Vázquez H, Dappe Y J, Ortega J, Flores F
Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
J Chem Phys. 2007 Apr 14;126(14):144703. doi: 10.1063/1.2717165.
A unified model, embodying the "pillow" effect and the induced density of interface states (IDIS) model, is presented for describing the level alignment at a metal/organic interface. The pillow effect, which originates from the orthogonalization of the metal and organic wave functions, is calculated using a many-body linear combination of atomic orbitals Hamiltonian, whereby electron long-range interactions are obtained using an expansion in the metal/organic wave function overlap, while the electronic charge of both materials remains unchanged. This approach yields the pillow dipole and represents the first effect induced by the metal/organic interaction, resulting in a reduction of the metal work function. In a second step, we consider how charge is transferred between the metal and the organic material by means of the IDIS model: Charge transfer is determined by the relative position of the metal work function (corrected by the pillow effect) and the organic charge neutrality level, as well as by an interface parameter S, which measures how this potential difference is screened. In our approach, we show that the combined IDIS-pillow effects can be described in terms of the original IDIS alignment corrected by a screened pillow dipole. For the organic materials considered in this paper, we see that the IDIS dipole already represents most of the realignment induced at the metal/organic interface. We therefore conclude that the pillow effect yields minor corrections to the IDIS model.
提出了一种统一模型，该模型体现了“枕形”效应和界面态诱导密度（IDIS）模型，用于描述金属/有机界面处的能级对齐。源于金属和有机波函数正交化的枕形效应，是使用多体原子轨道哈密顿量线性组合来计算的，通过金属/有机波函数重叠展开来获得电子长程相互作用，而两种材料的电子电荷保持不变。这种方法产生了枕形偶极子，代表了由金属/有机相互作用诱导的第一种效应，导致金属功函数降低。第二步，我们通过IDIS模型考虑电荷如何在金属和有机材料之间转移：电荷转移由金属功函数（经枕形效应校正）与有机电荷中性能级的相对位置以及一个界面参数S决定，该参数衡量这种电位差是如何被屏蔽的。在我们的方法中，我们表明IDIS - 枕形效应的组合可以用经屏蔽的枕形偶极子校正的原始IDIS对齐来描述。对于本文中考虑的有机材料，我们看到IDIS偶极子已经代表了在金属/有机界面处诱导的大部分重新排列。因此我们得出结论，枕形效应仅对IDIS模型产生微小校正。
