Highly effective organic light-emitting diodes containing thermally activated delayed fluorescence emitters with horizontal molecular orientation

Chan Hee Lee; Shin Hyung Choi; Sung Joon Oh; Jun Hyeon Lee; Jae Won Shim; Chihaya Adachi; Sae Youn Lee

doi:10.1039/d0ra07865d

Highly effective organic light-emitting diodes containing thermally activated delayed fluorescence emitters with horizontal molecular orientation

RSC Adv. 2020 Nov 26;10(70):42897-42902. doi: 10.1039/d0ra07865d. eCollection 2020 Nov 23.

Authors

Chan Hee Lee¹, Shin Hyung Choi¹, Sung Joon Oh¹, Jun Hyeon Lee¹, Jae Won Shim², Chihaya Adachi^{3

4}, Sae Youn Lee¹

Affiliations

¹ Department of Energy and Materials Engineering, Dongguk University Seoul 04620 Republic of Korea saeyounlee@dongguk.edu.
² School of Electrical Engineering, Korea University Seoul 02841 South Korea.
³ Center for Organic Photonics and Electronics Research (OPERA), Kyushu University 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan.
⁴ Department of Chemistry and Biochemistry, Kyushu University 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan.

Abstract

In this study, we report new thermally activated delayed fluorescence (TADF) emitters, AcPYM (10,10'-(pyrimidine-2,5-diylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine)) and PxPYM (10,10'-(pyrimidine-2,5-diylbis(4,1-phenylene))bis(10H-phenoxazine)), by employing donor units at the 2,5-positions of the pyrimidine acceptor unit. The donor-acceptor-donor (D-A-D) units combined in the linear molecular structure of AcPYM or PxPYM enhanced the horizontally oriented alignment, and the horizontal transition dipole moments were realized by up to 87% in the host matrix. Organic light-emitting diodes (OLEDs) containing AcPYM and PxPYM emitters realized external quantum efficiencies (η _ext) of 16.8% for blue and green emissions.