High-efficiency thermally activated delayed fluorescence emitters via a high horizontal dipole ratio and controlled dual emission. Issue 24 (16th June 2020)

• Record Type: Journal Article
• Authors: Lee, Youngnam; Hong, Jong-In
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 24(2020)
• Page Start: 8012
• Page End: 8017
• Publication Date: 2020-06-16
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0tc01644f
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : OLED devices based on linear rod-like TADF emitters exhibited high device efficiencies of 29.9% and 25.8% by means of high horizontal emitting dipole orientation 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-(10 H -phenoxazin-10-yl)phenyl)-1, 5-naphthyridine (NyDPO ) and 2, 6-bis(4-(10 H -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.