Photonic Crystals with Tunable Lattice Structures Based on Anisotropic Metal–Organic Framework Particles and Their Application in Anticounterfeiting

Abstract

Photonic crystals (PCs) with controllable lattice structures, photonic bandgaps, and brilliant colors are fabricated by the self-assembly of the monodispersed anisotropic metal-organic framework (MOF) ZIF-8 particles into long-range ordered superstructures. The shape parameter (m) of the particles is used to quantify to what degree the particle shape has deformed from that of a perfect sphere (m = 2) and that of a perfect cube (m = ∞). It is exptl. proven that m value is the key for controlling the lattice structures. Three PCs with different m values of ZIF-8 particles (9.7, 4.7, and 2.5) are found to be simple cubic, rhombohedral, and face-centered-cubic structures, resp. Different from the conventional spherical particles-based PCs, brilliant colors can be generated from the second-order diffraction of the nonspherical MOFs-based PCs. Taking advantage of this unique characteristic, a new information encryption technol. is developed by combing the first-order diffraction of rhombohedral PCs and first-second-order diffraction of simple-cubic PCs. This work paves a way to explore nonspherical particle-based PCs materials with different crystal forms and provides a new insight in novel optical characteristics of the PCs, which will promote their applications in anticounterfeiting, color displays, and printings.