# Circularly Polarized Light Emission From Single Chiral Hedgehog Particles Coated with Nanofilms of Achiral Perovskites

## TL;DR

Researchers created particles that emit circularly polarized light by coating chiral structures with non-chiral perovskite nanofilms.

## Contribution

A new method to generate circularly polarized light using achiral perovskites on chiral templates is demonstrated.

## Key findings

- Circularly polarized light emission is achieved from perovskite-coated chiral hedgehog particles.
- Post-emission scattering from the chiral surfaces dominates the observed polarization.
- The method allows for tunable and controllable polarization rotation in single-particle emitters.

## Abstract

Metal‐halide perovskites are known for their strong and tunable luminescence. However, the synthesis of perovskite‐based particles with circularly polarized light emission (CPLE) remains challenging due to the complex interplay of metal‐ligand chemistries, crystallization patterns, and chirality transfer mechanisms. Achiral perovskites can be deposited on chiral “hedgehog” particles (CHIPs) with twisted spikes, producing chiroptically active materials with spectroscopic bands specific to the perovskite and chirality specific to the template CHIPs. Left‐ and right‐handed CPLE is engineered into complex particles comprised of a layer of perovskite deposited onto CHIPs coated with an intermediate silica layer. The spectral position of chiroptical bands, the optical asymmetry g‐factors, and single‐particle circularly polarized microscopy indicate that the observed CPLE is dominated by the post‐emission scattering from the twisted spikes of the parent particle. Templating luminescent nanofilms on CHIPs provides a simple pathway to a wide range of complex chiroptical materials; the dispersibility of the CHIPs in various solvents and the tunability of their chiral geometry enable their applications as single‐particle emitters with strong and controllable polarization rotation.

Left‐ and right‐handed circularly polarized light emission (CPLE) is observed from chiral “hedgehog” particles (CHIPs) coated with a nanofilm of achiral perovskite, with spectroscopic bands specific to the perovskites and chirality specific to the template CHIPs. Careful analysis of optical activity indicates that the CPLE of perovskite luminescence is dominated by post‐emission scattering from the chiral surfaces of the same CHIPs.