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Yun Liu

My goal is to jump-start organic photovoltaics research by testing the idea that the use of non-fullerene acceptors (NFAs) can allow OPVs to operate in the high-efficiency radiative limit that materials like GaAs and halide perovskites. Highly-absorbing non-fullerene acceptor (NFA) materials, have recently achieved power conversion efficiencies over 13%. Our hypothesis is that charge separation is possible even in highly-luminescent polymer/NFA OPVs, suggesting a novel photogeneration mechanism as compared to their non-luminescent fullerene-based counterparts. Since the light absorbed by NFAs accounts for a significant fraction of photocurrent generation in devices, hole transfer from the NFAs to the donor is particularly important. I will use ultrafast spectroscopy to study the kinetics of exciton dissociation and charge generation in model polymer/NFA blends. By exciting different exciton species in NFAs, I will also investigate ‘hot’ exciton dissociation. This will provide one of the first detailed understandings of charge carrier generation in polymer/NFA systems.

Advisor: David Ginger – Chemistry