The use of acids in the exfoliation of carbon nanotubes and its application toward fabricating chemically stable and highly conducting transparent films

Abstract Carbon nanotube (CNT) is a promising material for fabricating a stretchable and transparent electrode for future customer electronics. Acid doping is the most popular method to improve the performance of CNT transparent conductive films. Unfortunately, such a method uses volatile dopants, which are sensitive to the air atmosphere, usually resulting in an unstable conductivity. Here, we demonstrate a general strategy to achieve high conductivity and high durability by introducing acid treatments before CNT dispersion. SEM and optical spectroscopies indicate that the assistance of moderate acids can significantly improve the exfoliation of CNTs while their structural damages can be negligible. This approach can increase the conductivity of CNT-polymeric acid transparent films by a factor of above 2, which is comparable to the enhancement by general acid doping after film deposition. Notably, CNT films with H2SO4-assisted dispersion 84% and 91% transmittances exhibit sheet resistances of 75 and 150 Ω/square, respectively. Furthermore, the accelerated reliability tests under high temperature and high relative humidity demonstrate the excellent chemical stability of films with acid-assisted dispersion.