A review of high-temperature selective absorbing coatings for solar thermal applications

Abstract

Solar selective absorbing coatings directly harvest solar energy in the form of heat. The higher temperatures are required to drive higher power-cycle efficiencies in favor of lower costs of energy. According to different dielectrics, high temperature coatings can mainly be divided to double cermet solar selective coatings, transition metal nitride multilayer coatings and transition metal oxide multilayer coatings. This paper assesses the photothermal conversion efficiency and thermal stability, and discusses the challenges and strategies of improving both thermal and optical properties. Double cermet layers can stabilize nanocrystalline structures by alloying, while transition metal nitride/oxide layers generally choose the reliable materials with superior mechanical properties and thermal stability. The purpose of this review is to get the optimized systems, and propose further research directions at higher temperature, such as all-ceramic absorbing coatings. Keywords: High temperature, Solar selective absorbing coatings, Photothermal conversion efficiency, Spectral selectivity, Thermal stability