Emission and absorption tuning in TADF B,N-doped heptacenes: towards ideal-blue hyperfluorescent OLEDs

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)
3 Downloads (Pure)


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.
Original languageEnglish
Article number2200688
Number of pages9
JournalAdvanced Optical Materials
Issue number17
Early online date14 Jun 2022
Publication statusPublished - 5 Sept 2022


  • Hyperfluorescence
  • Multi-resonant thermally activated delayed fluorescence
  • OLEDs
  • Organic light-emitting diodes


Dive into the research topics of 'Emission and absorption tuning in TADF B,N-doped heptacenes: towards ideal-blue hyperfluorescent OLEDs'. Together they form a unique fingerprint.

Cite this