Visibly Transparent and Infrared Reflective Coatings for Personal Thermal Management and Thermal Camouflage

Abstract

Tailoring thermal radiation using low-infrared-emissivity materials has drawn significant attention for diverse applications, such as passive radiative heating and thermal camouflage. However, the previously reported low-infrared-emissivity materials have the bottleneck of lacking independent control over visible optical properties. Here, a novel visibly transparent and infrared reflective (VTIR) coating by exploiting a nano-mesh patterning strategy with an oxide-metal-oxide tri-layer structure is reported. The VTIR coating shows simultaneously high transmittance in the visible region (>80% at 550 nm) and low emissivity in the mid-infrared region (< 20% in 7-14 mu m). The VTIR coating not only achieves a radiative heating effect of 6.6 degrees C for indoor conditions but also enables a synergetic effect with photothermal materials to keep human body warm at freezing temperatures for outdoor conditions, which is 10-15 degrees C warmer than normal cotton and Mylar film. Moreover, it demonstrates an excellent thermal camouflage effect at various temperatures (34-250 degrees C) and good compatibility with visible camouflage on the same object, making it ideal for both daytime and nighttime cloaking. With its unique and versatile spectral features, this novel VTIR design has great potential to make a significant impact on personal heat management and counter-surveillance applications.