Advanced (1)H, (13)C, and (31)P solution- and solid-state NMR studies combined with XPS were used to probe, at the molecular scale, the composition (of the core, the shell, and the interface) and the surface chemistry of InP/ZnS core/shell quantum dots prepared via a non-coordinating solvent strategy. The interface between the mismatched InP and ZnS phases is composed of an amorphous mixed oxide phase incorporating InPO(x) (with x = 3 and predominantly 4), In(2)O(3), and InO(y)(OH)(3-2y) (y = 0, 1). Thanks to the analysis of the underlying reaction mechanisms, we demonstrate that the oxidation of the upper part of the InP core is the consequence of oxidative conditions brought by decarboxylative coupling reactions (ketonization). These reactions occur during both the core preparation and the coating process, but according to different mechanisms.

Control over particle surfaces and interfaces is a principal requirement to fully take advantage of semiconducting Quantum Dot (QDs) properties. In the case of indium phosphide, the sensitivity of the material to water renders it challenging to synthesize oxide-free particles. We demonstrate the ability to achieve complete control over the surface by developing synthetic strategies based on a novel reactive indium precursor, tris(N,N'diisopropylacetamidinato) indium(III). This complex permits the synthesis of InP QDs at temperatures as low as 150°C with no inherent surface oxidation. At higher temperatures (230°C), the concomitant use of an H 2 atmosphere yields oxide-free InP QDs. The prevention of such an amorphous oxide layer provides a clean surface suitable for subsequent growth. An extensive solid-state 2 H NMR spectroscopy study demonstrates an unprecedented H 2 bond dissociation at the QD surface yielding QDs-H species and in so doing protecting the surface from oxidation. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Experimental section, TEM, UV-Vis, XRD and solid state NMR data of InP QDs 1-4, and the ZnScoated versions 5-6.