Carbon Nanotubes - Gradient Transparent Conductive Coatings

The use of carbon nanotubes (CNTs) for the fabrication of transparent conductive coatings, has been very attractive due to the exceptional electrical and mechanical properties as well as the room temperature, solution-based processes compatible with a wide variety of high-volume, low-cost coating and printing technologies (wet deposition).

Recently, we have developed a novel method to integrate CNTs onto a polymer substrate with "built-in" conductivity features based on Emitech's proprietary CNT spraying technology. Our preliminary results demonstrate an excellent incorporation of CNTs in the polymeric transparent substrate due to the softening of the polymer surface layer upon CNT spraying. Thus, the CNT film (with low resistance/ high transparency) is naturally integrated to the polymer matrix (from spraying side) providing a "built in" conductivity feature. As distinct from other CNT films deposited on plastic substrate forming bi-layer structures and ITO deposited films, our gradient coating is extremely durable, which can withstand rigorous bending and harsh environmental conditions.

Image of flexing of CNT-composite film (left panel) and sheet resistance values as a function of the bending numbers (right panel).

The figure shows the image of the flexing of CNT-composite film (left panel) and sheet resistance values as a function of the bending numbers (right panel). The diameter of the bending is one quarter inch.