High-clarity multifunctional Cu/Ni transparent films for efficient electromagnetic interference shielding

Transparent conductive materials still face significant challenges in simultaneously achieving high optical transmittance, broadband electromagnetic interference (EMI) shielding, and excellent environmental stability. In this work, a hexagonal-Voronoi composite metal mesh (HV-CMM) is proposed by integrating a periodic hexagonal framework with stochastic Voronoi substructures, which effectively suppresses optical diffraction while maintaining structural stability. By tuning the characteristic size of the Voronoi features, a synergistic optimization of optical and electromagnetic performance is achieved. The fabricated HV-CMM exhibits high optical transmittance of 78-83% and low haze of 4.5-4.8% in the visible range. Owing to the disruption of long-range periodicity, coherent diffraction is effectively suppressed, leading to improved visual uniformity. In the 1-18 GHz frequency range, the samples demonstrate stable EMI shielding performance, with an average shielding effectiveness of 38.5 dB and a maximum value of 47.8 dB at 12 GHz. In addition, the HV-CMM shows rapid and uniform electrothermal response, reaching a temperature of 143 °C within 150 s under an applied voltage of 1 V. The introduction of a Ni passivation layer significantly enhances environmental stability, reducing the variation in sheet resistance from 152.9% for pure Cu to 42.4% after 240 h under 85 °C/85% RH conditions. This work presents a structure-material co-design strategy, providing a new pathway for multifunctional transparent conductive meshes in applications such as optical windows, defogging/deicing systems, and electromagnetic protection.