An <i>in situ</i> and real time study of the formation of CdSe NCs

Palencia, Cristina; Seher, Robert; Krohn, Jan; Thiel, F. A.; Lehmkühler, Felix; Weller, Horst

doi:10.1039/d0nr05879c

Cited by 14 publications

(24 citation statements)

References 27 publications

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“…It is noteworthy that the accurate composition, size,a nd structure are not available yet, which stands for the persistent challenge for colloidal semiconductor clusters. [36][37][38][39][40][41][42][43][44] To avoid CdTeM SC-371 being present during the initial stage of the MSC-399 to MSC-422 transformation, we decided to use one-day incubated samples in which MSC-399 had evolved. [2] Similarly,t he incubated samples (60 and 120 mL) were dispersed in 3.00 mL of Toland OTAmixtures with the OTAa mounts of 0.10 and 0.20 mL.…”

Section: Methodsmentioning

confidence: 99%

Transformation Pathways in Colloidal CdTeSe Magic‐Size Clusters

Yang

Luan

et al. 2021

Angew Chem Int Ed

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Ararely studied transformation in colloidal ternary magic-size clusters (MSCs) is addressed. We report the first observation of the transformation from ternary CdTeSe MSC-399 to MSC-422, whichoccurs at room temperature.These two MSC types displaysharp optical absorption resonances at 399 and 422 nm, respectively,and are related in that they are quasi isomers,together with their counterpart precursor compounds (PCs). Binary CdTea nd CdSe samples were prepared in the prenucleation stage also called the induction period (IP). After they were mixed and placed in am ixture of toluene and octylamine,the transformation was found to take place and to be assisted by the addition of the CdSe IP sample.Abinary IP sample contains corresponding binary PCs and monomers (Mo) and fragments (Fr). We argue that the transformation pathway is enabled by the corresponding ternary PCs,involving the substitution reaction, namely CdTeSe PC-399 + CdSe (Mo/Fr)-1 ) CdTeSe PC-422 + CdSe (Mo/Fr)-2. The present study provides an in-depth understanding of the formation characteristics of the MSCs.

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Section: Methodsmentioning

confidence: 99%

Transformation Pathways in Colloidal CdTeSe Magic‐Size Clusters

Yang

Luan

et al. 2021

Angew Chem Int Ed

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“…We argue that such a tubular configuration would make (RNH 2 ) n ([CdTe] 13 ) MSCs very favorable as nuclei for nanowires. We note that MSCs have been shown to function as monomer reservoirs under suitable conditions, redissolving to feed the growth of nanocrystals . This scenario, however, can be ruled out in the present case because growth of the MSNWs proceeds long after the spectral signatures attributed to the MSCs have disappeared.…”

Section: Resultsmentioning

confidence: 72%

“…We note that MSCs have been shown to function as monomer reservoirs under suitable conditions, redissolving to feed the growth of nanocrystals. 56 This scenario, however, can be ruled out in the present case because growth of the MSNWs proceeds long after the spectral signatures attributed to the MSCs have disappeared. The same argument can be used to exclude the possibility that NW-373 MSNWs form by oriented attachment of CdTe MSCs.…”

Section: Resultsmentioning

confidence: 76%

Room-Temperature Interconversion Between Ultrathin CdTe Magic-Size Nanowires Induced by Ligand Shell Dynamics

et al. 2022

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The formation mechanisms of colloidal magic-size semiconductor nanostructures have remained obscure. Herein, we report the room temperature synthesis of three species of ultrathin CdTe magic-size nanowires (MSNWs) with diameters of 0.7 ± 0.1 nm, 0.9 ± 0.2 nm, and 1.1 ± 0.2 nm, and lowest energy exciton transitions at 373, 418, and 450 nm, respectively. The MSNWs are obtained from Cd(oleate) 2 and TOP-Te, provided diphenylphosphine and a primary alkylamine (RNH 2 ) are present at sufficiently high concentrations, and exhibit sequential, discontinuous growth. The population of each MSNW species is entirely determined by the RNH 2 concentration [RNH 2 ] so that single species are only obtained at specific concentrations, while mixtures are obtained at concentrations intermediate between the specific ones. Moreover, the MSNWs remain responsive to [RNH 2 ], interconverting from thinner to thicker upon [RNH 2 ] decrease and from thicker to thinner upon [RNH 2 ] increase. Our results allow us to propose a mechanism for the formation and interconversion of CdTe MSNWs and demonstrate that primary alkylamines play crucial roles in all four elementary kinetic steps (viz., monomer formation, nucleation, growth in length, and interconversion between species), thus being the decisive element in the creation of a reaction pathway that leads exclusively to CdTe MSNWs. The insights provided by our work thus contribute toward unravelling the mechanisms behind the formation of shape-controlled and atomically precise magic-size semiconductor nanostructures.

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“…For instance, using Monte Carlo methods [230,231] different populations of Au NPs have recently been measured, [166] and the size evolution of NPs can be tracked in in situ experiments. [232]…”

Section: Small Angle X-ray Scattering (Saxs)mentioning

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

Self Cite

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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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An in situ and real time study of the formation of CdSe NCs

Abstract: Magic Size Clusters (MSCs) have been identified in the last years as intermediates in the synthesis of nanocrystals (NCs) and ever since there have been an increased interest on understanding...

Cited by 14 publications

References 27 publications

Transformation Pathways in Colloidal CdTeSe Magic‐Size Clusters

Transformation Pathways in Colloidal CdTeSe Magic‐Size Clusters

Room-Temperature Interconversion Between Ultrathin CdTe Magic-Size Nanowires Induced by Ligand Shell Dynamics

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

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