In organic electronic devices, the interfacial dipole at organic/metal interfaces is critical in determining the carrier injection or extraction that limits the performance of the device. A novel technique to enable the direct measurement of underburied dipoles is developed and demonstrated. By tilting the shadow mask by a small angle, metal atoms diffuse into the opening slit to form an ultrathin metal layer during the evaporation process. As the ultrathin metal layer cannot screen out the dipole-induced surface work function change, the dipole strength and direction at the organic/metal interface can be revealed. It was found that the polarity of the organic material, the Fermi-level pinning and the interface morphology all play important roles in dipole formation. By comparing the energy level shifts at the organic/pre-deposited metal and organic/post-deposited metal interfaces, the dipole formed by molecular interactions could be distinguished from the dipole formed by Fermi-level pinning.

中文翻译：

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在有机/金属界面上与预沉积和后沉积金属形成偶极子

在有机电子设备中，有机/金属界面上的界面偶极子对于确定限制设备性能的载流子注入或提取至关重要。开发和演示了一种能够直接测量地下偶极子的新颖技术。通过将荫罩倾斜一个小角度，在蒸发过程中，金属原子扩散到开口狭缝中，形成超薄金属层。由于超薄金属层无法屏蔽偶极子引起的表面功函数的变化，因此偶极子的强度和方向在有机物/金属界面可以显示出来。发现有机材料的极性，费米能级钉扎和界面形态都在偶极子形成中起重要作用。通过比较有机/预沉积金属和有机/后沉积金属界面处的能级位移，可以将分子相互作用形成的偶极子与费米能级钉扎形成的偶极子区分开。