Near-infrared photoluminescence of PbS QDs precipitated in the glass matrix

Abstract

Optical properties of PbS quantum dots (QDs) precipitated inside the oxide glass matrix were investigated. Photoluminescence (PL) spectra were recorded with peak wavelengths located at 1170-1680 nm with peak width of 150-500 nm. Radii of QDs in glasses were 2.0-3.7 nm depending upon the thermal treatment conditions. Changes in temperatures and excitation intensities resulted in the shift of photoluminescence bands as large as 70 nm, due to the laser-induced local heating. Photoluminescence from PbS QDs showed darkening and brightening behavior. Intensity of the photoluminescence increased with time at low temperature (< 150 K) especially when the excitation intensity was low. Photo-darkening was observed when temperature and/or illumination intensities increased. Competition between the photo-brightening and photo-darkening determined the final steady-state photoluminescence intensity.