Nanoscale interfaces in organic electronic and optoelectronic materials

有机材料为传统半导体提供了一种有趣的替代品，因为它们可以为电子产品，显示器和太阳能转换提供低成本，重量轻，灵活的组件，生产所需的能源相对较少。通过化学改性也可以引入巨大的可变性，基于相对较少，丰富的元素创建大量的材料。然而，分子组分在电荷载流子的传导、光激发和在器件中固有必要的界面处发生的相互作用方面表现得与传统半导体不同。这些材料对局部环境的变化高度敏感，大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。在设计用于电子和光电应用的有机材料时，这就引出了一个问题：我们能否以同样的方式设计出能够控制关键界面和环境的人工材料？为了了解有机和混合有机-无机界面以及纳米级的分子环境，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。这一系列的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特性，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集成的技术，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性质的影响。我们还将研究受体-供体界面的影响，这些界面出现在例如有机光伏系统中，并且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一个基本的原子尺度的界面和局部环境如何影响有机材料的器件相关性能，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.