3D Anti-Counterfeiting strategies based on the bidirectional competitive shape memory of asymmetric photonic crystals

Structural color anti-counterfeiting based on “hidden-display” generally drives from a “one input one output” mode, which makes nanophotonic cryptography too rudimentary to resist the increasing theft of information. Herein, by creating asymmetric photonic crystals (APCs), we report bidirectional competitive shape memory (CSM) and propose structural color-based “one input three outputs” 3D anti-counterfeiting strategies. The wetting-evaporation of the solvent triggers the three outputs of the structural color of APC. 3D decryption effects include solvent-wetting-induced display of source code (1st-level), solvent-evaporation-triggered structural color evolution or pseudocode interference (2nd-level), and complementary authentication of code (3rd-level). Dipole-dipole thermal reconfiguration dissipates the entropic elasticity temporarily stored in cold-programed longitudinal asymmetrical inverse opals and locks the skeleton network, appending transverse asymmetry. Such bidirectional asymmetry of the skeleton drives the solvent to generate multidimensional Laplace pressure differences (Δ P ) during wetting and evaporation, resulting in the competitive shape evolution of the macropore skeleton in both longitudinal and transverse directions. Moreover, the differential thickness of the inner inverse opal also enables such bidirectional CSM. Unprecedented 3D anti-counterfeiting techniques have been demonstrated. This work opens up new methods for stepwise editing and extracting complex structurally colored codes, providing design inspirations for high-level nanophotonic anti-counterfeiting.