Issue 12, 2024

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.

Graphical abstract: Evaluation of acenes as potential acceptors in thermally activated delayed fluorescence emitters and the promise of a phenoxazine–naphthalene emitter for OLEDs

Supplementary files

Article information

Article type
Paper
Submitted
21 Nov 2023
Accepted
16 Jan 2024
First published
18 Jan 2024
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2024,12, 4273-4286

Evaluation of acenes as potential acceptors in thermally activated delayed fluorescence emitters and the promise of a phenoxazine–naphthalene emitter for OLEDs

O. S. Lee, N. Sharma, T. Matulaitis, A. M. Z. Slawin, Y. Olivier, I. D. W. Samuel, M. C. Gather and E. Zysman-Colman, J. Mater. Chem. C, 2024, 12, 4273 DOI: 10.1039/D3TC04292H

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