Atomistic effect of laterally and vertically growth shell on physical behaviours of CdSe/CdTe type-II core/crown and core/shell nanoplatelets: tight-binding theory

Abstract Utilizing the atomistic tight-binding theory, the impact of the lateral and vertical potential confinement by the coated shell on the CdSe/CdTe core/crown and core/shell nanoplatelets (NPLs) is attained. The spatial charge separation and encapsulated shell have a noteworthy impact on the electronic structures and optical properties because of the type-II band profile. The reduced band gaps with the growing laterally and vertically passivated shell thicknesses are due to the quantum confinement phenomena. The optical band gaps adjusted across the visible light are achieved by the shell thickness change. The excitonic binding energies of CdSe/CdTe core/shell NPLs are larger than those of CdSe/CdTe core/crown NPLs. Thanks to the spatial charge separation, a shortening of the oscillation strengths is concomitant with an increase of the radiative lifetimes. Overall, this scientific research underlines the importance of the theoretical understanding and practical control by lateral and vertical confinement of heterostructure NPLs.

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Surface States in Passivated, Unpassivated and Core/Shell Nanocrystals: Electronic Structure and Optical Properties

MRS Proceedings ◽

10.1557/proc-789-n13.2 ◽

2003 ◽

Vol 789 ◽

Cited By ~ 4

Author(s):

Garnett W. Bryant ◽

W. Jaskolski

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Semiconductor Nanocrystals ◽

Tight Binding ◽

Surface States ◽

Surface Effects ◽

Atomic Scale ◽

Core Shell ◽

Binding Theory ◽

Theoretical Understanding

ABSTRACTSurface effects significantly influence the functionality of semiconductor nanocrystals. A theoretical understanding of these surface effects requires models capable of describing surface details at an atomic scale, passivation with molecular ligands, and few-monolayer capping shells. We present an atomistic tight-binding theory of the electronic structure and optical properties of passivated, unpassivated and core/shell nanocrystals to study these surface effects.

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Stokes shift and fine-structure splitting in CdSe / CdTe invert type-II and CdTe / CdSe type-II core / shell nanocrystals: Atomistic tight-binding theory

Pramana ◽

10.1007/s12043-017-1513-x ◽

2018 ◽

Vol 90 (2) ◽

Author(s):

Worasak Sukkabot

Keyword(s):

Fine Structure ◽

Stokes Shift ◽

Tight Binding ◽

Core Shell ◽

Type Ii ◽

Binding Theory ◽

Fine Structure Splitting ◽

Structure Splitting

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Atomistic Tight-Binding Theory of Electron-Hole Exchange Interaction in Morphological Evolution of CdSe/ZnS Core/Shell Nanodisk to CdSe/ZnS Core/Shell Nanorod

Journal of Nanomaterials ◽

10.1155/2016/1572641 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Worasak Sukkabot

Keyword(s):

Exchange Interaction ◽

Ground State ◽

Heavy Hole ◽

Morphological Evolution ◽

Tight Binding ◽

Core Shell ◽

Binding Theory ◽

Electron Hole ◽

Aspect Ratios ◽

The Impact

Based on the atomistic tight-binding theory (TB) and a configuration interaction (CI) description, the electron-hole exchange interaction in the morphological transformation of CdSe/ZnS core/shell nanodisk to CdSe/ZnS core/shell nanorod is described with the aim of understanding the impact of the structural shapes on the change of the electron-hole exchange interaction. Normally, the ground hole states confined in typical CdSe/ZnS core/shell nanocrystals are of heavy hole-like character. However, the atomistic tight-binding theory shows that a transition of the ground hole states from heavy hole-like to light hole-like contribution with the increasing aspect ratios of the CdSe/ZnS core/shell nanostructures is recognized. According to the change in the ground-state hole characters, the electron-hole exchange interaction is also significantly altered. To do so, optical band gaps, ground-state electron character, ground-state hole character, oscillation strengths, ground-state coulomb energies, ground-state exchange energies, and dark-bright (DB) excitonic splitting (stoke shift) are numerically demonstrated. These atomistic computations obviously show the sensitivity with the aspect ratios. Finally, the alteration in the hole character has a prominent effect on dark-bright (DB) excitonic splitting.

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Manipulation of structural and optical properties in ZnO/ZnS type-II and ZnS/ZnO inverted type-II core/shell nanocrystals: tight-binding theory

Journal of Computational Electronics ◽

10.1007/s10825-017-0985-8 ◽

2017 ◽

Vol 16 (3) ◽

pp. 756-764 ◽

Cited By ~ 1

Author(s):

Worasak Sukkabot

Keyword(s):

Optical Properties ◽

Tight Binding ◽

Core Shell ◽

Type Ii ◽

Binding Theory ◽

Structural And Optical Properties

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Atomistic effect of internal and external shell on physical behaviours of InP/GaP/ZnS core/shell/shell nanocrystals: Empirical tight-binding theory

Computational Materials Science ◽

10.1016/j.commatsci.2019.01.037 ◽

2019 ◽

Vol 161 ◽

pp. 46-52 ◽

Cited By ~ 2

Author(s):

Worasak Sukkabot

Keyword(s):

Tight Binding ◽

Core Shell ◽

Binding Theory ◽

External Shell

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Atomistic tight-binding theory in CdSe/ZnSe wurtzite core/shell nanocrystals

Computational Materials Science ◽

10.1016/j.commatsci.2014.09.046 ◽

2015 ◽

Vol 96 ◽

pp. 336-341 ◽

Cited By ~ 7

Author(s):

Worasak Sukkabot

Keyword(s):

Tight Binding ◽

Core Shell ◽

Binding Theory

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A SELF-CONSISTENT-CHARGE DENSITY-FUNCTIONAL TIGHT-BINDING THEORY BASED MOLECULAR DYNAMICS SIMULATION OF A ZWITTERIONIC GLYCINE IN AN EXPLICIT WATER ENVIRONMENT

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633613500193 ◽

2013 ◽

Vol 12 (04) ◽

pp. 1350019 ◽

Cited By ~ 3

Author(s):

Y. ZHAI ◽

Y. L. ZHAO

Keyword(s):

Molecular Dynamics ◽

Amino Acids ◽

Charge Density ◽

Density Functional ◽

Water Environment ◽

Tight Binding ◽

Water Molecules ◽

Binding Theory ◽

Self Consistent ◽

The Impact

A zwitterionic glycine (zGLY) is adopted as an example to study the impact of water environment (310 H2O molecules) on the molecular structure and energetics using a self-consistent-charge density-functional tight-binding theory based molecular dynamics (SCC-DFTB/MD) method. It is found that maximal eight hydrogen bonds could be formed simultaneously between eight water molecules and the zGLY. The ability of the COO- terminal to adsorb water molecules is stronger than the [Formula: see text] terminal with respect to hydrogen bonding with more water molecules and exhibits lower adiabatic adsorption energies. The zGLY's intramolecular hydrogen bond appeared unpredictably, without involving any proton transfer and generally helpful for enhancing the system stability. Water molecules play an important role to stabilize the zwitterionic amino acids and restrain the proton migration from the [Formula: see text] to the COO− group. Our results show that the SCC-DFTB/MD method could successfully describe geometry dynamical evolutions and energetics of biomolecules in a nanoscale simulation with the presence of a large number of water molecules. Our study not only verified the feasibility of a QM level methodology for describing the aqueous states of biochemical molecules, but also gave a clear evidence for the impact of water environment on amino acids.

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