(Invited) Signatures of Charge Carrier (De)Localization in Semiconducting Single-Walled Carbon Nanotubes

Abstract

Semiconducting single-walled carbon nanotubes (s-SWCNTs) are attractive materials for a variety of opto-electronic devices and applications due their strong and energetically tunable optical absorption, and high charge carrier mobilities that result from the delocalized nature of the π-electron system. To realize the full potential of s-SWCNTs in these applications, it is critical to understand the generation, transport, interfacial transfer, and recombination of free charge carriers (electrons and holes). As with many pi-conjugated semiconductors, there remain uncertainties regarding the degree of (de)localization for charge carriers generated in s-SWCNTs either through photogenerated exciton dissociation or through charge injection by adsorbed redox dopants or gating. In this presentation, I will compare the various signatures of charge carrier localization and delocalization that appear in spectroscopic and transport studies of s-SWCNTs in a variety of different environments and over several decades of carrier density. These comparisons help to elucidate the important roles of intrinsic and extrinsic factors on carrier (de)localization and the information that spectroscopic signatures in the visible, near-IR, and mid-IR can provide on such (de)localization.