Experimental Study on the Relation between the Thermal Radiative Properties and Plasma Wavelength of ITO Films for Heat Mirror Applications

There is an increasing interest for the heat mirror films, especially, deposited on rigid or flexible black substrates used as a spectral selective absorbing coating which differs from the common selective absorber needing a metal substrate with low emissivity. The single layer indium tin oxides heat mirror films (HMF) were deposited onto unheated glass and rigid or flexible plastic substrates by conventional RF sputtering technique. The relation between the thermal radiative properties and the plasma wavelength of indium tin oxides heat mirror films were obtained based on experimental studies. The results show that it is impossible to get ITO HMF simultaneously with maximum reflectance in thermal long wavelength region and minimum reflectance in the solar spectral region. However, the plasma wavelength can be take as a criterion to predict the thermal radiative properties of ITO HMF, approximately.