Optical Rashba effect in a monolithic light-emitting perovskite metasurface

TL;DR

This paper demonstrates an active, monolithic halide perovskite metasurface that exhibits a strong optical Rashba effect, enabling highly directional chiral photoluminescence with significant circular polarization at room temperature.

Contribution

It introduces a novel all-dielectric, monolithic perovskite metasurface with broken in-plane symmetry that actively exhibits the optical Rashba effect, surpassing previous passive and hybrid devices.

Findings

Achieved 40% circular polarization of photoluminescence.

Demonstrated highly directional chiral emission at room temperature.

Surpassed state-of-the-art chiral perovskite performance.

Abstract

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 either the propagation direction of surface plasmons or circularly polarized light into nanostructures, or the directional emission of polarized luminescence from metamaterials hybridized with light-emitting media. Here we demonstrate an active device underpinned by the optical Rashba effect, 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 40% at room temperature - more than one order of magnitude greater than in state of art chiral perovskites.