Degradation of Organic Semiconductors: Functional and Mechanistic Descriptions from Macroscale to Nanoscale

非技术摘要能够导电的有机材料被称为有机半导体，被用于许多新兴的下一代技术中，包括有机发光二极管、有机太阳能电池、热电材料和化学传感器。有机半导体的好处包括更低的成本、更好的性能、灵活性、透明度和更低的环境影响，但人们仍然担心它们的长期稳定性和寿命。该项目的重点是功能性质的降解，这是一个必须克服的基本材料化学挑战，才能在有机电子器件领域取得进展。在材料研究部固态和材料化学计划的支持下，研究人员在基础水平上促进了对材料和化学降解途径的理解，这最终将促进新材料设计标准的发展。因此，这项工作提供了重要的新见解，推动了新分子和聚合物的创造，并有助于美国在可打印电子材料和设备方面的长期稳定和技术相关性。固态和材料化学计划的支持还促进了有机半导体系统的独特能力的开发，这些能力可以很容易地转换到其他活性材料化学应用中，并能够识别从微米到纳米的长度尺度上伴随材料降解的化学路径。化学家和工程师之间的这种内在的跨学科努力是为从事研究的研究生和本科生提供跨学科培训的平台。通过这一努力发展了新的跨学科研究生和本科生水平的实验室经验，并在从K到灰色的公共宣传努力中探索了这一重要类别材料的特性。技术摘要推拉型或施主-受体型分子和聚合物结构以其优于早期分子设计的性能指标，已成为有机电子领域中占主导地位的一类活性材料。然而，对长期稳定的理解却鲜有人关注。这项基础性的工作直接检查和比较复杂的推挽有机半导体(OSC)结构的化学结构、电子结构和电荷传输特性作为分子构建块组成的函数，以了解降解的化学、光化学和光物理机制起源和功能影响。这一努力的第二个影响是为更强大的OSC制定新的设计标准。这项工作建立在通过之前的NSF DMR奖(DMR-1608289)所做的成功努力的基础上，在该奖项中，开始了对有机半导体降解的多学科合作调查。以前证明的方法包括在导致降解的条件下调查功能特征，以及详细的光谱分析方法来了解分子的机制起源。在这个项目中，能力得到扩展，包括具有现场特定分子和电子成像能力的局部物理结构，这使得能够在从微米到纳米的长度尺度上研究基础材料化学。除了为新兴技术改进材料设计外，这项工作的更广泛影响通过许多教育和外联活动体现出来。化学家和工程师之间的合作是从事研究的研究生和本科生进行跨学科培训的平台。通过这一努力发展了新的跨学科研究生和本科生水平的实验室经验，并在从K到灰色的扩展努力中解释和探索了这一重要类别材料的性质和用途。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical AbstractOrganic materials capable of conducting electricity – termed organic semiconductors - are used in many emerging, next-generation technologies including organic light emitting diodes, organic-based solar cells, thermoelectrics, and chemical sensors. The benefits of organic semiconductors include lower cost, improved performance, flexibility, transparency, and lower environmental impact, but concerns persist about their long-term stability and lifetime. The focus of this project – degradation of functional properties – is a fundamental materials chemistry challenge that must be overcome to progress the field of organic electronic devices. With support from the Solid State and Materials Chemistry Program in the Division of Materials Research, the researchers advance the understanding of materials and chemical degradation pathways at a fundamental level, which will eventually facilitate development of new materials design criteria. Hence, this work provides important new insights that drive the creation of new molecules and polymers and contributes to long-term stability and technological relevance of the United States in printable electronic materials and devices. Support from the Solid State and Materials Chemistry program also advances the development of unique capabilities for in operando characterization of organic semiconductor systems that are readily translatable to other active materials chemistry applications and enable identification of the chemical pathways that accompany degradation in materials at length scales from microns to nanometers. This inherently interdisciplinary effort between chemists and engineers is a platform for interdisciplinary training for the graduate and undergraduate students engaged in research. New interdisciplinary graduate- and undergraduate-level laboratory experiences are developed through this effort, and the properties of this important class of materials are explored in K-to-gray public outreach efforts. Technical AbstractPush-pull or donor-acceptor-type molecular and polymeric architectures have become the dominant class of active materials in organic electronics with performance metrics superior to earlier molecular designs. However, little attention has been devoted to understanding long-term stability. This fundamental effort directly examines and compares chemical structure, electronic structure, and charge transport characteristics of complex push-pull organic semiconductor (OSC) architectures as a function of molecular building block composition to understand the chemical, photochemical and photophysical mechanistic origins and functional impacts of degradation. The secondary impact of this effort is formulation of new design criteria for more robust OSCs. This work builds on successful efforts through a previous NSF DMR award (DMR-1608289) in which a collaborative, multi-disciplinary investigation of organic semiconductor degradation was initiated. Previously-demonstrated approaches include surveying functional characteristics under conditions that lead to degradation, coupled with detailed spectroscopic analysis methodologies to understand mechanistic molecular origins. In this project, capabilities are expanded to include local physical structure with site-specific molecular and electronic imaging capabilities, which enables investigation of fundamental materials chemistry across length scales ranging from microns to nanometers. In addition to improving materials design for emerging technologies, the broader impacts of this work manifests through numerous education and outreach activities This collaboration between chemists and engineers is a platform for interdisciplinary training for the graduate and undergraduate students engaged in research. New interdisciplinary graduate- and undergraduate-level laboratory experiences are developed through this effort, and the properties and uses of this important class of materials are explained and explored in K-to-gray outreach efforts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.