Azaborine as a Versatile Weak Donor for Thermally Activated Delayed Fluorescence

Sudhakar, Pagidi; Kuila, Suman; Stavrou, Kleitos; Danos, Andrew; Slawin, Alexandra M.Z.; Monkman, Andrew; Zysman-Colman, Eli

Abstract

Extensive research has been devoted to the development of thermally activated delayed fluorescence emitters, especially those showing pure-blue emission for use in lighting and fullcolor display applications. Towards that goal, herein we report a novel weak donor, 1,4-azaborine (AZB), with complementary electronic and structural properties compared to the widely used dimethylacridan (DMAC) or carbazole (Cz) donors. Coupled with a triazine acceptor, AZB-Ph- TRZ is the direct structural analogue of the high-performance and well-studied green TADF emitter DMAC-TRZ, and has a ΔEST of 0.39 eV, a photoluminescence quantum yield (FPL) of 27% and a λPL at 415 nm in 10 wt% doped mCP films. A shortened analogue AZB-TRZ possesses red-shifted emission with a reduced singlet-triplet gap (ΔEST of 0.01 eV) and fast reverse intersystem crossing (kRISC of 5 × 106 s-1) in mCP. Despite a moderate FPL of 34%, OLEDs with AZB-TRZ in mCP showed sky-blue emission with CIE1931(x,y) of (0.22,0.39) and a maximum external quantum efficiency (EQEmax) of 10.5%. Expanding the chemist’s toolkit for the design of blue donor-acceptor TADF materials will enable yet further advances in the future, as AZB is paired with a wider range of acceptor groups.

Citation

Sudhakar, P., Kuila, S., Stavrou, K., Danos, A., Slawin, A. M., Monkman, A., & Zysman-Colman, E. (2023). Azaborine as a Versatile Weak Donor for Thermally Activated Delayed Fluorescence. ACS Applied Materials and Interfaces, 15(21), 25806-25818. https://doi.org/10.1021/acsami.3c05409

• Journal Article Type: Article
• Acceptance Date: May 3, 2023
• Online Publication Date: May 18, 2023
• Publication Date: May 31, 2023
• Deposit Date: May 9, 2023
• Publicly Available Date: Jul 31, 2023
• Journal: ACS Applied Materials & Interfaces
• Print ISSN: 1944-8244
• Electronic ISSN: 1944-8252
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 21
• Pages: 25806-25818
• DOI: https://doi.org/10.1021/acsami.3c05409
• Public URL: https://durham-repository.worktribe.com/output/1173303
• Publisher URL: https://pubs.acs.org/journal/aamick