Metallodielectric photonic glass paints enable hyperchromatic, angle-independent structural color across the full visible spectrum

초록

Colloidal photonic glasses are attractive as dye-free, solution-processable pigments that show weak angle dependence, but their red hues are notoriously washed out, because single-particle Rayleigh/Mie scattering produces a strong blue background (form factor). Here, we report metallodielectric photonic glass paints that deliver hyperchromatic structural colors, including vivid angle-independent red. We disperse monodisperse Au@SiO2 core-shell colloids at 34 vol% in a photocurable, refractive-index-matched ethoxylated trimethylolpropane triacrylate resin. The Au core introduces selective absorption below similar to 500 nm wavelength, suppressing form factor scattering that would otherwise leak blue light, while index matching sharpens the structure factor-driven reflection by reducing diffuse multiple scattering. A modified Monte Carlo multiple-scattering model predicts spectral narrowing only when both effects are combined. Derjaguin, Landau, Verwey, and Overbeek calculations and Langevin molecular-dynamics simulations reveal that Au-enhanced van der Waals attraction favors reaction-limited crystallization; adding NaCl reduces the Debye length and switches assembly to diffusion-limited aggregation, yielding amorphous short-range order. After ultraviolet (UV) curing into similar to 100 mu m-thick films, the resulting photonic glasses exhibit bright, angle-independent structural colors across the visible range through particle-size tuning. In particular, 230 nm Au@SiO2 colloidal glasses show a reflectance band confined to 600 to 800 nm wavelengths, producing a saturated red with minimal blue leakage. Because the precursor is a stable liquid resin, the photonic glasses can be freehand-painted to create large-area coatings and fine graphics with high brightness even under sunlight. This work establishes design rules for completing the structural color palette in photonic glasses and provides a practical route to structural color paints.

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