Enhancement of Luminescence of Colloidal Ag2S Quantum Dots by Thionine Molecules

Abstract

Enhancement of IR luminescence (1205 nm) of colloidal Ag2S quantum dots (QDs) with an average size of 2.5 ± 0.3 nm was detected upon excitation in the absorption band of thionine dye molecules (530–610 nm). It is found that the observed effect occurs during a hybrid association of Ag2S QDs with monomers of the cationic thionine (Th + ) molecule. It is concluded that the photosensitization of IR luminescence of colloidal Ag2S QDs is realized due to a resonance nonradiative transfer of electronic excitation energy directly to the centers of radiative recombination from the excited Th + molecules.