Fabrication and characterization of high-quality and stable thin film using organic alloy method, and application of the film to organic devices

我们采用共蒸发法制备了有机合金薄膜。在本研究中，我们讨论了用于有机电致发光二极管的空穴传输材料和空穴阻挡材料。在空穴传输材料方面，我们制备了由三苯二胺衍生物(TPD)和萘基取代二胺衍生物(NPD)组成的有机合金薄膜。结果表明，有机合金薄膜中的多晶现象比两种单一薄膜都受到了显著的抑制。在空穴阻挡材料方面，我们将空穴传输材料的NPD、电子传输材料的恶二唑衍生物(PBD)、空穴阻挡材料的非取代BCP(Bphen)和电子注入材料的锂喹啉(Liq)组合在一起，制备了Baococproin(BCP)基合金薄膜。BCP薄膜具有不稳定的薄膜形态，在蒸发几个小时后立即结晶。而有机合金法获得了稳定、高质量的BCP基合金薄膜。但由于BCP与LiQ的尺寸匹配性较差，制备BCP有机合金薄膜的方法并不成功。下一步，我们以铝喹啉(Alq3)为发光材料，通过引入有机合金膜制备了有机电致发光器件。这些具有有机合金膜的OLED表现出与传统的没有有机合金膜的OLED相似的器件性能。也就是说，有机合金化方法对有机电致发光器件的载流子输运几乎没有影响。然而，在空穴阻挡层的情况下，尽管与Bphen和PBD密切相关的有机合金薄膜具有稳定的薄膜结构和优异的电子性能，但与空穴传输材料的NPD结合的有机合金薄膜具有稳定的薄膜结构，但空穴阻挡性能较低。因此，NPD不能作为BCP的对抗分子。

We fabricated organic alloy films by a co-evaporation method. In this study, we discussed hole-transport materials and hole-blocking materials which are used in organic light-emitting diodes. In the case of hole-transport material, we fabricated organic alloy films consisting of a triphenyl diamine derivative (TPD) and naphthyl-substituted diamine derivative (NPD). We clarified that the polycrystallization in organic alloy films is remarkably suppressed as compared with both single films. In the case of hole-blocking material, we fabricated bathocuproin (BCP) -based alloy films combined with NPD of hole-transport material, oxadiazole derivative(PBD)of electron-transport material, non-substituted BCP (Bphen) of hole-blocking material and lithium quinoline(Liq)of electron-injection material. BCP thin films have a unstable film morphology and immediately crystallize after a few hours from evaporation. However, we obtained stable and high-quality BCP-based alloy films by the organic alloy method. But it was not successful to fabricate organic alloy film consisting of BCP and because the size matching between BCP and Liq is poor. As the next step, we fabricated OLEDs with aluminum quinoline (A1q3) as an emitting material by the introduction of organic alloy films. These OLEDs with an organic alloy film showed the similar device performance as the conventional OLED without an organic alloy film. That is, organic alloy method was found little to affect carrier transport of OLEDs. In the case of hole-blocking layer, however, although the organic alloy films combined with closely-related Bphen and PBD showed a stable film structure and an excellent electronic property, the organic alloy films combined with NPD of hole-transport material showed a stable film structure but a low hole-blocking property. Therefore, NPD could not be used as the counter molecule against BCP.