基于咪唑并吡啶的双极性绿色磷光主体材料合成及其性能

Synthesis and Performance of Bipolar Green Phosphorescent Host Material Based on Imidazopyridine

高效的磷光有机电致发光器件有赖于主体材料,而双极性主体材料相对于传统主体材料不仅能降低驱动电压,提高电流效率和功率效率,还能加快载流子迁移率和平衡载流子的通量。因此本文基于咪唑并吡啶设计了两种给体-受体型双极性绿光主体材料,即9-苯基-3-(9-(4-(3-苯基咪唑并[1,2-a]吡啶-2-基)苯基)二苯并[b,d]呋喃-2-基)-9H-咔唑(CzDFDp)和9-苯基-3-(3-(9-(4-(3-苯基咪唑并[1,2-a]吡啶-2-基)苯基)二苯并[b,d]呋喃-2-基)苯基)-9H-咔唑(CzPDFDp),对其结构进行核磁表征。通过光物理研究表明CzDFDp和CzPDFDp具有较高的三线态能级2.8 eV和2.49 eV,和较高的分解(509℃和529℃)与玻璃转化(130℃和138℃)温度,十分有利于磷光器件效率和器件的热稳定提升。以CzDFDp或CzPDFDp为主体、三(4-甲基-2,5-二苯基吡啶)合铱(GD-Ir)为发光掺杂材料制作绿光器件,启亮电压只有2.6 V,最大电流效率分别达到44.9 cd·A^(-1)和47.2 cd·A^(-1),最大功率效率达到50.4 lm·W^(-1)和57 lm·W^(-1),远优于CBP为主体材料参比的器件(3.6 V,14.4 cd·A^(-1),5.8 lm·W^(-1)),两个主体材料的启亮电压降低了1 V,电流效率提高3倍以上,且功率效率提高了8倍以上,表明本文两个双极性主体材料具有良好的传输性质,能够有效地平衡载流子通量,是优异的绿光主体材料。

High-performance phosphorescent organic electroluminescent devices rely on host materials.Compared with normal host materials,bipolar host materials can not only reduce driving voltage,improve current efficiency and power efficiency,but also accelerate carrier mobility and balance current carriers.Therefore,in this paper,two donor-acceptor type bipolar green host materials named 9-phenyl-3-(9-(4-(3-Phenylimidazo[1,2-a]pyridin-2-yl)phenyl)dibenzo[b,d]furan-2-yl)-9H-carbazole(CzDFDp)and 9-Phenyl-3-(3-(9-(4-(3-phenylimidazo[1,2-a]pyridin-2-yl)phenyl)dibenzo[b,d]furan-2-Phenyl)-9H-carbazole(CzPDFDp)were developed by using 9-phenylcarbazole and dibenzofuran as the electron donor units,respectively,and imidazopyridine as the electron acceptor group.Their structures were characterized by HNMR.Photophysical studies show that CzDFDp and CzPDFDp have higher triplet states energy levels of 2.8 eV and 2.49 eV,the decomposition temperatures(T_(d),decomposition temperature at 5%loss)are 509℃and 529℃,and the glass transition temperatures(T_(g))are 130℃ and 138℃,respectively,indicating that it has good thermal stability and morphological stability,which is conducive to device evaporation and film formation.Therefore,GD-Ir-based doped devices using CzDFDp and CzPDFDp as host matrix exhibit low driving voltage(V_(on),1 cd·m-2)of only 2.6 V,the maximum current efficiency of 44.9 cd·A^(-1) and 47.2 cd·A^(-1),and the maximum power efficiency of 50.4 lm·W^(-1) and 57 lm·W^(-1).Compared to device using the conventional host CBP(3.6 V,14.4 cd·A^(-1),5.8 lm·W^(-1)),these two host materials-based devices show 1 V lower in the driving voltage,the current efficiency is increased by more than 3 times,and the power efficiency is increased by more than 8 times,indicating that these two novel bipolar host materials have good transmission properties and can effectively balance carriers,and are excellent green host materials.