Energy level alignment and electronic properties at weakly-reactive interfaces for organic electronics

该项目的目标是全面了解由π共轭有机分子组成的异质结的基本电子性质和平衡机制，尽管与有机电子学相关，但仍然缺乏这些知识。我们建议使用直接和反向光电发射来确定有机分子吸附在由金属单晶衬底支撑的有机、碱卤化物和氧化物层间薄膜上形成的界面上达到电子平衡的电子结构和相关机制。低能电子衍射和扫描隧道显微镜将被用来确定这些系统的结构性质。我们将定量地将π共轭有机分子的关键性质（即电离能、电子亲和和轨道简并）和中间层的关键性质（即功函数、薄膜厚度和介电常数）与所得到的能级排列联系起来。这些数据将作为理论框架发展的基准，以解释观测到的电子结构，包括费米-狄拉克统计、静电学和界面特定效应。因此，我们的目标是揭示在弱耦合实体形成界面时建立电子平衡的基本机制，并提供能够准确预测此类系统的能级对准的模型。

The goal of this project is to acquire comprehensive knowledge about the fundamental electronic properties and equilibration mechanisms at heterojunctions comprising pi-conjugated organic molecules, which, despite the relevance for organic electronics, is still lacking. We propose to use direct and inverse photoemission to determine the electronic structure and the associated mechanisms of reaching electronic equilibrium at interfaces formed by organic molecules adsorbed on organic, alkali-halide, and oxide interlayer thin films supported by metal single-crystal substrates. Low energy electron diffraction and scanning tunneling microscopy will be employed to determine the structural properties of these systems. We will correlate quantitatively key properties of the pi-conjugated organic molecules (i.e., ionization energy, electron affinity, and orbital degeneracy) and those of the interlayers (i.e., work function, film thickness, and dielectric constant) with the resulting energy level alignment. The data will serve as benchmark for the development of a theoretical framework to explain the observed electronic structure, including Fermi-Dirac statistics, electrostatics, and interface-specific effects. We thus aim to unravel the fundamental mechanisms that establish electronic equilibrium upon formation of interfaces from weakly coupled entities and to provide a model that is able to accurately predict the energy level alignment for such systems.