Synthesis and characterization of PbSe quantum dots in phosphate glass

Abstract

The controlled synthesis of PbSe nanocrystal quantum dots with narrow size distributions was achieved through phase decomposition of the PbSe solid solution in a phosphate glass host. Structural characterization by electron microscopy and x-ray diffraction shows that the dots have mean diameters between 2 and 15 nm. The exciton Bohr radius $a_B\text{=46\hspace{0.17em}}\mathrm{nm}$ in PbSe, so these quantum dots provide unusual and perhaps unique access to the regime of strong quantum confinement. The optical absorption spectra are compared to the predictions of a theoretical treatment of the electronic structure. The theory agrees well with experiment for dots larger than $\text{∼7\hspace{0.17em}}\mathrm{nm},$ but for smaller dots there is some deviation from the theoretical predictions.