Synthesis of ultrasmall CsPbBr₃ nanoclusters and their transformation to highly deep-blue-emitting nanoribbons at room temperature

Abstract

Discretely sized semiconductor clusters have attracted considerable attention due to their intriguing optical properties and self-assembly behaviors. While lead halide perovskite nanostructures have been recently intensively explored, few studies have addressed perovskite clusters and their self-assembled superstructures. Here, we report the room-temperature synthesis of sub-2 nm CsPbBr clusters and present strong evidence that these ultrasmall perovskite species, obtained under a wide range of reaction conditions, possess a specific size, with optical properties and self-assembly characteristics resembling those of well-known II-VI semiconductor magic-sized clusters. Unlike conventional CsPbBr nanocrystals, the as-synthesized CsPbBr nanoclusters spontaneously self-assemble into a hexagonally packed columnar mesophase in solution, which can be further converted to single-crystalline CsPbBr quantum nanoribbons with bright deep-blue emission at room temperature. Such a conversion of CsPbBr nanoclusters to nanoribbons is found to be driven by a ligand-destabilization-induced crystallization and mesophase transition process. Our study will facilitate the investigation of perovskite nanoclusters and offer new possibilities in the low-temperature synthesis of anisotropic perovskite nanostructures.

Green-Emitting Powders of Zero-Dimensional Cs4PbBr6: Delineating the Intricacies of the Synthesis and the Origin of Photoluminescence

“…The 3D precipitated from the 0.5 M DMSO solution is likely due to the high concentration that results in significant interaction between adjacent octahedra after the addition of the antisolvent. 35 In fact, upon direct addition of the antisolvent, we observed a white precipitate, which is most probably in the 0D phase or ultrasmall 3D clusters 36 that in a few seconds turned into orange-colored 3D perovskites.…”

Hollow metal halide perovskite nanocrystals with efficient blue emissions

“…Various approaches have recently been developed to achieve synthetic control of the composition, size, and shape of perovskite NCs to obtain emissions covering the whole visible spectrum, from deep blue to near-infrared (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). For instance, by manipulating the quantum size effect, the emission of CsPbBr 3 NCs can be tuned from green for NCs with sizes larger than the exciton bohr radius (~7 nm) to deep blue for quantum dots, nanowires, and nanoplatelets with strong quantum confinement (15)(16)(17)(18)(19)(20). Several recent studies have demonstrated NC size control within the quantum confinement regime by introducing organic salts (21), controlling the acid-base environment (22), varying Pb-to-halide ratio (23), etc.…”

Deep Blue Layered Lead Perovskite Light‐Emitting Diode

“…This problem is particularly serious in the preparing deep blue PeLED device. 2) Perovskite quantum dot, [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] a nano-sized perovskite encapsulated by a long chain of oleic acid, turns a large-scale crystal into a small quantum dot. For the quantum confinement effect, [45] the long chain conjugation of metal halide is inhibited, which shows a wide bandgap and high quantum efficiency of luminescence.…”