Development and function of novel electron-transporters realizinghigher order organic nanostructure for next generation organic LED

磷光有机发光器件(有机LED)可以实现比荧光有机LED高四倍的效率。到目前为止，我们团队已经开发出了外量子效率为30%的高效率天蓝、绿色和白色有机LED。这些显著的进展是通过使用新型的磷光材料，特别是含有苯基吡啶的电子传输材料(ETM)来实现的。然而，很少有关于这种ETMS的有效分子设计的论文。一般来说，密度泛函计算被认为是设计有前途的材料的有力工具，然而，这种计算在真空中只能给出有限的结构和光学性质。而在有机LED中，通常使用非晶态分子玻璃，固态特性是实现高效率器件的关键。从这一角度出发，我们研究了(1)密度泛函计算、(2)物理性能和(3)器件总体性能之间的关系，重点是单晶X射线衍射分析。基于这些分析，我们成功地提出了一种可以利用固态吡啶之间的CH/N氢键自组装的ETM的设计方案。

Phosphorescent organic light-emitting device (organic LED) can realize four times higher efficiency than that in fluorescent organic LED. So far, our group has already developed high-efficiency sky-blue, green, and white organic LEDs with external quantum efficiency of 30%. These remarkable advances have been achieved by use of novel phosphorescent materials, especially phenylpyridine-containing electron transport materials (ETMs). However, there is few papers dealing with an effective molecular design for such ETMs. Generally, DFT calculation has been recognized as a powerful tool to design a promising material, however, this calculation can give only limited structural and optical properties in vacuum. While in organic LEDs, amorphous molecular glasses are normally used and solid state properties are critical for realizing high-efficiency devices. From this perspective, we have investigated the relationships among (1) DFT calculation, (2) physical properties and (3) overall device performances of novel ETMs with emphasis on the single crystal XRD analyses. Based on these analyses, we have successfully proposed a promising design for an ETM that can be self-assembled by using CH/N hydrogen bonds between pyridines in the solid state.