Inhibited thermal degradation of CsPbBr₃ perovskite quantum dots by dual-Shell engineering towards stable LEDs

Halide perovskite quantum dots (PeQDs) have garnered significant attention for their exceptional optoelectronic properties, particularly in light-emitting diode (LED) applications. However, their susceptibility to thermal degradation at elevated temperatures (>100 °C) poses a critical barrier to commercialization. In this study, we address this challenge through a synergistic ZnF₂ post-treatment strategy applied to CsPbBr₃ PeQDs. Comprehensive experimental characterizations and density functional theory (DFT) calculations reveal that the ZnF₂ treatment induces the formation of a dual-shell structure: CsPbBr₃: F inner shell and a zinc-rich outer shell chemically that bonds with Br and F ions from the CsPbBr₃: F layer. The inner shell primarily suppresses thermal degradation, while both shells collaboratively mitigate surface defects. This dual-shell engineering endows the CsPbBr₃ PeQDs with remarkable thermal stability, maintaining their optical properties and crystallinity even after heating at 120 °C for 60 min, alongside achieving near-unity photoluminescent quantum yield. Furthermore, the dual-shell PeQDs exhibit a 24-fold enhancement in device lifespan in electroluminescent LEDs and superior operational stability in photoluminescent white LEDs. This work offers a simple yet highly effective approach to fabricating thermally stable PeQDs, paving the way for their practical application in next-generation optoelectronic devices.