We report a colloidal synthesis of blue emissive, stable cube-shaped CsPbBr₃ quantum dots (QDs) in the strong quantum confinement regime via dissolution–recrystallization starting from pre-syntesized (K_xCs_1–x)₄PbBr₆ nanocrystals which are then reacted with PbBr₂. This is markedly different from the known case of Cs₄PbBr₆ nanocrystals that react within seconds with PbBr₂ and get transformed into much larger, green emitting CsPbBr₃ nanocrystals. Here, instead, the conversion of (K_xCs_1–x)₄PbBr₆ nanocrystals to CsPbBr₃ QDs occurs in a time span of hours, and tuning of the QD size is achieved by adjusting the concentration of the precursors. The QDs exhibit excitonic features in optical absorption that are tunable in the 420–452 nm range, accompanied by blue photoluminescence with quantum yield around 60%. Detailed spectroscopic investigations in both the single and multiexciton regime reveal the exciton fine structure and the effect of Auger recombination of these CsPbBr₃ QDs, confirming theoretical predictions for this system.

中文翻译：

---

使用 K 合金 Cs4PbBr6 纳米晶体作为前驱体的超小型 CsPbBr3 蓝色发射钙钛矿量子点

我们报告了在强量子限制条件下，通过从预合成的 (K _x Cs _{1– x} ) ₄ PbBr ₆纳米晶体开始溶解-重结晶，胶体合成了蓝色发射的稳定立方体 CsPbBr ₃量子点 (QD) ，然后将其制成与PbBr ₂反应。这与已知的 Cs ₄ PbBr ₆纳米晶体的情况明显不同，Cs 4 PbBr 6 纳米晶体在几秒钟内与 PbBr ₂反应并转化为更大的、发出绿光的 CsPbBr ₃纳米晶体。相反，(K _x Cs _{1– x} ) ₄ PbBr ₆纳米晶体在数小时内即可转化为 CsPbBr ₃ QD，并且通过调节前驱体的浓度来实现 QD 尺寸的调节。量子点在光吸收方面表现出激子特征，可在 420-452 nm 范围内调谐，并伴有量子产率约为 60% 的蓝色光致发光。单激子和多激子状态的详细光谱研究揭示了这些 CsPbBr ₃ QD的激子精细结构和俄歇复合效应，证实了该系统的理论预测。