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

Abstract 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-insul...

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Autores principales:	Luman Qu, Márton Vörös, Gergely T. Zimanyi
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/4e12e36045644e08bcc5e55413c56e12
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spelling	oai:doaj.org-article:4e12e36045644e08bcc5e55413c56e122021-12-02T12:32:57ZMetal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations10.1038/s41598-017-06497-12045-2322https://doaj.org/article/4e12e36045644e08bcc5e55413c56e122017-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-06497-1https://doaj.org/toc/2045-2322Abstract 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.Luman QuMárton VörösGergely T. ZimanyiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-10 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Luman Qu Márton Vörös Gergely T. Zimanyi Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations
description	Abstract 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.
format	article
author	Luman Qu Márton Vörös Gergely T. Zimanyi
author_facet	Luman Qu Márton Vörös Gergely T. Zimanyi
author_sort	Luman Qu
title	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_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_sort	metal-insulator transition in nanoparticle solids: insights from kinetic monte carlo simulations
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/4e12e36045644e08bcc5e55413c56e12
work_keys_str_mv	AT lumanqu metalinsulatortransitioninnanoparticlesolidsinsightsfromkineticmontecarlosimulations AT martonvoros metalinsulatortransitioninnanoparticlesolidsinsightsfromkineticmontecarlosimulations AT gergelytzimanyi metalinsulatortransitioninnanoparticlesolidsinsightsfromkineticmontecarlosimulations
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Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations

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