Highly Stable Ni-Based Flexible Transparent Conducting Panels Fabricated by Laser Digital Patterning

A novel simple laser digital patterning process to fabricate Ni-based flexible transparent conducting panels using solution-processed nonstoichiometric nickel oxide (NiOx) thin films and their applications for flexible transparent devices are reported in this study. A large-scale synthesis route to produce NiOx nanoparticle (NP) ink is also demonstrated. A low-power continuous-wave laser irradiation photothermochemically reduces and sinters selected areas of a NiOx NP thin film to produce Ni electrode patterns. Owing to the innovative NiOx NP ink and substantially lowered applied laser power density, Ni conductors can be fabricated, for the first time to the best of the authors' knowledge, even on a polyethylene terephthalate substrate, which is known to have one of the lowest glass-transition temperatures among polymers. The resultant Ni electrodes exhibit a high-temperature oxidation resistance up to approximately 400 degrees C, and high corrosion resistance in tap water and even in seawater. Moreover, a superior mechanical stability of the Ni conductors is confirmed by tape-pull, ultrasonic-bath, bending/twisting, and cyclic bending (up to 10 000 cycles) tests. Finally, flexible transparent touch screen panels and electrical heaters are fabricated with mesh-type Ni conductors to demonstrate possible applications.