Oxygen-bridged boron derivatives as electron transport and thermally activated delayed fluorescence host materials for high-performance phosphorescent organic light-emitting diodes

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 11; no. 46; pp. 16288 - 16296
• Main Authors: Jeong, Sook Hee, Im, Jun Seop, Lee, Dong Ryun, Ahn, Han Jin, Kim, Jun Yun, Baek, Ji-Ho, Lee, Jun Yeob
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 30.11.2023
• Subjects: Anthracene; Boron; Carbazoles; Electron transport; Fluorescence; Organic light emitting diodes; Oxygen; Phosphorescence; Quantum efficiency; System effectiveness
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc03142j

Oxygen-bridged boron (BO) derivatives, 3,11-di(9 H -carbazol-9-yl)-5,9-dioxa-13 b -boranaphtho[3,2,1- de ]anthracene ( p -BO-2Cz ) and 2,12-di(9 H -carbazol-9-yl)-5,9-dioxa-13 b -boranaphtho[3,2,1- de ]anthracene ( m -BO-2Cz ), were successfully developed as n-type (electron transport type) hosts with thermally activated delayed fluorescence (TADF) characteristics. These hosts were created by introducing an electron-donating carbazole unit at the meta - and para -positions of the boron in the BO core for p -BO-2Cz and m -BO-2Cz , respectively. Notably, p -BO-2Cz exhibited a higher triplet energy in solid state than m -BO-2Cz , making it suitable for various device applications. In terms of device performance, p -BO-2Cz demonstrated high external quantum efficiency (EQE) of 24.0% and 28.1% in blue and green phosphorescent devices, respectively. On the other hand, m -BO-2Cz exhibited a high EQE of 26.5% only in the green phosphorescent device. These results emphasize the significance of the carbazole substitution position in the BO core, as it plays a critical role in determining the performance of phosphorescent devices. Overall, the introduction of carbazole-modified BO derivatives as electron transport and TADF-type hosts in mixed host systems was proven to be highly effective for PhOLEDs. Oxygen-bridged boron derivatives 3,11-di(9 H -carbazol-9-yl)-5,9-dioxa-13 b -boranaphtho[3,2,1- de ]anthracene and 2,12-di(9 H -carbazol-9-yl)-5,9-dioxa-13 b -boranaphtho[3,2,1- de ]anthracene were successfully developed as n-type (electron transport type) hosts with TADF characteristics.