Significant decrease of the optical losses in the coupling between colloidal CdSe/CdS nanocrystals and a flat gold film at cryogenic temperature

We investigate the influence of the temperature (between 4 K and room temperature) on the fluorescence of colloidal thick-shell CdSe/CdS nanocrystals coupled with a flat gold film. First, we deduce the complex dielectric function (SIC) from the spectrophotometric measurements on the flat gold film. Then, when compared to a nanocrystal deposited on a glass coverslip, calculations show that the enhancement of the photoluminescence decay rate is divided by a factor of 2.3 between 11 and 293 K due to the reduction of optical losses. Our analysis well accounts for the experiments performed on single CdSe/CdS nanocrystals.