# Synergistic Surface Modification of Bromocarboxylic Acid-Oleylamine Dual Ligands for Highly Stable and Luminescent CsPbBr3 Perovskite Nanocrystals

## TL;DR

Scientists improved the stability and brightness of perovskite nanocrystals using a new surface modification strategy, making them suitable for practical applications like LEDs.

## Contribution

A dual-ligand strategy using bromocarboxylic acids and oleylamine is introduced to enhance the stability and luminescence of CsPbBr3 nanocrystals.

## Key findings

- The modified nanocrystals achieved a photoluminescence quantum yield of 85.2% and retained 90.2% of their initial brightness after 63 days.
- A prototype white LED using these nanocrystals achieved a color gamut of 122.1% NTSC and a luminous efficacy of 64.6 lm/W.

## Abstract

The poor stability of CsPbBr3 perovskite nanocrystals (PNCs) caused by weak and dynamic ligand coordination severely limits their commercial applications. Herein, a dual-ligand synergistic modification strategy based on bromocarboxylic acids (BCAs) and oleylamine (OAm) was developed to mediate the surface structures and luminescent dynamics of CsPbBr3 PNCs. The results reveal that carboxylate groups of BCA ligands modulate crystal growth, while its terminal Br atom forms a strong coordination with exposed Pb2+ on the PNCs surface, which can effectively passivate lead- and bromine-related defects. The synergistic protection of OAm ligands enhances the stability of PNCs via amino-halide electrostatic interactions and steric hindrance effects. Notably, based on the relatively dense surface coating of 4-bromobutyric acid (BBA) and OAm dual-ligands, the prepared CsPbBr3 PNCs exhibit a high photoluminescence quantum yield (PLQY) of 85.2 ± 2.4% and remarkable storage stability, retaining 90.2 ± 1.7% of their initial PL intensity after being stored for 63 days under ambient conditions. Furthermore, a prototype white light-emitting diode (WLED) fabricated with these PNCs displays a wide color gamut covering 122.1% of the NTSC standard and a luminous efficacy of 64.6 lm/W. This work provides a facile and feasible ligand engineering strategy to obtain highly stable and emissive PNCs.