Understanding the charge transfer mechanism in a donor-acceptor cavity system

The performance of organic donor-acceptor heterojunctions in solar cell devices is fundamentally determined by factors such as charge separation efficiency, charge carrier mobility, exciton diffusion lengths, and energy losses due to exciton recombination. Despite advancements in organic photovoltaic materials, exciton transport is frequently hindered by structural disorder, which limits overall device efficiency. Exciton-polaritons, formed through the strong coupling of cavity-coupled organic materials, exhibit delocalized states that enhance exciton transport and reduce the effects of disorder. Thus, it is of interest to elucidate the influence of strong coupling on charge transfer dynamics in organic photovoltaic materials. Using transient absorption spectroscopy, we explore the effect of cavity-strong-coupling in DBPC70 donor-acceptor blends integrated with a distributed Bragg reflector cavity. We find that the presence of the cavity slows the charge transfer process in such heterojunction systems.