Bidentate Ligand-Passivated CsPbI₃ Perovskite Nanocrystals for Stable Near-Unity Photoluminescence Quantum Yield and Efficient Red Light-Emitting Diodes

TLDR

Halide perovskite nanocrystals promise optoelectronic applications but suffer from chemical and phase instability, and common capping ligands form insulating layers that hinder device performance. The study aims to develop a post‑synthesis passivation strategy for CsPbI₃ nanocrystals using the bidentate ligand 2,2′‑iminodibenzoic acid. The authors post‑synthesize CsPbI₃ nanocrystals with 2,2′‑iminodibenzoic acid to passivate surface sites and reduce defects. The passivated nanocrystals exhibit near‑unity quantum yield, improved stability, and enable red LEDs with 5.02 % external quantum efficiency and 748 cd m⁻² luminance, outperforming non‑passivated devices.

Abstract

Although halide perovskite nanocrystals (NCs) are promising materials for optoelectronic devices, they suffer severely from chemical and phase instabilities. Moreover, the common capping ligands like oleic acid and oleylamine that encapsulate the NCs will form an insulating layer, precluding their utility in optoelectronic devices. To overcome these limitations, we develop a postsynthesis passivation process for CsPbI3 NCs by using a bidentate ligand, namely 2,2′-iminodibenzoic acid. Our passivated NCs exhibit narrow red photoluminescence with exceptional quantum yield (close to unity) and substantially improved stability. The passivated NCs enabled us to realize red light-emitting diodes (LEDs) with 5.02% external quantum efficiency and 748 cd/m2 luminance, surpassing by far LEDs made from the nonpassivated NCs.