Thermally activated photoluminescence in lead selenide colloidal quantum dots.

The thermal activation processes in PbSe colloidal quantum dots and their influence on the ground-state exciton emission are discussed. Activation of a dark exciton occurs at 1.4-7 K, assisted by an acoustic phonon coupling.

Nanocrystals of PbSe core, PbSe/PbS, and PbSe/PbSxS(1-x) core/shell as saturable absorbers in passively Q-switched near-infrared lasers.

The saturable optical absorption properties of PbSe core nanocrystals (NCs), and their corresponding PbSe/PbScore/shell and PbSe/PbSexS(1-x) core/alloyed-shell NCs, were examined at lambda = 1.54 microm. Saturation intensities of approximately 100 MW/cm2 were obtained.