Bi-layered TiAlN based tandem absorbers deposited on Cu and Si substrates using DC magnetron reactive sputtering system have been reported. The TiAlN layer was graded with SiO2 to suppress the surface reflections. A high value of absorptance (0.92) and very low emittance (0.06) at 70 degrees C was achieved because of columnar TiAlN structure and porous surface of the tandem absorber. UV-Visible spectroscopy, scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy techniques were employed to test the thermal stability. The tandem absorber showed high thermal stability in air at 550 degrees C. XPS results confirmed that the TiAlN layer also acts as a diffusion barrier for Cu and therefore the absorption property was not degraded even on heating at high temperature for 4 h. (C) 2016 Elsevier Ltd. All rights reserved.