Abstract: 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.

Key words: thermal radiative properties, heat mirror films, solar selective absorber