The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors

Kenneth Graham; Guy Olivier Ngongang Ndjawa; Sarah M. Conron; Rahim Munir; Koen Vandewal; John J. Chen; Sean Sweetnam; Mark E. Thompson; Alberto Salleo; Michael D. Mcgehee; Aram Amassian

doi:10.1002/aenm.201601211

The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors

Kenneth Graham, Guy Olivier Ngongang Ndjawa, Sarah M. Conron, Rahim Munir, Koen Vandewal, John J. Chen, Sean Sweetnam, Mark E. Thompson, Alberto Salleo, Michael D. Mcgehee, Aram Amassian

Research output: Contribution to journal › Article › peer-review

47 Scopus citations

Abstract

The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge-transfer (CT) state energies (ECT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and ECT values are highly dependent on structural order and phase composition. In the sexithiophene:C60 system both the IEs of sexithiophene and C60 shift by over 0.4 eV while ECT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C60 system the IE of rubrene and C60 vary by ≤0.11 eV and ECT varies by ≤0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Original language	English (US)
Pages (from-to)	1601211
Journal	Advanced Energy Materials
Volume	6
Issue number	22
DOIs	https://doi.org/10.1002/aenm.201601211
State	Published - Aug 17 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: K.R.G. and G.O.N.N. contributed equally to this work. K.R.G. and A.A. acknowledge SABIC for a postdoctoral fellowship. G.O.N.N., K.R.G., M.D.M., and A.A. acknowledge the KAUST GCR for a GRP-CF award. M.D.M. and S.S. acknowledge support from the Department of the Navy, Office of Naval Research Award No. N00014-14-1-0580. J.J.C and M.E.T. acknowledge support from the National Science Foundation Award No. CBET 1511757. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.

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10.1002/aenm.201601211

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Graham, K., Ngongang Ndjawa, G. O., Conron, S. M., Munir, R., Vandewal, K., Chen, J. J., Sweetnam, S., Thompson, M. E., Salleo, A., Mcgehee, M. D., & Amassian, A. (2016). The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors. Advanced Energy Materials, 6(22), 1601211. https://doi.org/10.1002/aenm.201601211

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title = "The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors",

abstract = "The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge-transfer (CT) state energies (ECT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and ECT values are highly dependent on structural order and phase composition. In the sexithiophene:C60 system both the IEs of sexithiophene and C60 shift by over 0.4 eV while ECT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C60 system the IE of rubrene and C60 vary by ≤0.11 eV and ECT varies by ≤0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases. {\textcopyright} 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",

author = "Kenneth Graham and {Ngongang Ndjawa}, {Guy Olivier} and Conron, {Sarah M.} and Rahim Munir and Koen Vandewal and Chen, {John J.} and Sean Sweetnam and Thompson, {Mark E.} and Alberto Salleo and Mcgehee, {Michael D.} and Aram Amassian",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: K.R.G. and G.O.N.N. contributed equally to this work. K.R.G. and A.A. acknowledge SABIC for a postdoctoral fellowship. G.O.N.N., K.R.G., M.D.M., and A.A. acknowledge the KAUST GCR for a GRP-CF award. M.D.M. and S.S. acknowledge support from the Department of the Navy, Office of Naval Research Award No. N00014-14-1-0580. J.J.C and M.E.T. acknowledge support from the National Science Foundation Award No. CBET 1511757. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.",

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doi = "10.1002/aenm.201601211",

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Graham, K, Ngongang Ndjawa, GO, Conron, SM, Munir, R, Vandewal, K, Chen, JJ, Sweetnam, S, Thompson, ME, Salleo, A, Mcgehee, MD & Amassian, A 2016, 'The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors', Advanced Energy Materials, vol. 6, no. 22, pp. 1601211. https://doi.org/10.1002/aenm.201601211

The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors. / Graham, Kenneth; Ngongang Ndjawa, Guy Olivier; Conron, Sarah M. et al.
In: Advanced Energy Materials, Vol. 6, No. 22, 17.08.2016, p. 1601211.

Research output: Contribution to journal › Article › peer-review

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T1 - The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors

AU - Graham, Kenneth

AU - Ngongang Ndjawa, Guy Olivier

AU - Conron, Sarah M.

AU - Munir, Rahim

AU - Vandewal, Koen

AU - Chen, John J.

AU - Sweetnam, Sean

AU - Thompson, Mark E.

AU - Salleo, Alberto

AU - Mcgehee, Michael D.

AU - Amassian, Aram

N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: K.R.G. and G.O.N.N. contributed equally to this work. K.R.G. and A.A. acknowledge SABIC for a postdoctoral fellowship. G.O.N.N., K.R.G., M.D.M., and A.A. acknowledge the KAUST GCR for a GRP-CF award. M.D.M. and S.S. acknowledge support from the Department of the Navy, Office of Naval Research Award No. N00014-14-1-0580. J.J.C and M.E.T. acknowledge support from the National Science Foundation Award No. CBET 1511757. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.

PY - 2016/8/17

Y1 - 2016/8/17

N2 - The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge-transfer (CT) state energies (ECT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and ECT values are highly dependent on structural order and phase composition. In the sexithiophene:C60 system both the IEs of sexithiophene and C60 shift by over 0.4 eV while ECT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C60 system the IE of rubrene and C60 vary by ≤0.11 eV and ECT varies by ≤0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

AB - The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge-transfer (CT) state energies (ECT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and ECT values are highly dependent on structural order and phase composition. In the sexithiophene:C60 system both the IEs of sexithiophene and C60 shift by over 0.4 eV while ECT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C60 system the IE of rubrene and C60 vary by ≤0.11 eV and ECT varies by ≤0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

UR - http://hdl.handle.net/10754/622125

UR - http://onlinelibrary.wiley.com/doi/10.1002/aenm.201601211/full

UR - http://www.scopus.com/inward/record.url?scp=84982224378&partnerID=8YFLogxK

U2 - 10.1002/aenm.201601211

DO - 10.1002/aenm.201601211

M3 - Article

SN - 1614-6832

VL - 6

SP - 1601211

JO - Advanced Energy Materials

JF - Advanced Energy Materials

IS - 22

ER -

The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors

Abstract

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