Degradation Mechanism of Colloidal Perovskite Nanocrystals and its Stabilization Strategy

The commercialization of colloidal perovskite nanocrystals (PeNCs) has been impeded by their rapid degradation in response to environmental factors and potential toxicity concerns due to lead leakage. Furthermore, the spectral stability of red-emitting and blue-emitting PeNCs is limited by light-induced halide segregation, restricting their spectral tunability.<br/>Herein, we present a novel approach to address these issues. We have developed a facile and versatile method based on hierarchical confinement, involving the construction of a multi-layered structure. This technique facilitates the fabrication of CsPbBr3 PeNC films with a photoluminescence quantum yield (PLQY) exceeding 84%. Importantly, the hierarchical confinement method significantly enhances the aging stability of CsPbBr₃ PeNCs, extending their operational lifetime at 60°C and 90% relative humidity and under blue light irradiation to 3400 hours and over 6000 hours, respectively. Moreover, this hierarchical confinement strategy proves to be versatile, effectively stabilizing mixed halide perovskite lattices, thereby suppressing halide segregation in mixed halide red-emitting PeNC films (QY: 83%) and blue-emitting PeNC films (QY: 40%) for 800 hours and 500 hours, respectively.<br/>Most importantly, the hierarchical confined structure successfully prevents the leakage of lead ions, mitigating the toxicity concerns associated with the PeNC film material. Consequently, these findings render the PeNCs biocompatible, paving the way for their utilization in wearable devices and virtual/augmented reality display applications in the future.