Nanohelix Arrays with Giant Circular Dichroism through Patch-Enthalpy-Driven Self-Confined Self-Assembly of Janus Nanoparticles.

Plasmonic nanohelix arrays, exhibiting strong circular dichroism, are among the most promising optical chiral metamaterials. However, achieving chiral plasmonic effects in the visible range remains challenging with current manufacturing techniques, as it requires structures small enough to resonate at visible wavelengths. Herein, we propose a novel strategy for constructing nanohelix arrays through patch-enthalpy-driven self-confined self-assembly of Janus nanoparticles. The hexagonal columnar structures, self-assembled from Janus nanoparticles, create a cylindrical self-confined environment within each column, where patch-enthalpy drives the particles to form helical structures. Numerical simulations reveal that patch-enthalpy induces the sequential formation of helical structures within each column, from multiple helices to double helix and finally to single helix. Additionally, optical property calculations demonstrate that these nanohelix arrays exhibit giant circular dichroism and high g-factors at visible frequencies. Our proposed construction strategy offers a promising route for developing optical chiral metamaterials through patch-enthalpy-driven self-confined self-assembly of Janus nanoparticles.