High temperature annealing effects on optical performance of TiAlN-based solar selective absorber with TiN IR reflector

Higher operating temperature of concentrating solar power plant could help to improving the solar-electricity conversion efficiency. However, solar selective absorber with stability higher than 700 degrees C is still lacking. Here, we explored the potential of a tandem structure absorber of TiN/Ti0.5Al0.5N/Ti0.33Al0.67N/CrAlSiO. The asdeposited tandem absorber had a solar selectivity of 0.887/0.134, which was maintained at 800 degrees C for 1 h. With the annealing temperature increasing from 800 degrees C to 1000 degrees C, the solar absorptance first slowly decreased from 0.887 to 0.866, then dramatically decreased to 0.7 after annealing at 1100 degrees C. Optical simulation indicated that thermal annealing would induced higher optical constants both for the Ti0.5Al0.5N and Ti0.33Al0.67N layers, which is caused by the spinodal decomposition of the cubic TiAlN phase. While the thermal emittance slightly increased from 0.134 to 0.154, as the TiN IR reflector maintained its layer structure even up to 1100 degrees C.