Optical Rashba Effect in a Light‐Emitting Perovskite Metasurface

• Published in: Advanced materials (Weinheim) 2022-03, Vol.34 (12), p.e2109157-n/a
• Main Authors: Tian, Jingyi, Adamo, Giorgio, Liu, Hailong, Klein, Maciej, Han, Song, Liu, Hong, Soci, Cesare
• Format: Article
• Language: English
• Subjects: bound states in the continuum; Chirality; Circular polarization; circularly polarized luminescence; directional emission; Electron spin; Embossing; Helicity; hybrid perovskite metasurfaces; Materials science; Metasurfaces; Momentum; monolithic integration; optical Rashba effect; Perovskites; Photoluminescence; Polarization (spin alignment); Purcell enhancement; Room temperature; Spin-orbit interactions; Splitting; Symmetry
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202109157

The Rashba effect, i.e., the splitting of electronic spin‐polarized bands in the momentum space of a crystal with broken inversion symmetry, has enabled the realization of spin‐orbitronic devices, in which spins are manipulated by spin–orbit coupling. In optics, where the helicity of light polarization represents the spin degree of freedom for spin–momentum coupling, the optical Rashba effect is manifested by the splitting of optical states with opposite chirality in the momentum space. Previous realizations of the optical Rashba effect relied on passive devices determining the surface plasmon or light propagation inside nanostructures, or the directional emission of chiral luminescence when hybridized with light‐emitting media. An active device underpinned by the optical Rashba effect is demonstrated here, in which a monolithic halide perovskite metasurface emits highly directional chiral photoluminescence. An all‐dielectric metasurface design with broken in‐plane inversion symmetry is directly embossed into the high‐refractive‐index, light‐emitting perovskite film, yielding a degree of circular polarization of photoluminescence of 60% at room temperature. The optical Rashba effect in active halide perovskite metasurfaces with broken in‐plane inversion symmetry, which allows generation, routing, and enhancement of chiral photoluminescence, is demonstrated. A degree of circular polarization of 60% at room temperature and a sixfold enhancement of photoluminescence intensity are experimentally achieved.