High-color-purity, angle-invariant, and bidirectional structural colors based on higher-order resonances.

Structural colors with high color purity and low fabrication cost are highly desired in a wide variety of applications including displays, light emitting diodes, decorations, and optical detections. Here, we demonstrate a semitransparent pentalayer structure for creating angle-insensitive, high-purity reflective colors that exploit a higher-order cavity resonance. Moreover, the designed structure in a symmetric configuration presents bright and saturated colors from both directions with a high efficiency up to 85% and a high angular tolerance up to ±60°. The described scheme involves one deposition run, thereby providing a significant step toward large-area applications in various areas.