Room-temperature synthesis of pure perovskite-related Cs4PbBr6 nanocrystals and their ligand-mediated evolution into highly luminescent CsPbBr3 nanosheets

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 19; no. 7
• Main Authors: Yang, Liu, Li, Dongmei, Wang, Cong, Yao, Wei, Wang, Hao, Huang, Kaixiang
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-07-2017
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Inorganic Chemistry; Lasers; Materials Science; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Research Paper; Cs; Transformation; Nanocomposites; Colloidal nanocrystals; PbBr; Shape evolution; Solvent; Surface ligands
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-017-3959-7

Currently, all-inorganic cesium lead-halide perovskite nanocrystals have attracted enormous attentions owing to their excellent optical performances. While great efforts have been devoted to CsPbBr
3
nanocrystals, the perovskite-related Cs
4
PbBr
6
nanocrystals, which were newly reported, still remained poorly understood. Here, we reported a novel room-temperature reaction strategy to synthesize pure perovskite-related Cs
4
PbBr
6
nanocrystals. Size of the products could be adjusted through altering the amount of ligands, simply. A mixture of two good solvents with different polarity was innovatively used as precursor solvent, being one key to the high-yield Cs
4
PbBr
6
nanocrystals synthesis. Other two keys were Cs
+
precursor concentration and surface ligands. Ingenious experiments were designed to reveal the underlying reaction mechanism. No excitonic emission was observed from the prepared Cs
4
PbBr
6
nanocrystals in our work. We considered the green emission which was observed in other reports originated from the avoidless transformation of Cs
4
PbBr
6
into CsPbBr
3
nanocrystals. Indeed, the new-prepared Cs
4
PbBr
6
nanocrystals could transform into CsPbBr
3
nanosheets with surface ligands mediated. The new-transformed two-dimensional CsPbBr
3
nanosheets could evolve into large-size nanosheets. The influences of surface ligand density on the fluorescent intensity and stability of transformed CsPbBr
3
nanosheets were also explained. Notably, the photoluminescence quantum yield of the as-transformed CsPbBr
3
nanosheets could reach as high as 61.6% in the form of thin film. The fast large-scale synthesis of Cs
4
PbBr
6
nanocrystals and their ligand-mediated transformation into high-fluorescent CsPbBr
3
nanosheets will be beneficial to the future optoelectronic applications. Our work provides new approaches to understand the structural evolution and light-emitting principle of perovskite nanocrystals.
Graphical abstract
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