Transient photoluminescence and simultaneous amplified spontaneous emission from multiexciton states in CdSe quantum dots

We use transient photoluminescence to spectrally resolve the emission from 1, 2, and 3 electron-hole pairs states in CdSe colloidal quantum dots with radii ranging between 2.3 and 5.2 nm. The power dependence of the triexciton, biexciton and single exciton emission intensities are reported. We incorporate CdSe/ZnS core-shell nanocrystals into a TiO2 host matrix and observe simultaneous amplified spontaneous emission from the 1S(3/2)-1Se and 1P(3/2)-1P(e) quantum dot transitions. The achievement of amplified spontaneous emission from the 1P(e) QD state suggests that the 1P(e) state sixfold degeneracy might be lifted by the e-h exchange interaction.