Combined Experimental and Theoretical Approach to Grain Boundary Engineering in Organic Semiconducting Crystals

有机半导体晶体晶界工程的实验与理论相结合的方法

• 批准号: 536757824
• 负责人: Professor Dr. Konstantin Amsharov
• 金额: --
• 依托单位: I. Physikalisches Institut - Festkörper- und Tieftemperaturphysik -
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/536757824?language=en
• 关键词: Combined; Experimental; Theoretical; Approach; Grain

Organic semiconductor materials (OSC) have the potential to disruptively transform a number of industries—such as the IT sector or the field of photovoltaics—and are indeed already being used in some applications. They offer a number of improvements over traditional inorganic semiconductors such as low energetic production costs, novel materials properties and composition of only earth-abundant elements. Experimental and theoretical design efforts of new materials for OSCs for a long time mostly focused on incremental improvements of known materials, with modern data-driven efforts only very recently finding their use. Yet, all of these efforts to date only considered the properties of the bulk material, often in an idealized setting. Realistic materials, on the other hand, will always show imperfections such as boundaries between different grains and the recent discovery of barriers and traps for charge carriers demonstrated that any comprehensive design effort will have to include the influence of barriers. In the proposed work, we will therefore employ a combined experimental and theoretical approach for the optimization of organic molecular materials including the transport inefficiencies due to grain boundaries. On the theory side, we will explicitly compute the energetic barriers to charge transport at grain boundaries. Experimentally, real-space imaging by scanning probe microscopy, charge carrier transport as well as (photocurrent-)spectroscopy will experimentally identify grain boundary heights and compare this to theory computations based on a combination of density functional theory and effective modelling. While the scanning probe microscopy method and transport measurements are established to identify grain boundary heights, it is a serial and comparably slow technique to map grain boundaries. In contrast, the photocurrent spectroscopy method has up to now only been used for inorganic quantum wells, and will be her firstly adopted for organic materials and allow a fast screening of grain boundary heights of various materials. Initially, we will restrict ourselves to chemical modifications of perylene-based molecules as they have shown to generate thin films of reproducibly high quality. Theory will thereby not only elucidate the atomistic details of charge transport across the interfaces but also show the correlation of barriers with various properties of the employed molecules and the interfaces. It will also lay the foundation for a further, expanded investigation of other molecules beyond the initial perylene structures. Finally, we will adapt the machine learning approach developed by one of us to include cross-grain transport parameters. With this scheme, which will also be modified to incorporate experimental data, we will be able to efficiently search the molecular design space to identify promising molecules for use in organic semiconductors.

有机半导体材料（OSC）有可能颠覆性地改变许多行业，例如IT部门或光化学领域，并且确实已经在某些应用中使用。与传统的无机半导体相比，它们提供了许多改进，例如低能量生产成本，新颖的材料特性和仅由地球丰富的元素组成。长期以来，OSC新材料的实验和理论设计工作主要集中在已知材料的渐进式改进上，现代数据驱动的工作直到最近才找到它们的用途。然而，迄今为止所有这些努力都只考虑了散装材料的性质，通常是在理想化的环境中。另一方面，现实的材料总是会显示出不完美的地方，比如不同晶粒之间的边界，最近发现的载流子势垒和陷阱表明，任何全面的设计工作都必须包括势垒的影响。因此，在拟议的工作中，我们将采用实验和理论相结合的方法来优化有机分子材料，包括由于晶界而导致的传输效率低下。在理论方面，我们将明确计算在晶界电荷传输的能量障碍。在实验上，通过扫描探针显微镜、电荷载流子传输以及（光电流）光谱的真实空间成像将通过实验确定晶界高度，并将其与基于密度泛函理论和有效建模相结合的理论计算进行比较。虽然扫描探针显微镜法和输运测量法已被建立来确定晶界高度，但它是一种连续和缓慢的晶界定位技术。相比之下，光电流光谱法到目前为止仅用于无机量子威尔斯，并且将首先用于有机材料，并且允许快速筛选各种材料的晶界高度。最初，我们将限制自己的化学改性的二萘嵌苯为基础的分子，因为他们已经证明，产生薄膜的可重复的高品质。因此，理论将不仅阐明跨界面的电荷传输的原子细节，而且还显示了所采用的分子和界面的各种性质的障碍的相关性。这也将奠定基础，进一步扩大调查的其他分子以外的初始结构。最后，我们将调整我们中的一个开发的机器学习方法，以包括交叉颗粒传输参数。有了这个方案，它也将被修改，以纳入实验数据，我们将能够有效地搜索分子设计空间，以确定有前途的分子用于有机半导体。