Metal halide perovskite interfaces and heterostructures are crucial for engineering future technologies based on these new classes of semiconductors. The structure–function role of the CsPbBr₃ and Cs₄PbBr₆ as mixed phases and their synergistic contribution to emission and efficiency are intensely debated. We show a clear connection between the growth of the competing Cs₄PbBr₆ phase and the presence of Br vacancies, which serve as the growth nucleation sites. Our understanding is fuelled by a unique cryogenic ultrafast time-resolved cathodoluminescence (TRCL) spectroscopy study of CsPbBr₃ and mixed-phase microcrystals. This method precisely pinpoints the spatial location of emission centers and analyzes them spectrally and temporally, unveiling their defect-based origin. Bromide vacancies act as trap states at cryogenic temperatures, resulting in an apparent spectral split easing their detection. We find nonheteroepitaxial growth at the interface of the two phases CsPbBr₃/Cs₄PbBr₆ and agglomeration of precipitants that are bromide-depleted. Our data connects the underpassivated bromide vacancy states at the interface to the enhanced emission from the CsPbBr₃/Cs₄PbBr₆ heterostructures.

中文翻译：

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非异质外延 CsPbBr3/Cs4PbBr6 界面导致未钝化的亮溴化物空位

金属卤化物钙钛矿界面和异质结构对于设计基于这些新型半导体的未来技术至关重要。_{CsPbBr 3}和 Cs ₄ PbBr ₆作为混合相的结构-功能作用以及它们对排放和效率的协同贡献引起了激烈的争论。我们展示了竞争 Cs ₄ PbBr ₆相的生长与作为生长成核位点的 Br 空位的存在之间的明确联系。CsPbBr _{3的独特低温超快时间分辨阴极发光 (TRCL) 光谱研究推动了我们的理解}和混合相微晶。该方法精确地确定了发射中心的空间位置，并对它们进行光谱和时间分析，揭示了它们基于缺陷的起源。溴化物空位在低温下充当陷阱状态，导致明显的光谱分裂，便于检测。我们发现非异质外延生长在两相 CsPbBr ₃ /Cs ₄ PbBr ₆的界面和溴化物耗尽的沉淀剂的团聚。我们的数据将界面处的未钝化溴化物空位状态与来自 CsPbBr ₃ /Cs ₄ PbBr ₆异质结构的增强发射联系起来。