Reflective angle-insensitive structural colors with a wide color gamut employing a Ni/ Ge2Sb2Te5 bilayer broadband absorber

Abstract

A novel approach is proposed for generating reflective angle-insensitive structural colors with high purity, high brightness, and a wide color gamut in an asymmetric Fabry-Perot structure based on an ultra-thin bilayer absorber composed of Ni and Ge2Sb2Te5. The bilayer absorber is designed to have broadband absorption, enhancing the optical absorption across the entire visible spectrum and suppressing the reflection of complementary colors, thereby improving the color purity of reflective colors. By constructing a simplified five-layer structure and controlling only the thickness of the oxide layers, different colors can be achieved while maintaining high levels for all colors. The prepared structural color devices (yellow, cyan, magenta, green, blue, and purple) demonstrate exceptional angle-robust appearance within an incident light range of 0°–60° with reflection peaks exceeding 80%, as demonstrated theoretically and experimentally. This device offers a simple yet effective structure that utilizes a novel material combination and enables cost-effective mass production through just one coating run process. It holds significant potential for diverse applications in micro-nano displays, anti-counterfeiting, color filters, printing, illumination systems, and decorations.