FRG: Spin Response in Organic Semiconductors with Tuned Hyperfine Interaction

技术摘要本研究的目标是研究电子自旋在有机双端器件中的注入、操纵、输运和探测，以及在这些器件中注入的电子自旋和核自旋之间的相互关系。特别是，我们将深入研究自旋排列的注入载流子动力学，由此产生的核极化的动力学及其对电子自旋响应的影响，以及自旋有机发光二极管的电致发光响应。这些新颖的实验将在基于聚合物、小分子和富勒烯等有机半导体的自旋电子学设备中进行，其中一些构建块原子将被具有不同超精细强度的不太丰富的同位素取代。这包括用重氢(2H)取代质子化氢(1H)；和/或用13C同位素取代12C。这些研究将有助于理解控制有机自旋装置中自旋响应的物理过程，并有可能彻底改变它们的性能。该项目将支持两名博士生在这些先进技术方面的教育，这对从学术界到我们最先进的技术行业的许多科学职业来说都是极好的培训。这些实验有望引起科学界的普遍兴趣，并提供新的自旋电子学技术，特别是在寻找新的信息承载介质方面。非技术摘要最近，除了电子电荷外，与其内部磁矩有关的电子作为信息承载介质的自旋自由度也得到了研究。据预测，在未来的器件中，电流将被自旋电流增大。有机半导体已经开始在电子和显示行业以及太阳能收集方面发挥重要作用。有机自旋电子学是一个新的概念，它是在有机半导体器件中操纵自旋的。这项提议涉及有机电子设备中的自旋操纵。自旋将被注入、控制和检测到各种有机材料中，这些有机材料的分子构件包含不同的同位素，如取代氢的氚和取代有机物中更丰富的12C的13C。据推测，电子自旋相干性的丧失是因为有机体中的原子核也携带自旋；这是由于电子-自旋/核-自旋相互作用，也称为超精细相互作用。这种相互作用虽然非常微小，但在自旋电子学中起到了破坏性的作用，因为材料中有如此多的原子核。在这项提议中，将研究同位素交换在一些有机自旋装置中的作用，目的是改善自旋相干时间。一名本科生干部和两名研究生将参加这些项目，获得前沿科学研究的培训和实践经验。通过研究经验，这些学生将为继续研究生教育或在半导体/纳米技术行业开始职业生涯做好准备。

Technical AbstractThe goals of the proposed research are the study of electron spin injection, manipulation, transport and detection in organic two-terminal devices such as spin-valves, diodes, and light emitting diodes; as well as the inter-relation between the injected electron spins and nuclear spins in these devices. In particular the injected spin aligned carrier dynamics, the dynamic of the resulting nuclear polarization and its influence on the electronic spin response, as well as the electroluminescence response in spin-organic light emitting diodes will be thoroughly investigated. The novel experiments will be conducted in spintronics devices based on organic semiconductors such as polymers, small molecules, and fullerenes, in which some of the building block atoms would be replaced by less abundant isotopes having different hyperfine strength. This includes replacing protonated hydrogen (1H) by deuterated hydrogen (2H); and/or 12C by the 13C isotope. The studies will contribute to the understanding of the physical processes that govern the spin response in organic spin devices, and have the potential to revolutionize their performance. This project will support the education of two PhD students in these advanced technologies, which is excellent training for many scientific careers from academia to our most advanced technology industries. These experiments are expected to be of general interest to the scientific community and provide new spintronics techniques especially for pursing new information bearing media.Non-Technical AbstractRecently the spin degree of freedom of the electron that is associated with its internal magnetic moment has been investigated as an information carrying medium, in addition to the electron charge. It has been predicted that the electrical current would be augmented by spin current in future devices. The organic semiconductor has started to play an important role in the electronics and displays industries, as well as in solar energy harvesting. Organic spintronics is a new concept, where the spin is manipulated in organic semiconductor devices. This proposal deals with spin manipulation in organic electronic devices. Spins will be injected, controlled and detected in various organic materials of which molecular building blocks contain different isotopes such as deuterium that replaces hydrogen, and 13C that replaces the more abundant 12C in the organics. It is postulated that the electron spin coherence is lost because of the nuclei in the organic that also carry spins; this occurs due to the electron-spin/nuclear-spin interaction also known as hyperfine interaction. Although very tiny, this interaction plays a destructive role in spintronics because there are so many nuclei in the material. In this proposal the role of isotope exchange will be investigated in a number of organic spin devices, with the goal to improve the spin coherence time. A cadre of undergraduate students as well as 2 graduate students will participate in the projects, gaining training and hands-on experience in frontier scientific research. Through the research experience, the students will be well equipped to pursue a graduate education or start a career in the semiconductor/nanotechnology industries.