A New Simple Route to ZnS Quantized Particles with Tunable Size and Shape, and Size/Shape-Dependent Optical Properties

Abstract

<p class="MsoNormal"> <span style="font-family:Verdana;">With the features of convenience and eco-friendly, the low-temperature solid-state reaction synthesis was successfully developed as a new approach to prepare quantum-sized ZnS nanocrystals. One major achievement is that the size and shape of ZnS nanocrystals can be tuned by adjusting the surfactant and its feed. The UV-Vis absorption spectra of quasispherical and one-dimensional quantum-sized ZnS nanocrystals all showed a blue-shift from the bulk counterpart, indicating large quantum confinement effects of ZnS nanocrystals. These ZnS nanocrystals all showed well-defined excitonic emission features. Contrastive studies on photo</span><span style="font-family:Verdana;">luminescence performances indicated that the bandedge emission experienced only the size-dependent quantum confinement effect, while the trap-state emission experienced the size- and shape-dependences. So we can design a purposeful synthesis route to ZnS nanocrystals with target luminescence emission performances.</span><o:p></o:p> </p> <p class="MsoNormal"> <o:p> </o:p> </p

A single source-precursor route for the one-pot synthesis of highly luminescent CdS quantum dots as ultra-sensitive and selective photoluminescence sensor for Co2+and Ni2+ions

“…The intensity of the second PL peak is substantially low, which could be due to the little amount of deep trap sulfur vacancies, or deep level traps that tend to undergo non-radiative recombination by emitting phonons. 30 Finally, because of clustering of QDs, quantum connement is lost and densely packed CdS particles would behave as bulk CdS, which may be a possible cause for considerable decrease in PL intensity of both peaks with reuxing time. 66…”

“…29 On the other hand, deep-trap states are essentially localized in space at a lattice site defect and lie in the middle of the band gap, having a tendency to undergo non-radiative recombination by emitting phonons. 30 As the crystallite size decreases, shallow traps should respond to the quantum connement process more effectively than deep trap states and shi to higher energy due to the localization of the deep-trap state electronic wave-function. 28,31 The emission occurs when a trapped electron recombines with holes in the valence band or holes in the trap state near the valence band.…”

“…28,31 The emission occurs when a trapped electron recombines with holes in the valence band or holes in the trap state near the valence band. 30 Nowadays, functionalized QDs have generated incredible interest in the sensing applications owing to their high photoluminescence (PL) quantum yield, broad absorbance spectra, and narrow size-tunable emission from visible to infrared wavelengths and high photochemical stability. 32 CdS QD-based sensing of several ions [33][34][35][36] and biomolecules [37][38][39] has been reported to date.…”

Magnetic, Phonon and Optical Properties of Transition Metal and Rare Earth Ion Doped ZnS Nanoparticles

“…Such decrease in the spontaneous magnetization for higher dopant concentrations x has also been reported in ZnO nanostructures. Hu et al [ 54 ] and Li et al [ 21 ] have observed reduction of M with raising the Cr dopants in ZnO thin films.…”

(Ga,In)P nanowires grown without intentional catalyst

“…These peaks are at E 1.85-1.65 and 1.4-1.35 eV. However, at low temperature (8 K) several small shoulders characteristic of quantum transitions are observed [34,35].…”