Thermally activated delayed fluorescence from 3n π ∗ to 1n π∗ up-conversion and its application to organic light-emitting diodes

Jie Li, Qisheng Zhang, Hiroko Nomura, Hiroshi Miyazaki, Chihaya Adachi

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44 Citations (Scopus)


Intense nπ∗ fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the nπ∗ transition and the higher energy of the 3ππ∗ state than the 3nπ∗ one lead to a small energy difference between the lowest singlet (S1) and triplet (T1) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T1 → S1 pathway in the electroluminescent process.

Original languageEnglish
Article number013301
JournalApplied Physics Letters
Issue number1
Publication statusPublished - Jul 7 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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