3D Printing of Multi‐Layer Diffraction Gratings for Additive Mixing of Structural Colors

ABSTRACT Structural coloration by diffraction grating offers a robust alternative to pigment‐based color generation, yet producing extra‐spectral colors such as magenta remains a challenge. Additive color mixing from multiple diffraction gratings can achieve such coloration, but often at the cost of reduced spatial resolution. Here, we demonstrate 3D printing of multi‐layer diffraction gratings for additive mixing of structural colors from a single pixel. A direct ink writing process involving a non‐contact lateral printing technique allowed for the fabrication of double‐layer diffraction gratings composed of orthogonally aligned nanowire arrays. Subsequent thermal annealing was introduced to rearrange the nanowires to produce distinct structural colors from each layer. The multi‐layer gratings facilitate additive color mixing, successfully generating magenta from the superposition of red and blue diffraction light. The demonstration of additive color mixing from a single pixel suggests potential applications in high‐resolution color displays, filters, and sensors.