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Carrier Induced Hopping to Band Conduction in Pentacene
Charge transport in organic thin films which are generally polycrystalline is typically limited by the localization of the carriers at lattice defects resulting in low carrier mobilities and carriers move from one state to another state by hopping. However, charge transport in organic semiconductors...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934786/ https://www.ncbi.nlm.nih.gov/pubmed/31882781 http://dx.doi.org/10.1038/s41598-019-56558-w |
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author | Rani, Varsha Kumar, Pramod Sharma, Akanksha Yadav, Sarita Singh, Budhi Ray, Nirat Ghosh, Subhasis |
author_facet | Rani, Varsha Kumar, Pramod Sharma, Akanksha Yadav, Sarita Singh, Budhi Ray, Nirat Ghosh, Subhasis |
author_sort | Rani, Varsha |
collection | PubMed |
description | Charge transport in organic thin films which are generally polycrystalline is typically limited by the localization of the carriers at lattice defects resulting in low carrier mobilities and carriers move from one state to another state by hopping. However, charge transport in organic semiconductors in their single crystalline phase is coherent due to band conduction and mobilities are not limited by disorder resulting in higher carrier mobility. So it is a challenge to enhance the carrier mobility in a thin film which is the preferred choice for all organic devices. Here, we show that it is possible to increase the carrier mobility in polycrystalline thin films by injecting sufficient carriers such that Fermi level can be moved into the region of high density in Gaussian density of states of molecular solids. When the hopping transport happens through the molecular energy levels whose density is low, mobility is decided by incoherent transport however, when the the hopping transport happens through the energy levels with high density, mobility is decided by coherent transport, as in band conduction. We present results highlighting the observation of both band-like and hopping conduction in polycrystalline organic thin films by varying the concentration of injected charge. More importantly the transition from hopping to band transport is reversible. The observed carrier mobilities in both the regimes match well with theoretical estimates of hopping mobility and band mobility determined from first principles density functional theory. |
format | Online Article Text |
id | pubmed-6934786 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-69347862019-12-31 Carrier Induced Hopping to Band Conduction in Pentacene Rani, Varsha Kumar, Pramod Sharma, Akanksha Yadav, Sarita Singh, Budhi Ray, Nirat Ghosh, Subhasis Sci Rep Article Charge transport in organic thin films which are generally polycrystalline is typically limited by the localization of the carriers at lattice defects resulting in low carrier mobilities and carriers move from one state to another state by hopping. However, charge transport in organic semiconductors in their single crystalline phase is coherent due to band conduction and mobilities are not limited by disorder resulting in higher carrier mobility. So it is a challenge to enhance the carrier mobility in a thin film which is the preferred choice for all organic devices. Here, we show that it is possible to increase the carrier mobility in polycrystalline thin films by injecting sufficient carriers such that Fermi level can be moved into the region of high density in Gaussian density of states of molecular solids. When the hopping transport happens through the molecular energy levels whose density is low, mobility is decided by incoherent transport however, when the the hopping transport happens through the energy levels with high density, mobility is decided by coherent transport, as in band conduction. We present results highlighting the observation of both band-like and hopping conduction in polycrystalline organic thin films by varying the concentration of injected charge. More importantly the transition from hopping to band transport is reversible. The observed carrier mobilities in both the regimes match well with theoretical estimates of hopping mobility and band mobility determined from first principles density functional theory. Nature Publishing Group UK 2019-12-27 /pmc/articles/PMC6934786/ /pubmed/31882781 http://dx.doi.org/10.1038/s41598-019-56558-w Text en © The Author(s) 2019 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 Rani, Varsha Kumar, Pramod Sharma, Akanksha Yadav, Sarita Singh, Budhi Ray, Nirat Ghosh, Subhasis Carrier Induced Hopping to Band Conduction in Pentacene |
title | Carrier Induced Hopping to Band Conduction in Pentacene |
title_full | Carrier Induced Hopping to Band Conduction in Pentacene |
title_fullStr | Carrier Induced Hopping to Band Conduction in Pentacene |
title_full_unstemmed | Carrier Induced Hopping to Band Conduction in Pentacene |
title_short | Carrier Induced Hopping to Band Conduction in Pentacene |
title_sort | carrier induced hopping to band conduction in pentacene |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934786/ https://www.ncbi.nlm.nih.gov/pubmed/31882781 http://dx.doi.org/10.1038/s41598-019-56558-w |
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