Band gap energy of PbS quantum dots in oxide glasses as a function of concentration

PbS nanocrystals embedded in glass matrix (SiO2–Na2CO3–Al2O3–B2O3) were synthesized by means of the fusion method using four different PbS concentrations (0.05, 0.1, 1.5, and 2.0 wt%). Thermal treatment was performed at 550 °C with annealing time of 6 h. Measurements of optical absorption and photoluminescence were carried out as a function of PbS concentration. It is argued that, with the same thermal treatment and annealing time, the formation of large nanocrystals becomes easier as the PbS concentration increases. Optical absorption spectra showed that the band-gap energy increases as the PbS concentration decreases, making this relationship important in the obtainment of a desired band-gap in PbS-doped glasses.