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Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy
Confirmation of direct photogeneration of intrinsic delocalized free carriers in small-molecule organic semiconductors has been a long-sought but unsolved issue, which is of fundamental significance to its application in photo-electric devices. Although the excitonic description of photoexcitation i...
Autores principales: | , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661463/ https://www.ncbi.nlm.nih.gov/pubmed/26611323 http://dx.doi.org/10.1038/srep17076 |
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author | He, Xiaochuan Zhu, Gangbei Yang, Jianbing Chang, Hao Meng, Qingyu Zhao, Hongwu Zhou, Xin Yue, Shuai Wang, Zhuan Shi, Jinan Gu, Lin Yan, Donghang Weng, Yuxiang |
author_facet | He, Xiaochuan Zhu, Gangbei Yang, Jianbing Chang, Hao Meng, Qingyu Zhao, Hongwu Zhou, Xin Yue, Shuai Wang, Zhuan Shi, Jinan Gu, Lin Yan, Donghang Weng, Yuxiang |
author_sort | He, Xiaochuan |
collection | PubMed |
description | Confirmation of direct photogeneration of intrinsic delocalized free carriers in small-molecule organic semiconductors has been a long-sought but unsolved issue, which is of fundamental significance to its application in photo-electric devices. Although the excitonic description of photoexcitation in these materials has been widely accepted, this concept is challenged by recently reported phenomena. Here we report observation of direct delocalized free carrier generation upon interband photoexcitation in highly crystalline zinc phthalocyanine films prepared by the weak epitaxy growth method using ultrafast spectroscopy. Transient absorption spectra spanning the visible to mid-infrared region revealed the existence of short-lived free electrons and holes with a diffusion length estimated to cross at least 11 molecules along the π−π stacking direction that subsequently localize to form charge transfer excitons. The interband transition was evidenced by ultraviolet-visible absorption, photoluminescence and electroluminescence spectroscopy. Our results suggest that delocalized free carriers photogeneration can also be achieved in organic semiconductors when the molecules are packed properly. |
format | Online Article Text |
id | pubmed-4661463 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-46614632015-12-02 Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy He, Xiaochuan Zhu, Gangbei Yang, Jianbing Chang, Hao Meng, Qingyu Zhao, Hongwu Zhou, Xin Yue, Shuai Wang, Zhuan Shi, Jinan Gu, Lin Yan, Donghang Weng, Yuxiang Sci Rep Article Confirmation of direct photogeneration of intrinsic delocalized free carriers in small-molecule organic semiconductors has been a long-sought but unsolved issue, which is of fundamental significance to its application in photo-electric devices. Although the excitonic description of photoexcitation in these materials has been widely accepted, this concept is challenged by recently reported phenomena. Here we report observation of direct delocalized free carrier generation upon interband photoexcitation in highly crystalline zinc phthalocyanine films prepared by the weak epitaxy growth method using ultrafast spectroscopy. Transient absorption spectra spanning the visible to mid-infrared region revealed the existence of short-lived free electrons and holes with a diffusion length estimated to cross at least 11 molecules along the π−π stacking direction that subsequently localize to form charge transfer excitons. The interband transition was evidenced by ultraviolet-visible absorption, photoluminescence and electroluminescence spectroscopy. Our results suggest that delocalized free carriers photogeneration can also be achieved in organic semiconductors when the molecules are packed properly. Nature Publishing Group 2015-11-27 /pmc/articles/PMC4661463/ /pubmed/26611323 http://dx.doi.org/10.1038/srep17076 Text en Copyright © 2015, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Article He, Xiaochuan Zhu, Gangbei Yang, Jianbing Chang, Hao Meng, Qingyu Zhao, Hongwu Zhou, Xin Yue, Shuai Wang, Zhuan Shi, Jinan Gu, Lin Yan, Donghang Weng, Yuxiang Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title | Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title_full | Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title_fullStr | Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title_full_unstemmed | Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title_short | Photogenerated Intrinsic Free Carriers in Small-molecule Organic Semiconductors Visualized by Ultrafast Spectroscopy |
title_sort | photogenerated intrinsic free carriers in small-molecule organic semiconductors visualized by ultrafast spectroscopy |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661463/ https://www.ncbi.nlm.nih.gov/pubmed/26611323 http://dx.doi.org/10.1038/srep17076 |
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