Ambient‐Spray Ni–Cu(–O)/Ag Nanowire Transparent Heaters for High‐Temperature Heating and Far‐/Near‐Field EMI Suppression

ABSTRACT Modern optoelectronics demand highly efficient transparent heaters that concurrently suppress electromagnetic interference (EMI). To address this, we present a fully solution‐processed, vacuum‐free Ni–Cu(–O)/Ag nanowire platform stabilized by a silica‐hybrid overcoat. The conformal Ni–Cu(–O) shell bridges interwire junctions, transforming fragile point contacts into robust pathways. This architectural breakthrough dramatically enhances Joule heating efficiency and thermal stability. At ∼75% transmittance, the ultrathin (55.6 nm) films deliver an exceptional heating performance up to 438°C (458°C·cm2·V−1) without defect‐driven failure, alongside extreme mechanical durability (ΔR/R0 < 1% over ∼7000 bending cycles). Crucially, this high‐performance heating platform also provides highly tunable EMI shielding. By tuning the Ni/Cu ratio, we effectively modulate the relative contributions of reflection and absorption loss. While high reflection governs far‐field shielding (total effectiveness ≥ 32 dB), adequate non‐reflective absorption is essential to dissipate trapped electromagnetic energy and prevent secondary internal reflections in integrated devices. Supported by direct near‐field magnetic scanning, our tailored core–shell architecture introduces a vital dissipative channel that actively suppresses this local magnetic noise, ensuring supreme electrothermal heating while enabling optimal, on‐demand EMI protection.