Postsynthetic metal salt treatments are frequently employed in the luminescence enhancement of quantum dots (QDs); however, its microscopic picture remains unclear. CsPbBr₃-QDs, featuring strong excitonic absorption and high photoluminescence (PL) quantum yield, are ideal QDs to unravel the intricate interaction between QDs and such surface-bound metal salts. Herein, we study this interaction based on the controlled PL quenching of CsPbBr₃-QDs with BiBr₃. Upon the addition of BiBr₃, an instant and complete PL quenching is observed, which can be fully recovered after the addition of an excess of PbBr₂. This, together with the complete preservation of the excitonic absorption suggests a surface-driven adsorption equilibrium. Additionally, time-resolved studies reveal a non-homogeneous surface trap formation. Based on the so-called sphere of action model for the adsorption process, we show that already a single BiBr₃ adsorption suffices to completely quench a QD’s luminescence. This approach is expanded to analyze size-, ligand-, and metal-dependent quenching dynamics. Facet junctions are identified as regions of enhanced surface reactivity. A Langmuir-type ligand coverage is exposed with a strong impact on adsorption. Our results provide a detailed mechanistic insight into postsynthetic interaction of QDs with metal salts, opening pathways for future surface manipulations.

中文翻译：

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作用域模型揭示量子点金属盐相互作用

合成后金属盐处理常用于量子点（QD）的发光增强；然而，其微观图景仍不清楚。CsPbBr ₃ -QD 具有强激子吸收和高光致发光 (PL) 量子产率，是解开 QD 与此类表面结合金属盐之间复杂相互作用的理想 QD。_{在此，我们基于 CsPbBr 3} -QD 与 BiBr ₃的受控 PL 猝灭来研究这种相互作用。添加 BiBr ₃后，观察到瞬间且完全的 PL 猝灭，在添加过量的 PbBr _{2后可以完全恢复}。这与激子吸收的完全保留一起表明存在表面驱动的吸附平衡。此外，时间分辨研究揭示了非均匀表面陷阱的形成。基于吸附过程的所谓作用球模型，我们表明单次 BiBr ₃吸附就足以完全猝灭 QD 的发光。该方法扩展到分析尺寸、配体和金属相关的猝灭动力学。小面连接被认为是表面反应性增强的区域。朗缪尔型配体覆盖暴露对吸附有强烈影响。我们的结果为量子点与金属盐的合成后相互作用提供了详细的机制见解，为未来的表面操作开辟了途径。