Self-Limited ultraviolet laser sintering of liquid metal particles for μm-Thick flexible electronics devices

Nanosecond pulsed ultraviolet laser sintering of insulting liquid metal submicron particles films has been proposed to fabricate flexible electromagnetic interference shielding films and electromagnetic metamaterials. The thickness of laser sintered liquid–metal-based films can be prepared as low as around 2 μm, and their sheet resistances are reduced at least seven orders of magnitude, down to 2 Ω/sq. [Display omitted] •High conductive, μm-thick liquid metal particles films were fabricated via UV laser sintering and the self-limited sintering depth is shallow enough to minimize damage even to living leaves substrates.•The sheet resistance of laser sintered liquid metal particles film reduces at least seven orders of magnitude, down to 2 Ω/sq.•Localized surface plasmon resonance effect is simulated to illustrate the UV laser sintering process and the calculated outcomes agree well with the experimental results.•High-Performance electromagnetic interference shielding thin film and electromagnetic metamaterials are applied. Lightweight, deformable and highly conductive conductors are rather appealing in flexible electronics devices such as electromagnetic interference (EMI) shielding films; however, the most commonly used metallic foils or carbon nanomaterials suffer from critical limitation of either film thickness or electrical conductivity. Herein, we present a facile approach to rapidly fabricate sintered liquid metal submicron particles (LMSPs) films in combination spray-coating with direct nanosecond ultraviolet (UV) laser sintering. High conductive, μm-thick sintered LMSPs films were prepared owing to the self-limited penetration depth of UV laser, and their sheet resistances are easily tuned at least seven orders of magnitude by the laser processing parameters. A calculated parametric map upon particle diameter and laser fluence whether or not a liquid metal particle is ruptured has been obtained and it is quite well in accordance to the experiment results. Such laser-sintered LMSPs films are finally utilized to fabricate shielding films with superior EMI shielding effectiveness (SE) of ∼33 dB and specific EMI SE over thickness (SSE/t) of ∼27500 dB•cm2•g−1, and flexible electromagnetic metamaterials with a high absorption above 99.9 % at resonance frequency of 12.9 GHz and 14.3 GHz, showing their high potential for flexible EMI shielding and electromagnetic wave absorption applications.