Length-controlled few-walled carbon nanotubes and their effect on the electrical property of flexible transparent conductive films

We investigated the effect of the length of carbon nanotubes (CNTs) on the electrical property of CNT-based flexible, transparent, and conductive films (TCFs). We grew vertically aligned CNTs with controlled lengths, dispersed them in ethanol by ultrasonication, and spray coated them onto polyethylene terephthalate (PET) sheets. We focused on the variation in the sheet resistance and transmittance of the above-mentioned films as a function of the CNT length, and we found that the optimum CNT length was 200 mu m. We concluded that the CNT length should be carefully optimized because a shorter tube affords the advantage of efficient dispersion, while a longer tube helps in reducing the number of contact points between tubes along the electrical conduction path.