Quantum Interference and Coherence Effects on Charge Transport in Organic Semiconductors

非技术性描述：本项目致力于由具有电子特性的有机分子制成的新材料的制备和研究，以提高半导体的性能。这些电子性质决定了电子如何在半导体中沿着沿着多条可能的路径流动，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实施以了解包括这些新的有机分子的半导体中的电子电荷传输的细节。这样的半导体可以用于显著增强处于通信和信息技术的核心的超快光学或电子设备的性能。这些廉价的材料，虽然有吸引力的实施改善设备的性能，因此也可能对经济产生重大影响。该项目涵盖了材料科学的各种学科，为所有学术水平的科学家提供培训机会。推广计划还包括西北大学正在进行的努力，将K-12年级的学生纳入教育活动。技术说明：有机半导体中的光引发电荷转移事件可以在很大的时间范围内发生。然而，电子相干性的独特量子力学方面通常仅持续10秒至100秒的飞秒（fs）。该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结果来增强有机半导体中的电荷产生和传输。飞秒时间分辨光谱被用来研究电荷输运动力学的最早阶段，在那里的电子相干的影响是显而易见的。更具体地说，该项目正在研究如何在有机半导体的分子构建块内发生从供体到两个或更多个电子受体的相干电荷转移。另外，该项目研究有机半导体固体薄膜中的相干电荷转移。此外，多路径电荷转移过程中的量子干涉对有机半导体中电子空穴对产生的速率和效率的影响进行了解决。通过量子相干效应定制有机半导体的设计和性能的能力预计将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.