Control of direction of nonradiative resonance energy transfer in hybrid associates of colloidal Ag₂S/TGA QDs with thionine molecules

The possibilities of changing the direction of electronic excitations transfer in hybrid associates are analyzed. Studies of hybrid associates of colloidal Ag₂S quantum dots (QDs), stabilized with thioglycolic acid (TGA) with thionine (TH⁺) molecules, were realized by transmission electron microscopy, absorption and luminescence spectroscopy, and photoluminescence decay studies (time correlated single photon counting). The increase in the average size of QDs from 1.8 to 5.5 nm, as well as shift of QDs luminescence peak from 630 to 950 nm were observed, when TGA molecules together with sodium sulfide was used as a sulfur precursor. The hybrid association of QDs (1.8 nm) with TH⁺ molecules leads to quenching of QDs luminescence in the luminescence band with peak at 630 nm and simultaneously decreases in luminescence lifetime from 13.7 to 6.5 ns. In the case of QDs association with a luminescence peak at 950 nm with TH⁺ molecules, it leads to quenching of TH⁺ luminescence and decrease in its luminescence lifetime from 0.43 to 0.3 ns. It is concluded that the decreasing in the luminescence lifetime is caused by nonradiative resonance energy transfer between components of associates. An increase in the average size of QDs leads to a change in the direction of energy transfer between associate components.