ABSTRACT Tunable modulation of infrared (IR) radiation while preserving visible transparency is highly desirable for applications such as information concealment, energy‐efficient windows, and adaptive building envelopes. Mechanical actuation provides a broadband, low‐power, and durable strategy for IR modulation by physically reconfiguring structures rather than relying on electronic or thermal effects. However, most existing mechanically actuated IR modulators employ simple metallic films whose high visible band reflectance causes strong glare and poor optical compatibility, limiting their integration with color‐tuned or transparent surfaces. Here, we demonstrate a visibly‐transparent mechanically‐tunable IR modulator that maintains over 80% visible transmittance while continuously varying IR reflectance (3–15 µm) from 92% to 48%. The device comprises an indium tin oxide/silver/indium tin oxide (ITO/Ag/ITO, IAI) tri‐layer film on a broadband‐transparent flexible substrate. The ITO layers optimize the Ag film's optical admittance to suppress visible Fresnel losses, while mechanical strain induces microcrack formation that opens IR pathways without degrading visible transparency. This simple and scalable platform enables independent multispectral operation, including IR information concealment with preserved appearance, radiative heating regulation, and daytime/nighttime temperature control on colored surfaces. The concept offers a practical route toward dynamic IR management for multispectral camouflage, smart windows, and adaptive thermal regulation.
Li et al. (Sun,) studied this question.