Two‐dimensional (2D) lead‐free halide perovskites have generated enormous perception in the field of optoelectronics due to their fascinating optical properties. However, an in‐depth understanding on their shape‐controlled charge‐carrier recombination dynamics is still lacking, which could be resolved by exploring the photoluminescence (PL) blinking behaviour at the single‐particle level. Herein, we demonstrate, for the first time, the synthesis of nanocrystals (NCs) and 2D nanosheets (NSs) of layered mixed halide, Cs₃Bi₂I₆Cl₃, by solution‐based method. We applied fluorescence microscopy and super‐resolution optical imaging at single‐particle level to investigate their morphology‐dependent PL properties. Narrow emission line widths and passivation of non‐radiative defects were evidenced for 2D layered nanostructures, whereas the activation of shallow trap states was recognized at 77 K. Interestingly, individual NCs were found to display temporal intermittency (blinking) in PL emission. On the other hand, NS showed temporal PL intensity fluctuations within localized domains of the crystal. In addition, super‐resolution optical image of the NS from localization‐based method showed spatial inhomogeneity of the PL intensity within perovskite crystal.

中文翻译：

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Cs3 Bi2 I6 Cl3钙钛矿的无铅二维纳米结构的合成和局部光致发光闪烁。

二维（2D）无铅卤化物钙钛矿因其引人入胜的光学特性而在光电学领域引起了巨大的轰动。然而，仍然缺乏对其形状控制的电荷-载流子复合动力学的深入了解，这可以通过在单粒子水平上探索光致发光（PL）闪烁行为来解决。在这里，我们首次证明了层状混合卤化物Cs ₃ Bi ₂ I ₆ Cl ₃的纳米晶体（NCs）和二维纳米片（NSs）的合成，采用基于解决方案的方法。我们在单颗粒水平上应用了荧光显微镜和超分辨率光学成像技术，以研究其形态学相关的PL特性。二维层状纳米结构证明了窄的发射线宽度和非辐射缺陷的钝化，而在77 K处识别到了浅陷阱态的激活。有趣的是，发现单个NC在PL发射中表现出时间间歇性（闪烁）。另一方面，NS在晶体的局部区域内显示出暂时的PL强度波动。此外，基于定位方法的NS超分辨率光学图像显示了钙钛矿晶体内PL强度的空间不均匀性。