As the field of semiconducting quantum dots (QDs) continues to mature, the variation of nanocrystal sizes present in a synthesized sample is still an obstacle. Because the properties of QDs are size dependent, it is crucial to produce QD samples of only one nanocrystal size. This will allow for accurate study of structure-property relationships. Magic-sized clusters (MSCs) circumvent the polydispersity seen in QDs, as growth is discrete and limited to only certain sized clusters. Synthesis can be optimized such that few cluster sizes are synthesized, which can then be separated to provide monodisperse QDs. In spite of this promise, MSCs remain poorly studied. MSCs typically exhibit broad emission with low photoluminescence quantum yields (PLQY). This presentation will describe our efforts towards CdSe MSCs with sharp, high efficiency PLQY. We achieved this by tuning the surface chemistry of existing clusters. We show that post-synthetic ligand exchange of CdSe MSCs leads to a reduction in emission from mid-gap states with a subsequent rise in overall PLQY. Furthermore, these CdSe MSCs were coated with a higher band gap shelling material to provide highly luminescent core-shell MSCs. These bright, monodisperse MSCs will allow for a variety of studies on the source of their optoelectronic properties. Furthermore, these MSCs are an exciting candidate for use in a variety of applications such as lighting and lasing.<br/>

Strategies for enhancing the photoluminescence of CdSe magic-sized clusters

ACS Fall 2020 Virtual Meeting

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