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Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations

Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator tran...

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Autores principales: Qu, Luman, Vörös, Márton, Zimanyi, Gergely T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5539282/
https://www.ncbi.nlm.nih.gov/pubmed/28765599
http://dx.doi.org/10.1038/s41598-017-06497-1
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author Qu, Luman
Vörös, Márton
Zimanyi, Gergely T.
author_facet Qu, Luman
Vörös, Márton
Zimanyi, Gergely T.
author_sort Qu, Luman
collection PubMed
description Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator transition (MIT). To simulate MIT in NP films, we developed a hierarchical Kinetic Monte Carlo transport model. Electrons transfer between neighboring NPs via activated hopping when the NP energies differ by more than an overlap energy, but transfer by a non-activated quantum delocalization, if the NP energies are closer than the overlap energy. As the overlap energy increases, emerging percolating clusters support a metallic transport across the entire film. We simulated the evolution of the temperature-dependent electron mobility. We analyzed our data in terms of two candidate models of the MIT: (a) as a Quantum Critical Transition, signaled by an effective gap going to zero; and (b) as a Quantum Percolation Transition, where a sample-spanning metallic percolation path is formed as the fraction of the hopping bonds in the transport paths is going to zero. We found that the Quantum Percolation Transition theory provides a better description of the MIT. We also observed an anomalously low gap region next to the MIT. We discuss the relevance of our results in the light of recent experimental measurements.
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spelling pubmed-55392822017-08-07 Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations Qu, Luman Vörös, Márton Zimanyi, Gergely T. Sci Rep Article Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator transition (MIT). To simulate MIT in NP films, we developed a hierarchical Kinetic Monte Carlo transport model. Electrons transfer between neighboring NPs via activated hopping when the NP energies differ by more than an overlap energy, but transfer by a non-activated quantum delocalization, if the NP energies are closer than the overlap energy. As the overlap energy increases, emerging percolating clusters support a metallic transport across the entire film. We simulated the evolution of the temperature-dependent electron mobility. We analyzed our data in terms of two candidate models of the MIT: (a) as a Quantum Critical Transition, signaled by an effective gap going to zero; and (b) as a Quantum Percolation Transition, where a sample-spanning metallic percolation path is formed as the fraction of the hopping bonds in the transport paths is going to zero. We found that the Quantum Percolation Transition theory provides a better description of the MIT. We also observed an anomalously low gap region next to the MIT. We discuss the relevance of our results in the light of recent experimental measurements. Nature Publishing Group UK 2017-08-01 /pmc/articles/PMC5539282/ /pubmed/28765599 http://dx.doi.org/10.1038/s41598-017-06497-1 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Qu, Luman
Vörös, Márton
Zimanyi, Gergely T.
Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title_full Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title_fullStr Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title_full_unstemmed Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title_short Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
title_sort metal-insulator transition in nanoparticle solids: insights from kinetic monte carlo simulations
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5539282/
https://www.ncbi.nlm.nih.gov/pubmed/28765599
http://dx.doi.org/10.1038/s41598-017-06497-1
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