Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs

Stavrou, Kleitos; Madayanad Suresh, Subeesh; Hall, David; Danos, Andrew; Kukhta, Nadzeya A.; Slawin, Alexandra M.Z.; Warriner, Stuart; Beljonne, David; Olivier, Yoann; Monkman, Andrew; Zysman‐Colman, Eli

Abstract

Developing high-efficiency purely organic blue organic light-emitting diodes (OLEDs) that meet the stringent industry standards is a major current research challenge. Hyperfluorescent device approaches achieve in large measure the desired high performance by combining the advantages of a high-efficiency thermally activated delayed fluorescence (TADF) assistant dopant with a narrowband deep-blue multi-resonant TADF (MR-TADF) terminal emitter. However, this approach requires suitable spectral overlap to support Förster resonance energy transfer (FRET) between the two. Here, a color tuning of a recently reported MR-TADF B,N-heptacene core through control of the boron substituents is demonstrated. While there is little impact on the intrinsic TADF properties—as both singlet and triplet energies decrease in tandem—this approach improves the emission color coordinate as well as the spectral overlap for blue hyperfluorescence OLEDs (HF OLEDs). Crucially, the red-shifted and more intense absorption allows the new MR-TADF emitter to pair with a high-performance TADF assistant dopant and achieve maximum external quantum efficiency (EQEmax) of 15% at color coordinates of (0.15 and 0.10). The efficiency values recorded for the device at a practical luminance of 100 cd m–2 are among the highest reported for HF TADF OLEDs with CIEy ≤ 0.1.

Citation

Stavrou, K., Madayanad Suresh, S., Hall, D., Danos, A., Kukhta, N. A., Slawin, A. M., …Zysman‐Colman, E. (2022). Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs. Advanced Optical Materials, 10(17), Article 2200688. https://doi.org/10.1002/adom.202200688

• Journal Article Type: Article
• Online Publication Date: Jun 14, 2022
• Publication Date: Sep 5, 2022
• Deposit Date: Jun 29, 2022
• Publicly Available Date: Feb 3, 2023
• Journal: Advanced Optical Materials
• Electronic ISSN: 2195-1071
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 17
• Article Number: 2200688
• DOI: https://doi.org/10.1002/adom.202200688
• Public URL: https://durham-repository.worktribe.com/output/1200959