Surface Bromination of CsPbI3 Perovskite Nanocrystals for Highly Efficient Pure Red Light-emitting Diodes in Skin-attachable Displays

Abstract

Metal halide perovskites, known for high photoluminescence quantum yield, color purity, and tunable bandgap, are promising for next-generation displays. However, producing pure red emissions from ~10 nm CsPbI3 perovskite nanocrystals (PeNCs) is challenging for light-emitting diodes (PeLEDs). We present a surface bromination strategy for CsPbI3 PeNCs to achieve pure red PeLEDs. Mild post-ligand treatment produces surface-brominated PeNCs (CsPbI3) while preserving their crystal structure. These CsPbI3 PeNCs show bright red luminescence and improved electrical properties. PeLEDs made with these PeNCs achieve a remarkable 19.8% external quantum efficiency (EQE). We also demonstrate their use as skin-attachable PeLEDs, maintaining stability under mechanical deformation. This study offers a method for pure red PeNCs and highlights their potential in wearable electronics.