Characterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phases

Handle URI:
http://hdl.handle.net/10754/563791
Title:
Characterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phases
Authors:
Sweetnam, Sean; Graham, Kenneth; Ngongang Ndjawa, Guy Olivier ( 0000-0001-7400-9540 ) ; Heumüller, Thomas; Bartelt, Jonathan A.; Burke, Timothy M.; Li, Wentao; You, Wei; Amassian, Aram ( 0000-0002-5734-1194 ) ; McGehee, Michael D.
Abstract:
Theoretical and experimental studies suggest that energetic offsets between the charge transport energy levels in different morphological phases of polymer:fullerene bulk heterojunctions may improve charge separation and reduce recombination in polymer solar cells (PSCs). In this work, we use cyclic voltammetry, UV-vis absorption, and ultraviolet photoelectron spectroscopy to characterize hole energy levels in the polymer phases of polymer:fullerene bulk heterojunctions. We observe an energetic offset of up to 150 meV between amorphous and crystalline polymer due to bandgap widening associated primarily with changes in polymer conjugation length. We also observe an energetic offset of up to 350 meV associated with polymer:fullerene intermolecular interactions. The first effect has been widely observed, but the second effect is not always considered despite being larger in magnitude for some systems. These energy level shifts may play a major role in PSC performance and must be thoroughly characterized for a complete understanding of PSC function.
KAUST Department:
Materials Science and Engineering Program; Physical Sciences and Engineering (PSE) Division; Solar and Photovoltaic Engineering Research Center (SPERC); Organic Electronics and Photovoltaics Group
Publisher:
American Chemical Society (ACS)
Journal:
Journal of the American Chemical Society
Issue Date:
8-Oct-2014
DOI:
10.1021/ja505463r
Type:
Article
ISSN:
00027863
Sponsors:
This publication was based on work supported by the Center for Advanced Molecular Photovoltaics (CAMP) (award no. KUS-C1-01S-21), made possible by KAUST. S.S. acknowledges support from the National Science Foundation through the National Science Foundation Graduate Research Fellowship under grant no. DGE-114747 and support from Stanford University through a Benchmark Stanford Graduate Fellowship. 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 Office of Competitive Research Funds for a GRP-CF award. T.H. gratefully acknowledges a "DAAD Doktorantenstipendium" and the SFB 953 "Synthetic Carbon Allotropes". J.A.B. acknowledges government support by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. We thank the group of Martin Heeney for providing the pBTTT used for this study and William R. Mateker for his assistance with manuscript preparation.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorSweetnam, Seanen
dc.contributor.authorGraham, Kennethen
dc.contributor.authorNgongang Ndjawa, Guy Olivieren
dc.contributor.authorHeumüller, Thomasen
dc.contributor.authorBartelt, Jonathan A.en
dc.contributor.authorBurke, Timothy M.en
dc.contributor.authorLi, Wentaoen
dc.contributor.authorYou, Weien
dc.contributor.authorAmassian, Aramen
dc.contributor.authorMcGehee, Michael D.en
dc.date.accessioned2015-08-03T12:10:14Zen
dc.date.available2015-08-03T12:10:14Zen
dc.date.issued2014-10-08en
dc.identifier.issn00027863en
dc.identifier.doi10.1021/ja505463ren
dc.identifier.urihttp://hdl.handle.net/10754/563791en
dc.description.abstractTheoretical and experimental studies suggest that energetic offsets between the charge transport energy levels in different morphological phases of polymer:fullerene bulk heterojunctions may improve charge separation and reduce recombination in polymer solar cells (PSCs). In this work, we use cyclic voltammetry, UV-vis absorption, and ultraviolet photoelectron spectroscopy to characterize hole energy levels in the polymer phases of polymer:fullerene bulk heterojunctions. We observe an energetic offset of up to 150 meV between amorphous and crystalline polymer due to bandgap widening associated primarily with changes in polymer conjugation length. We also observe an energetic offset of up to 350 meV associated with polymer:fullerene intermolecular interactions. The first effect has been widely observed, but the second effect is not always considered despite being larger in magnitude for some systems. These energy level shifts may play a major role in PSC performance and must be thoroughly characterized for a complete understanding of PSC function.en
dc.description.sponsorshipThis publication was based on work supported by the Center for Advanced Molecular Photovoltaics (CAMP) (award no. KUS-C1-01S-21), made possible by KAUST. S.S. acknowledges support from the National Science Foundation through the National Science Foundation Graduate Research Fellowship under grant no. DGE-114747 and support from Stanford University through a Benchmark Stanford Graduate Fellowship. 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 Office of Competitive Research Funds for a GRP-CF award. T.H. gratefully acknowledges a "DAAD Doktorantenstipendium" and the SFB 953 "Synthetic Carbon Allotropes". J.A.B. acknowledges government support by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. We thank the group of Martin Heeney for providing the pBTTT used for this study and William R. Mateker for his assistance with manuscript preparation.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleCharacterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phasesen
dc.typeArticleen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentSolar and Photovoltaic Engineering Research Center (SPERC)en
dc.contributor.departmentOrganic Electronics and Photovoltaics Groupen
dc.identifier.journalJournal of the American Chemical Societyen
dc.contributor.institutionMaterials Science and Engineering Department, Stanford UniversityStanford, CA, United Statesen
dc.contributor.institutionDepartment of Chemistry, University of North Carolina at Chapel HillChapel Hill, NC, United Statesen
kaust.authorGraham, Kennethen
kaust.authorAmassian, Aramen
kaust.authorNgongang Ndjawa, Guy Olivieren
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