Characterization of TiAlSiN/TiAlSiON/SiO2 optical stack designed by modelling calculations for solar selective applications

Preparation and characterization of TiAlSiN/TiAlSiON/SiO2 solar selective absorber is reported in this contribution. All layers were deposited in a continuous mode using an industrial equipment. The nitride and oxynitride were prepared by reactive magnetron sputtering and the SiO2 layer by Plasma Enhanced Chemical Vapour Deposition. The optical constants of individual layers were calculated by modelling of spectral transmittance and reflectance of the individual layers. The three layered stack absorber was then designed using those optical properties. The thickness of the individual layers was optimised until a solar absorptance of 96% was obtained resulting in a total thickness of about 200 nm, deposited in copper and extruded aluminium absorbers. An emissivity of 5% for an absorber temperature of 100 °C was obtained by analyzing the measured data from a FTIR spectrometer with integrating sphere. After the test duration of 600 h, the samples subjected to a thermal annealing at 278 °C in air showed a performance criterion (PC) below 4%, while the samples in the humidity tests showed a PC below 2%.

► TiAlSiN/TiAlSiON/SiO2 tandem absorber for solar selective absorption.
► Dielectric function of each layer was modelled and used to build the absorber.
► A solar absorptance of 96% and an emissivity of 5% were obtained.
► After thermal annealing at 278 °C for 600 h the performance criterion was below 4%.
► The performance criterion of aluminium substrates subjected to humidity test was 2%.