Effective surface passivation of multi-shelled InP quantum dots through a simple complexing with titanium species

Abstract

Fluorescent efficiency of various visible quantum dots (QDs) has been incessantly improved to meet industrially high standard mainly through the advance in core/shell heterostructural design, however, their stability against degradable environments appears still lacking. The most viable strategy to cope with this issue was to exploit chemically inert oxide phases to passivate QD surface in the form of either individual overcoating or matrix embedding. Herein, we report a simple but effective means to passivate QD surface by complexing its organic ligands with a metal alkoxide of titanium isopropoxide (Ti(i-PrO)(4)). For this, highly efficient red-emitting InP QDs with a multi-shell structure of ZnSeS intermediate plus ZnS outer shell are first synthesized and then the surface of resulting InP/ZnSeS/ZnS QDs is in-situ decorated with Ti(i-PrO)(4). The presence of Ti-O species from Ti(i-PrO)(4) on QD surface is verified by x-ray photoelectron and Fourier transform infrared spectroscopic analyses. Two comparative dispersions of pristine versus Ti(i-PrO)(4)-complexed QDs are exposed for certain periods of time to UV photon and heat and their temporal changes in photoluminescence are monitored, resulting in a huge improvement in QD stability from the latter ones through Ti(i-PrO)(4)-mediated better surface passivation. (C) 2017 Elsevier B.V. All rights reserved.