# The Combination of Chiral Assembly and Chiral Template Effects Boosts Circularly Polarized Luminescence of Perovskite Nanocrystals

## TL;DR

This paper shows how combining chiral assembly and chiral templates can significantly enhance the circularly polarized luminescence of perovskite nanocrystals for use in display and communication technologies.

## Contribution

The study introduces a new method to boost CPL in perovskite nanocrystals using chiral liquid-crystalline templates and hierarchical assembly.

## Key findings

- Composite thin films of PNCs in chiral matrices achieved a CPL dissymmetry factor (glum) up to ≈ 0.24.
- CPL enhancement results from chiral assembly and selective filtering by the chiral matrix.
- The system allows spectral tuning and control over CPL properties in thin films.

## Abstract

Perovskite nanocrystals (PNCs) exhibiting circularly polarized luminescence (CPL) represent a promising class of materials for display and light communication technologies, owing to their emission covering the entire visible range with near‐unity photoluminescence efficiency. However, these materials suffer from low selectivity in the handedness of the emitted light, with most studies focusing on green emission. We address these issues by exploiting and broadening the scope of interactions between achiral PNCs and chiral organic templates. For this purpose, we select three types of PNCs with red, green, and blue emissions and introduce them into a chiral liquid‐crystalline matrix in the form of composite thin films. Electron microscopy confirmed the assembly of PNCs within nanoscale gaps formed by supramolecular, liquid crystalline structures. The obtained composites displayed a CPL dissymmetry factor glum
 up to ≈ 0.24. The highly dissymmetric CPL properties were found to result from an interplay between two effects: chiral assembly of PNCs within a chiral environment (intrinsic) and the selective filtering by the chiral matrix. This system enables control over the dominant factors by adjusting the CPL spectral region and type of particle assembly, providing thin film materials with highly dissymmetric and spectrally tunable CPL responses.

We show that the hierarchical order of perovskite nanocrystal assemblies formed within a nanostructured, chal liquid‐crystalline template exhibits extremely high circularly polarized luminescence (CPL). This is due to the helical arrangement of PNCs in the template voids and capitalizes on the inherent electrooptic properties of the template. Ultimately, this enables the fabrication of CPL‐active thin films with practically relevant chiroptical functionality.