# Rational Design of Amino Acid-Modified Halide Perovskites for Highly Efficient and Cost-Effective Light-Emitting Diodes

## TL;DR

This paper introduces a low-cost method to improve the efficiency of perovskite LEDs using amino acid ligands.

## Contribution

A novel use of amino acids as zwitterionic ligands for passivating perovskite quantum dots, enabling efficient and scalable LED fabrication.

## Key findings

- Amino acid ligands achieve a photoluminescence quantum yield (PLQY) of 87.2% in perovskite QDs.
- The method enables an external quantum efficiency (EQE) of 5.6% and luminance over 9000 cd/m².
- Amino acids allow interface energy level engineering through side-chain functional group modification.

## Abstract

Formamidinium lead bromide (FAPbBr3) quantum dots (QDs) have shown potential in light-emitting diodes (LEDs). However, their performance is constrained by surface defects and the limitations of charge transport. Zwitterionic ligands, owing to their twin functions of Lewis base coordination and electrostatic compensation, passivate surface defects of perovskite QDs. Some other zwitterionic ligands are high-cost, while amino acids, as zwitterionic ligands, are inexpensive, readily available, and have efficient passivation capabilities. Their short main chain and programmable side chain can control the volume and dipole at Å-scale range through functional group selection and feed ratio regulation, achieving interface energy level engineering. This work adopts green-emitting FAPbBr3 QDs as the model, tuning ligand properties by modifying side-chain functional groups, thereby achieving PLQY of 87.2%. Experimental results and DFT reveal that amino acids preferentially undergo coordination and can be further fine-tuned through conjugated contacts. Without severe site competition and without affecting coordination occupation and ligand uniformity, the EQE reaches 5.6% and the luminance exceeds 9000 cd/m2. This low-cost technology is easily scalable and broadly manufacturable, providing a replicable material and interface design route for green zone perovskite LEDs.