Frequency-dependent spontaneous emission rate from CdSe and CdTe nanocrystals: influence of dark states

Phys Rev Lett. 2005 Dec 2;95(23):236804. doi: 10.1103/PhysRevLett.95.236804. Epub 2005 Dec 1.


We studied the rate of spontaneous emission from colloidal CdSe and CdTe nanocrystals at room temperature. The decay rate, obtained from luminescence decay curves, increases with the emission frequency in a supralinear way. This dependence is explained by the thermal occupation of dark exciton states at room temperature, giving rise to a strong attenuation of the rate of emission. The supralinear dependence is in agreement with the results of tight-binding calculations.