Polymer bearing ortho-substituted benzene with face-to-face stacked hole-electron-transport-pair as host for PhOLED

• Published in: Dyes and pigments Vol. 163; pp. 17 - 29
• Main Authors: Lin, Che-Tseng, Yi-Mei, Huang, Leung, Man-kit
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2019
• Subjects: Bipolar homopolymer; Phosphorescence OLED; Polymeric light emitting diodes; Thermally activated delayed fluorescence OLED; Bipolar homopolymer; Polymeric light emitting diodes; Thermally activated delayed fluorescence OLED; Phosphorescence OLED
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2018.11.038

Bipolar homopolymers PCBZOXD and PCBZTAZ have been synthesized through free radical polymerization. In these polystyrene based polymers, bipolar ortho-carbazolyl-1,3,4-oxadiazolyl and ortho-carbazolyl-1,2,4-triazolyl substituted benzenes function as the charge transporting side units. Due to their rigid structure, both polymers show good thermal stability with high glass transition temperature (Tg > 180 °C) and decomposition temperature (Td > 430 °C). The ortho-connected bipolar groups effectively interrupt their pi-conjugation, and results in higher triplet energy (ET). These materials are therefore suitable host materials for blue and green phosphorescence and thermally activated delayed fluorescence light emitting devices (PhOLED and TADF-OLED). The single layer solution-processed PhOLEDs with the configuration of ITO/PEDOT: PSS/PCBZOXD: FIrpic or Ir(ppy)3/SPPO13/Mg/Ag shows good performance, with the current efficiency of 11 cd/A for sky-blue emission, and 23.7 cd/A for green emission being recorded. When 4CzIPN, a TADF green emitter, is employed, a high current efficiency of 27.3 cd/A can be achieved. [Display omitted] •Polystyrenes bearing hole-electron transporting ortho-substituents.•Polymer hosts for phosphorescence and thermally activated delayed fluorescence PLED.•Polymers for solution processed PLED with high performance.