Abstract
Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, blinking behavior of single QD is an intrinsic drawback for some biological and photoelectric applications based on single-particle emission. Herein we present a rational strategy for fabrication of non-blinking (Zn)CuInS/ZnS QDs in organic phase through in situ interfacial alloying approach. This new strategy includes three steps: synthesis of CuInS QDs, eliminating the interior traps of QDs by forming graded (Zn)CuInS alloyed QDs, modifying the surface traps of QDs by introducing ZnS shells onto (Zn)CuInS QDs using alkylthiols as sulfur source and surface ligands. The suppressed blinking mechanism was mainly attributed to modifying QDs traps from interior to exterior via a step-by-step modification. Non-blinking QDs show high quantum yield, symmetric emission spectra and excellent crystallinity, and will enable applications from biology to optoelectronics that were previously hindered by blinking behavior of traditional QDs.
Highlights
Suppressed by the introduction of a thick CdS shell to CdSe quantum dots (QDs), and the sizes of these “giant” QDs were significantly increased to 13–20 nm in this case[13,22]
Single QD fluorescence experiments have been performed with a total internal reflection fluorescence microscopy (TIRFM) imaging system as described in the supplementary information (Supplementary Fig. S1)
We investigated the effects of ZnS shell formation on single-particle optical properties of the other two (Zn)CuInS/ZnS QDs (Cu:In:ZnS shells onto (Zn) stoichiometric ratios of 1:1:3 and 1:6:3)
Summary
Suppressed by the introduction of a thick CdS shell to CdSe QDs, and the sizes of these “giant” QDs were significantly increased to 13–20 nm in this case[13,22]. Bawendi’s group dramatically suppressed the blinking behavior of CdSe/CdS QDs by using octanethiol as sulfur source at high synthesis temperature, and the “on time” fraction of QDs were enhanced to 94%12. Peng’s group prepared phase-pure zinc-blende CdSe/CdS core/shell QDs with non-blinking behavior (“on time” fraction ≥ 95%)[23]. Great progress have been made in suppressing QDs blinking, to prepare non-blinking QDs (“on time” fraction = 100%) with high quantum yield, symmetric emission spectrum and excellent crystallinity is still a great challenge. The current studies mostly focused on the blinking behavior of CdSe and CdTe QDs9,11–14,16–19,22–25 Up to now, it is not clear whether CuInS QDs possess blinking behavior. The as-prepared QDs exhibit non-blinking, high quantum yield, narrow and symmetric emission spectrum and excellent crystallinity
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