Ultrathin Plasmonic Optical/Thermal Barrier: Flash-Light-Sintered Copper Electrodes Compatible with Polyethylene Terephthalate Plastic Substrates.

In recent years, highly conductive, printable electrodes have received tremendous attention in various research fields as the most important constituent components for large-area, low-cost electronics. In terms of an indispensable sintering process for generating electrodes from printable metallic nanomaterials, a flash-light-based sintering technique has been regarded as a viable approach for continuous roll-to-roll processes. In this paper, to satisfy these requisites in both material and process, we report cost-effective, printable Cu electrodes that can be applied to vulnerable polyethylene terephthalate (PET) substrates, by incorporating a heretofore-unrecognized ultrathin plasmonic thermal/optical barrier, which is composed of a 30 nm-thick Ag nanoparticle layer. The different plasmonic behaviors during a flash-light-sintering process are investigated for both Ag and Cu nanoparticles, based on a combined interpretation of experimental results and theoretical calculations. It is demonstrated that by a continuous printing process and a continuous flash-light-sintering process, large-area Cu electrodes are formed successfully on PET substrates, with a sheet resistance of 0.24 Ω/square and a resistivity of 22.6 μΩ·cm.