Multilayer Diffraction Reveals That Colloidal Superlattices Approach the Structural Perfection of Single Crystals

Toso, Stefano; Баранов, Д. А.; Altamura, Davide; Scattarella, Francesco; Dahl, Jakob; Wang, Xingzhi; Marras, Sergio; Alivisatos, A. Paul; Singer, Andrej; Giannini, Cinzia; Manna, Liberato

doi:10.1021/acsnano.0c08929

Cited by 34 publications

(95 citation statements)

References 69 publications

(121 reference statements)

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“…Furthermore, both Pb–Pb distances are longer than those found in bulk CsPbBr 3 (vertical = +0.75% [010] bulk, horizontal = +0.22% ⟨101⟩ bulk, Pnma setting, ICSD-97851). 50 This finding is in line with the known tendency of lead halides to relax their structure anisotropically at the nanoscale 8 , 38 and provides insight about the lattice symmetry.…”

Section: Resultssupporting

confidence: 79%

“… 41 The samples were probed in θ:2θ out-of-plane diffraction experiments, producing signals in the form of equally spaced fringes whose intensity and sharpness decreased at higher angles. Such diffraction fringes appear when the structural perfection of the multilayer reaches the angstrom level, 38 far beyond what can be probed optically, and encode the structure of the film along its vertical direction. This includes the overall periodicity of the multilayer and its stacking disorder, as well as the vertical coordinates and the electron densities of all the atomic planes in the sample.…”

Section: Resultsmentioning

confidence: 99%

“… 28 , 33 − 36 Our groups recently expanded the domain of application of Multilayer Diffraction to superlattices of colloidal semiconductor nanocrystals. 37 , 38 Briefly, these materials can be considered as multilayers where high-density inorganic domains ( i.e. , the nanocrystals) alternate with low-density organic layers ( i.e.…”

mentioning

confidence: 99%

“…We also measured the anisotropic structural expansion of nanoplatelets with respect to bulk CsPbBr 3 , confirming a behavior reported for cesium lead halide nanostructures in the past. 8 , 38 , 39 …”

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confidence: 99%

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Structure and Surface Passivation of Ultrathin Cesium Lead Halide Nanoplatelets Revealed by Multilayer Diffraction

et al. 2021

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The research on two-dimensional colloidal semiconductors has received a boost from the emergence of ultrathin lead halide perovskite nanoplatelets. While the optical properties of these materials have been widely investigated, their accurate structural and compositional characterization is still challenging. Here, we exploited the natural tendency of the platelets to stack into highly ordered films, which can be treated as single crystals made of alternating layers of organic ligands and inorganic nanoplatelets, to investigate their structure by multilayer diffraction. Using X-ray diffraction alone, this method allowed us to reveal the structure of ∼12 Å thick Cs–Pb–Br perovskite and ∼25 Å thick Cs–Pb–I–Cl Ruddlesden–Popper nanoplatelets by precisely measuring their thickness, stoichiometry, surface passivation type and coverage, as well as deviations from the crystal structures of the corresponding bulk materials. It is noteworthy that a single, readily available experimental technique, coupled with proper modeling, provides access to such detailed structural and compositional information.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Structure and Surface Passivation of Ultrathin Cesium Lead Halide Nanoplatelets Revealed by Multilayer Diffraction

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“…Toso et al introduced a multilayer diffraction method based on XRD for characterization of supercrystals build up from PbS platelets and CsPbBr 3 perovskite NPs. [324] One advantage of their method is that it does not need highly intense X-rays from synchrotron radiation sources. Therein, the NPs were treated as scattering sources that form a so-called self-probing interferometer.…”

Section: Temperature-induced Assembliesmentioning

confidence: 99%

Recent Notable Approaches to Study Self‐Assembly of Nanoparticles with X‐Ray Scattering and Electron Microscopy

