The production of flexible and transparent conductive films of carbon nanotube/graphene networks coordinated by divalent metal (Cu, Ca or Mg) ions

Divalent metal ions (M2+, M = Cu, Ca or Mg) are used to coordinate oxidized carbon nanotubes (CNTs) and chemically modified graphene (CMG) by the oxygen-containing functional groups. Flexible and transparent conductive films of M2+-coordinated CNT/CMG networks are produced by spin coating. The lowest sheet resistance is 680 Ω/sq at 86% transmittance. Chemical doping with SOCl2 further decreases the value to 370 Ω/sq with only 1% loss in transmittance. The M2+-coordinated CNT/CMG films can withstand 200 bending cycles without losing much in sheet resistance. This method provides a new route to transparent electrode materials with high flexibility and strength.