Microstructures of responsive photonic crystals on the stimuli-responsive performance: Effects and simulation

Nature provides abundant photonic structures which give a great inspiration on the synthesis of stimuli-responsive photonic crystals (PCs) with unique structures. However, the intrinsic effects of microstructures on the responsive properties of the hierarchical PCs are still not clear. Herein, the relationship between the photonic structures and the responsive properties is investigated by choosing three natural photonic structures replicated from templates, Morpho Menelaus and Morpho peleides both with a 1D tree-like hierarchical structure while having eight and four layers, respectively and Papilio paris, with an eight layered 1D concave structure. Humidity responsive PCs were prepared by in-situ polymerizing polyacrylamide (PAAm) onto the surface of the butterfly wing scales. The 1D concave (Papilio paris) structured PCs exhibited a higher humidity sensitivity: a wavelength redshift of 92 nm when the relative humidity rose from 11 to 97 %, as compared with the Morpho menelaus PCs, which have about 70 nm redshift for the same rise of the relative humidity. The eight layer 1D tree-like structured Morpho menelaus PCs had a higher reflectance intensity. The results were also supported by a finite-difference time-domain (FDTD) simulation. This work paves a new avenue to design responsive PCs with a diversity of structures from nature and controllable responsive properties.