Conductivity vs functionalization in single-walled carbon nanotube films

Abstract

Diazo functionalization is a chemical method that changes the conductance of metallic single-walled carbon nanotubes (SWCNTs) by disrupting the C–C double bonds. Its application to native mixtures of metallic and semiconducting SWCNTs is a promising way of large-scale production of semiconducting SWCNTs for use in electronics. This has been well studied on isolated SWCNTs, but the implications on the conductivity of SWCNT materials are still unclear. Here, we study the conductivity of such functionalized SWCNT films with a progressively decreased metallic/semiconducting ratio in a wide range of temperatures (4–300 K) to unravel the charge transport mechanisms of metallic and semiconducting SWCNT subnetworks to show how these components participate in the total conductivity of the films. At low functionalization degree (below 0.2 mol%), the conductivity is dominated by a subnetwork of metallic SWCNTs through two parallel mechanisms: a Luttinger liquid mechanism and a Variable Range Hopping process. Higher functionalization (over 0.4 mol%) destroys the Luttinger liquid mechanism, and a second parallel Variable Range Hopping process arises, attributed to the conduction through the semiconducting SWCNTs. At these high functionalization degrees, the SWCNT film behaves as a material with the desired semiconducting properties.Graphical abstractWe studied the conductivity of chemically functionalized Single Walled Carbon Nanotube films with a progressively decreased metallic/semiconducting ratio in a wide range of temperatures (4–300 K) to unravel the charge transport mechanisms of metallic and semiconducting SWCNT subnetworks to show how these components participate in the total conductivity of the films.