Unique Solid-State Emission Behavior of Aromatic Difluoroboronated β-Diketones as an Emitter in Organic Light-Emitting Devices

Hisahiro Sasabe; Kanako Sasaki; Michitaka Mamiya; Yurie Suwa; Taiki Watanabe; Natsuki Onuma; Kohei Nakao; Minoru Yamaji; Junji Kido

doi:10.1002/asia.201700800

Unique Solid-State Emission Behavior of Aromatic Difluoroboronated β-Diketones as an Emitter in Organic Light-Emitting Devices

Chem Asian J. 2017 Sep 5;12(17):2299-2303. doi: 10.1002/asia.201700800. Epub 2017 Aug 3.

Authors

Hisahiro Sasabe^{1

2

3}, Kanako Sasaki³, Michitaka Mamiya⁴, Yurie Suwa⁴, Taiki Watanabe³, Natsuki Onuma³, Kohei Nakao³, Minoru Yamaji⁵, Junji Kido^{1

2

3}

Affiliations

¹ Research Center for Organic Electronics (ROEL), Japan.
² Frontier Center for Organic Materials (FROM), Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata, 992-8510, Japan.
³ Department of Organic Materials Science, Graduate School of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata, 992-8510, Japan.
⁴ Education Program of Materials and Bioscience, Graduate School of Science and Engineering, Gunma University, Kiryu, Gunma, 376-8515, Japan.
⁵ Division of Molecular Science, Graduate School of Science and Engineering, Gunma University, Kiryu, Gunma, 376-8515, Japan.

PMID: 28703482
DOI: 10.1002/asia.201700800

Abstract

Aromatic difluoroboronated β-diketone (BF₂ DK) derivatives are a widely known class of luminescent organic materials that exhibit high photoluminescent quantum efficiency and unique aggregation-dependent fluorescence behavior. However, there have been only a few reports on their use in solid-state electronic devices, such as organic light-emitting devices (OLEDs). Herein, we investigated the solid-state properties and OLED performance of a series of π-extended BF₂ DK derivatives that have previously been shown to exhibit intense fluorescence in the solution state. The BF₂ DK derivatives formed exciplexes with a carbazole derivative and exhibited thermally activated delayed fluorescence (TADF) behavior to give orange electroluminescence with a peak external quantum efficiency of 10 % that apparently exceeds the theoretical efficiency limit of conventional fluorescent OLEDs (7.5 %), assuming a light out-coupling factor of 30 %.

Keywords: aggregation; conjugation; exciplexes; luminescence; organic light-emitting diodes; thermally activated delayed fluorescence.