# Ligand-Assisted Purification of Mixed-Halide Perovskite Nanocrystals with Near-Unity PLQY for High-Color-Purity Display Applications

## TL;DR

Researchers developed a new purification method for perovskite nanocrystals that preserves their high-quality optical properties for use in advanced color displays.

## Contribution

A ligand-assisted purification strategy that achieves near-unity PLQY and narrow emission for mixed-halide perovskite nanocrystals.

## Key findings

- Post-synthetic ligand supplementation minimizes halide loss and trap states in nanocrystals.
- Green- and red-emissive nanocrystals achieved near-unity PLQY with narrow emission linewidths.
- The method enhances color purity for potential use in next-generation display technologies.

## Abstract

Cesium halide perovskite nanocrystals (PNCs) have emerged as promising materials for application in high-color-purity displays due to their exceptional optoelectronic properties, which include narrow emission linewidths, tunable bandgaps, and high photoluminescence quantum yields (PLQYs). However, preserving these characteristics during purification remains a major challenge as surface ligand detachment during the washing process can lead to increased defect states, reduced quantum efficiency, and spectral broadening. The choice of anti-solvent plays a crucial role in maintaining the structural and optical integrity of PNCs, as it directly influences ligand retention and material stability. In this study, we propose an optimized purification strategy for mixed-halide perovskite nanocrystals that incorporates post-synthetic ligand supplementation, in which controlled amounts of oleic acid (OA) and oleylamine (OAm) are sequentially introduced into the crude solution prior to anti-solvent treatment. This approach reinforces surface passivation, suppresses trap state formation, and minimizes halide loss. Consequently, a near-unity PLQY with narrow full-width-at-half-maximum emissions is achieved for both green- and red-emissive nanocrystals, markedly enhancing color purity and providing a promising route toward next-generation wide-color-gamut display technologies.