Schulz

Lokteva

Parak

et al. 2021

Part & Part Syst Charact

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several issues far from being resolved: for many systems long-range periodic order is not routinely achieved, reproducibility is often not optimal and truly emergent and new properties arising from the supercrystal formation could be demonstrated for just a few systems. [3][4][5][6][7] From the materials science perspective there is no established figure of merit or common set of parameters allowing to quantify "quality" of NP superlattices and supercrystals. In lieu of such standard procedures, terms as well-ordered, crystalline order, quasicrystalline, etc., are usually used in literature. However, there exist no commonly accepted definitions of what qualifies, e.g., as "well-ordered."In this review, we want to highlight some recent experimental developments and new approaches to study self-assembly of NPs or structure formation of NP supercrystals and their final structure. We focus on NP, the broad field of photonic materials prepared by self-assembly of larger colloidal particles is not covered herein. [8][9][10] The introduction of the basic concepts of NP self-assembly will be kept short and should be considered as an overview, for more background and details excellent comprehensive reviews are available. [2,11] We will then briefly address and discuss the expectations associated with self-assembled materials, especially the proposed emergence of new properties directly related to order. In the second part of the review, we will present recent innovative approaches for the investigation of self-assembly and self-assembled structures that go beyond the standard characterization. We focus mainly on structure and structure formation and less on properties, so most of the studies are based on scattering and electron microscopy. Figure 1 provides an overview roughly following this outline. Self-Assembly of NanoparticlesSelf-assembly is a broad term and occurs on all scales from atoms, ions, and molecules to galaxies, as pointed out by Whitesides and Grzybowski. [12] It can be defined as the autonomous organization of multiple discrete components into ordered structures, driven by energetics or entropy or both. [2,13] In nature, countless examples of highly complex and functional structures resulting from self-assembly can be found, Self-assembly of nanoparticles (NPs) has evolved into a powerful tool for the synthesis of superstructures with tailored properties. The quality, diversity, and complexity of synthesized structures are continuously improving and fascinating new collective properties are demonstrated. At the same time, the rapid development of electron microscopy and synchrotron sources for X-rays has enabled new exciting experimental approaches to study structure and structure formation in the context of NP self-assembly. In this review, some recent studies and what can be learned from them are highlighted and discussed. It is started with a general introduction covering important concepts, experimental approaches, commonly obtained structures, the ideas of artificial atoms, and emerging properties a...

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Entropic Ligand Mixing for Engineering 2D Layered Perovskite from Colloidal Monolayer Building Blocks

Massasa,

Strassberg,

Shechter

et al. 2023

Adv Funct Materials

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Layered 2D perovskites are solution‐processed quantum‐wells. Their effective band‐gap is determined via the inorganic perovskite layer thickness and exciton quantum confinement effects. Alternatively, by changing the organic moieties, one can tune the dielectric constant and distance between the monolayers modifying the excitonic interactions. In colloidal perovskites, a dynamic equilibrium exists between the free organic moieties in the solution and the surface of the nanocrystal. Colloidal synthesis is used to make single monolayer L2PbBr4 platelets and assemble these into layered 2D stacks. In the experiment, L is an alkylamine surface ligand whose length (4‐18 carbons) determines the interlayer distances between the quantum‐wells. The dynamic equilibrium of ligand mixtures in solution and perovskite surfaces leads to optimal mixing of the molecules. During the self‐assembly of monolayers, the distance between the inorganic layers is thus engineered. The interlayer distance is proportional to the average ligand mixture length. This results in controlled interactions between the 2D‐excitons, enabling red‐shifted absorption and emission and extended lifetimes for longer alkyl chains. Using entropic mixing of ligands for the engineering of 2D excitonic interactions is therefore demonstrated. Formation of layered 2D perovskites from colloidal building blocks allows intermixing of dissimilar materials opening possibilities for new heterostructures and junctions.

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Multilayer Diffraction Reveals That Colloidal Superlattices Approach the Structural Perfection of Single Crystals

Cited by 34 publications

References 69 publications

Structure and Surface Passivation of Ultrathin Cesium Lead Halide Nanoplatelets Revealed by Multilayer Diffraction

Structure and Surface Passivation of Ultrathin Cesium Lead Halide Nanoplatelets Revealed by Multilayer Diffraction

Recent Notable Approaches to Study Self‐Assembly of Nanoparticles with X‐Ray Scattering and Electron Microscopy

Entropic Ligand Mixing for Engineering 2D Layered Perovskite from Colloidal Monolayer Building Blocks

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