Bipyridyl-substituted benzo[1,2,3]triazoles as a thermally stable electron transporting material for organic light-emitting devices
作者:Musubu Ichikawa、Shunji Mochizuki、Hyeon-Gu Jeon、Shuichi Hayashi、Norimasa Yokoyama、Yoshio Taniguchi
DOI:10.1039/c1jm10901d
日期:——
We developed new electron-transporting materials (ETMs) for organic light-emitting devices (OLEDs) based on benzo[1,2,3]triazole and two bipyridines. Four derivatives based on the same skeleton were synthesized with four different substituents: phenyl (BpyBTAZ-Ph), biphenyl (-BP), m-terphenyl (-mTP), and o-terphenyl (-oTP). These BpyBTAZ compounds have good thermal stabilities, and their decomposition temperatures were greater than 410 °C, which is significantly higher than that of tris(8-quinolinolato)aluminium (Alq), the conventional OLED material. BpyBTAZ compounds show preferable amorphous nature, and moreover, the glass transition temperatures (Tgs) of both BpyBTAZ-TP compounds exceed 100 °C. Furthermore, BpyBTAZ-BP exhibits no melting point and is fully amorphous. The electron affinities of the materials are as large as 3.3 eV and their electron mobility is sufficiently high. These characteristics accounted for a reduction in the operational voltage of OLEDs with BpyBTAZ compounds compared with the reference device with Alq as an ETM. Specifically, the electron mobility of all the BpyBTAZ compounds exceeds 1 × 10−4 cm2 V−1s−1 at an electric field of 1 MV cm−1. In addition, it was revealed that both BpyBTAZ-TP-based devices showed longer luminous lifetimes and smaller voltage increases during continuous operation at 50 mA cm−2, compared with the Alq reference device.
我们以苯并[1,2,3]三唑和两种联吡啶为基础,开发了用于有机发光器件(OLED)的新型电子传输材料(ETM)。基于相同的骨架,合成了四种不同取代基的衍生物:苯基(BpyBTAZ-Ph)、联苯(-BP)、间三联苯(-mTP)和邻三联苯(-oTP)。这些 BpyBTAZ 化合物具有良好的热稳定性,其分解温度高于 410 ℃,明显高于传统 OLED 材料三(8-喹啉醇)铝(Alq)的分解温度。此外,BpyBTAZ-TP 化合物的玻璃化转变温度(Tgs)均超过 100 ℃。此外,BpyBTAZ-BP 没有熔点,完全是无定形的。这些材料的电子亲和力高达 3.3 eV,电子迁移率也很高。与使用 Alq 作为 ETM 的参考器件相比,使用 BpyBTAZ 化合物的有机发光二极管的工作电压有所降低,原因就在于这些特性。具体来说,在 1 MV cm-1 的电场下,所有 BpyBTAZ 化合物的电子迁移率都超过了 1 × 10-4 cm2 V-1s-1。此外,与 Alq 参考器件相比,基于 BpyBTAZ-TP 的两种器件在 50 mA cm-2 下连续工作时,发光寿命更长,电压升高更小。