Noniridescent and Robust Structural-Colored Coating for Automotives Based on the Mie Scattering of ZnO Spheres

Compared with pigments, the structural colors of photonic crystals (PCs) or amorphous PCs attract broad attention. Especially, antifading properties make them good candidates for automotive coatings. However, covering the topcoat on their surface, which is necessary to make the color layer robust, will greatly decrease the color brightness due to the nearly same refractive index of the topcoat and PCs. Here, we propose an alternative strategy for achieving structural-colored automotive coatings based on the Mie scattering of ZnO spheres. The disordered ZnO thin layers on the primer/steel panels are obtained by a spraying method, which can generate vivid noniridescent structural colors due to the strong Mie scattering of ZnO spheres. It is worth noting that the covering of varnish does not decrease the color brightness obviously due to the different color-generating mechanisms. The structural color can be tuned by changing the diameter of ZnO spheres. Furthermore, complex patterns can be easily obtained by spray-coating ZnO spheres using masks. The patterned or fully covered Mie coating with good chemical and mechanical stability can be prepared on different substrates, where the robust noniridescent vivid structural colors offer a convenient and eco-friendly choice for automotive coatings.