Tuning the Interfacial Stoichiometry of InP Core and InP/ZnSe Core/Shell Quantum Dots

Abstract

We demonstrate fine-tuning of the atomic composition of InP/ZnSe QDs at the core/shell interface. Specifically, we control the stoichiometry of both anions (P, As, S, and Se) and cations (In, Zn) and correlate these changes with the resultant steady-state and time-resolved optical properties of the nanocrystals. Anion deposition on the InP QD surface results in a redshift in the absorption, quenching of the excitonic photoluminescence, and a relative increase in the intensity of the broad trap-based photoluminescence, consistent with delocalization of the exciton wavefunction and relaxation of exciton confinement. Time-resolved photoluminescence data show an overall small change in the decay dynamics on the ns timescale, suggesting the relatively low photoluminescence quantum yields may be attributed to the creation of new thermally activated charge trap states. Cluster-model density functional theory calculations show that the presence of core/shell interface anions give rise to electronic defects contributing to the redshift in the absorption.

Colloidal, Room Temperature Growth of Metal Oxide Shells on InP Quantum Dots

“…InP QDs were prepared from carboxylate-capped InP magic-sized clusters used as a single source precursor. 43,44 The resulting InP QDs were purified by multiple precipitation-centrifugation-redissolution cycles followed by size-selective gelpermeation chromatography. 45,46 An InP QD stock solution was then prepared in toluene with an In concentration of 0.051 mmol/mL.…”