Powerful doping of chirality-sorted carbon nanotube films

A fast and convenient method to create n-doped or p-doped carbon nanotube (CNT) films of improved electrical conductivity is presented herein. Free-standing thin flexible films made from unsorted CNTs and composed of predominantly (6,5) or (7,6) chiral angle were exposed to hydrazine (N₂H₄) or boron trifluoride (BF₃) solutions, which decreased the sheet resistance by almost up to an order of magnitude. Analysis of the CNT films surface chemistry indicates that despite benign influence of the dopants on their composition, they strongly, but favorably affected electronic structure. Depending on the type of employed dopant, the Fermi level was strongly shifted upwards or downwards to enhance conduction of electrons or holes for employed n-doping and p-doping agents, respectively. This work provides an effective approach for the formation of CNT or graphene-based macroscopic assemblies such as films or fibers of high electrical conductivity with predetermined type of predominant charge carriers without excessive processing. • A method of n-doping and p-doping of carbon nanotube (CNT) films was developed.• Hydrazine or boron trifluoride reduced sheet resistance by up to an order of magnitude.• Doping has got the strongest influence on the films made from (7,6) and (6,5) sorted CNTs.