Colloidal synthesis techniques can be used to obtain atomic-scale control over the internal structure of semiconductor nanocrystals. It is becoming increasingly clear that this level of control is required for the establishment and optimization of a range of important photophysical properties. A specific example from our group is the ability to eliminate detrimental processes of fluorescence intermittency (blinking), photobleaching, non-radiative recombination channels and self-reabsorption in semiconductor quantum dots (QDs) by precise “nanoengineering” of core/shell structure. This includes nanoscale composition, size and interface effects, and where successful has important implications for light-emission technologies from solid-state lighting to single-photon sources. Our approach has involved the growth of thick epitaxial shells of a higher bandgap material onto a QD core, where the band alignments often entail offset or type II character. The resulting thick-shell or giant QDs (g-QDs) have to date been most successful at red and near-infrared wavelengths. It has remained an outstanding challenge to synthesize green-emitting non-blinking, ultra-stable g-QDs. Here, we report the single-dot photophysical properties of new “green giants” comprising CdSe, ZnS and their alloys. By correlating internal nanocrystal structure and composition (defect density, extent of alloying, shell thickness, etc.) with blinking and photobleaching properties, we draw clear lines between synthesis conditions and resulting structure and function. Finally, we show how further development of this system and discovery of new functional QDs can be promoted by automating the process of precision hetero-nanostructure growth.

Suppressed-blinking green-emitting giant quantum dots: From synthesis to structure to function

253rd National Meeting (2017)

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