Uniform color coating of multilayered TiO2/Al2O3 films by atomic layer deposition

Thin film optics, based on light interference characteristics, are attracting increasing interest because of their ability to enable a functional color coating for various applications in optical, electronic, and solar industries. Here, we report on the dependence of coloring characteristics on single-layer TiO 2 thicknesses and alternating TiO 2 /Al 2 O 3 multilayer structures prepared by atomic layer deposition (ALD) at a low growth temperature. The ALD TiO 2 and Al 2 O 3 thin films were studied at a low growth temperature of 80°C. Then, the coloring features in the single-layer TiO 2 and alternating TiO 2 /Al 2 O 3 multilayers using both the ALD processes were experimentally examined on a TiN/cut stainless steel sheet. The Essential Macleod software was used to estimate and compare the color coating results. The simulation results revealed that five different colors of the single TiO 2 layers were shown experimentally, depending on the film thickness. For the purpose of highly uniform pink color coating, the film structures of TiO 2 /Al 2 O 3 multilayers were designed in advance. It was experimentally demonstrated that the evaluated colors corresponded well with the simulated color spectrum results, exhibiting a uniform pink color with wide incident angles ranging from 0° to 75°. This article advances practical applications requiring highly uniform color coatings of surfaces in a variety of optical coating areas with complex topographical structures.