Thermally activated delayed fluorescence from {sup 3}nπ to {sup 1}nπ up-conversion and its application to organic light-emitting diodes

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 {sup 3}ππ* state than the {sup 3}nπ* one lead to a sma...

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Bibliographic Details
Published in:Applied physics letters 2014-07, Vol.105 (1)
Main Authors: Li, Jie, Zhang, Qisheng, Nomura, Hiroko, Miyazaki, Hiroshi, Functional Materials Laboratory, Nippon Steel and Sumikin Chemical Co., Ltd, 46–80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804–8503, Adachi, Chihaya, International Institute for Carbon Neutral Energy Research
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONVERSION
DOPED MATERIALS
ELECTROLUMINESCENCE
EXCITED STATES
EXCITONS
FLUORESCENCE
HETEROCYCLIC COMPOUNDS
LIGHT EMITTING DIODES
NITROGEN ADDITIONS
ORGANIC SEMICONDUCTORS
PHOTOLUMINESCENCE
QUANTUM EFFICIENCY
TOLUENE
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Summary: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 {sup 3}ππ* state than the {sup 3}nπ* one lead to a small energy difference between the lowest singlet (S{sub 1}) and triplet (T{sub 1}) 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 T{sub 1} → S{sub 1} pathway in the electroluminescent process.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4887346