Lead sulfide quantum dots in glasses containing rare-earth ions

The size and spatial distribution of PbS QDs in glasses need to be controlled in order to achieve desired optical characteristics. This paper reports on the use of several rare-earth oxides such as Ho2O3, Er2O3, and La2O3 to control the size of PbS QDs in silicate glasses. Additions of rare-earth oxides result in blue shifts of the absorption bands from 1344 nm to 930 nm, and the wavelengths of PL bands can be controlled between 1421 nm and 1035 nm. Additions of up to 0.8 mol% of Ho2O3 decreased the diameters of PbS QDs from 4.82 nm to 3.02 nm. The same tendencies were found for both Er2O3 and La2O3 additions, although the size of PbS QDs increased as the ionic radius of rare-earth ions increased. It is proposed that clusters of RE–O bonds act as nucleating agents for the precipitation of PbS QDs.