Achievements in mid and high-temperature selective absorber coatings by physical vapor deposition (PVD) for solar thermal Application-A review

Solar energy can be harnessed using different evolving technologies like photovoltaic (PV), artificial photosynthesis, solar heating, solar thermal power plant, etc., whose progress depends on the materials in the collector. Most solar collectors use spectrally selective absorber coating with high absorptance and low emittance in the solar and at the infrared spectrum range respectively. Several efforts have been put since 1990s by different authors towards synthesizing highly efficient and thermally stable solar absorber coating for mid to high temperature applications using different deposition methods. It has been established that, the photothermal conversion efficiency of solar thermal power plant depends on the selective absorber coating with high thermal stability and excellent optical properties. This paper reviews the different types of solar absorber coatings and the current state of the art of the existing mid and high temperature absorber coatings with an emphasis on the sputter deposited coatings. A detail survey on the commercially available mid and high temperature absorber coatings with high absorptance and low emittance have been carried out. The aim of this review article is to know what has been achieved so far on the performance and thermal stability of absorber coatings especially in an air ambient. Also, the scope of performance improvement has been highlighted in this paper.