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Title: Large bipolaron density at organic semiconductor/electrode interfaces

Abstract

Bipolaron states, in which two electrons or two holes occupy a single molecule or conjugated polymer segment, are typically considered to be negligible in organic semiconductor devices due to Coulomb repulsion between the two charges. Here we use charge modulation spectroscopy to reveal a bipolaron sheet density >10 10 cm –2 at the interface between an indium tin oxide anode and the common small molecule organic semiconductor N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine. We find that the magnetocurrent response of hole-only devices correlates closely with changes in the bipolaron concentration, supporting the bipolaron model of unipolar organic magnetoresistance and suggesting that it may be more of an interface than a bulk phenomenon. These results are understood on the basis of a quantitative interface energy level alignment model, which indicates that bipolarons are generally expected to be significant near contacts in the Fermi level pinning regime and thus may be more prevalent in organic electronic devices than previously thought.

Authors:
 [1];  [2];  [3];  [4];  [1];  [3]; ORCiD logo [1]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept of Electrical Engineering
  2. Pennsylvania State Univ., University Park, PA (United States). Dept of Chemistry
  3. Dow Chemical Co., Midland, MI (United States)
  4. Pennsylvania State Univ., University Park, PA (United States). Dept of Materials Science
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1523500
Grant/Contract Number:  
SC0012365
Resource Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Dhanker, Rijul, Gray, Christopher L., Mukhopadhyay, Sukrit, Nunez, Sean, Cheng, Chiao -Yu, Sokolov, Anatoliy N., and Giebink, Noel C. Large bipolaron density at organic semiconductor/electrode interfaces. United States: N. p., 2017. Web. doi:10.1038/s41467-017-02459-3.
Dhanker, Rijul, Gray, Christopher L., Mukhopadhyay, Sukrit, Nunez, Sean, Cheng, Chiao -Yu, Sokolov, Anatoliy N., & Giebink, Noel C. Large bipolaron density at organic semiconductor/electrode interfaces. United States. doi:10.1038/s41467-017-02459-3.
Dhanker, Rijul, Gray, Christopher L., Mukhopadhyay, Sukrit, Nunez, Sean, Cheng, Chiao -Yu, Sokolov, Anatoliy N., and Giebink, Noel C. Thu . "Large bipolaron density at organic semiconductor/electrode interfaces". United States. doi:10.1038/s41467-017-02459-3. https://www.osti.gov/servlets/purl/1523500.
@article{osti_1523500,
title = {Large bipolaron density at organic semiconductor/electrode interfaces},
author = {Dhanker, Rijul and Gray, Christopher L. and Mukhopadhyay, Sukrit and Nunez, Sean and Cheng, Chiao -Yu and Sokolov, Anatoliy N. and Giebink, Noel C.},
abstractNote = {Bipolaron states, in which two electrons or two holes occupy a single molecule or conjugated polymer segment, are typically considered to be negligible in organic semiconductor devices due to Coulomb repulsion between the two charges. Here we use charge modulation spectroscopy to reveal a bipolaron sheet density >1010 cm–2 at the interface between an indium tin oxide anode and the common small molecule organic semiconductor N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine. We find that the magnetocurrent response of hole-only devices correlates closely with changes in the bipolaron concentration, supporting the bipolaron model of unipolar organic magnetoresistance and suggesting that it may be more of an interface than a bulk phenomenon. These results are understood on the basis of a quantitative interface energy level alignment model, which indicates that bipolarons are generally expected to be significant near contacts in the Fermi level pinning regime and thus may be more prevalent in organic electronic devices than previously thought.},
doi = {10.1038/s41467-017-02459-3},
journal = {Nature Communications},
number = 1,
volume = 8,
place = {United States},
year = {2017},
month = {12}
}

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Cited by: 3 works
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Works referenced in this record:

Fermi-level pinning at conjugated polymer interfaces
journal, January 2006

  • Tengstedt, Carl; Osikowicz, Wojciech; Salaneck, William R.
  • Applied Physics Letters, Vol. 88, Issue 5, Article No. 053502
  • DOI: 10.1063/1.2168515