Spectral and dynamical characterization of multiexcitons in colloidal CdSe semiconductor quantum dots
Abstract
Femtosecond photoluminescence (PL) up-conversion studies in polychromatic mode and laser-power-dependence studies of the PL were carried out on colloidal solutions of CdSe quantum dots with diameters ranging from 2.4to4nm . The main features of the spectra consist, in addition to the band-gap luminescence, of three bands, one 120-130meV and another 30-40meV at low energy to the band-gap luminescence, while the third lies 220-260meV higher in energy. The first band is attributed to a positively charged biexciton and the second to a neutral biexciton, while the blue band is attributed to a neutral triexciton. These assignments are based on the energetics, the lifetimes, and the pump-power dependence of the various bands. The energetics and lifetimes are in good agreement with the theoretical studies present in literature.
- Publication:
-
Physical Review B
- Pub Date:
- May 2005
- DOI:
- 10.1103/PhysRevB.71.205317
- Bibcode:
- 2005PhRvB..71t5317B
- Keywords:
-
- 78.67.Hc;
- 78.55.Et;
- 78.47.+p;
- 73.22.-f;
- Quantum dots;
- II-VI semiconductors;
- Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter;
- Electronic structure of nanoscale materials: clusters nanoparticles nanotubes and nanocrystals