Issue 24, 2020

High-efficiency thermally activated delayed fluorescence emitters via a high horizontal dipole ratio and controlled dual emission

Abstract

Thermally activated delayed fluorescence (TADF) emitters containing 1,5-naphthyridine as an electron acceptor and phenoxazine and phenothiazine as electron donors, namely, 2,6-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,5-naphthyridine (NyDPO) and 2,6-bis(4-(10H-phenothiazin-10-yl)phenyl)-1,5-naphthyridine (NyDPt), were developed. Because of the linear molecular structures, NyDPO and NyDPt showed high horizontal emitting dipole ratios of 81% and 84%, respectively. Furthermore, NyDPO and NyDPt exhibited TADF characteristics with photoluminescence quantum yields (PLQYs) of 79% and 45%, respectively. In particular, NyDPt showed dual photoluminescence (PL) emission from quasi-axial and quasi-equatorial conformers. However, only quasi-equatorial emission was observed in the organic light-emitting diode (OLED) at low current density, resulting in a high device efficiency despite a low PLQY. OLED devices based on NyDPO and NyDPt exhibited high external quantum efficiencies of 29.9% and 25.8%, and maximum luminance values of 33 540 cd m−2 and 14 480 cd m−2, respectively.

Graphical abstract: High-efficiency thermally activated delayed fluorescence emitters via a high horizontal dipole ratio and controlled dual emission

Supplementary files

Article information

Article type
Communication
Submitted
01 ⵉⴱⵔ 2020
Accepted
31 ⵎⴰⵢ 2020
First published
16 ⵢⵓⵏ 2020

J. Mater. Chem. C, 2020,8, 8012-8017

High-efficiency thermally activated delayed fluorescence emitters via a high horizontal dipole ratio and controlled dual emission

Y. Lee and J. Hong, J. Mater. Chem. C, 2020, 8, 8012 DOI: 10.1039/D0TC01644F

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