Single-wall carbon nanotubes (SWCNTs) have several fundamental properties that make them attractive for photovoltaics, including high electron and hole mobilities, size-tunable ionization potentials and electron affinities in an energy range relevant to many PV devices, and strong optical transitions in the visible and near-infrared spectral regions. These properties have motivated the use of thin SWCNT films for both charge extraction in PV electrodes <i>and</i> charge generation in PV active layers. In both of these applications, the time scales and mechanisms for interfacial charge separation and recombination play crucial roles in determining the resulting photovoltaic efficiencies. In this presentation, I will discuss time-resolved spectroscopic studies of charge separation and recombination across PV-relevant interfaces with SWCNTs. I will discuss two model interfaces – (1) SWCNT/perovskite interfaces, where the SWCNTs are used to extract holes from the perovskite active layer, and (2) SWCNT/fullerene interfaces, where charges are generated via interfacial dissociation of SWCNT excitons. 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. These time-resolved measurements are correlated with device results to provide a window into the connection between interfacial energetics/kinetics and device function.

Charge separation and recombination at single-walled carbon nanotube photovoltaic interfaces

251st National Meeting (2016)

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