High-Chroma, High-Contrast Tunable Color Coatings Using Sb2S3 in a Metal-Dielectric Stack

Abstract

Thin-film coatings are a versatile option for creating color. These coatings can be made tunable by introducing phase-change materials (PCMs), whose optical response changes due to an external signal. However, commonly used PCMs such as Ge₂Sb₂Te₅ (GST) are limited in their applications for color coatings, due to high absorption of visible light. Here, the alternative PCM Sb₂S₃ is used, and a novel coating design is demonstrated, which incorporates the PCM layer into an asymmetric Fabry–Perot cavity with Ag, SiO₂ and Ti layers. Simulations are used to show that this design yields high-chroma colors in a wide range of hues, which exhibit a large tunable hue shift when the phase of the Sb₂S₃ layer changes. Three coatings are deposited to experimentally verify these results, which give good agreement with the simulations. The phase change of the Sb₂S₃ layer is demonstrated using direct heating using a hotplate, and also using laser annealing, which allows microscale image writing to be realized on the coatings.