LAUSR

Highly efficient solar–thermal energy conversion requires refractory absorbers harnessing full spectrum of sunlight, minimal thermal emission, and structural stability at higher operating temperatures. Herein, an ultrathin ultrabroadband omnidirectional silicon carbide–tungsten (SiC‐W) refractory nanocomposite is fabricated by high‐throughput co‐sputtering with superior thermal and oxidation stability. The as‐fabricated SiC‐W nanocomposite (78 nm) deposited on tungsten layer with top anti‐reflective film exhibits high solar absorptance of 95.45% in the wide range of 250–2500 nm with thermal emittance below 0.05 at ambient temperature. The ultrabroadband absorption is achieved by plasmonic resonances triggered by self‐formed tungsten nanoclusters in the range of 500–1500 nm combined with SiC intrinsic absorption below λ < 500 nm. SiC as diffusion barrier also prevents interlayer diffusion and oxidation of tungsten nanoclusters to achieve superior thermal/oxidation stability, when annealed at 900 K (air) and 1050 K (vacuum). This work demonstrates outstanding capability of refractory nanocomposites in high‐performance solar thermal technologies for both terrestrial and space environments.