Compact high-quality CdSe–CdS core–shell nanocrystals with narrow emission linewidths and suppressed blinking

Abstract

High particle uniformity, high photoluminescence quantum yields, narrow and symmetric emission spectral lineshapes and minimal single dot emission intermittency (known as blinking) have been recognized as universal requirements for the successful use of colloidal quantum dots (QDs) in nearly all optical applications. However, synthesizing samples that simultaneously meet all these four criteria has proven challenging. Here, we report the synthesis of such high-quality CdSe/CdS core/shell QDs in an optimized process which maintains a slow growth rate of the shell through the use of octanethiol and cadmium oleate as precursors. In contrast with previous observations, single-QD blinking is significantly suppressed with only a relatively thin shell. In addition, we demonstrate the elimination of the ensemble luminescence photodarkening that is an intrinsic consequence of QD blinking statistical aging. Furthermore, the small size and high photoluminescence quantum yields of these novel QDs render them superior in vivo imaging agents compared to conventional QDs. We anticipate that this new generation of QDs will also result in significant improvement in the performance of QDs in other applications such as solid-state lighting and illumination.

Tuning the Lattice Parameter of InxZnyP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots

“…38 However, in this case, as our QDs are around 3 nm in diameter, this technique probes the whole QD volume. The reference pure InP QD sample (black spectrum in figure 2a) shows a In 3d 5 The agreement between XPS and ICP-OES results therefore strongly supports the formation of an In x Zn y P alloy structure.…”

“…3,4 For QDs to be employed in lighting applications they must have the stringent requirements of high photoluminescence (PL) quantum yield (QY) and high stability. Whilst these requirements have been met, to a high degree, for Cd based QDs, 5,6 the toxicity of cadmium is a major issue for consumer applications. InP-based QDs are among the most investigated nontoxic Cd-free systems, owing to their comparable emission range.…”

Ultrafast Charge Dynamics in Trap‐Free and Surface‐Trapping Colloidal Quantum Dots

“…For instance, even freshly‐synthesized CdSe CQDs typically exhibit a PL quantum yield (QY) considerably less than 100% because of the nonradiative pathways enabled by unsaturated surface bonds. Until recently, the only CQDs reported to have close to unity QY have been Type I core/shell CQDs 3, 25. In this structure, the shell acts as a barrier between carriers generated in the core and the surface of the shell; a graduation between core and shell materials is also necessary to ensure that there is no nonradiative recombination caused by an abrupt interface.…”

Energy-saving quality road lighting with colloidal quantum dot nanophosphors

“…Orange-red emitting CdSe/CdS core/shell QDs are synthesized according to Ref. [43]. These QDs acquire a peak emission wavelength of 604 nm with a full-width at half maximum of 33 nm.…”