Optical parameters of a novel competitive selective absorber for low temperature solar thermal applications

Up to now many efforts have been put into environmentally friendly techniques for designing high quality selective absorbers to take advantage of the abundant and clean solar energy sources. In this paper a new selective absorber for low temperature thermal applications is presented. It is a multilayered absorber, specifically a three layer configuration, with only one layer of absorber material. It is composed of CuMnOx thin film and two consecutive antireflective coatings: FeMnCuOx and SiO2. The CuMnOx film and the FeMnCuOx antireflective layer were prepared from alcoholic solutions containing metal nitrates while the solution used to prepare the SiO2 coating was prepared from silicon alkoxides. The deposition of the three layers onto the aluminum substrate achieves solar absorptance values of 0.957 and thermal emittance values of 0.038 at 100 °C. In this way, it is obtained a very good selective absorber with three layers configuration by using a simple, reproducible and cost-effective method such as dip coating.