Improved luminescent InP/ZnS quantum dots by ZnF2 assisted one-pot aminophosphine synthesis strategy

Abstract

Indium phosphide (InP) Quantum dots (QDs) are becoming one of the most favorable alternatives of cadmium-based QDs in view of their heavy metal-free and tunable luminescence. However, the photoluminescence performances of InP QDs still remain to be improved especially for the aminophosphine based synthesis method. In this work, we present a one-pot synthesis route of InP/ZnS red QDs based on tris(dimethylamino)phosphine (DMP) phosphorus precursor by using ZnF2 to generate HF and F ions in situ for the elimination of surface oxidative layer of InP cores and the passivation of indium dangling bonds. The synthesis conditions in terms of ZnF2 concentration, reaction temperature and growth time, were further investigated in order to obtain an optimization of fluorescence properties of InP QDs. It is found that the PL QY of both InP and InP/ZnS QDs are significantly improved by the ZnF2 additive. The PL QY of ∼16.4%, FWHM of 50 nm for pristine InP QDs and PL QY of ∼73%, emission peak of 628 nm, FWHM of 55 nm for ZnS shelled InP QDs can be obtained when the ratio of ZnF2 to ZnCl2, reaction temperature and growth time are 1:1, 200 °C and 40 min, respectively. Compared with the InP/ZnS QDs synthesized without ZnF2 treatment (55% PL QY, 611 nm emission peak, 62 nm FWHM), the PL QY is increased by 32.7%.