Graded Shells in Semiconductor Nanocrystals

Boldt, Klaus

doi:10.1515/zpch-2016-0882

Cited by 4 publications

(4 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One can clearly see that the fwhm value was not altered after the 4 ML shell growth, as compared to that of the initial core sample (the two x -axes have been shifted for superposition of the peaks). This observation suggests the preservation of the standard size deviation of the heterostructured NCs under the employed synthesis conditions, a result which is almost unattainable by means of other shell growth techniques . The data presented in Table reveals that the growth process is quite homogeneous, although for some shell compositions we can notice slight broadening of the PL spectra during c-ALD.…”

Section: Resultsmentioning

confidence: 99%

Precise Engineering of Nanocrystal Shells via Colloidal Atomic Layer Deposition

et al. 2017

View full text Add to dashboard Cite

We present a general strategy for a facile synthesis of complex multifunctional nanoscale materials via colloidal atomic layer deposition (c-ALD). The c-ALD technique is based on self-limiting half-reactions of ionic precursors on the surface of a nanocrystal (NC) occurring at room temperature. Using this technique, uniform layers of CdS and ZnS semiconductor shells were epitaxially grown on CdSe semiconductor cores with different shell combinations, leading to the precise control of the optical properties of these heterostructures. All core-shell multicomponent nanoparticles preserve narrow size distributions, phase crystallinity, and shape homogeneity of the initial NCs. Furthermore, we attempted to extend the toolbox of the c-ALD to combine materials with intrinsically different properties, such as Au/CdS core/shell structures with substantial lattice mismatch. The results presented in this work demonstrate great opportunities for creating functional materials with programmable properties for electronics and optoelectronics

show abstract

Section: Resultsmentioning

confidence: 99%

Precise Engineering of Nanocrystal Shells via Colloidal Atomic Layer Deposition

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Boldt et al observed a redshift during heating CdSe/CdS/ZnS core/ multishell QDs at 310 °C, and attributed it to the formation of CdSe/Cd x Zn 1¹x S core/graded shell structure due to interfacial alloying. 40,41 While alloying at the type I core/shell interface typically results in an increased bandgap for the core, the graded composition creates a stepless band-edge potential curve, which broadens the electron wavefunction. If this broadening effect is more pronounced than the increase in the core's bandgap, a redshift would occur.…”

Section: Discussionmentioning

confidence: 99%

Photoluminescence Redshift of AgInS<sub>2</sub> Quantum Dots by Employing Shells with Graded Composition

KROBKRONG,

UEMATSU,

TORIMOTO

et al. 2023

Electrochemistry

View full text Add to dashboard Cite

Silver indium sulfide (AIS)/gallium sulfide (Ga-S) core/shell QDs exhibit a narrow band-edge photoluminescence (PL) in the yellow color region, and shifting the PL wavelength is crucial for optical applications. In this study, we attempt to redshift the band-edge PL by incorporating indium sulfide (In-S) shells, which have a smaller bandgap than Ga-S and are expected to broaden the exciton wavefunction. When coated with In-S shells instead of Ga-S shells, a redshift of the band-edge PL was attained. However, an increase in defective PL and a reduction in PL quantum yield occurred due to carrier trapping associated with the extended wavefunction. To address these issues, we coated the AIS/In-S cores/shell QDs with Ga-S shells using recently developed procedures, resulting in spectrally narrow PL in the red region. Interestingly, compositional and structural analyses revealed a decrease in the In ratio, which typically leads to blue shift. The observed redshift, reaching up to 40 nm, is discussed in relation to the formation of shells with graded composition, which provide a broader wavefunction in the excited state compared to discrete shells.

show abstract

“…Slejko et al carried out an important study on Cd(Zn)S shell growth by colloidal atomic layer deposition (c-ALD) on CdSe nanocrystals. This technique developed by Ithurria et al results in uniform-layer-structured shells and allows the conservation of the size distribution of the NPLs, unlike other shell growth methods. , The authors followed the shell growth by measuring the UV–vis absorption and PL spectra of their CdSe core–Cd(Zn)S shell nanocrystals after the deposition of each atomic layer and could obtain important information on the structural aspects of stepwise shell formation. However, they used spherical quantum dots in their study , that are known to expose several different crystal surfaces .…”

Section: Introductionmentioning

confidence: 99%

Combined Computational and Experimental Study of CdSeS/ZnS Nanoplatelets: Structural, Vibrational, and Electronic Aspects of Core–Shell Interface Formation

et al. 2018

View full text Add to dashboard Cite

In the past few years, core−shell nanoparticles have opened new perspectives for the optoelectronic applications of semiconductor quantum dots. In particular, it has become possible to localize electrons in either part of these heterostructures. Understanding and controlling this phenomenon require a thorough characterization of the interfaces. In this study, we prepared quasi-2D CdSeS/ZnS core−shell nanoplatelets (NPLs) by colloidal atomic layer deposition. This technique allows fine control over the quantum confinement, the surfaces, and the interfaces. The layer-by-layer formation of a the ZnS shell around the CdSeS core was monitored using UV−vis absorption, XRD, and Raman spectroscopy. The measured band gaps and structural distortions were compared with results obtained from density functional theory (DFT) calculations. Modeling has also shown that 34% of the photoexcited electrons are delocalized into the ZnS shell. The herein presented combined modeling and experimental characterization strategy is of general interest since it can be applied to a large choice of layered semiconductor heterostructures in optoelectronics. The present approach paves the way for the synthesis of nanocrystals with precisely engineered properties for light-emitting diodes and solar cells.

show abstract

Graded Shells in Semiconductor Nanocrystals

Cited by 4 publications

References 55 publications

Precise Engineering of Nanocrystal Shells via Colloidal Atomic Layer Deposition

Precise Engineering of Nanocrystal Shells via Colloidal Atomic Layer Deposition

Photoluminescence Redshift of AgInS<sub>2</sub> Quantum Dots by Employing Shells with Graded Composition

Combined Computational and Experimental Study of CdSeS/ZnS Nanoplatelets: Structural, Vibrational, and Electronic Aspects of Core–Shell Interface Formation

Contact Info

Product

Resources

About