Crystalline thin film growth in anisotropic mixtures: a combined approach by experiment, theory and simulation

我们将采用实验、理论和模拟相结合的方法，研究各向异性颗粒混合物在衬底上的薄膜生长。第一个中心目标是探索和解释近平衡增长和动力学确定的增长之间的交叉，通过分析合适的粗粒度模型，不同的理论和模拟方法，在不同的长度和时间尺度。从这些调查的见解和发现应适用于实验系统的有机半导体在不同的基板上的双组分混合物，在其吸引力的有机分子的强度不同。这些系统在有机电子学中的潜在应用是相关的。我们想在表面热力学和表面相图的背景下理解这些特定系统的生长。这些表面相图将是理论和模拟为基础的调查的中心结果。作为第二个中心目标，我们的目标是通过利用各向异性材料的体和表面热力学的衬底温度和生长速率协议的变化，在各向异性膜生长的结构控制。建议的调查方法是：（i）以基本测度理论为基础的经典密度泛函理论，非常适合于确定各向异性混合物的粗粒模型中的体积和表面热力学，（ii）晶格上和晶格外模拟，以确定相图并覆盖膜生长过程中的不同时间和长度尺度，以及（iii）实时界面-灵敏的散射技术（X射线反射率[XRR]，掠入射X射线衍射[GIXD]，掠入射小角度X射线散射[GISAXS] /漫散射）结合生长后原子力显微镜（AFM）的生长结构的表征。特别强调的是相互关联的方法：理论和非晶格模拟将建立相图，并提供参数，为更粗粒度的动力学蒙特卡罗类型的晶格模拟，并将进行实验，以探索已相应确定的表面相变附近的生长条件。因此，我们期望获得这类系统增长的全面情况。

We will investigate thin film growth in mixtures of anisotropic particles on substrates using a combined approach by experiment, theory and simulation. The first central goal is to explore and explain the crossover between near-equilibrium growth and kinetically determined growth by analyzing suitable coarse-grained models with different theoretical and simulation methods on different length and time scales. Insights and findings from these investigations shall be applied to the experimental systems of two-component mixtures of organic semiconductors on different substrates, varying in their attraction strength for the organic molecules. These systems are relevant for potential applications in organic electronics. We want to understand growth in these particular systems in the context of surface thermodynamics and surface phase diagrams. These surface phase diagrams will be a central result of the theoretical and simulation-based investigations. As the second central goal, we aim at control over structures in anisotropic film growth through variation of substrate temperature and growth rate protocol by exploiting the bulk and surface thermodynamics of the anisotropic material. The proposed methods of investigation are: (i) classical density functional theory on the basis of Fundamental Measure Theory, ideally suited for the determination of bulk and surface thermodynamics in coarse-grained models of anisotropic mixtures, (ii) on-lattice and off-lattice simulations to determine phase diagrams and to cover different time and length scales in the film growth process and (iii) real-time interface-sensitive scattering techniques (X-ray reflectivity [XRR], grazing incidence X-ray diffraction [GIXD], grazing incidence small-angle X-ray scattering [GISAXS] / diffuse scattering) combined with post-growth atomic force microscopy (AFM) for the characterization of grown structures. Special emphasis lies on the interconnected approach: theory and off-lattice simulations will establish phase diagrams and provide parameters for more coarse-grained on-lattice simulations of Kinetic Monte Carlo type, and experiments will be carried out to explore growth conditions near surface phase transitions which have been determined correspondingly. Thus we expect to obtain a comprehensive picture of growth in such systems.