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Spontaneous exciton dissociation enables spin state interconversion in delayed fluorescence organic semiconductors.

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cam.issuedOnline2021-11-17
dc.contributor.authorGillett, Alexander J
dc.contributor.authorTonnelé, Claire
dc.contributor.authorLondi, Giacomo
dc.contributor.authorRicci, Gaetano
dc.contributor.authorCatherin, Manon
dc.contributor.authorUnson, Darcy ML
dc.contributor.authorCasanova, David
dc.contributor.authorCastet, Frédéric
dc.contributor.authorOlivier, Yoann
dc.contributor.authorChen, Weimin M
dc.contributor.authorZaborova, Elena
dc.contributor.authorEvans, Emrys W
dc.contributor.authorDrummond, Bluebell H
dc.contributor.authorConaghan, Patrick J
dc.contributor.authorCui, Lin-Song
dc.contributor.authorGreenham, Neil C
dc.contributor.authorPuttisong, Yuttapoom
dc.contributor.authorFages, Frédéric
dc.contributor.authorBeljonne, David
dc.contributor.authorFriend, Richard H
dc.contributor.orcidGillett, Alexander J [0000-0001-7572-7333]
dc.contributor.orcidTonnelé, Claire [0000-0003-0791-8239]
dc.contributor.orcidLondi, Giacomo [0000-0001-7777-9161]
dc.contributor.orcidCasanova, David [0000-0002-8893-7089]
dc.contributor.orcidCastet, Frédéric [0000-0002-6622-2402]
dc.contributor.orcidChen, Weimin M [0000-0002-6405-9509]
dc.contributor.orcidEvans, Emrys W [0000-0002-9092-3938]
dc.contributor.orcidDrummond, Bluebell H [0000-0001-5940-8631]
dc.contributor.orcidGreenham, Neil C [0000-0002-2155-2432]
dc.contributor.orcidPuttisong, Yuttapoom [0000-0002-9690-6231]
dc.contributor.orcidFages, Frédéric [0000-0003-2013-0710]
dc.contributor.orcidBeljonne, David [0000-0001-5082-9990]
dc.contributor.orcidFriend, Richard H [0000-0001-6565-6308]
dc.date.accessioned2022-01-07T16:50:50Z
dc.date.available2022-01-07T16:50:50Z
dc.date.issued2021-11-17
dc.date.updated2022-01-07T16:50:49Z
dc.description.abstractEngineering a low singlet-triplet energy gap (ΔEST) is necessary for efficient reverse intersystem crossing (rISC) in delayed fluorescence (DF) organic semiconductors but results in a small radiative rate that limits performance in LEDs. Here, we study a model DF material, BF2, that exhibits a strong optical absorption (absorption coefficient = 3.8 × 105 cm-1) and a relatively large ΔEST of 0.2 eV. In isolated BF2 molecules, intramolecular rISC is slow (delayed lifetime = 260 μs), but in aggregated films, BF2 generates intermolecular charge transfer (inter-CT) states on picosecond timescales. In contrast to the microsecond intramolecular rISC that is promoted by spin-orbit interactions in most isolated DF molecules, photoluminescence-detected magnetic resonance shows that these inter-CT states undergo rISC mediated by hyperfine interactions on a ~24 ns timescale and have an average electron-hole separation of ≥1.5 nm. Transfer back to the emissive singlet exciton then enables efficient DF and LED operation. Thus, access to these inter-CT states, which is possible even at low BF2 doping concentrations of 4 wt%, resolves the conflicting requirements of fast radiative emission and low ΔEST in organic DF emitters.
dc.identifier.doi10.17863/CAM.79833
dc.identifier.eissn2041-1723
dc.identifier.issn2041-1723
dc.identifier.otherPMC8599618
dc.identifier.other34789719
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/332387
dc.languageeng
dc.language.isoeng
dc.publisherSpringer Science and Business Media LLC
dc.publisher.urlhttp://dx.doi.org/10.1038/s41467-021-26689-8
dc.rightsAttribution 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.sourceessn: 2041-1723
dc.sourcenlmid: 101528555
dc.subjectphysics.app-ph
dc.subjectphysics.app-ph
dc.subjectcond-mat.mtrl-sci
dc.titleSpontaneous exciton dissociation enables spin state interconversion in delayed fluorescence organic semiconductors.
dc.typeArticle
dcterms.dateAccepted2021-10-14
prism.issueIdentifier1
prism.publicationNameNat Commun
prism.volume12
pubs.funder-project-idEuropean Research Council (670405)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/M005143/1)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/M01083X/1)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/L01551X/1)
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0/
rioxxterms.versionVoR
rioxxterms.versionofrecord10.1038/s41467-021-26689-8

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