Synthesis of Oxide-Free InP Quantum Dots: Surface Control and H2-Assisted Growth

Abstract

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 H2 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 2H NMR spectroscopy study demonstrates an unprecedented H2 bond dissociation at the QD surface yielding QDs-H species and in so doing protecting the surface from oxidation.