skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

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:
Journal Article: 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},
issn = {2041-1723},
number = 1,
volume = 8,
place = {United States},
year = {2017},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 5 works
Citation information provided by
Web of Science

Figures / Tables:

Fig. 1 Fig. 1: Fig. 1 Polaron and bipolaron spectroscopy. a Absorption spectra of the TPD cation and dication in solution. The solution consists of 55 μM TPD dissolved in dichloromethane with a 0.5M tetrabutylammonium tetrafluoroborate electrolyte. Electrochemically oxidizing the initially clear solution (black line) for 1 h at 0.55 V withmore » respect to a Ag/Ag+ reference electrode causes it to turn orange due to the formation of TPD cations that absorb in the blue and near-infrared (red line). Further oxidizing the solution at 0.9 V for 2 h (blue line) causes it to turn dark green due to a new absorption band at λ = 734 nm originating from TPD dications. The cyclic voltammetry scan in the inset yields first and second oxidation potentials E$^+_{1/2}$ = 0:45 V and E$^{2+}_{1/2}$ = 0:71 V, respectively. b Absorption coefficient of a 50 nm thick film of TPD thermally co-evaporated with 10wt% MoO3. c Charge modulation difference spectra recorded for an ITO (100 nm)/TPD (250 nm)/Ag (100 nm) hole-only device pulsed at −5 V reverse bias (black data points) and 5 V forward bias (red data points) using s-polarized light incident at a 45° angle. Increasing the voltage to 6.5 V (blue data points) confirms the emergence of the bipolaron absorption band at λ ~ 780nm. d Similar data for a 200 nm thick device, demonstrating the optical interference-induced spectral shift that occurs for the polaron and bipolaron absorption bands. The solid lines in (c, d) are produced by a transfer matrix optical model based on the polaron and bipolaron lineshapes in (b) under the assumption that both species are located in a 1 nm thick layer adjacent to the ITO anode« less

Save / Share:

Works referenced in this record:

Hole transport in the organic small molecule material α-NPD: evidence for the presence of correlated disorder
journal, June 2010

  • van Mensfoort, S. L. M.; Shabro, V.; de Vries, R. J.
  • Journal of Applied Physics, Vol. 107, Issue 11
  • DOI: 10.1063/1.3407561

Tuning Ground States of Bis(triarylamine) Dications: From a Closed-Shell Singlet to a Diradicaloid with an Excited Triplet State
journal, February 2014

  • Su, Yuanting; Wang, Xingyong; Zheng, Xin
  • Angewandte Chemie International Edition, Vol. 53, Issue 11
  • DOI: 10.1002/anie.201309458

Negative capacitance caused by electron injection through interfacial states in organic light-emitting diodes
journal, April 2006

  • Bisquert, Juan; Garcia-Belmonte, Germà; Pitarch, Ángeles
  • Chemical Physics Letters, Vol. 422, Issue 1-3
  • DOI: 10.1016/j.cplett.2006.02.060

Optical detection of charge carriers in multilayer organic light-emitting diodes: Experiment and theory
journal, March 2001

  • Book, K.; Nikitenko, V. R.; Bässler, H.
  • Journal of Applied Physics, Vol. 89, Issue 5
  • DOI: 10.1063/1.1343889

Non-conventional charge transport in organic semiconductors: magnetoresistance and thermoelectricity
journal, January 2017

  • Fenwick, Oliver; Orgiu, Emanuele
  • Molecular Systems Design & Engineering, Vol. 2, Issue 1
  • DOI: 10.1039/C6ME00079G

Bipolaron Mechanism for Organic Magnetoresistance
journal, November 2007


Towards an understanding of structure–property relationships in hole-transport materials: The influence of molecular conformation on oxidation potential in poly(aryl)amines
journal, January 2005

  • Low, Paul J.; Paterson, Michael A. J.; Yufit, Dmitry S.
  • Journal of Materials Chemistry, Vol. 15, Issue 23
  • DOI: 10.1039/b417962e

