Blue-Emitting CsPbBr₃ Perovskite Quantum Rods and Their Wide-Area 2D Self-Assembly

Abstract

A self-digestive process leading to strong blue-emitting nearly monodisperse CsPbBr3 quantum rods in wide-area 2D self-assembly is reported. These are facilitated by aging the presynthesized ultrathin CsPbBr3 nanowires dispersed in appropriate solvent. The time frame was unusual, and the reaction continued for 3–5 days to observe such intriguing patterns. Interfering species such as unreacted precursors, amines, or acids were intentionally minimized with repeated purification for triggering this self-digestive process, which led to the quantum-confined nanorods. Carrying out this reaction in different solvents and in the presence of various additives, the reaction mechanism for such a slow process is established. These nanorods and their large-area self-assembly remained unique in perovskite nanostructures, and the chemistry of the slow process also provided new fundamental insights of the crystallization process of nanorods and their self-assembly.

State of the Art and Prospects for Halide Perovskite Nanocrystals

“…Self-assembly of other shapes including nanorods, nanowires, , and nanoplatelets has also been reported. For instance, Yang and co-workers reported the self-assembly of 2D perovskite nanosheets by a layer-by-layer approach.…”

“…The forces that drive NC self-assembly range from hard- to soft-particle interactions. Taking advantage of previous knowledge gained on the self-assembly of conventional monodisperse colloidal NCs, a large variety of self-assembly techniques have been reported over the years such as evaporation-driven or destabilization-driven approaches, as well as spontaneous and template-assisted self-assembly. ,, Recently, these techniques have been extended to self-assembly of halide perovskite NCs into highly ordered SLs for exploration of their collective properties that can be very different from their individual constituents. ,,,,,,,− Near monodispersity of NCs and high shape uniformity are important factors to obtain long-range ordered NC SLs. ,, Fortunately, these conditions are easily met for all-inorganic CsPbX 3 perovskite NCs as they are often prepared with near monodispersity regardless of the synthesis method, as discussed in the synthesis section. ,,,, As a result, these perovskite nanocubes tend to self-assemble into 1D or 2D SLs on a TEM grid upon solvent evaporation from a droplet of high concentrated colloidal solution. Initial examples of CsPbBr 3 nanocube SLs date back to 2017, when 2D and 3D assemblies were obtained by the solvent evaporation method. ,, In reference small superlattice domains on TEM grids exhibit a simple cubic packing of the nanocubes with a lattice constant of ≈12.5 nm and an interparticle separation of ≈2.3 nm.…”

Seed‐Mediated Synthesis of Colloidal 2D Halide Perovskite Nanoplatelets

“…combined PbBr 2 , oleic acid, and oleylamine at elevated temperatures, and then cooled the reaction mixture down to room temperature. Subsequently, the prepared reaction mixture was reacted with Cs‐oleate at room temperature and nanoplatelets were generated [35–36] . In another study, Udayabhaskararao et al.…”

Reversible Color Switching in Dual-Emitting Mn(II)-Doped CsPbBr3 Perovskite Nanorods: Dilution versus Evaporation

“…Mn(II)-doped CsPbBr 3 nanorods were synthesized by adopting a postsynthesis dopant adsorption approach at room temperature. Synthesis of host CsPbBr 3 nanorods was first carried out following our previously reported method, 33 and then, these were purified, dispersed in toluene, and stirred with MnBr 2 for dopant insertion. Within 10 min, the emission color of the solution turned to orange, indicating doping of Mn(II) ions in nanorods.…”