Hue–Brightness Structural Colors with High Saturation Empowered by Bound States in a Continuum

Structure colors play a key role in display devices, imaging security certification, optical data storage, and so on. However, relatively little work has been done on controlling color brightness, and the reported structures are unable to maintain high saturation at the same time. We demonstrate a symmetry-breaking-driven titanium dioxide (TiO2) dimer metasurface. By precisely inducing quasi-BIC (q-BIC), this structure achieves a spectral response in the visible light band with a reflectance approaching 1 and a full width at half maximum (FWHM) of less than 7.2 nm. Utilizing global size scaling enables support for an ultra-wide color gamut display covering approximately 149.9% of the sRGB color space. By perturbing the structure on one side, we have achieved independent control over the brightness of structural color whilst maintaining high saturation. Furthermore, it is found that this metasurface structure exhibits good robustness against geometric distortions. The structure proposed in this paper opens the way for a wide range of 3D nanoprinting and modern advanced displays in both scientific fields and practical applications.