Highly Luminescent and Multifunctional Zero-Dimensional Cesium Lanthanide Chloride (Cs(3)LnCl(6)) Colloidal Nanocrystals

Abstract

Herein, the synthesis of novel, highly luminescent, and nearly monodisperse zero-dimensional (0D) cesium lanthanide chloride (Cs(3)LnCl(6); Ln = Y, Ce, Gd, Er, Tm, Yb) colloidal nanocrystals (NCs) is reported for the first time. The Cs(3)LnCl(6) NCs are synthesized using a heating-up method and exhibit highly uniform size and shape. The monoclinic-phase Cs(3)LnCl(6) NCs contain completely isolated [LnCl(6)](3-) octahedral units, resulting in 0D ternary metal halide structures. Therefore, these NCs exhibit deep-blue photoluminescence under ultraviolet excitation, and this photoluminescence can be tuned by changing the lanthanide cations within the [LnCl(6)](3-) octahedral units. High photoluminescence quantum yields of up to 60% and 90% are observed for the Cs3YbCl6 and Cs3YCl6 NCs, respectively, at room temperature and under ambient conditions. The Cs(3)LnCl(6) NCs exhibit characteristic optical and magnetic properties owing to the f-orbitals of the lanthanide elements. For example, near-infrared-to-visible upconversion luminescence appears when Cs(3)LnCl(6) NCs are doped with Er3+ and Yb3+ ions. In addition, the Cs3GdCl6 NCs demonstrate paramagnetic properties owing to the unpaired electrons within the f-orbitals of the trivalent gadolinium ions. This study provides guidance for the rational design and synthesis of novel lanthanide-based 0D metal halide NCs, which can potentially be used as highly efficient, multifunctional NC emitters.