Visible‐to‐MIR broadband modulating electrochromic metal oxides‐based coating for thermal management

Abstract The overheating/cooling of spacecraft solar cells under the contrastive temperature variation due to solar influence leads to severe consequences on both its performance and its long‐term stability. Radiative thermal management by broadband optical modulating coating provides a versatile and effective solution for spatial environments. Here we design a visible‐to‐mid‐infrared broadband modulating metal oxide‐based electrochromic coating for spacecraft solar cell thermal management. Upon impedance matching between multilayered architecture and control of crystallinity of WO 3 with optimized morphology, the final coating successfully presents reversible transition from solar transmitter and thermal emitter to heat preserving coating with infrared (IR) stealth ability. The transmission spectrum of the coating in its bleached state fits the solar spectrum curve (0.3‐1.2 μm) for photocurrent harvesting and it transmits up to 88% at 450 nm, at the solar radiation peak. The average mid‐infrared (MIR) (2‐16 μm) emissivity of the coating is 80%, with a tunability of 20% in average. The demonstrated capabilities of broadband modulating electrochromic coating are highly promising for solar cell thermoregulation in space or terrestrial environments and also for IR‐stealth applications in the defense sector.