LUMO gap of the constituting molecules is smaller than 0.56 eV. For larger energy separation, the blend emission is just given by the superposition of the emission spectra of the constituting molecules.