Chiral Metasurface Synthesis by Circularly Polarized Light

Although many geometrically complex structures have been accomplished in colloids by imposing intrinsic chirality of the nanostructure and/or exerting local chiral bias during chemical process and self-assembly, chiral 3D plasmonic superstructures on the surface/interface using solution process hitherto remains virtually unexplored, which is essential for practical applications of their intriguing electromagnetic/optical properties. In addition to the challenge in aligning the main anisotropic axis of the chiral nanoparticles (NPs) with the normal vector of the substrate surface, aggregation of the particles with high-density deposition causes undesirable inter-particle coupling effects; A significant loss in chiroptical efficiency of the NPs, the lower <i>g</i>-factor, have been reported in many studies upon depositing them on the substrate. In this work, we established a new path to pattern chiral metasurfaces using circularly polarized light (CPL). Direct chirality transfer from photons to nanostructures enabled the fabrication of CPL-induced nanotwisters on the surface area with light exposure. The rotational axis of twisted assemblies is well aligned with the normal vector of the substrate surface, leading to high g-factors. This new technique offers fast (minutes) printing metasurfaces on many substrates including plastic, glass, and flexible polymer substrate without a prior seeding process. The spectral range for chiroptical activities of the printed structures can be modulated by altering the wavelength of light source. The photon-to-matter chirality transfer shown in this technique has the potential to be applied to other light-sensitive materials outside of plasmonic, such as semiconductor and dielectric materials. This simple and versatile fabrication technique can be used for extensive applications, including but not limited to photonic, optoelectronic, and electromechanical devices as well as enantioselective catalytic and sensing systems.