Fluxional macromolecular pi-electronics via rational manipulation of aromaticity and spin

通过芳香性和自旋的合理操纵实现流态高分子π电子学

• 批准号: 1607821
• 负责人: John Tovar
• 金额: $ 54万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607821&HistoricalAwards=false
• 关键词: Fluxional; macromolecular; pi; electronics; via

The Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division supports the project by Professors John D. Tovar and Arthur E. Bragg. Professors Tovar and Bragg are faculty members in the Department of Chemistry at Johns Hopkins University. They are developing new electrically conductive plastics with adjustable electronic properties. Most electronic devices are manufactured from non-carbon materials such as silicon. Carbon-containing plastics are much easier to process, allowing them to be fashioned into lightweight, large area, and even flexible devices. Applications for these plastic devices range from portable photovoltaic cells, light-emitting displays and paintable electronics to new biocompatible medical materials. Researchers working in Professor Tovar's group gain valuable training in the design and construction of electronically active plastics, while Bragg's students learn to investigate and analyze the properties of these new plastics using lasers. The interaction between the two groups fosters cross-fertilization of ideas in chemistry and physics. The collaboration provides broad training to students working on this project. The Tovar and Bragg groups promote increased exposure to chemistry research among high school, undergraduate and graduate-level students within Baltimore City and beyond. Underrepresented minority students at all levels participate in this research program. This project investigates pi-conjugated oligomeric and polymeric organic semiconductors that are derived from tunable aromatic segments positioned along the conjugated main chain backbone. Non-benzenoid aromatic building blocks that depart from the classical six pi-electron aromatic nuclei of benzene, thiophene, pyrrole, etc. are used. Fundamental issues of aromaticity, torsional strain and disorder in conjugated polymers are investigated with the goal to optimize and regulate the resulting effective conjugation lengths. The conjugation lengths are measured using electronic absorption and photoluminescence, coupled with computational and charge carrier studies. A new polymer design is proposed that decouples the photochemical switching event from polymer macromolecular conformational changes, thereby enabling rapid and efficient tuning of electronic properties as a function of an applied photochemical stimulus. Electrical properties of these polymers are assessed through electrical measurements before and after photoinduced switching events, and their electronic structures are probed using sophisticated ultra-fast laser spectroscopy in order to capture possible fleeting structures. The ultra-fast spectroscopy is used to characterize photophysical mechanisms underlying their functional responses and to unravel how these depend on molecular structure. The broader impacts include outreach to local high schools to introduce them to the properties of electronic materials.

化学系的大分子、超分子和纳米化学项目支持了约翰·D。托瓦尔和亚瑟E.布拉格托瓦尔教授和布拉格教授是约翰霍普金斯大学化学系的教员。他们正在开发具有可调节电子特性的新型导电塑料。 大多数电子设备是由非碳材料如硅制成的。 含碳塑料更容易加工，使它们能够制成重量轻，面积大，甚至灵活的设备。这些塑料设备的应用范围从便携式光伏电池、发光显示器和可涂漆电子产品到新的生物相容性医疗材料。在Tovar教授的小组中工作的研究人员在电子活性塑料的设计和构造方面获得了宝贵的培训，而布拉格的学生则学习使用激光来研究和分析这些新塑料的特性。这两个小组之间的相互作用促进了化学和物理学思想的相互促进。该合作为从事该项目的学生提供了广泛的培训。托瓦尔和布拉格小组促进巴尔的摩市内外的高中、本科和研究生水平的学生更多地接触化学研究。 各级代表性不足的少数民族学生参加了这项研究计划。本计画主要研究由沿着共轭主链的可调芳香族链段衍生的π共轭低聚与聚合有机半导体。使用非苯型芳族结构单元，其偏离苯、噻吩、吡咯等的经典六π电子芳族核。共轭聚合物的芳香性，扭转应变和无序的基本问题进行了研究，以优化和调节所得的有效共轭长度的目标。共轭长度测量使用电子吸收和光致发光，再加上计算和电荷载流子的研究。提出了一种新的聚合物设计，其使聚合物大分子构象变化的光化学转换事件发生变化，从而能够快速有效地调节作为所施加的光化学刺激的函数的电子性质。这些聚合物的电性能进行评估，通过电气测量之前和之后的光致开关事件，和他们的电子结构进行探测，使用先进的超快激光光谱，以捕捉可能的短暂结构。 超快光谱用于表征其功能反应的物理机制，并揭示这些机制如何依赖于分子结构。更广泛的影响包括对当地高中进行宣传，向他们介绍电子材料的特性。