Enhanced passive thermal stealth properties of VO2 thin films via gradient W doping

Thermal stealth and camouflage have been intensively studied for blending objects with their surroundings against remote thermal image detection. Adaptive control of infrared emissivity has explored extensively as a promising way stealth, but it still requires an additional feedback control. Passive modulation emissivity, however, remained great challenge which precise engineering over wide temperature range. Here, we report drastic improvement passive thin films capable concealing at near room without any control, consists vanadium dioxide (VO2) layer gradient tungsten (W) concentration. The W-doping widens the metal-insulator transition width, accomplishing self-adaptive smooth change emissivity. Our simple approach, applicable to other similar materials improving cloaking, will find applications, such camouflage, urban energy-saving smart windows, improved sensors.