Colour tuning of blue electroluminescence using bipolar carbazole–oxadiazole molecules in single-active-layer organic light emitting devices (OLEDs)
作者:Katharine E. Linton、Alison L. Fisher、Christopher Pearson、Mark A. Fox、Lars-Olof Pålsson、Martin R. Bryce、Michael C. Petty
DOI:10.1039/c2jm31825c
日期:——
A synthetically versatile strategy has been employed for luminescence colour tuning in a new series of bipolar carbazoleâ2,5-diaryl-1,3,4-oxadiazole hybrid molecules 1â7. Their syntheses, solution absorption and emission properties and cyclic voltammetric data are reported. Calculations using DFT (density functional theory) establish that they possess molecular orbitals which favour bipolar charge-transport. Single-active-layer organic light emitting devices (OLEDs) have been fabricated by thermal evaporation using the bipolar compounds as the emitters in the architecture ITO:PEDOT-PSS:X:Ca/Al (X = 1â7). The structureâproperty relationships within the series of compounds are assessed with emphasis on the OLED performance and emission colour. The HOMOâLUMO gap has been varied by systematic modifications of the molecular subunits of 1â7, allowing the colour of the electroluminescence to be tuned from deep blue (CIE x,y 0.157, 0.079) through to green (CIE x,y 0.151, 0.096). These materials are very attractive for further development due to the combination of good processability of the molecules, their bipolar structure, colour tunability and efficient performance of OLEDs using a simple device architecture.
在一系列新的双极性咔唑-2,5-二芳基-1,3,4-恶二唑杂化分子 1-7 中,采用了一种综合通用策略来调节发光颜色。报告了它们的合成、溶液吸收和发射特性以及循环伏安数据。使用 DFT(密度泛函理论)的计算表明它们具有有利于双极电荷传输的分子轨道。单活性层有机发光器件 (OLED) 是通过热蒸发法使用双极性化合物作为 ITO:PEDOT-PSS:X:Ca/Al (X = 1-7) 结构中的发射极来制造的。该系列化合物的结构与性能关系的评估重点是 OLED 性能和发射颜色。 HOMO-LUMO 间隙通过 1-7 分子亚基的系统修饰而变化,从而使电致发光的颜色从深蓝色 (CIE x,y 0.157, 0.079) 调整到绿色 (CIE x, y 0.151, 0.096)。由于分子的良好加工性、双极结构、颜色可调性以及使用简单器件架构的 OLED 的高效性能,这些材料对于进一步开发非常有吸引力。