Solvothermal Synthesis of Ultrathin Cesium Lead Halide Perovskite Nanoplatelets with Tunable Lateral Sizes and Their Reversible Transformation into Cs₄PbBr₆ Nanocrystals

Abstract

The versatility of perovskite crystal structure has become the great advantage of lead halide perovskite nanocrystals (NCs) during their functional applications. Here we report an effective solvothermal method for the controllable synthesis of CsPbBr3 nanoplatelets (NPLs) and their transformation to Cs4PbBr6 NCs. Through solvothermal reaction of a mixture of Cs-oleate and PbBr2 precursors, CsPbBr3 NPLs can be synthesized in mass production. The lateral sizes of CsPbBr3 NPLs can be precisely tuned by varying the solvothermal reaction temperatures and times, while the thickness of NPLs remains constant at ∼4.2 nm, which is in the quantum confinement regime. The fine-tuning of lateral NPL sizes results in precise modulation of their photoluminescence emission. Moreover, an interesting phase transformation from cubic CsPbBr3 NPLs to rhombohedral Cs4PbBr6 NCs, and the reversible transformation from Cs4PbBr6 NCs to CsPbBr3 NPLs can be readily achieved by changing the solvothermal reaction sources. The present solvothermal approach is simple, convenient, controllable, and can be easily extended to preparation of other perovskite NCs with different halide compositions.

Metal Halide Perovskite Nanocrystals: Synthesis, Post-Synthesis Modifications, and Their Optical Properties

“…In 2017, Zhai et al adopted the solvothermal approach, 126 and they were able to transform CsPbBr 3 NPLs into Cs 4 PbBr 6 NCs. 136 …”

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

“…Different sized CsPbBr 3 nanoplates and Cs 4 PbBr 6 NCs were successfully obtained by adjusting the Cs precursor concentration. [128] Interestingly, the product could be readily scaled up by using this method, [82,129] which could reach up to 1.5 g per 40 mL solvents.…”

“…[25] Compared to CsPbBr 3 prepared by direct synthesis, this PbBr 2 -induced transformation entailed the formation of structural defects acting as trapping sites, which would require further modification. This PbX 2 -insertion theory has been widely applied to induce the transformation from 0D Cs 4 PbX 6 to 3D CsPbX 3 NCs, [128] and accounts for the opaque phenomenon observed in the synthesis of perovskite NCs. [62] This PbX 2 insertion approach could be further modified to introduce various cations into the perovskite structure.…”

Highly efficient radiative recombination in intrinsically zero-dimensional perovskite micro-crystals prepared by thermally-assisted solution-phase synthesis

“…73-2478). 15,18,19 The scanning electron microscopy (SEM) image (Fig. 1c) shows that the perovskite micro-crystals maintain a regular cuboidal structure over several micrometres.…”

“…It has been suggested the emission arises from a low density of CsPbBr 3 impurities, while others suggest that the luminescence originates from carriers conned to 0D unit-cells with connement imposed by the intrinsic 0D structure. [13][14][15][16][17] In this work, we have synthesized 0D perovskite microcrystals by a simple thermally-assisted solution synthesis method. The PL quantum efficiency of the 0D perovskite microcrystals reaches 45%.…”