Quantum Interference and Coherence Effects on Charge Transport in Organic Semiconductors

非技术描述：本项目旨在制备和研究由具有电子特性的有机分子制成的新材料，以增强半导体的性能。这些电子特性决定了电子如何在半导体中沿着多种可能的路径流动，因此预计会影响材料的行为。利用超快激光的光学探针技术被用于了解包含这些新的有机分子的半导体中的电子电荷传输的细节。这种半导体可用于显著提高通信和信息技术核心的超快光学或电子设备的性能。这些廉价的材料，虽然对实现设备性能的改进很有吸引力，但也可能对经济产生重大影响。该项目涵盖了材料科学的各个学科，为所有学术水平的科学家提供了培训机会。拓展计划还包括西北大学正在进行的将K-12年级学生纳入教育活动的努力。技术描述：在有机半导体中，光引发的电荷转移事件可以在非常大的时间尺度范围内发生。然而，电子相干的独特量子力学方面通常只持续10到100飞秒（fs）。本项目设计和合成新的有机半导体，以更容易地检测和利用这些电子相干性，并研究如何利用相干电荷转移的后果来增强有机半导体中的电荷产生和传输。飞秒时间分辨光谱用于研究电荷输运动力学的早期阶段，其中电子相干的影响是明显的。更具体地说，这个项目正在研究在有机半导体的分子构建块中，从一个供体到两个或更多电子受体的相干电荷转移是如何发生的。另外，该项目研究了有机半导体固体薄膜中的相干电荷转移。此外，还讨论了多径电荷转移过程中量子干涉对有机半导体中电子-空穴对产生速率和效率的影响。通过量子相干效应定制有机半导体的设计和性能的能力有望提高半导体器件的性能，从而影响现代通信和信息技术中常用的电子和光子器件。

Nontechnical description: This project addresses preparation and investigation of new materials made of organic molecules possessing electronic properties that enhance the performance of semiconductors. These electronic properties determine how electrons flow along multiple possible pathways in the semiconductor, and therefore are anticipated to affect the material's behavior. Optical probe techniques utilizing ultra-fast lasers are implemented to understand the details of electronic charge transport in semiconductors comprising these new organic molecules. Such semiconductors may be utilized to significantly enhance the performance of ultra-fast optical or electronic devices that are at the core of communications and information technologies. These inexpensive materials, while attractive for implementing improvements to device performance, may therefore also have major impact on the economy. This project encompasses a wide variety of disciplines in materials science, offering training opportunities to scientists at all academic levels. Outreach plans further include ongoing efforts at Northwestern University to integrate students in grades K-12 in educational activities.Technical description: Photo-initiated charge transfer events in organic semiconductors can occur over a very large range of timescales. However, the uniquely quantum mechanical aspect of electronic coherence generally persists for only 10s to 100s of femtoseconds (fs). This project designs and synthesizes new organic semiconductors to more easily detect and exploit these electronic coherences, and to investigate how the consequences of coherent charge transfer can be used to enhance charge generation and transport in organic semiconductors. Femtosecond time-resolved spectroscopies are used to study the charge transport dynamics at the earliest stages, where the influence of electronic coherences is manifest. More specifically, this project is investigating how coherent charge transfer from a donor to two or more electron acceptors occurs within molecular building blocks of organic semiconductors. Separately, the project investigates coherent charge transfer in thin solid films of organic semiconductors. Additionally, the influence of quantum interference in multi-path charge transfer processes on the rate and efficiency of electron-hole pair production in organic semiconductors is addressed. The ability to tailor the design and performance of organic semiconductors via quantum coherence effects is anticipated to enhance semiconductor device performance, therefore impacting electronic and photonic devices commonly used in modern communications and information technologies.