Inducing Efficient and Multiwavelength Circularly Polarized Emission From Perovskite Nanocrystals Using Chiral Metasurfaces.

Chiral nano-emitters have recently received great research attention due to their technological applications and the need for a fundamental scientific understanding of the structure-property nexus of these nanoscale materials. Lead halide perovskite nanocrystals (LHP NCs) with many interesting optical properties have anticipated great promise for generating chiral emission. However, inducing high anisotropy chiral emission from achiral perovskite NCs remains challenging. Although chiral ligands have been used to induce chirality, their anisotropy factors (g_lum) are low [10^-3 to 10^-2]. Herein, the generation of high anisotropy circularly polarized photoluminescence (CPL) from LHP NCs is demonstrated using chiral metasurfaces by depositing nanocrystals on top of prefabricated resonant photonic structures (2D gammadion arrays). This scalable approach results in CPL with g_lum to a record high of 0.56 for perovskite NCs. Furthermore, the differences between high-index dielectric chiral metasurfaces and metallic ones are explored for inducing chiral emission. More importantly, the generation of simultaneous multi-wavelength circularly polarized light is demonstrated by combining dielectric and metallic chiral metasurfaces.