Nanoscale interfaces in organic electronic and optoelectronic materials

有机材料为传统半导体提供了一种耐人寻味的替代品，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，而这些组件生产所需的能源相对较少。通过化学修饰也可以引入巨大的可变性，在相对较少、丰富的元素的基础上创造出大量的材料调色板。然而，在电荷载流子的传导、光激发和发生在器件固有必需的界面上的相互作用方面，分子组件的行为不同于传统半导体。这些材料对当地环境的变化高度敏感，自然通过对活性成分周围环境的精细控制来处理这些变化。在电子和光电子应用的有机材料设计中，这回避了一个问题：我们能否设计出对关键接口和环境具有相同控制能力的人造材料？ 为了在纳米尺度上了解有机和杂化有机-无机界面和分子环境，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成像和探测纳米级表面上分子的局部电子性质，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性质的局部视图。在此基础上，我们将研究不同的衬底和缺陷结构对分子性质的影响，以及不同的分子结构对电子和光电性质的影响。我们还将研究受体-施主界面的影响，例如，在有机光伏系统中，受体-施主界面在电荷分离过程中起着至关重要的作用，电荷分离过程导致激发后器件中的自由电荷。我们的主要目标是构建一个基本的原子尺度图，说明界面和局部环境如何影响有机材料的器件相关特性，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.