A new two-step synthetic protocol to yield monodisperse spherical zero-dimensional (0D) Cs4 PbX6 nanocrystals (NCs) and three-dimensional (3D) CsPbX3 NCs is described. The first step of the reaction involves the colloidal synthesis of spherical PbX2 seed NCs, which are subsequently converted to Cs4 PbX6 and CsPbX3 NCs through hot injection of a Cs precursor at the desired reaction temperatures. By employing less reactive Pb and halide precursors, the reaction time was extended from several seconds to about five minutes, thereby allowing greater control during the crystallization and growth stages. The adjustment of halide ratios allows color tuning over a wide spectral range (411-669 nm) for CsPbX3 NCs, with high photoluminescence quantum yields (6-65 %) and narrow emission line widths (ca. 13-30 nm). We envisage our spherical NCs to become a starting point for shell growth (e.g., ZnS, CdS, PbS) by overcoming the difficulty of shell growth around thermodynamically unfavorable (i.e., high surface free energy) cuboid-shaped NCs.

中文翻译：

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在多维铯卤化物钙钛矿纳米晶体中诱导各向同性生长。

描述了一种新的两步合成方案，可产生单分散球形零维（0D）Cs4 PbX6纳米晶体（NCs）和三维（3D）CsPbX3 NCs。反应的第一步涉及球形PbX2种子NC的胶体合成，随后通过在所需反应温度下热注入Cs前驱体将其转化为Cs4 PbX6和CsPbX3 NC。通过使用反应性较小的Pb和卤化物前体，反应时间从几秒钟延长到大约五分钟，从而在结晶和生长阶段可以进行更大的控制。卤化物比率的调整可实现CsPbX3 NC的宽光谱范围（411-669 nm）的颜色调节，具有高的光致发光量子产率（6-65％）和窄的发射线宽度（约13-30 nm）。