Magnetically Tunable 1D Plasmonic Photonic Crystals

Structurally colored materials<b> </b>have been attractive for many years due to their vivid colors, long stability, and easy tunability. Within them, plasmonic and photonic nanostructures are two powerful systems that generate structure colors with easy control of the photonic colors. Although promising, the combination of plasmonic resonance and photonic bandgap within a single system is challenging. In this work, 1D plasmonic photonic crystals with angular-dependent structural colors are fabricated by assembling magneto-plasmonic colloidal nanoparticles under an external magnetic field. Different from conventional 1D photonic crystals, the assembled 1D periodic structures show angular-dependent colors from the selective activation of photonic diffraction and plasmonic scattering. Furthermore, the magneto-plasmonic nanoparticle chains can be fixed in an elastic polymer matrix to produce a photonic film with angular-dependent as well as mechanically tunable optical properties. Thanks to the easy and precise modulation of magnetic assembly, the orientation of the nanochains within the polymer matrix can be precisely controlled to produce photonic films with desired patterns, showing versatile colors from the backward photonic diffraction and forward plasmonic scattering. This work demonstrates an easy way to combine plasmonic and photonic properties within a single system, showing synergetic optical properties and the potential for the development of programmable optical functions for applications in color display, optical devices, and information encryption.