Electron and hole transport in the organic small molecule α-NPD
journal, February 2017

  • Rohloff, R.; Kotadiya, N. B.; Crăciun, N. I.
  • Applied Physics Letters, Vol. 110, Issue 7
  • DOI: 10.1063/1.4976205

Charge transfer-induced horizontal orientation of organic molecules near transition metal oxide surfaces
journal, April 2013


Characterization of treated indium–tin–oxide surfaces used in electroluminescent devices
journal, August 1999

  • Mason, M. G.; Hung, L. S.; Tang, C. W.
  • Journal of Applied Physics, Vol. 86, Issue 3
  • DOI: 10.1063/1.370948

Redox States of Long Oligothiophenes: Two Polarons on a Single Chain
journal, August 1998


Isolation and Crystal Structures of Two Singlet Bis(Triarylamine) Dications with Nonquinoidal Geometries
journal, February 2006

  • Zheng, Shijun; Barlow, Stephen; Risko, Chad
  • Journal of the American Chemical Society, Vol. 128, Issue 6
  • DOI: 10.1021/ja0541534

Diffusion-Limited Current in Organic Metal-Insulator-Metal Diodes
journal, October 2013


Formation of Ohmic hole injection by inserting an ultrathin layer of molybdenum trioxide between indium tin oxide and organic hole-transporting layers
journal, December 2007

  • Matsushima, Toshinori; Kinoshita, Yoshiki; Murata, Hideyuki
  • Applied Physics Letters, Vol. 91, Issue 25
  • DOI: 10.1063/1.2825275

Kinetics of interface state-limited hole injection in α-naphthylphenylbiphenyl diamine (α-NPD) thin layers
journal, March 2009


Organic semiconductor density of states controls the energy level alignment at electrode interfaces
journal, June 2014

  • Oehzelt, Martin; Koch, Norbert; Heimel, Georg
  • Nature Communications, Vol. 5, Issue 1
  • DOI: 10.1038/ncomms5174

Plasmonic Internal Photoemission for Accurate Device In Situ Measurement of Metal-Organic Semiconductor Injection Barriers
journal, May 2014

  • Dhanker, Rijul; Chopra, Neetu; Giebink, Noel C.
  • Advanced Functional Materials, Vol. 24, Issue 30
  • DOI: 10.1002/adfm.201400344

P-type doping of organic wide band gap materials by transition metal oxides: A case-study on Molybdenum trioxide
journal, August 2009


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

Bipolaron Formation in Organic Solar Cells Observed by Pulsed Electrically Detected Magnetic Resonance
journal, October 2010


Bipolaron mechanism for bias-stress effects in polymer transistors
journal, August 2003


Energetics of metal–organic interfaces: New experiments and assessment of the field
journal, March 2009

  • Hwang, Jaehyung; Wan, Alan; Kahn, Antoine
  • Materials Science and Engineering: R: Reports, Vol. 64, Issue 1-2
  • DOI: 10.1016/j.mser.2008.12.001

Unified percolation model for bipolaron-assisted organic magnetoresistance in the unipolar transport regime
journal, August 2016


Magnetoconductance Response in Unipolar and Bipolar Organic Diodes at Ultrasmall Fields
journal, October 2010


Interface-limited injection in amorphous organic semiconductors
journal, August 2001


Integer charge transfer states in organic light-emitting diodes: Optical detection of hole carriers at the anode∣organic interface
journal, January 2011

  • Marchetti, A. P.; Sassin, K. E.; Young, R. H.
  • Journal of Applied Physics, Vol. 109, Issue 1
  • DOI: 10.1063/1.3525592

Identification of both bipolaron and electron-hole pair contributions to organic magnetoresistance in a regioregular polythiophene device
journal, September 2017


Optical spectroscopy of field-induced charge in self-organized high mobility poly(3-hexylthiophene)
journal, March 2001


Band Bending in Conjugated Polymer Layers
journal, May 2011


    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.