Self-doped W–WOx nanocermet multilayer films fabricated by single tungsten target reactive sputtering for selective solar absorption

Abstract

Metal–dielectric (cermet) solar selective absorber coatings (SSACs) have been extensively utilized in photo-thermal conversion due to their strong broad-band absorbance properties. To achieve plasmonic metal nanoparticles embedded in a dielectric matrix, co-sputtering with two or more targets is required. This makes the preparation process more complex, inevitably increasing the fabrication cost. Therefore, simplifying the production process of SSACs to yield platforms with excellent solar-thermal conversion efficiencies is highly desired. Herein, we developed novel self-doped W–WO_x nanocermet multilayer SSACs using only a single tungsten target with limited reactive sputtering. During the process, the limited O₂ consumed only part of the sputtered W atoms to form WO_x, so that plasmonic W nanoparticles were embedded in the WO_x dielectric matrix and yielded self-doped W–WO_x nanocomposite films. The resulting deposited self-doped W–WO_x SSACs possessed high absorptance reaching up 0.93 and low thermal emittance of 0.058. It also possessed excellent thermal stability reaching up 250 °C in air over prolonged periods. Obviously, high-performance self-doped W–WO_x SSACs are very promising for low-cost and large-scale industrial production.