Optical properties and structure of Ag-doped InP quantum dots prepared by a phosphine synthetic route

We report a novel technique for doping InP quantum dots (QDs) with silver that makes use of a AgCl·TOP complex as a source of silver and PH3 as a phosphorus precursor. Formation of two types of nanoparticles in the reaction mixture is observed: Ag-doped InP QDs form at lower silver concentrations and novel Ag/InP core-shell nanostructures form at high Ag-precursor concentrations. Ag-doped QDs possess two luminescent bands: an excitonic band at approx. 670 nm and an IR-band, indicative of dopant luminescence, at approx. 900 nm. Post-synthetic covering of the quantum dots with ZnS leads to a significant increase in both types of luminescence. The core-shell Ag/InP nanoparticles did not emit any luminescence in the visible and near-IR spectral regions.