Medium-Entropy Nitride ZrNbMo-W-N Nanofilm-Based Substrate-Independent Selective Solar Absorber by a Cosputtering Method

Harvesting solar energy across the broad spectrum yet suppressing radiative heat loss in the infrared region has essential implications for solar-thermal applications. Multicomponent alloy nitride nanofilms are a promising class of materials that boost the solar-thermal conversion efficiency. Here, we build up a medium-entropy nitride ZrNbMo-W-N nanofilm-based selective solar absorber (SSA) by a cosputtering method. By fully studying the optical properties of single-layer ZrNbMo-W-N films, the optimized absorber with a trilayer structure achieves a significant boost in the optical performance, that is, an exceptional solar absorptance of 95.2% and a low emittance of 18.7% (400 °C), as well as angle-insensitive absorption. Moreover, the medium-entropy nitride-based absorber also enables remarkable structural and optical robustness, which retains a sound absorptance of 93.8% and a suppressed thermal emittance of 10.3% after annealing at 400 °C for 168 h, promising great potential for medium- and low-temperature applications. More significantly, our designed SSA can be easily fabricated on various substrates using optimized deposition parameters. In particular, the absorber is well deposited on a flexible cotton substrate, showing excellent solar absorption. It is believed that the combination of a multicomponent strategy and a cosputtering method, which can further modulate optical properties by suitably tailoring the elemental content and species, paves an effective way to investigate this kind of state-of-the-art solar-thermal materials.