Evaluation of acenes as potential acceptors in thermally activated delayed fluorescence emitters and the promise of a phenoxazine–naphthalene emitter for OLEDs
Abstract
Thermally activated delayed fluorescence (TADF) is one of the most promising technologies for harvesting triplet excitons in all-organic emitters, a property that is essential for achieving high efficiency in devices. Compounds that operate via this mechanism for emission typically rely on a combination of electron donating and accepting moieties separated by an aromatic bridge. Here we demonstrate that although naphthalene is underutilised as an acceptor, it can nonetheless be used in a donor–acceptor TADF emitter when coupled to two phenoxazines in the 1- and 4-positions. The compound 1,4-PXZ-Nap-PXZ emits at 508 nm, has a photoluminescence quantum yield of 48% and a delayed lifetime of 22.7 ms in a 20 wt% doped film in 1,3-bis(N-carbazolyl)benzene (mCP). An organic light-emitting diode (OLED) using this emitter showed a maximum external quantum efficiency (EQEmax) of 11% and green emission at λEL of 505 nm, demonstrating for the first time the potential of naphthalene-acceptor based emitters for devices. Finally, we have demonstrated by way of a density functional theory (DFT) study why naphthalene alone amongst linear acenes is suitable for this role.
Citation
Lee , O S , Sharma , N , Matulaitis , T , Slawin , A M Z , Olivier , Y , Samuel , I D W , Gather , M C & Zysman-Colman , E 2024 , ' Evaluation of acenes as potential acceptors in thermally activated delayed fluorescence emitters and the promise of a phenoxazine–naphthalene emitter for OLEDs ' , Journal of Materials Chemistry C , vol. 12 , no. 12 , pp. 4273-4286 . https://doi.org/10.1039/d3tc04292h
Publication
Journal of Materials Chemistry C
Status
Peer reviewed
ISSN
2050-7526Type
Journal article
Description
Some computations were performed using resources kindly provided by the University of Mons (UMONS), supported by the Belgian National Fund for Scientific Research (FRS-FNRS). These computational resources were provided by the Consortium des Équipements de Calcul Intensif (CÉCI) funded by F. R. S.-FNRS under Grant 2.5020.11. Y. O. acknowledges funding by the Fonds de la Recherche Scientifique-FNRS under Grant no. F.4534.21 (MIS-IMAGINE).Collections
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