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dc.contributor.authorMatheson, Andrew B.
dc.contributor.authorRuseckas, Arvydas
dc.contributor.authorPearson, Scott J.
dc.contributor.authorSamuel, Ifor D. W.
dc.identifier.citationMatheson , A B , Ruseckas , A , Pearson , S J & Samuel , I D W 2019 , ' Hole delocalization as a driving force for charge pair dissociation in organic photovoltaics ' , Materials Horizons , vol. Advance Article .
dc.identifier.otherPURE: 257948775
dc.identifier.otherPURE UUID: b6adff55-1eb8-4e4c-83da-421d99241eab
dc.identifier.othercrossref: 10.1039/C8MH01204K
dc.identifier.otherORCID: /0000-0001-9114-3522/work/54819052
dc.identifier.otherScopus: 85065995331
dc.identifier.otherWOS: 000474145200014
dc.descriptionThis work was supported by the Engineering and Physical Sciences Research Council (grants EP/L017008/1, EP/G03673X/1 and EP/J009016/1) and the European Research Council (grant 321305). I. D. W. S. acknowledges a Royal Society Wolfson Research Merit Award.en
dc.description.abstractCharge carrier photogeneration is studied in photovoltaic blends of the conjugated polymer PTB7 with the electron acceptor PC71BM at low excitation densities using broadband transient absorption spectroscopy. In the optimized blend we observe a rise of hole polaron absorption on a 500 ps time scale which implies an increase of hole delocalization when photo-generated charge pairs dissociate into free charges. This concept is supported by the observed saturation of polaron absorption with electrochemical oxidation of polymer films, and the significant differences in transient absorption spectra observed in an inefficient blend due to bound charge transfer (CT) states. Our results suggest that hole polaron delocalization on polymer chains and entropy provide driving force for charge separation by lowering the free energy of the spatially separated charge pair. A potential barrier to the reformation of CT states appears as a result of carrier delocalization which also helps to reduce non-geminate carrier recombination.
dc.relation.ispartofMaterials Horizonsen
dc.rightsCopyright 2019 the Author(s). This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.en
dc.subjectQC Physicsen
dc.subjectTK Electrical engineering. Electronics Nuclear engineeringen
dc.subjectSDG 7 - Affordable and Clean Energyen
dc.titleHole delocalization as a driving force for charge pair dissociation in organic photovoltaicsen
dc.typeJournal articleen
dc.contributor.sponsorThe Royal Societyen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. Organic Semiconductor Centreen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. Condensed Matter Physicsen
dc.contributor.institutionUniversity of St Andrews. Centre for Biophotonicsen
dc.description.statusPeer revieweden

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