Biphenylvinylene quinolinol derivatives and their light‐emitting properties

• Published in: Journal of the Chinese Chemical Society (Taipei) Vol. 69; no. 8; pp. 1504 - 1518
• Main Authors: Chang, Ying‐Ju, Yang, Jye‐Shane, Chang, Yuan Jay, Chow, Tahsin J.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley‐VCH Verlag GmbH & Co. KGaA 01.08.2022; Wiley Subscription Services, Inc
• Subjects: biphenyl; bisquinoline; Electric potential; electroluminescence; Electron transport; Emission spectra; Hydroquinone; hydroxyquinoline; Light emitting diodes; Luminous intensity; OLED; Polyvinyl carbazole; PPV; Quantum efficiency; Thermal stability; Voltage; White light
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.202200165

A series of poly(p‐phenylenevinylene) (PPV) type dyes: QoBp, QoBm, QpBp, and QpBm containing biphenyl (B) and 8‐alkoxyquinoline (Q) moieties connected at either ortho (o) or para (p) position are synthesized for the application of organic light‐emitting diodes. The structure design takes the advantages of the good luminescent property of biphenylvinylene and the electron transporting nature of quinolinol. Two polymeric materials: poly‐QoBp and poly‐QoAp were also prepared, whereas the biphenyl moiety of the latter was replaced by a para‐hydroquinone (Ap) moiety. All compounds exhibited high thermal stability with Td values exceeding 300°C. A typical blue light device made with QoBp showed a turn‐on voltage of 4 V, a maximal intensity of 2.30 × 103 cd/m2 at 20 V, and a highest external quantum efficiency (EQE) of 0.43%. Devices of the polymers were made by doping into PVK. The device made with poly‐QoBp exhibited a turn‐on voltage of 9.5 V, and a maximal intensity of 360 cd/m2 at 15 V. A white light device was made successfully by the combination of the blue emission of QoBp and the red emission of 2,3‐bisindolyl‐N‐methylmaleimide. It showed a maximal intensity of 940 cd/m2 at 15 V with a highest EQE of 0.14%. A series of organic dyes containing biphenyl and 8‐alkoxyquinoline moieties connected at either ortho or para position are synthesized for the application of organic light‐emitting diodes (OLEDs). In addition to monomeric dyes, two polymeric materials are also prepared. They are used on OLEDs, which are fabricated according to five different types of configuration. A white light device is obtained successfully by the combination of the blue emission of the dye and the red emission of 2,3‐bisindolyl‐N‐methylmaleimide.