Flexoelectricity and Charge Separation in Carbon Nanotubes
Vasilii I. Artyukhov, Sunny Gupta, Alex Kutana, Boris I. Yakobson
Abstract
The effect of flexoelectric voltage on the electronic and optical properties of single- and double-wall carbon nanotubes is evaluated by the first-principles calculations. The voltage between the inner channel of curved sp2 carbon nanostructures and their surroundings scales linearly with nanotube wall curvature and can be boosted/reversed by appropriate outer wall functionalization. We predict and verify computationally that in double-wall nanotubes, flexoelectricity causes a straddling to staggered band gap transition. Accurate band structure calculations taking into account quasiparticle corrections and excitonic effects lead to an estimated critical diameter of ∼24 Å for this transition. Double-wall nanotubes above this diameter have staggered band alignment and could be potentially used for charge separation in photovoltaic devices.