New synthesis of two-dimensional CdSe/CdS core@shell dot-in-hexagonal platelet nanoheterostructures with interesting optical properties

Abstract

A new strategy for the synthesis of fluorescent monodispersed 2-dimensional (2D) CdSe/CdS core/shell hexagonal platelet nanocrystals has been demonstrated. Because of the stronger affinity of the -NH2 group of oleylamine to the (0001Se) facet comprising three dangling bonds in CdSe seeds, oleylamine acts as the sole surfactant responsible for hindering the growth of the CdS shell in the 0001 and 0001[combining macron] facets and for helping the shell growth anisotropically in the 〈100〉 direction. The as-synthesized products were thoroughly characterized using XRD, TEM/HRTEM, HAADF and STEM for determining the crystal structure, growth mechanism and the position of the seed inside a core/shell nanocrystal. Optical absorption, PL, PLE and TRPL studies revealed efficient photoexcitation and the possibility of polarized emission from 2D core/shell nanocrystals.

Cadmium Chalcogenide Nano‐Heteroplatelets: Creating Advanced Nanostructured Materials by Shell Growth, Substitution, and Attachment

“…As seen in the TEM image in Figure f, the shell in this structure resembles a “box” rather than a “crown.” Similarly, CdSe/Cd@ZnS dot‐in‐plates were obtained to investigate the influence of differences in the parameters of the crystal lattices. The second method was the rapid injection of a seed/oleylamine/S mixture into a Cd precursor solution . Oleylamine was reported to be the essential ingredient for obtaining a platelet‐shaped shell rather than a conventional core/shell quantum dot structure.…”

“…The second method was the rapid injection of a seed/oleylamine/S mixture into a Cd precursor solution. [77] Oleylamine was reported to be the essential ingredient for obtaining a platelet-shaped shell rather than a conventional core/shell quantum dot structure. Despite the interesting results observed in dot-in-plates, the development of this type of nano-heterostructure remained nearly unnoticed.…”

Preferential growth of Au on CdSe quantum dots using Langmuir–Blodgett technique

“…CdSe QD seeds were prepared following a recent report by Chauhan et al 34 CdO 1.0 mmol (0.128 g), oleic acid 6.3 mmol (2 ml), trioctylphosphine oxide 5.17 mmol (2.0 g) and 1-octadecene 15.6 mol (5 ml) were loaded into a 50 ml three necked round bottom ask and heated to 150 C for 1 h under vacuum. This mixture was heated to 300 C under N 2 atmosphere.…”

Ultrafast Photoluminescence from the Core and the Shell in CdSe/CdS Dot‐in‐Rod Heterostructures

“…[9] CdSe/CdS heterostructures can be synthesized in severalm orphologies, including spherical core/shell, dot-inrod, dot-in-plate,o rm ultipods tructures. [10][11][12][13][14][15] Further, the electronic structureo fC dSe/CdS nano-heterostructures varies from Type I, in which the both the electrona nd hole localizes to the CdSe, to Type II (orq uasi-Type II), in which the hole localizes to the CdSe and the electron delocalizes through the structure. [16] The structure and electronic properties of CdSe/CdS nano-heterostructures have been synthetically tuned to control quantum yields, [11,17] optical polarization, [18][19][20] thermal stability, [21] suppressed blinking, [22] Auger recombination, [23,24] self-assembly, [10,25] opticalgain, [26][27][28] and photocatalytic activity.…”

“…Heterostructured semiconductor nanocrystals, and CdSe/CdS core/shell nano‐heterostructures in particular, have generated technological interest for applications in lighting and displays, lasers, solar concentration, photocatalysis, photodetectors, optical information storage, and biological imaging . CdSe/CdS heterostructures can be synthesized in several morphologies, including spherical core/shell, dot‐in‐rod, dot‐in‐plate, or multipod structures . Further, the electronic structure of CdSe/CdS nano‐heterostructures varies from Type I, in which the both the electron and hole localizes to the CdSe, to Type II (or quasi‐Type II), in which the hole localizes to the CdSe and the electron delocalizes through the structure .…”