Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands

Handle URI:
http://hdl.handle.net/10754/623882
Title:
Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands
Authors:
Ndjawa, Guy O. Ngongang; Graham, Kenneth; Mollinger, Sonya; Wu, Di M.; Hanifi, David; Prasanna, Rohit; Rose, Bradley Daniel ( 0000-0002-1774-3981 ) ; Dey, Sukumar; Yu, Liyang; Bredas, Jean-Luc ( 0000-0001-7278-4471 ) ; McGehee, Michael D.; Salleo, Alberto; Amassian, Aram ( 0000-0002-5734-1194 )
Abstract:
In organic solar cells (OSCs), the energy of the charge-transfer (CT) complexes at the donor-acceptor interface, E , determines the maximum open-circuit voltage (V ). The coexistence of phases with different degrees of order in the donor or the acceptor, as in blends of semi-crystalline donors and fullerenes in bulk heterojunction layers, influences the distribution of CT states and the V enormously. Yet, the question of how structural heterogeneities alter CT states and the V is seldom addressed systematically. In this work, we combine experimental measurements of vacuum-deposited rubrene/C bilayer OSCs, with varying microstructure and texture, with density functional theory calculations to determine how relative molecular orientations and extents of structural order influence E and V . We find that varying the microstructure of rubrene gives rise to CT bands with varying energies. The CT band that originates from crystalline rubrene lies up to ≈0.4 eV lower in energy compared to the one that arises from amorphous rubrene. These low-lying CT states contribute strongly to V losses and result mainly from hole delocalization in aggregated rubrene. This work points to the importance of realizing interfacial structural control that prevents the formation of low E configurations and maximizes V .
KAUST Department:
KAUST Solar Center (KSC); Physical Sciences and Engineering (PSE) Division
Citation:
Ndjawa GON, Graham KR, Mollinger S, Wu DM, Hanifi D, et al. (2017) Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands. Advanced Energy Materials: 1601995. Available: http://dx.doi.org/10.1002/aenm.201601995.
Publisher:
Wiley-Blackwell
Journal:
Advanced Energy Materials
Issue Date:
16-Jan-2017
DOI:
10.1002/aenm.201601995
Type:
Article
ISSN:
1614-6832
Sponsors:
The Office of Competitive Research Funds at the King Abdullah University of Science and Technology supported this work in part under the CRG-3 program (A.A. and J.-L.B.). J.-L.B. acknowledges support in part from the Office of Naval Research–Global under Award No. N62909-15-1-2003. This work was also supported in part by the ONR Award Nos. N00014-14-1-0580 and N00014-16-1-2520. Portions of this work were done at the Cornell High Energy Synchrotron Source (CHESS). 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. K.R.G. and A.A. acknowledge SABIC for a postdoctoral fellowship. A.A. acknowledges SABIC for the Career Development SABIC Chair. The authors thank Dr. Detlef-M. Smilgies for help with acquisition of GIWAXS data at CHESS. CHESS was supported by the NSF & NIH/NIGMS via NSF Award No. DMR-1332208. The authors also acknowledge Dr. Sean Ryno for helpful discussions. Figure 3 was updated on January 17, 2017 to remove a formatting error. The scientific content was not changed.
Additional Links:
http://onlinelibrary.wiley.com/doi/10.1002/aenm.201601995/full
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorNdjawa, Guy O. Ngongangen
dc.contributor.authorGraham, Kennethen
dc.contributor.authorMollinger, Sonyaen
dc.contributor.authorWu, Di M.en
dc.contributor.authorHanifi, Daviden
dc.contributor.authorPrasanna, Rohiten
dc.contributor.authorRose, Bradley Danielen
dc.contributor.authorDey, Sukumaren
dc.contributor.authorYu, Liyangen
dc.contributor.authorBredas, Jean-Lucen
dc.contributor.authorMcGehee, Michael D.en
dc.contributor.authorSalleo, Albertoen
dc.contributor.authorAmassian, Aramen
dc.date.accessioned2017-05-31T11:23:11Z-
dc.date.available2017-05-31T11:23:11Z-
dc.date.issued2017-01-16en
dc.identifier.citationNdjawa GON, Graham KR, Mollinger S, Wu DM, Hanifi D, et al. (2017) Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands. Advanced Energy Materials: 1601995. Available: http://dx.doi.org/10.1002/aenm.201601995.en
dc.identifier.issn1614-6832en
dc.identifier.doi10.1002/aenm.201601995en
dc.identifier.urihttp://hdl.handle.net/10754/623882-
dc.description.abstractIn organic solar cells (OSCs), the energy of the charge-transfer (CT) complexes at the donor-acceptor interface, E , determines the maximum open-circuit voltage (V ). The coexistence of phases with different degrees of order in the donor or the acceptor, as in blends of semi-crystalline donors and fullerenes in bulk heterojunction layers, influences the distribution of CT states and the V enormously. Yet, the question of how structural heterogeneities alter CT states and the V is seldom addressed systematically. In this work, we combine experimental measurements of vacuum-deposited rubrene/C bilayer OSCs, with varying microstructure and texture, with density functional theory calculations to determine how relative molecular orientations and extents of structural order influence E and V . We find that varying the microstructure of rubrene gives rise to CT bands with varying energies. The CT band that originates from crystalline rubrene lies up to ≈0.4 eV lower in energy compared to the one that arises from amorphous rubrene. These low-lying CT states contribute strongly to V losses and result mainly from hole delocalization in aggregated rubrene. This work points to the importance of realizing interfacial structural control that prevents the formation of low E configurations and maximizes V .en
dc.description.sponsorshipThe Office of Competitive Research Funds at the King Abdullah University of Science and Technology supported this work in part under the CRG-3 program (A.A. and J.-L.B.). J.-L.B. acknowledges support in part from the Office of Naval Research–Global under Award No. N62909-15-1-2003. This work was also supported in part by the ONR Award Nos. N00014-14-1-0580 and N00014-16-1-2520. Portions of this work were done at the Cornell High Energy Synchrotron Source (CHESS). 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. K.R.G. and A.A. acknowledge SABIC for a postdoctoral fellowship. A.A. acknowledges SABIC for the Career Development SABIC Chair. The authors thank Dr. Detlef-M. Smilgies for help with acquisition of GIWAXS data at CHESS. CHESS was supported by the NSF & NIH/NIGMS via NSF Award No. DMR-1332208. The authors also acknowledge Dr. Sean Ryno for helpful discussions. Figure 3 was updated on January 17, 2017 to remove a formatting error. The scientific content was not changed.en
dc.publisherWiley-Blackwellen
dc.relation.urlhttp://onlinelibrary.wiley.com/doi/10.1002/aenm.201601995/fullen
dc.subjectCharge-transfer statesen
dc.subjectOpen-circuit voltageen
dc.subjectOrganic photovoltaicsen
dc.subjectSemicrystalline donoren
dc.subjectSmall molecule organic solar cellsen
dc.titleOpen-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bandsen
dc.typeArticleen
dc.contributor.departmentKAUST Solar Center (KSC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalAdvanced Energy Materialsen
dc.contributor.institutionDepartment of Materials Science and Engineering; Stanford University; Stanford CA 94305 USAen
dc.contributor.institutionDepartment of Chemistry; University of Kentucky; Lexington KY 40503 USAen
kaust.authorNdjawa, Guy O. Ngongangen
kaust.authorGraham, Kennethen
kaust.authorRose, Bradley Danielen
kaust.authorDey, Sukumaren
kaust.authorYu, Liyangen
kaust.authorBredas, Jean-Lucen
kaust.authorAmassian, Aramen
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