Halogen‐Bonding‐Assisted Synthesis of CsPbI ₃ Perovskite Nanocrystal Emission Materials for Stable and Efficient Pure‐Red LEDs

Abstract

ABSTRACT Perovskite nanocrystals (NCs) demonstrate exceptional potential as emitters to address Rec. 2020 standards for wide color gamut displays. However, the pure‐red‐targeted CsPbI 3 NCs generally suffer from imprecise synthetic control over emission wavelength and from structural instabilities that significantly diminish performance. We report a novel halogen engineering framework that addresses the otherwise unfavorable wavelength‐efficiency‐stability nexus. Our approach leverages surface I − ···I 2 interactions to simultaneously unlock exceptional optical characteristics and the elusive structural robustness needed for application. It achieves: (i) controlled quantum‐confinement‐tuned emission wavelength, (ii) near‐unity photoluminescence (PL) quantum yield through iodide vacancy defect management, and (iii) excellent environmental stability, even under harsh (85°C/85%) temperature and humidity conditions, through lattice‐distortion suppression. Rec. 2020 compliant, 638 nm peak light‐emitting diodes (LEDs) are then demonstrated with Commission Internationale de l'Éclairage coordinates (X, Y) = (0.703, 0.297), 22% external quantum efficiency, luminance ≥ 11,000 cd m −2 , and long lifetime, establishing a materials‐by‐design paradigm for advancing next‐generation perovskite display technologies.