Single core/shell CdSe/CdS colloidal nanocrystals are usually used as efficient single photon sources working at room temperature, with a narrow spectrum of =30nm. For large shell, they evidence a strong resistance to high excitation and can withstand a few 106W/cm2,. Under high excitation their emission change dramatically, emission evolves non linearly with laser excitation power and the spectrum range can reach a few 100nm.
In order to understand such a behavior, we use a statistical description of the electrons and holes population as fermi dirac distributions, followed by radiative recombination of excitons, which describes well experimental results.
|