Multilayer structures based on phase-change materials for reconfigurable structural color generation

We introduce multilayer structures based on phase-change materials (PCMs) for reconfigurable structural color generation. These structures can achieve multiple colors within a single pixel. Our optimized structures with a single PCM layer generate two distinct colors by switching between the two phases of the PCM. Similarly, our optimized structures with two PCM layers generate four distinct colors. To achieve maximally distinct colors in the two-color structures, we maximize the distance between the color coordinates on the International Commission on Illumination (CIE) chromaticity diagram. Similarly, in the four-color structures we maximize the minimum distance between the coordinates of the four colors. We use a memetic optimization algorithm to optimize both the material composition and the layer thicknesses of the multilayer structures. To achieve different colors, we consider several PCMs. We find that our design approach leads to large distances between the generated colors on the CIE diagram. Our results could lead to a new class of single-cell multicolor pixels with no power consumption required to retain each color, making them appealing for low refresh rate displays.