Using ligands to control reactivity, size and phase in the colloidal synthesis of WSe2 nanocrystals.

Colloidal chemistry is leveraged for size- and phase-tuning of transition metal dichalcogenide nanomaterials. Specifically, nucleation and growth of colloidal WSe2 nanocrystals are controlled via mixtures of oleic acid (OA) and trioctylphosphine oxide. Increased OA yields slower nucleation, larger nanocrystals and a shift from the 2H to 1T' phase.

Photon Antibunching in Small Clusters of CdSe/ZnS Core/Shell Quantum Dots.

Coincident photon histogram measurements of fluorescence antibunching via confocal microscopy correlated with atomic force microscopy were carried out on (i) individual CdSe/ZnS core/shell quantum dots (QDs), (ii) several well separated QDs, and (iii) clusters of QDs. Individual QDs and well separated QDs showed the expected degree of antibunching for a single emitter and several independent emitters, respectively. The degree of antibunching in small, compact clusters was more characteristic of a single emitter than multiple emitters. The antibunching in clusters provides strong evidence of nonradiative energy transfer between QDs in a cluster. A minimal phenomenological model of energy transfer gives reasonable quantitative agreement with the experimental results.