Tunable reflectance of inverse opal-chiral nematic liquid crystal multilayer device by electric- or thermal-control
A new type of electric- or thermal-responsive multilayer device composed of SiO2 bilayer inverse opal (IOP) and chiral nematic liquid crystal (N*LC) was developed. The bilayer IOP was fabricated by layer-by-layer assembly of polystyrene (PS) spheres with two different sizes and showed a reflectance in an extended range of near-infrared region. Furthermore, electric- or thermal-tunable reflectance of the bilayer-IOP-N*LC device was investigated. The device exhibited the photonic bandgap (PBG) of N*LC-IOP composite structure with electric field applied (voltage-on) while presented the reflectance of N*LC without electric field (voltage-off) and the electric-responsive behaviour could be reversibly switched. Besides, the device exhibited gradient redshift of reflectance as temperature increased below the clearing point (Tc) while showed the PBG of N*LC-IOP composite structure when the temperature was above Tc.