Plasmonic-Tuned Flash Cu Nanowelding with Ultrafast Photochemical-Reducing and Interlocking on Flexible Plastics

Herein, a high-performance copper nanowire (Cu NW) network (sheet resistance ≈ 17 Ω sq⁻¹, transmittance 88%) fabricated by plasmonic-tuned flash welding (PFW) with ultrafast interlocking and photochemical reducing is reported, which greatly enhance the mechanical and chemical stability of Cu NWs. Xenon flash spectrum is tuned in an optimized distribution (maximized light intensity at 600 nm wavelength) through modulation of electron kinetic energy in the lamp by generating drift potential for preferential photothermal interactions. High-intensity visible light is emitted by the plasmonic-tuned flash, which strongly improves Cu nanowelding without oxidation. Near-infrared spectrum of the flash induced an interlocking structure of NW/polyethylene terephthalate interface by exciting Cu NW surface plasmon polaritons (SPPs), increasing adhesion of the Cu nanonetwork by 208%. In addition, ultrafast photochemical reduction of Cu NWs is accomplished in air by flash-induced electron excitations and relevant chemical reactions. The PFW effects of localized surface plasmons and SPPs on junction welding and adhesion strengthening of Cu network are theoretically studied as physical behaviors by finite-difference time-domain simulations. Finally, a transparent resistive memory and a touch screen panel are demonstrated by using the flash-induced Cu NWs, showing versatile and practical uses of PFW-treated Cu NW electrodes for transparent flexible electronics.