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

Handle URI:
http://hdl.handle.net/10754/622125
Title:
The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductors
Authors:
Graham, Kenneth; Ngongang Ndjawa, Guy Olivier ( 0000-0001-7400-9540 ) ; Conron, Sarah M.; Munir, Rahim ( 0000-0002-6029-3760 ) ; Vandewal, Koen; Chen, John J.; Sweetnam, Sean; Thompson, Mark E.; Salleo, Alberto; Mcgehee, Michael D.; Amassian, Aram ( 0000-0002-5734-1194 )
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.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Graham KR, Ndjawa GON, Conron SM, Munir R, Vandewal K, et al. (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: 1601211. Available: http://dx.doi.org/10.1002/aenm.201601211.
Publisher:
Wiley-Blackwell
Journal:
Advanced Energy Materials
Issue Date:
17-Aug-2016
DOI:
10.1002/aenm.201601211
Type:
Article
ISSN:
1614-6832
Sponsors:
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.
Additional Links:
http://onlinelibrary.wiley.com/doi/10.1002/aenm.201601211/full
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorGraham, Kennethen
dc.contributor.authorNgongang Ndjawa, Guy Olivieren
dc.contributor.authorConron, Sarah M.en
dc.contributor.authorMunir, Rahimen
dc.contributor.authorVandewal, Koenen
dc.contributor.authorChen, John J.en
dc.contributor.authorSweetnam, Seanen
dc.contributor.authorThompson, Mark E.en
dc.contributor.authorSalleo, Albertoen
dc.contributor.authorMcgehee, Michael D.en
dc.contributor.authorAmassian, Aramen
dc.date.accessioned2017-01-01T13:44:45Z-
dc.date.available2017-01-01T13:44:45Z-
dc.date.issued2016-08-17en
dc.identifier.citationGraham KR, Ndjawa GON, Conron SM, Munir R, Vandewal K, et al. (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: 1601211. Available: http://dx.doi.org/10.1002/aenm.201601211.en
dc.identifier.issn1614-6832en
dc.identifier.doi10.1002/aenm.201601211en
dc.identifier.urihttp://hdl.handle.net/10754/622125-
dc.description.abstractThe 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.en
dc.description.sponsorshipK.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.en
dc.publisherWiley-Blackwellen
dc.relation.urlhttp://onlinelibrary.wiley.com/doi/10.1002/aenm.201601211/fullen
dc.subjectCharge-transfer statesen
dc.subjectIonization energiesen
dc.subjectOrganic electronicsen
dc.subjectOrganic photovoltaicsen
dc.subjectUltraviolet photoelectron spectroscopyen
dc.titleThe Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge-Transfer State Energies in Organic Semiconductorsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalAdvanced Energy Materialsen
dc.contributor.institutionDepartment of Materials Science and Engineering; Stanford University; Stanford 94305 CA USAen
dc.contributor.institutionDepartment of Chemistry; University of Kentucky; Lexington 40506 KY USAen
dc.contributor.institutionDepartment of Chemistry; University of Southern California; Los Angeles 90089 CA USAen
dc.contributor.institutionDresden Integrated Center for Applied Physics and Photonic Materials and Institute for Applied Physics; Technische Universität Dresden; George-Bähr-Str. 1 01069 Dresden Germanyen
kaust.authorGraham, Kennethen
kaust.authorNgongang Ndjawa, Guy Olivieren
kaust.authorMunir, Rahimen
kaust.authorAmassian, Aramen
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.