(Invited) Charge Separation and Recombination at Semiconducting Single-Walled Carbon Nanotube Interfaces

The time scales and mechanisms for interfacial charge separation and recombination play crucial roles in determining efficiencies of excitonic photovoltaics. Semiconducting SWCNTs are robust light absorbers that have garnered increasing attention as the electron-donating or electron-accepting components in excitonic solar cells. In particular, near-infrared photons are harvested efficiently by semiconducting single-walled carbon nanotubes (SWCNTs) paired with appropriate electron acceptors, such as fullerenes (e.g. C60). While the reported AM1.5 power conversion efficiencies of such devices are steadily increasing, significant improvements remain to be made if a better fundamental understanding is reached for the kinetics and thermodynamics of exciton dissociation and charge recombination. In this presentation, I will discuss a number of time-resolved spectroscopic studies on donor:acceptor heterojunctions that incorporate semiconducting SWCNTs with widely varying band gaps and frontier orbital energies. Following the evolution of excitons and charges with multiple techniques provides a platform for understanding the time scales and quantum yields for interfacial charge transfer, recombination rates and mechanisms, and the dependence of charge transfer rates and yields on interfacial energetics.