Antireflection coatings with FeSi2 layer: Application to spectrally selective infrared emitter

We have developed efficient spectrally selective infrared (IR) emitters that can be utilized for thermophotovoltaic (TPV) power generation by using stainless steel (SUS304) substrates coated with β- FeSi2 thin films. To develop spectrally selective emitters, we theoretically propose antireflection (AR) coatings consisting of a single layer of a dielectric material having a high refractive index (∼5) and are appropriate for use with metals such as stainless steels in the IR region. This type of AR coating is fabricated by sputtering a β- FeSi2 thin film on a polished SUS304 substrate. The reflectance in the IR region is successfully reduced to less than 10%. In addition, the AR properties are stable even at 700 K in air. Therefore, metals with AR coatings of β- FeSi2 can be applied to IR emitters in TPV systems.