Wen Hsin-Yi, Ho Shou-Yi
Department of Chemical and Materials Engineering, National Kaohsiung University of Science and Technology Kaohsiung 80778 Taiwan
RSC Adv. 2022 Oct 3;12(43):28128-28136. doi: 10.1039/d2ra05124a. eCollection 2022 Sep 28.
Efficient white lighting sources based on phosphorescent organic light emitting diodes (PhOLEDs) have been predicted as the next generation of highly efficient general illumination systems. This study proposed a novel host material, CzppT, featuring the characteristics of bipolarity while possessing electron-withdrawing pyridine and electron-donating carbazole groups in the hexaphenylbenzene core, suitable for use in both blue and white PhOLEDs. The CzppT possesses a high triplet energy level and thermally activated delayed fluorescence stable which is confirmed by the high value of (480 °C). The effect of the emission layer deposition method on the characteristics of the device was studied in the dicarbazole derivative fabricated in a hole and electron-only device to ensure the bipolarity of CzppT. A blue PhOLED device exhibited a maximum external quantum efficiency of 11.0% with CIE coordinates (, ) of (0.18, 0.41). Moreover, a white PhOLED device doped with a dye has a maximum external quantum efficiency of 11.3%, and CIE coordinates (, ) of (0.32, 0.36). These results demonstrate that the hexaphenylbenzene derivative was conveniently synthesized with bipolarity and hole- and electron-transporting ability and high triplet energy level. Moreover, as a host material, it is expected to be applied to bipolar, high EL efficiency OLEDs in the future.
基于磷光有机发光二极管（PhOLEDs）的高效白色光源已被预测为下一代高效通用照明系统。本研究提出了一种新型主体材料CzppT，其在六苯基苯核中具有吸电子吡啶和供电子咔唑基团，具有双极性特征，适用于蓝色和白色PhOLEDs。CzppT具有较高的三重态能级和热激活延迟荧光稳定性，这由较高的（480°C）值所证实。在空穴和仅电子器件中制备的二咔唑衍生物中研究了发射层沉积方法对器件特性的影响，以确保CzppT的双极性。蓝色PhOLED器件的最大外量子效率为11.0%，CIE坐标（，）为（0.18，0.41）。此外，掺杂染料的白色PhOLED器件的最大外量子效率为11.3%，CIE坐标（，）为（0.32，0.36）。这些结果表明，六苯基苯衍生物易于合成，具有双极性、空穴和电子传输能力以及较高的三重态能级。此外，作为主体材料，预计未来可应用于双极性、高EL效率的OLEDs。
