Strong electron-electron (e-e) interactions play an important role in determining the electrical and optical properties of nanomaterials. Our group uses individually-contacted carbon nanotubes (CNTs) as a model experimental system to investigate the physics and applications of these strong interactions. I will discuss: (1) The quantum efficiency of CNT photodiodes,¹ (2) renormalization of the band gap in semiconducting CNTs,² (3) the emergence of a Mott insulating state in metallic CNTs. All three of these topics depend critically on the strength of e-e interactions which we tune experimentally using dielectric screening. We also gain new insights by using photocurrent spectroscopy to precisely identify CNT diameter/chirality, and photocurrent microscopy to quantify intrinsic region lengths.

¹ Aspitarte, McCulley, Minot, “Photocurrent Quantum Yield in Suspended Carbon Nanotube PN Junctions” Nano Letters16, 5589 (2016)

² Aspitarte, McCulley, Bertoni, Island, Ostermann, Rontani, Steele & Minot, “Giant modulation of the electronic band gap of carbon nanotubes by dielectric screening”, Scientific Reports7, 8828 (2017)