Inkjet-Printed Multilayer Silver Nanowire Films with Tunable Near-Infrared Photothermal Response for Passive Anti-Counterfeiting Applications

While silver nanowire (AgNW) networks are established as next-generation transparent electrodes, their deliberate engineering for spectrally selective near-infrared (NIR) photothermal functionality remains underexplored. This study presents a facile strategy for fabricating AgNW-based passive anti-counterfeiting tags via inkjet printing. By precisely controlling the number of printed layers (1–6), we achieve fine-tuning of the optical and photothermal properties in the NIR region. The transmittance at 550[Formula: see text]nm decreases from 95.4% (1 layer) to 90.5% (6 layers), while the NIR absorption (at 2400[Formula: see text]nm) significantly increases from [Formula: see text]0.01 to [Formula: see text]0.14. More critically, under NIR illumination, the photothermal response exhibits a strong layer-number dependence, with the equilibrium temperature rising from 62.0[Formula: see text]C (1 layer) to 90.9[Formula: see text]C (6 layers) after 60[Formula: see text]s of irradiation. The printed ultra-thin AgNW patterns are visually transparent yet produce stark contrast under an infrared thermal camera without any external excitation. This excitation-free, scalable printing approach, coupled with the tunable photothermal effect, positions inkjet-printed AgNWs as a promising platform for high-security, low-cost anti-counterfeiting technologies.