New 2,5-diaryl-1,3,4-oxadiazole–fluorene hybrids as electron transporting materials for blended-layer organic light emitting diodes
作者:Stephen Oyston、Changsheng Wang、Gregory Hughes、Andrei S. Batsanov、Igor F. Perepichka、Martin R. Bryce、Jin H. Ahn、Christopher Pearson、Michael C. Petty
DOI:10.1039/b413066a
日期:——
We describe the synthesis of 2,5-diaryl-1,3,4-oxadiazoleâfluorene hybrid molecules, e.g. 2,7-bis[2-(4-tert-butylphenyl-1,3,4-oxadiazol-5-yl]-9,9-dihexylfluorene 6, 2,7-bis4-[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]phenyl}-9,9-dihexylfluorene 10, 2,7-bis4-[2-(4-dodecyloxyphenyl)-1,3,4-oxadiazol-5-yl]phenyl}-9,9-dihexylfluorene 11, 2,7-bis4-[2-(4-dodecyloxyphenyl)-1,3,4-oxadiazol-5-yl]phenyl}-spirobifluorene 13 and analogue 16, comprising the 9,9-dihexylfluorene or spirobifluorene core units to which are attached aryl- or diaryl-oxadiazole units to provide linearly extended Ï-conjugated systems. The X-ray crystal structure is reported for compound 11. We have fabricated single-layer organic light-emitting diodes (OLEDs) using blends of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) as the emissive material with the electron transport (ET) compounds 6, 10, 11, 13 and 16 added to enhance electron injection. For all the devices studied electroluminescence originates exclusively from the MEH-PPV material. The external quantum efficiencies of the devices increased with increasing concentration of the ET compound up to 95% by weight, and are greatly enhanced (>two orders of magnitude) compared to pure MEH-PPV reference devices. Further improvements have been achieved by adding a layer of PEDOT : PSS and efficiencies reach ca. 0.4% at 30 mA cmâ2 for devices in the configuration ITO/PEDOT : PSS/MEH-PPVâ13 (5 : 95% by weight)/Al.
我们介绍了 2,5-二芳基-1,3,4-恶二唑和芴杂化分子的合成,例如2,7-bis[2-(4-tert-butylphenyl-1,3,4-oxadiazol-5-yl]-9,9-dihexylfluorene 6, 2,7-bis4-[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]phenyl}-9,9-dihexylfluorene 10, 2,7-bis4-[2-(4-dodecyloxyphenyl)-1,3,4-oxadiazol-5-yl]phenyl}-9,9-dihexylfluorene 11, 2,7-双4-[2-(4-十二烷氧基苯基)-1,3,4-恶二唑-5-基]苯基}-螺二芴 13 和类似物 16,包括 9,9-二己基芴或螺二芴核心单元,其上连接芳基或二芳基噁二唑单元,从而提供线性延伸的 Ï 共轭体系。报告了化合物 11 的 X 射线晶体结构。我们使用聚[2-甲氧基-5-(2-乙基己氧基)-1,4-苯基乙烯](MEH-PPV)混合物作为发光材料,并加入电子传输(ET)化合物 6、10、11、13 和 16 以增强电子注入,制造出了单层有机发光二极管(OLED)。所研究的所有器件的电致发光都完全来自 MEH-PPV 材料。器件的外部量子效率随着 ET 化合物浓度的增加而提高,最高可达 95%(按重量计),与纯 MEH-PPV 参考器件相比,大大提高(>两个数量级)。通过添加一层 PEDOT : PSS,装置的效率进一步提高,在 30 mA cmâ2 时,ITO/PEDOT : PSS/MEH-PPVâ13(5:95%(重量比))/Al 配置装置的效率达到约 0.4%。