Thermal imaging and analysis of carbon nanotube composites

Carbon nanotube (CNT) films have a broad range of applications, from solar cells and transistors to bolometers and mechanical reinforcement additives for polymers. However, surprisingly little is still known about the thermal properties of such CNT films, and in particular about the intertube junctions. This study examines suspended films of conductive single-wall CNT (SWNT) films through electrical measurements and optical infrared (IR) thermometry in order to simultaneously characterize their electrical and thermal properties. Using an IR microscope, the real-time temperature profile of such CNT films under bias is mapped and used to extract thermal conductivity. A computation model was also developed to fit the one-dimensional heat diffusion equation to the temperature profile captured by the IR scope, including the effect of thermal contact resistance and heat loss to ambient. Transfer length method measurements were used to extract electrical contact resistance between the film and the electrodes. These methods were applied to investigate the properties of CNT films with several different morphologies, revealing that both electrical and thermal properties are strongly dependent on CNT volume density and junction within the films. Understanding fundamental transport within CNT networks allows us to try and decouple the properties and engineer novel materials for applications such as energy harvesting using thermoelectric power generation