The Polymer Society of Korea

Abstract

Metal halide perovskites are promising for next-generation displays, yet achieving stable pure red emission remains challenging due to phase instability. Here, we report a robust surface engineering strategy using selective bromination to stabilize CsPbI₃ perovskite nanocrystals (PeNCs). Through precise ligand exchange, we formed a CsPbI₃:Br surface layer while preserving the cubic core. This surface-confined modification, combined with TBSI ligand passivation, significantly improved structural stability and optical performance. Consequently, our red PeLEDs achieved a competitive external quantum efficiency of 19.8%. Furthermore, we successfully integrated these PeNCs into an ultrathin, skin-attachable PeLED. The device demonstrated stable operation under mechanical deformation, underscoring the potential of our surface bromination strategy for wearable electronics.