High-triplet-energy tri-carbazole derivatives as host materials for efficient solution-processed blue phosphorescent devices
作者:Wei Jiang、Lian Duan、Juan Qiao、Guifang Dong、Deqiang Zhang、Liduo Wang、Yong Qiu
DOI:10.1039/c0jm03365k
日期:——
A novel series of solution-processible carbazole-based host materials, 3,6-bis(N-carbazolyl)-N-phenylcarbazole (BCC-36), 3,6-bis(3,6-di-tert-butyl-9-carbazolyl)-N-phenylcarbazole (BTCC-36), 2,7-bis(N-carbazolyl)-N-phenylcarbazole (BCC-27), and 2,7-bis(3,6-di-tert-butyl-9-carbazolyl)-N-phenylcarbazole (BTCC-27), is designed and synthesized. Owing to the highly twisted configuration, these hosts exhibit high triplet energy levels (2.90–3.02 eV) and high glass transition temperatures (147–210 °C). They also exhibit appropriate HOMO energy levels (−5.21–−5.36 eV), resulting in an improved hole-injection property. These novel compounds are employed to fabricate phosphorescent organic lighting-emitting diodes (OLEDs) as the host materials doped with the guests of iridium(III) bis(4,6-difluorophenylpyridinato)-picolinate (FIrpic) and iridium(III) bis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) by spin coating. The best device performance of FIrpic based blue-emitting devices has a rather low turn-on voltage of 3.9 V, a maximum efficiency of 27.2 cd A−1 (11.8 lm W−1), and a maximum external quantum efficiency of 14.0%. Moreover, the best device performance of FIr6 based deep-blue-emitting devices exhibits a turn-on voltage of 4.9 V, a maximum efficiency of 11.5 cd A−1 (4.9 lm W−1), and a maximum external quantum efficiency 6.8%. The performance data are outstanding for solution-processed blue phosphorescent OLEDs.
一种新型的可溶液加工的基于咔唑的主材料,包括3,6-bis(N-carbazolyl)-N-phenylcarbazole (BCC-36)、3,6-bis(3,6-di-tert-butyl-9-carbazolyl)-N-phenylcarbazole (BTCC-36)、2,7-bis(N-carbazolyl)-N-phenylcarbazole (BCC-27)和2,7-bis(3,6-di-tert-butyl-9-carbazolyl)-N-phenylcarbazole (BTCC-27),被设计和合成。由于高度扭曲的构型,这些主材料展现出高的三重态能级(2.90–3.02 eV)和高的玻璃转变温度(147–210 °C)。它们还表现出合适的HOMO能级(−5.21–−5.36 eV),从而改善了载流子的注入特性。这些新化合物用于制造磷光有机发光二极管(OLED),作为与铱(III) bis(4,6-difluorophenylpyridinato)-picolinate(FIrpic)和铱(III) bis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate(FIr6)掺杂的主材料,通过旋涂工艺制备。基于FIrpic的蓝光发射器件的最佳性能具有较低的开启电压为3.9 V,最高效率为27.2 cd A−1(11.8 lm W−1),以及最大外量子效率为14.0%。此外,基于FIr6的深蓝光发射器件的最佳性能表现为启动电压4.9 V,最高效率为11.5 cd A−1(4.9 lm W−1),以及最大外量子效率为6.8%。这些性能数据在溶液加工的蓝色磷光OLED中表现突出。