All-Carbon Composite Electrodes with Uniform Carbon Nanotube Networks for Durable and Transparent Conducting Electrode

Abstract

Development of indium tin oxide-free, flexible transparent conductive electrodes (TCEs) is essential for the future commercialization of flexible and wearable electronics. While carbon-based TCEs containing carbon nanotube (CNT) networks show promise, the poor dispersion properties limit their performance and practicality. In this work, we report a highly efficient and bending durable all-carbon composite TCE (ac-TCE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The excellent performance of the ac-TCEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds in the as-processed graphene. The sheet resistance of the ac-TCEs was increased only 6 % from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237 %. Mechanical bending of the ac-TCEs worsened the electrical performance by only ~1.7 % after 2,000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TCEs. The optimized, hole-doped ac-TCEs shows a typical sheet resistance of ~105 ± 15 ohm/sq at ~90 % transparency, closer to practical TCEs in wearable devices.