Stretchable, Ultrathin, Porous Metallic Films With Ultrahigh‐Conductivity for Ultrabroadband Ultraviolet–Visible–Infrared‐Microwave Management

ABSTRACT Lightweight, ultrathin, and mechanically ultraflexible electromagnetic interference (EMI) shielding materials are urgently needed for next‐generation electronics. Herein, we develop a stretchable, porous thin film featuring a low‐roughness copper nanolayer (CuNL) and highly fused polyurethane (PU) fiber networks via a facile, scalable combination of electrospinning, hot pressing, and electroless plating. The conformal core–shell architecture integrates a highly conductive CuNL with an elastic porous scaffold, delivering excellent conductivity (8.5 × 10 5 S m − 1 ), high stretchability (tensile strain >100%), air permeability, hydrophobicity, waterproof capability, and broadband high‐efficiency EMI shielding performance. At an ultralow thickness of 2.9 µm and density of 1.39 g cm − 3 , the film achieves an EMI shielding effectiveness (SE) of over 50 dB, a thickness‐normalized SE of 17 586 dB mm − 1 , and a surface‐specific SE of 127 500 dB cm 2 g − 1 , outperforming existing metal‐based and flexible EMI shields. Moreover, the wearable PU/CuNL film offers >90% ultraviolet–visible–infrared (UV–vis–IR) reflectance, enabling integrated UV protection, thermoregulation, and IR thermal‐radiation management. This work provides a promising platform for lightweight yet ultrathin multifunctional materials that combine high‐performance EMI shielding, mechanical deformability, and multispectral management for future flexible electronics and wearable devices.