State-Controlled Exclusive Colloidal Assembly for Composition-Invariant Structural Color Mixing

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Colloidal self-assembly offers pigment-free structural coloration.
• Conventional methods are limited to single photonic stopbands, restricting color gamut.

Purpose of the Study:

• To expand the structural color gamut by controlling assembled grain states in colloidal mixtures.
• To achieve precise color mixing without altering particle composition.

Main Methods:

• Utilized depletion forces and modified electrostatic repulsion to tune interparticle potentials.
• Investigated monodisperse, binary, and ternary colloidal mixtures.
• Controlled particle states (fluid, crystal, glass) by adjusting depletant and salt concentrations.

Main Results:

• Monodisperse particles showed tunable states from fluid to crystal to glass.
• Binary mixtures exhibited distinct crystallization and glass formation regimes based on particle size and attraction strength.
• Ternary mixtures achieved smooth, composition-invariant color transitions across the visible spectrum.

Conclusions:

• Developed a versatile strategy for high-fidelity structural color mixing.
• Demonstrated precise control over multiple stopbands and their contributions.
• Presented a robust and reproducible platform for advanced structural coloration.