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Superposition of Quantum Confinement Energy (SQCE) model for estimating shell thickness in core-shell quantum dots: Validation and comparison

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Title Superposition of Quantum Confinement Energy (SQCE) model for estimating shell thickness in core-shell quantum dots: Validation and comparison
 
Creator SARAN, AD
MEHRA, A
BELLARE, JR
 
Subject Quantum confinement
Core-shell quantum dot
Microemulsion
Shell thickness
CdSe-CdS
CdSe-ZnS
Fluorescence quantum yield
CADMIUM SELENIDE NANOCRYSTALS
SMALL-ANGLE SCATTERING
LIGHT-EMITTING-DIODES
SEMICONDUCTOR NANOCRYSTALS
CORE/SHELL NANOCRYSTALS
CDTE NANOCRYSTALS
CDSE NANOCRYSTALS
ZNS SHELL
NANOPARTICLES
MICROEMULSION
 
Description A novel theoretical model based on superposition of core and shell band-gaps, termed as SQCE model, is developed and reported here, which enables one to estimate the shell thickness in a core-shell quantum dot (QD), which is critically important in deciding its optical and electronic properties. We apply the model to two experimental core-shell QD systems, CdSe-CdS and CdSe-ZnS, which we synthesize by microemulsion method. We synthesize and study two series of samples, R and S to study the optical properties. The core size is varied in the R-series (by varying water-to-surfactant ratio, R) whereas the shell thickness is varied in the S-series (by varying the shell-to-core precursor molar ratio, 5). The core and core-shell QDs from R-series and S-series are characterized for particle size, shape and crystallographic information. The shell thickness for all core-shell QD samples is estimated by SQCE model, and experimentally measured with TEM and SAXS. A close match is observed between experimental values and model predictions, thus validating the model. Further, the optimum shell thickness (corresponding to maximum quantum yield) values for CdS and ZnS over a 4.26 nm CdSe core have been estimated as 0.585 nm and 0.689 nm, respectively, from the SQCE model. The SQCE model developed in this work is applicable to other core-shell quantum dots also, such as CdTe-CdS, CdTe-CdSe and CdS-ZnS, and will serve as a useful complement to experimental measurement. (C) 2012 Published by Elsevier
 
Publisher ACADEMIC PRESS INC ELSEVIER SCIENCE
 
Date 2014-10-15T10:28:31Z
2014-10-15T10:28:31Z
2012
 
Type Article
 
Identifier JOURNAL OF COLLOID AND INTERFACE SCIENCE, 37821-29
http://dx.doi.org/10.1016/j.jcis.2012.03.056
http://dspace.library.iitb.ac.in/jspui/handle/100/14746
 
Language en