In Operando Characterization of Degradation Processes in Organic Semiconductor Materials

摘要有机半导体材料在光电子学、热电学、生物电子学、能量收集和存储应用等许多现有和新兴技术中都有着非凡的前景。这些材料在使用过程中的降解是有机半导体商业化实施中的一个主要问题。这些降解途径被认为是暴露于环境大气中的少量气体和水分以及紫外线辐射所产生的复杂影响的组合。在固态和材料化学项目的支持下，这项基础工作允许基于光和电子与这些材料的相互作用开发复杂的，最先进的光谱工具，以确定伴随降解的化学途径，从而为解决这一复杂问题提供更好的解决方案。这种内在的跨学科努力通过研究生的专业发展具有实质性的广泛影响。研究生在另一位首席研究员的实验室进行部分论文研究，并在Next Energy Technologies， Inc.完成为期6周的实习。固态有机半导体材料是各种现有技术和新兴技术必不可少的有源元件，包括发光二极管激光器和基于有机的电子和光子器件。由于有机半导体在化学、光化学和光物理过程中不可避免地会发生降解，特别是在操作或操作条件下，这些技术的使用寿命有限。解决这些限制需要表征这些有机半导体材料在降解期间和降解后的分子结构、电子和电荷输运属性。为此，一套最先进的方法，包括环境到超高真空中的表面振动光谱（拉曼，PM-IRRAS）， x射线光电子能谱（XPS），紫外光电子能谱（UPS），逆光发射光谱（IPES）和电荷迁移率测量，用于研究化学和光电复杂性系统增加的环境中的有机半导体，包括在operando中。这项工作的主要目标是对有机半导体器件性能下降和最终失效的化学、光化学和光物理降解机制进行全面的基础研究。这项工作的第二个影响是制定了更坚固的有机半导体的新设计标准。

Non-technical AbstractOrganic semiconductor materials hold exceptional promise in a number of existing and emerging technologies including optoelectronics, thermoelectrics, bioelectronics, and energy harvesting and storage applications. Degradation of these materials during use is a major issue in the commercial implementation of organic semiconductors. These degradation pathways are thought to be a complex combination of effects resulting from exposure to small amounts of gases and moisture in the ambient atmosphere as well as ultraviolet radiation. With the support of the Solid State and Materials Chemistry program, this foundational effort allows development of sophisticated, state-of-the-art spectroscopic tools based on the interaction of light and electrons with these materials to identify the chemical pathways that accompany degradation, leading to better solutions to solve this complicated problem. This inherently interdisciplinary effort has substantial broader impact through the professional development of the graduate students involved. Graduate students conduct a portion of their dissertation research in the laboratory of the other Principal Investigator, as well as complete a 6-week internship at Next Energy Technologies, Inc. Technical AbstractSolid-state organic semiconductor materials are the essential active components of a variety of existing and emerging technologies, including light-emitting diode lasers and organic-based electronic and photonic devices. These technologies suffer from limited lifetimes due to the inevitable degradation of organic semiconductors through poorly defined chemical, photochemical and photophysical processes, especially in operando, or under conditions of operation. Addressing these limitations requires characterization of the molecular structural, electronic, and charge transport attributes of these organic semiconductor materials during and after degradation. Toward this end, a suite of state-of-the-art methods, including surface vibrational spectroscopies (Raman, PM-IRRAS) in ambient to ultrahigh vacuum, x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and charge mobility measurements, are used to study organic semiconductors in environments that systematically increase in chemical and optoelectronic complexity, including in operando. The primary objective of this effort is to undertake a comprehensive fundamental investigation of the chemical, photochemical, and photophysical mechanisms of degradation that underlie the diminished performance and eventual failure of organic semiconductor-based devices. The secondary impact of this effort is formulation of new design criteria for more robust organic semiconductors.