Indolo[3,2-b]carbazole/benzimidazole hybrid bipolar host materials for highly efficient red, yellow, and green phosphorescent organic light emitting diodes
作者:Hao-Chun Ting、You-Ming Chen、Hong-Wei You、Wen-Yi Hung、Sheng-Hsun Lin、Atul Chaskar、Shu-Hua Chou、Yun Chi、Rai-Hsung Liu、Ken-Tsung Wong
DOI:10.1039/c2jm30207a
日期:——
By incorporating electron-accepting benzimidazole and electron-donating indolo[3,2-b]carbazole into one molecule, two novel donor–acceptor bipolar host materials, TICCBI and TICNBI, have been synthesized. The photophysical and electrochemical properties of the hybrids can be tuned through the different linkages (C- or N-connectivity) between the electronic donor and acceptor components. The promising physical properties of these two new compounds made them suitable for use as hosts doped with various Ir or Os-based phosphors for realizing highly efficient phosphorescent organic light emitting diodes (PhOLEDs). PhOLEDs using TICCBI and TICNBI as hosts incorporated with Ir-based emitters such as green (PPy)2Ir(acac), yellow (Bt)2Ir(acac), and two new red emitters (35dmPh-6Fiq)2Ir(acac) (i3) and (4tBuPh-6Fiq)2Ir(acac) (i6) accomplished high external quantum efficiencies ranging from 14 to 16.2%. Nevertheless, the red PhOLED device incorporating TICNBI doped with the red emitter osmium(II) bis[3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolate]dimethylphenylphosphine [Os(bpftz)2(PPhMe2)2] achieved a maximum external quantum efficiency, current efficiency, and power efficiency of 22%, 28 cd A−1, and 22.1 lm W−1, respectively, with CIE coordinates of (0.65,0.35). The external quantum efficiency remained high (20%) as the brightness reached to 1000 cd m−2, suggesting balanced charge fluxes within the emitting layer, rendering devices with limited efficiency roll-off.
通过将电子受体苯并咪唑和电子供体吲哚并[3,2-b]咔唑结合到一个分子中,合成了两种新型供体-受体双极宿主材料--TICCBI 和 TICNBI。通过电子供体和受体成分之间的不同连接(C-或 N-连接),可以调整混合体的光物理和电化学特性。这两种新化合物具有良好的物理性质,适合用作掺杂各种基于 Ir 或 Os 的荧光粉的宿主,以实现高效磷光有机发光二极管(PhOLED)。以 TICCBI 和 TICNBI 为宿主,掺入了基于 Ir 的发光体(如绿色 (PPy)2Ir(acac)、黄色 (Bt)2Ir(acac),以及两种新型红色发光体 (35dmPh-6Fiq)2Ir(acac) (i3) 和 (4tBuPh-6Fiq)2Ir(acac) (i6))的 PhOLED 实现了 14% 至 16.2% 的高外部量子效率。然而,掺杂了红色发光体锇(II)双[3-(三氟甲基)-5-(4-叔丁基吡啶基)-1,2,4-三唑醇]二甲基苯基膦[Os(bpftz)2(PPhMe2)2]的 TICNBI 红色 PhOLED 器件的外部量子效率、电流效率和功率效率分别达到了 22%、28 cd A-1 和 22.1 lm W-1,CIE 坐标为 (0.65,0.35)。当亮度达到 1000 cd m-2 时,外部量子效率仍然很高(20%),这表明发光层内的电荷通量是平衡的,因此器件的效率衰减有限。