Quantum Interference and Coherence Effects on Charge Transport in Organic Semiconductors

Project: Research project

Project Details


The "Quantum Interference and Coherence Effects on Charge Transport in Organic Semiconductors" project would be led by PI, Dr. Michael Wasielewski, and would also include Co-I Dr. Ryan Young. Organic semiconductors suitable for photonic device applications must be designed for ultrafast photo-driven electron-hole pair formation and subsequent rapid charge transport over long distances. Many such materials are based on electron donor-bridge-acceptor (D-B-A) molecular components, such that optimizing the performance of organic semiconductors requires a fundamental understanding of the microscopic aspects of charge transfer in D-B-A systems at the quantum mechanical level. While charge transfer is inherently quantum mechanical, many of the salient features of electron transfer kinetics have been treated classically. However, these treatments largely ignore the role of quantum coherences between states as they are typically very short lived (~10-100 fs for electronic states) and as such are assumed to have decayed prior to electron transfer. As such, most electron transfer studies focus on the population times of each state and disregard the phase. Recent advances in spectroscopic techniques and improvements in time resolution now make it possible to probe processes on these timescales and observe these coherences and their effects on ultrafast charge transfer directly. Coherence phenomena have been implicated in numerous energy transfer phenomena, but the role of coherence in charge transfer remains largely unexplored. Theory predicts that maintaining electronic coherence in a charge transfer process can accelerate its rate, while controlling quantum interference effects in materials can result in rapid modulation of these rates. Enhancing the performance of organic semiconductors, whose applications depend largely on charge transfer and transport requires developing a detailed understanding of the role that quantum coherence and interference can play in determining the charge transfer and transport properties of these important materials. The ability to tailor the design and performance of organic semiconductors to take advantage of quantum coherence effects on electron-hole pair generation will immediately impact organic photonics and other organic electronics that rely on ultrafast charge transfer. Understanding the role of coherence in charge transfer may also lead to ways to control this phenomenon that could produce materials for ultrafast photonic or electronic switching applications that may impact communications and information science. Graduate education in the Wasielewski group is focused on an integrated approach that encourages students to be problem solvers. The students are taught to prepare complex molecules and at the same time learn the physical techniques necessary to answer the questions that are being addressed in their research problems. Students involved with this project will be strongly encouraged to develop an understanding and practical skills in whatever technique is necessary to solve their research problems. Former students and postdoctoral fellows from the Wasielewski group are pursuing careers in research in academia and industry, as well as in public policy, law, and consultancy. This broader perspective will have significant impact on public and corporate understanding of the value of science in society. Our long-time effort to place women in scientific careers continues with 40% of the current research group being female. In the past seven years four women from the Wasielewski group have o
Effective start/end date6/1/1711/30/20


  • National Science Foundation (DMR-1710104)


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