Luminescence of hybrid nanostructures based on colloidal Ag2S/TGA quantum dots and Indocyanine Green molecules

This work presents studies of IR luminescence sensitization of Indocyanine Green dye (ICG), observed during association with colloidal Ag2S quantum dots with an average size of 2.2 nm passivated with thioglycolic acid (Ag2S/TGA QD). The opportunity of enhancing the dye monomer luminescence (peak at 820 nm) by 4-6 times under excitation of 660 nm in the presence of Ag2S/TGA QDs (2.2 nm) was shown. At the same time, Ag2S/TGA QDs luminescence intensity does not change. quantum yield (QY) luminescence of ICG increases by 5 times. The luminescence lifetime obtained with use of luminescence decay analysis at wavelength of 820 nm increases by 2.2 times. The observed changes in ICG luminescent properties during its conjugation with Ag2S/TGA QDs are result of a decrease in the mobility of the dye polymethine chain due to coordination interaction with Ag2S/TGA QDs, which decreases the efficiency of non-radiative transitions.