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dc.contributor.authorHall, David
dc.contributor.authorSancho-García, Juan Carlos
dc.contributor.authorPershin, Anton
dc.contributor.authorRicci, Gaetano
dc.contributor.authorBeljonne, David
dc.contributor.authorZysman-Colman, Eli
dc.contributor.authorOlivier, Yoann
dc.identifier.citationHall , D , Sancho-García , J C , Pershin , A , Ricci , G , Beljonne , D , Zysman-Colman , E & Olivier , Y 2022 , ' Modeling of multiresonant thermally activated delayed fluorescence emitters─properly accounting for electron correlation is key! ' , Journal of Chemical Theory and Computation , vol. Articles ASAP .
dc.identifier.otherPURE: 280190603
dc.identifier.otherPURE UUID: 9382910f-9265-4775-aee9-63e8eb74c1eb
dc.identifier.otherRIS: urn:F3262EDEF3F00E50885C93253BBC636B
dc.identifier.otherRIS: urn:F3262EDEF3F00E50885C93253BBC636B
dc.identifier.otherORCID: /0000-0001-7183-6022/work/115631230
dc.identifier.otherScopus: 85134366084
dc.identifier.otherWOS: 000841159500001
dc.descriptionThe St Andrews team would like to thank the Leverhulme Trust (RPG-2016-047) for financial support. E. Z.-C. is a Royal Society Leverhulme Trust Senior Research fellow (SRF\R1\201089). Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F.R.S.-FNRS) under Grant No. 2.5020.11, as well as the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles, infrastructure funded by the Walloon Region under the grant agreement n1117545. G.R. acknowledges a grant from the “Fonds pour la formation à la Recherche dans l’Industrie et dans l’Agriculture” (F.R.I.A.) of the F.R.S.-F.N.R.S. Y.O. acknowledges funding by the Fonds de la Recherche Scientifique-FNRS under Grant n° F.4534.21 (MIS-IMAGINE). D.B. is a FNRS Research Director. J.C.S.G. acknowledges “Ministerio de Ciecia e Innovación” of Spain (PID2019-106114GB-I00).en
dc.description.abstractWith the surge of interest in multiresonant thermally activated delayed fluorescent (MR-TADF) materials, it is important that there exist computational methods to accurately model their excited states. Here, building on our previous work, we demonstrate how the spin-component scaling second-order approximate coupled-cluster (SCS-CC2), a wavefunction-based method, is robust at predicting the ΔEST (i.e., the energy difference between the lowest singlet S1 and triplet T1 excited states) of a large number of MR-TADF materials, with a mean average deviation (MAD) of 0.04 eV compared to experimental data. Time-dependent density functional theory calculations with the most common DFT functionals as well as the consideration of the Tamm-Dancoff approximation (TDA) consistently predict a much larger ΔEST as a result of a poorer account of Coulomb correlation as compared to SCS-CC2. Very interestingly, the use of a metric to assess the importance of higher order excitations in the SCS-CC2 wavefunctions shows that Coulomb correlation effects are substantially larger in the lowest singlet compared to the corresponding triplet and need to be accounted for a balanced description of the relevant electronic excited states. This is further highlighted with coupled cluster singles-only calculations, which predict very different S1 energies as compared to SCS-CC2 while T1 energies remain similar, leading to very large ΔEST, in complete disagreement with the experiments. We compared our SCS-CC2/cc-pVDZ with other wavefunction approaches, namely, CC2/cc-pVDZ and SOS-CC2/cc-pVDZ leading to similar performances. Using SCS-CC2, we investigate the excited-state properties of MR-TADF emitters showcasing large ΔET2T1 for the majority of emitters, while π-electron extension emerges as the best strategy to minimize ΔEST. We also employed SCS-CC2 to evaluate donor–acceptor systems that contain a MR-TADF moiety acting as the acceptor and show that the broad emission observed for some of these compounds arises from the solvent-promoted stabilization of a higher-lying charge-transfer singlet state (S2). This work highlights the importance of using wavefunction methods in relation to MR-TADF emitter design and associated photophysics.
dc.relation.ispartofJournal of Chemical Theory and Computationen
dc.rightsCopyright © 2022 American Chemical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at
dc.subjectQD Chemistryen
dc.titleModeling of multiresonant thermally activated delayed fluorescence emitters─properly accounting for electron correlation is key!en
dc.typeJournal articleen
dc.contributor.sponsorThe Royal Societyen
dc.contributor.sponsorThe Leverhulme Trusten
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. Centre for Energy Ethicsen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.description.statusPeer revieweden

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