Infrared Gasochromic Devices Based on Metal Thin Films

Variable infrared emissive materials and devices are effective for the dynamic modulation of infrared radiation. Herein, a new idea of dynamic emissivity modulation based on the hydrogen-induced metal-insulator phase transition from metallic yttrium (or yttrium dihydride) to dielectric yttrium trihydride is proposed, and infrared gasochromic devices based on yttrium/rhodium metal thin films and infrared-transparent covers are developed. By alternately injecting 4% hydrogen-argon gas mixture and air into the gasochromic device, the infrared emissivity of the device is dynamically modulated reversibly. The emissivity changes in the 340-nm-yttrium/6-nm-rhodium device are 0.25 and 0.39 in the 3-5 and 7.5-14 mu m atmospheric window regions, respectively, and the response time is <40 s. The emissivity change is affected by the surface morphology and thickness of the yttrium/rhodium film. Moreover, the infrared gasochromic device operates effectively over 100 cycles, and subsequent failure is attributed to oxidation of the yttrium film. The proposed device is easily enlarged and patterned because of its simple structure, thereby indicating that such metal thin films provide a new material platform for dynamic infrared radiation modulation, which has great application prospects in the fields of adaptive thermal camouflage, smart thermal management, and infrared information display.