Synthesis and luminescent properties of PbS/SiO2 core-shell quantum dots

Abstract

The research focuses on the development of techniques for creating core-shell structures, based on colloidal PbS quantum dots (PbS QDs) and establishing the influence of the dielectric SiO2 shell on the luminescent properties of PbS QDs. The objects of the study were PbS QDs with an average size of 3.0±0.5 nm, passivated with thioglycolic acid (TGA) and PbS/SiO2 QDs, based on them with an average size of 6.0±0.5 nm. When we passivated the PbS QD interfaces with thioglycolic acid molecules, there were two luminescence peaks at 1100 and at 1260 nm. It was found that increasing the temperature of the colloidal mixture to 60 °C provides an increase in the intensity of the long-wave peak. An analysis of the luminescence excitation spectra of both bands and the Stokes shift showed that the band at 1100 nm is associated with the radiative annihilation of an exciton, while the band at 1260 nm is due to recombination at trap levels. The formation of PbS/SiO2 QDs suppresses trap state luminescence, indicating the localization of luminescence centers predominantly at QD interfaces. The exciton luminescence at 1100 nm becomes more intensive

Keywords

• lead sulfide quantum dots
• core-shell structures
• sio2 shell
• luminescence spectra
• excitation spectra