Transparent, Conductive, and Flexible Carbon Nanotube Films and Their Application in Organic Light-Emitting Diodes

TLDR

The films were employed as hole‑injection electrodes for OLEDs on both rigid glass and flexible substrates. The authors compared HiPCO and arc‑discharge CNT films, then improved the arc‑discharge films with PEDOT passivation and SOCl₂ doping to enhance surface smoothness and lower sheet resistance. Arc‑discharge CNT films outperformed HiPCO films in roughness, resistance, and transparency, achieving ~160 Ω/□ at 87 % transparency and enabling OLEDs with high stability and long lifetimes.

Abstract

We have carried out comparative studies on transparent conductive thin films made with two kinds of commercial carbon nanotubes: HiPCO and arc-discharge nanotubes. These films have been further exploited as hole-injection electrodes for organic light-emitting diodes (OLEDs) on both rigid glass and flexible substrates. Our experiments reveal that films based on arc-discharge nanotubes are overwhelmingly better than HiPCO-nanotube-based films in all of the critical aspects, including surface roughness, sheet resistance, and transparency. Further improvement in arc-discharge nanotube films has been achieved by using PEDOT passivation for better surface smoothness and using SOCl2 doping for lower sheet resistance. The optimized films show a typical sheet resistance of ∼160 Ω/□ at 87% transparency and have been used successfully to make OLEDs with high stabilities and long lifetimes.