Thermostimulated luminescence of colloidal Ag2S quantum dots

The solution of the problem of investigating the energy structure of trap states and photophysical processes with their participation is necessary for the effective application of colloidal Ag2S quantum dots. These studies are important both for finding ways to increase the quantum yield of luminescence, and for the effective using of non-luminescent trap states in photocatalysis applications. In this paper, Ag2S quantum dots prepared with an aqueous synthesis in a gelatin matrix were investigated. The investigated Ag2S quantum dots have average sizes of 2.2 ± 0.3 nm, 2.5 ± 0.5 nm and 3.6 ± 0.5 nm, according to TEM data, and size-dependent spectra of UV-Vis absorption and photoluminescence. Temperature dependencies of IR recombination luminescence (1200-1250 nm) for ensembles of colloidal Ag2S quantum dots, dispersed in gelatin, were investigated. Thermostimulated luminescence, appearing under the variation of temperature and continuous photoexcitation of colloidal Ag2S quantum dots, was detected. The peak of thermoluminescence was found in the temperature region of 120-240 K, which consists of two components. Energies of activation of thermoluminescence and temperature quenching of IR luminescence were determined. The activation energy is in the region of 0.05-0.11 eV. And the energy of temperature quenching of IR luminescence is at 0.06-0.10 eV.