| Autor: |
Lin, Sheng-Jie, Cheng, Yu-Chieh, Chen, Chia-Hsun, Zhang, Yong-Yun, Lee, Jiun-Haw, Leung, Man-kit, Lin, Bo-Yen, Chiu, Tien-Lung |
| Zdroj: |
Journal of Materials Chemistry C; 1/7/2023, Vol. 11 Issue 1, p161-171, 11p |
| Abstrakt: |
Four bipolar molecules, named 1-, 2-, 3-, and 4-3cbzBIZ, composed of tricarbazole (3cbz) substituted benzimidazole, were synthesized and characterized. They not only exhibit good thermal stability with remarkably high glass transition temperatures and decomposition temperatures, especially 4-3CbzBIZ (Tg > 193 °C, Td > 453 °C), but also show superior thermal photoluminescence stability at elevated temperatures. Their morphological stabilities have also been affirmed using atomic force microscopy pictures after 30 min during 80 °C annealing. The FIrpic doped 4-3cbzBIZ organic light-emitting diode (OLED) shows sky-blue electroluminescence from FIrpic with a high external quantum efficiency (ηEQE) of 28.6% with an amazingly small efficiency roll-off (ηEQE = 27.3% at a luminance of 1000 cd m−2). Furthermore, the green OLED with Ir(ppy)3 doped in 4-3cbzBIZ exhibits excellent device thermal stability and a longer operational lifetime than the OLED with CBP as the host. In particular, a significant lifetime improvement by 11.6 times was obtained at an elevated temperature of 80 °C. The high efficiency and high-temperature stability of the OLED were ascribed to the balanced bipolar carrier-transporting properties, high Tg and rigidity of 4-3cbzBIZ. The present work of developing orthogonally linked donor–acceptor hosts provides a strategy of material design to develop high thermal stability OLEDs. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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