Preparation of PbS Quantum Dot Materials by the Sol-Gel Process

Quantum dot materials based on PbS-doped sodium borosilicate glasses were prepared by the sol-gel process using silicon methoxide (TMOS), boron ethoxide, sodium and lead acetates as starting materials. The chemical state of Pb species in the glasses fully densified at 590°C was identified to be PbS by X-ray photoelectron spectroscopy and electron diffraction. The amount of PbS crystallites in the glasses was 4-13wt% of mother glasses. The size of the crystallites was 5-15nm in diameter. The absorption edge of the glasses was near 2500nm, which was slightly shifted to higher energy from 3200nm for the bulk PbS crystal.