Cui Dongyue, Wang Shuai, Li Shuhong, Liu Yunlong, Gao Xuexi, Wang Wenjun, Dong Xiaochen
Opt Express. 2021 May 24;29(11):16845-16856. doi: 10.1364/OE.418566.
The transition dipole moment (TDM) orientation in the emission layer (EML) of organic light-emitting diodes (OLEDs) have attracted increasing attention from many researchers. But the study point at the molecular orientation in the hole transport layer (HTL) and electron transport layer (ETL) was not reported widely. In this paper, the molecular orientation of HTLs and ETLs were controlled by the deposition rate. The angle-dependent PL spectra and the variable angle spectroscopic ellipsometry (VASE) were used for evaluating the molecular orientation of B3PYMPM and TAPC, respectively. We found that fast deposition rate can boost preferentially vertical molecular orientation in both molecules and facilitate the hole and electron mobility, which was tested by the current density-voltage and capacitance-voltage curves of HODs and EODs. Moreover, the HTLs and ETLs were employed in OLED devices to verify the influence of molecular orientation on charge carrier mobility, which determined the performance of OLEDs significantly.
有机发光二极管（OLED）发光层（EML）中的跃迁偶极矩（TDM）取向已引起众多研究人员越来越多的关注。但关于空穴传输层（HTL）和电子传输层（ETL）中分子取向的研究报道并不广泛。在本文中，通过沉积速率来控制HTL和ETL的分子取向。分别使用角度依赖的光致发光光谱（PL）和可变角度光谱椭偏仪（VASE）来评估B3PYMPM和TAPC的分子取向。我们发现，快速沉积速率能够优先促进这两种分子中分子的垂直取向，并有利于空穴和电子迁移率，这通过空穴注入器件（HOD）和电子注入器件（EOD）的电流密度-电压曲线和电容-电压曲线进行了测试。此外，将HTL和ETL应用于OLED器件中，以验证分子取向对电荷载流子迁移率的影响，而电荷载流子迁移率对OLED的性能有显著影响。
