Nanoscale interfaces in organic electronic and optoelectronic materials

有机材料为传统半导体提供了一个有趣的替代品，因为它们可以为电子产品、显示器和太阳能转换提供成本低、重量轻、灵活的组件，而生产这些组件所需的能量相对较少。通过化学修饰也可以引入很大的可变性，以相对较少、丰富的元素为基础，创造出巨大的材料调色板。然而，分子组件在载流子的传导、光激发和发生在设备中固有必要的界面上的相互作用方面的表现与传统半导体不同。这些材料对当地环境的变化非常敏感，大自然通过对周围有效成分的精细控制来处理这些变化。在设计用于电子和光电子应用的有机材料时，这引出了一个问题：我们能否以同样的方式设计具有关键接口和环境控制的人工材料？为了在纳米尺度上理解有机和混合有机-无机界面以及分子环境，我们将使用扫描探针显微镜研究代表器件结构的模型系统。这一系列工具使我们能够在纳米尺度上对表面分子的局部电子特性进行成像和探测，我们的目标是进一步扩展这个工具箱，包括将光学与扫描探针相结合的技术，以获得表征这些材料所需的光电特性的局部视图。在此基础上，我们将研究不同衬底和缺陷结构对分子性质的影响，以及不同分子结构对电子和光电子性质的影响。我们还将研究在有机光伏系统中出现的受体-供体界面的影响，这些界面在激发后导致器件中自由电荷的电荷分离过程中至关重要。我们的主要目标是构建界面和局部环境如何影响有机材料器件相关特性的基本原子尺度图，以指导新材料的开发。

Organic materials offer an intriguing alternative to traditional semiconductors as they could provide low cost, light-weight, flexible components for electronics, displays and solar energy conversion that require comparatively little energy to produce. Great variability can also be introduced through chemical modification, creating a vast palette of materials based on relatively few, abundant elements. However, molecular components behave differently than traditional semiconductors in terms of conduction of charge carriers, optical excitation and interactions occurring at interfaces inherently necessary in devices. These materials are highly sensitive to variations in the local environment, which nature deals with through exquisite control over the surroundings of active components. In the design of organic materials for electronic and optoelectronic applications, this begs the question: can we design artificial materials with control over key interfaces and the environment in the same way? To gain an understanding of organic and hybrid organic-inorganic interfaces and the molecular environment at the nanoscale, we will study model systems representing device structures using scanning probe microscopy. This family of tools allows us to image and probe local electronic properties of molecules on surfaces on the nanoscale, and we aim to further expand this toolbox to include techniques that integrate optics with scanning probes to obtain a local view of optoelectronic properties needed to characterize these materials. With this, we will investigate the influence of different substrates and defect structures on molecular properties, as well as the influence that different molecular structures have on electronic and optoelectronic properties. We will also investigate the influence of acceptor-donor interfaces that appear, for example, in organic photovoltaic systems and are crucial in the charge separation process that leads to free charges in the device after excitation. Our principal aim is to construct a fundamental atomic scale picture of how interfaces and the local environment influence device-relevant properties of organic materials to guide the development of new materials.