Enhanced thermal stability of the metal/dielectric multilayer solar selective absorber by an atomic-layer-deposited Al2O3 barrier layer

Abstract To improve the thermal stability of multilayered solar selective absorber, an atomic-layer-deposited (ALD) Al2O3 layer was adopted to suppress the diffusion of metal atoms from the bottom reflection layer. The designed film structure was as that: Cu (>100.0 nm)/Al2O3 (59.8 nm)/Cr (17.8 nm)/SiO2 (66.3 nm)/Cr (4.4 nm)/SiO2 (83.0 nm). Multi-target magnetron sputtering method was employed to fabricate Cu, SiO2, and Cr layers, while for the Al2O3 layer, it was prepared by ALD. The sample has a solar absorptance of about 95.4% and a thermal emittance of 0.196 at the temperature of 773 K. The sample with the Al2O3 barrier layer work stably at 500 °C for 72 hours, demonstrating that the proposed multilayer solar selective absorber is suitable for applications at middle-temperature solar thermal conversion systems.