Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau, 999078 P. R. China.
Nanoscale. 2023 Mar 16;15(11):5241-5248. doi: 10.1039/d2nr06975j.
Although self-trapped exciton (STE) emissions in zero-dimensional metal halides have been intensively investigated, the understanding of the relationship between the coordination geometries of the metal halides and their photophysical properties is still lacking. In this work, we successfully synthesized single crystals, with strong STE emissions, of the bimetallic materials (Bmpip)PbBr (PbZn-Br) and (Bmpip)PbBr (PbMn-Br), where Bmpip is 1-butyl-1-methyl-piperidinium (CHN), a facile anti-solvent crystallization strategy. With respect to the monometallic material, (Bmpip)[PbBr] (Pb-Br), the introduction of Zn and Mn effectively alters the coordination geometry of the lead bromide polyhedral configuration from a PbBr tetrahedron to a PbBr trimer. As a result, the maximum emission peak of PbZn-Br exhibits an obvious red shift and the full width at half maximum is almost two-fold wider than that of Pb-Br due to stronger electron-phonon coupling. Moreover, due to the intrinsic emission of the Mn ions, an intriguing tunable emission was achieved in PbMn-Br with an impressively high photoluminescence quantum yield of up to 67%. The ultra-stable PbMn-Br single crystals show potential as an ideal down-conversion phosphor for use in UV-pumped white light-emitting diode devices.
尽管零维金属卤化物中的自陷激子（STE）发射已经得到了广泛的研究，但对于金属卤化物的配位几何形状与其光物理性质之间的关系的理解仍然不足。在这项工作中，我们成功地使用双金属材料（Bmpip）[PbBr]（ZnBr）（PbZn-Br）和（Bmpip）[PbBr]（MnBr）（PbMn-Br）的单晶体，通过简便的反溶剂结晶策略实现了强 STE 发射。与单金属材料（Bmpip）[PbBr]（Pb-Br）相比，引入 Zn 和 Mn 有效地改变了 PbBr 多面体配位几何形状，从 PbBr 四面体转变为 PbBr 三聚体。因此，PbZn-Br 的最大发射峰发生明显红移，半峰全宽几乎是 Pb-Br 的两倍，这是由于更强的电子-声子耦合。此外，由于 Mn 离子的本征发射，在 PbMn-Br 中实现了一种有趣的可调谐发射，其光致发光量子产率高达 67%。超稳定的 PbMn-Br 单晶有望成为用于紫外光激发白光发光二极管器件的理想下转换荧光粉。
