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Title: The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot

Abstract

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Advanced ScientificComputing Research
OSTI Identifier:
927244
Report Number(s):
LBNL-60147
Journal ID: ISSN 0021-9991; JCTPAH; R&D Project: K1117; TRN: US200811%%66
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Computational Physics; Journal Volume: 223; Journal Issue: 2; Related Information: Journal Publication Date: 05/2007
Country of Publication:
United States
Language:
English
Subject:
99; CONVERGENCE; QUANTUM DOTS; VALENCE; VECTORS

Citation Formats

Vomel, Christof, Tomov, Stanimire Z., Wang, Lin-Wang, Marques,Osni A., and Dongarra, Jack J. The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot. United States: N. p., 2006. Web.
Vomel, Christof, Tomov, Stanimire Z., Wang, Lin-Wang, Marques,Osni A., & Dongarra, Jack J. The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot. United States.
Vomel, Christof, Tomov, Stanimire Z., Wang, Lin-Wang, Marques,Osni A., and Dongarra, Jack J. Wed . "The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot". United States. doi:. https://www.osti.gov/servlets/purl/927244.
@article{osti_927244,
title = {The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot},
author = {Vomel, Christof and Tomov, Stanimire Z. and Wang, Lin-Wang and Marques,Osni A. and Dongarra, Jack J.},
abstractNote = {We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.},
doi = {},
journal = {Journal of Computational Physics},
number = 2,
volume = 223,
place = {United States},
year = {Wed May 10 00:00:00 EDT 2006},
month = {Wed May 10 00:00:00 EDT 2006}
}
  • We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.
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  • Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the bandmore » edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. We expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.« less
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