Structure and Electronic Gap State Density at Organic Semiconductor Interfaces

虽然已经提出了几种理论来确定两个有机半导体（OSC）界面上的电子能级对准，如极化子态模型或感应态密度模型，但到目前为止还没有一个令人满意的完整的预测能级偏移的理论。我们将利用互补技术对有机-有机（小分子）异质结构的电子水平排列进行全面研究，以了解结构缺陷与电子结构之间的关系。高分辨率x射线散射和高灵敏度UPS的创新组合可以详细描述位于间隙区域的结构缺陷和电子状态，这被认为在水平对准中起着至关重要的作用。特别是，我们将制备一系列具有不同电子（电离能，能隙）和结构（分子构象，晶体结构）性质的有机-有机异质结构。通过改变生长参数（衬底、生长速率、温度），我们将调整异质结构的结构特性，这将反过来改变电子特性。作为最终结果，我们的目标是得到相干散射材料体积（即本质上无缺陷的体积）与两个osc之间的homo能级偏移之间的直接关系。

Although several theories have been proposed to determine the electronic level alignment at the interface of two organic semiconductors (OSC), for example the polaron state model or the induced density of states model, so far no satisfying and complete theory for predicting the level offsets has been developed. We will conduct a comprehensive study of the electronic level alignment of organic-organic (small molecule) heterostructures using complementary techniques to understand the relationship between structural defects and electronic structure. The innovative combination of high-resolution X-ray scattering and high sensitivity UPS allows the detailed description of structural defects and electronic states located in the gap region, which are believed to play an essential role in the level alignment. In particular, we will prepare a series of organic-organic heterostructures with suitable material combinations with different electronic (ionization energy, energy gap) and structural (molecular conformation, crystal structure) properties. By variation of the growth parameters (substrate, growth rate, temperature) we will tune the structural properties of the heterostructure, which will in return modify the electronic properties. As the final result we aim for the direct relationship between coherently scattering material volume, that is the essentially defect free volume, versus the HOMO-level offset between the two OSCs.