Very thin transparent, conductive carbon nanotube films on flexible substrates

We investigate the morphological, electrical, and optical properties of carbon nanotube thin films, focusing on films with transmittance, T>90%. For films with T≈90% we measure sheet resistance of Rs<400 Ω/◻. However, we show that optoelectrical properties, such as σdc and σdc/σOp, degrade with decreasing film thickness, t, for percolating nanotube networks, i.e., those with t<20 nm and T>90%. Thus, while reducing t can give T>99%, the corresponding Rs increases to >40 kΩ/◻. Acid treatment improves the conductivity by doping, giving properties such as T≈98% for Rs≈10 kΩ/◻.