Nature nanotechnology · 2013
Thermal activation of non-radiative Auger recombination in charged colloidal nanocrystals.
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Javaux C, Mahler B, Dubertret B, Shabaev A, Rodina A V, Efros Al L, Yakovlev D R, Liu F, Bayer M, Camps G, Biadala L, Buil S, Quelin X, Hermier J-P
Аннотация
Applications of semiconductor nanocrystals such as biomarkers and light-emitting optoelectronic devices require that their fluorescence quantum yield be close to 100%. However, such quantum yields have not been obtained yet, in part, because non-radiative Auger recombination in charged nanocrystals could not be suppressed completely. Here, we synthesize colloidal core/thick-shell CdSe/CdS nanocrystals with 100% quantum yield and completely quenched Auger processes at low temperatures, although the nanocrystals are negatively photocharged. Single particle and ensemble spectroscopy in the temperature range 30-300 K shows that the non-radiative Auger recombination is thermally activated around 200 K. Experimental results are well described by a model suggesting a temperature-dependent delocalization of one of the trion electrons from the CdSe core and enhanced Auger recombination at the abrupt CdS outer surface. These results point to a route for the design of core/shell structures with 100% quantum yield at room temperature.