Photocatalysis‐Assisted Silver Reduction via ZnO Nanoparticles for High‐Resolution, Flexible, and Etch‐Free Printed Electronics

Abstract Recently, the development of environmentally friendly etch‐free micro‐printed circuit boards with fine‐line traces has garnered significant attention. A novel photonic‐assisted fabrication method is introduced that utilizes ultraviolet (UV) light and intense pulsed light (IPL) to produce highly conductive silver films on flexible substrates. Although silver organometallics can be reduced by the heating effect from localized surface plasmons (LSPs), this process alone is inefficient. Introducing zinc oxide nanoparticles (ZnO NPs) under UV illumination leverages their photocatalytic activity to accelerate Ag+ reduction, enabling faster film formation than silver‐only samples However, the resulting films initially exhibit relatively high resistivity (377.77 µΩ cm) due to insufficient light intensity. To address this, IPL is utilized to facilitate the reduction and sintering process. Optimizing IPL power and ZnO NP thermal uniformity produced ZnO/Ag films with low resistivity (6.3 µΩ cm) and fine lines (37.46 µm) in seconds, while suppressing defects typical of Ag‐only films. The resulting films demonstrate excellent mechanical and oxidative stability. Its conductivity arises from the synergistic interaction between the plasmonic resonance of silver and the photocatalytic activity of ZnO NPs, with the former also amplifying the latter. This tunable, energy‐efficient, and environmentally friendly method is promising for photonic‐integrated flexible systems and organic light‐emitting diodes.