Selective Directional Enhancement in Gold/Perovskite Quantum Dot Metasurfaces

Controlling directional radiation with minimal loss and fabrication effort through scalable methods is essential for integrating metasurfaces into photonic devices. Existing strategies enable tuning radiation properties by altering optical parameters of subwavelength dielectric gratings. Herein, a simple method is demonstrated to control the radiation direction of perovskite quantum dot (QD) metasurfaces through the addition of thin gold layers. This approach utilizes hybrid plasmonic modes and defect-free, template-assisted self-assembly techniques for low-loss, large-area production. This colloidal method allows precise control over nanostructure formation, ensuring reproducibility and enhanced optical properties. A 4.6-fold enhancement of the radiation toward the substrate and a 4.4-fold enhancement toward the cover region is achieved by evaporating a thin gold film with an optimal periodicity of 500 nm. Notably, the insertion of a metal layer allows the cover mode to exhibit enhancements that exceed typical expectations for plasmonic metasurfaces. This design is supported by plasmonic lattice theory and validated by electromagnetic modeling, allowing the gamma point to be customized to enhance emission in specific directions and media directly. This rational design strategy enhances the functionality of plasmonic perovskite-based metasurfaces for photonic on-chip applications, including nonlinear light-emitting devices and directional light sources.