Ligand-Induced Shape Transformation of PbSe Nanocrystals

Peters, Joep L.; Bos, K.H.W. van den; Aert, Sandra Van; Goris, Bart; Bals, Sara; Vanmaekelbergh, Daniël

doi:10.1021/acs.chemmater.7b01103

Cited by 44 publications

(75 citation statements)

References 41 publications

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“…S4 and S5. The observed large deformability of PbSe semiconductor nanocrystals may arise from the intrinsic nanoscale property that the surface atoms of a nanocrystal are highly mobile during reconstruction ( 29 , 30 ). In our experiment, the PbSe nanocrystals are exceedingly monodisperse.…”

Section: Resultsmentioning

confidence: 99%

Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions

et al. 2019

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The behavior of individual nanocrystals during superlattice phase transitions can profoundly affect the structural perfection and electronic properties of the resulting superlattices. However, details of nanocrystal morphological changes during superlattice phase transitions are largely unknown due to the lack of direct observation. Here, we report the dynamic deformability of PbSe semiconductor nanocrystals during superlattice phase transitions that are driven by ligand displacement. Real-time high-resolution imaging with liquid-phase transmission electron microscopy reveals that following ligand removal, the individual PbSe nanocrystals experience drastic directional shape deformation when the spacing between nanocrystals reaches 2 to 4 nm. The deformation can be completely recovered when two nanocrystals move apart or it can be retained when they attach. The large deformation, which is responsible for the structural defects in the epitaxially fused nanocrystal superlattice, may arise from internanocrystal dipole–dipole interactions.

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Section: Resultsmentioning

confidence: 99%

Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions

et al. 2019

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“… 30 This is in line with recent findings of Peters et al showing that oleate and Pb-oleate moieties are weakly bound to the {100} facets. 24 …”

Section: Resultsmentioning

confidence: 99%

Interfacial Self-Assembly and Oriented Attachment in the Family of PbX (X = S, Se, Te) Nanocrystals

et al. 2018

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The realization of materials with new optoelectronic properties draws much scientific attention toward the field of nanocrystal superstructures. Low-dimensional superstructures created by interfacial assembly and oriented attachment of PbSe nanocrystals are a striking example because theory showed that PbSe sheets with a honeycomb geometry possess non-trivial flat bands and Dirac cones in the valence and conduction bands. Here, we report on the formation of one-dimensional linear and zigzag structures and two-dimensional (2D) square and honeycomb structures for the entire lead chalcogenide family: PbX (X = S, Se, Te). We observe that PbTe, with a lower bulk melting temperature and enthalpy of formation than those of PbSe, shows a higher nanocrystal surface reactivity, such that the surface must be passivated and the reaction conditions moderated to obtain reasonably ordered superstructures. The present findings constitute a step forward in the realization of a larger family of atomically coherent 2D superstructures with variable IV–VI and II–VI compositions and with electronic properties dictated by the nanogeometry.

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“…We model a PbSe NC using a polybead structure. The beads forming the NC are disposed to reproduce a rhombicuboctahedron of size 6 nm, that is a typical experimental shape [76,92]. We simulate the dynamics of the NCs using the position-Verlet algorithm [94] to compute the bead's motion.…”

Section: A Outlinementioning

confidence: 99%

“…At this stage, ligands largely screen NC-NC attractive interactions and prevent NC assembly. In the experiments of interest [73,[85][86][87][88], the NC self-assembly is activated by chemically inducing the detachment of ligands from the PbSe NC f100g facets, i.e., where the bonding energy between ligand molecules and NC surface atoms is lowest [73,92]. Hence, during the self-assembly, NCs attract (and attach to) each other only by f100g facets, while NC-NC bonds by f110g and f111g facets are prevented by ligands.…”

Section: B Nc-nc Interactionsmentioning

confidence: 99%

“…This superlattice is formed by PbSe NCs, approximately having a 5-nm size and a rhombicuboctahedron shape, disposed as in the silicene lattice, i.e., in a periodically buckled honeycomb lattice, and all oriented with a f111g facet parallel to the superlattice plane. The PbSe NCs, before the self-assembly, i.e., when still dispersed in solvent, are fully covered by oleic acid ligands, which are strongly attached at the f111g, f110g facets and weakly bonded at the f100g facets [92]. The formation process of the PbSe silicene-honeycomb superlattice typically occurs at the solvent-air interface.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the Formation of PbSe Honeycomb Superstructures by Dynamics Simulations

Soligno

Vanmaekelbergh

2019

Phys. Rev. X

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Using a coarse-grained molecular dynamics model, we simulate the self-assembly of PbSe nanocrystals (NCs) adsorbed at a flat fluid-fluid interface. The model includes all key forces involved: NC-NC shortrange facet-specific attractive and repulsive interactions, entropic effects, and forces due to the NC adsorption at fluid-fluid interfaces. Realistic values are used for the input parameters regulating the various forces. The interface-adsorption parameters are estimated using a recently introduced sharpinterface numerical method which includes capillary deformation effects. We find that the final structure in which the NCs self-assemble is drastically affected by the input values of the parameters of our coarsegrained model. In particular, by slightly tuning just a few parameters of the model, we can induce NC selfassembly into either silicene-honeycomb superstructures, where all NCs have a f111g facet parallel to the fluid-fluid interface plane, or square superstructures, where all NCs have a f100g facet parallel to the interface plane. Both of these nanostructures have been observed experimentally. However, it is still not clear their formation mechanism, and, in particular, which are the factors directing the NC self-assembly into one or another structure. In this work, we identify and quantify such factors, showing illustrative assembled-phase diagrams obtained from our simulations. In addition, with our model, we can study the self-assembly dynamics, simulating how the NCs' structures evolve from few-NCs aggregates to gradually larger domains. For example, we observe linear chains, where all NCs have a f110g facet parallel to the interface plane as typical precursors of the square superstructure, and zigzag aggregates, where all NCs have a f111g facet parallel to the interface plane as typical precursors of the silicene-honeycomb superstructure. Both of these aggregates have also been observed experimentally. Finally, we show indications that our method can be applied to study defects of the obtained superstructures.

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Ligand-Induced Shape Transformation of PbSe Nanocrystals

Cited by 44 publications

References 41 publications

Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions

Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions

Interfacial Self-Assembly and Oriented Attachment in the Family of PbX (X = S, Se, Te) Nanocrystals

Understanding the Formation of PbSe Honeycomb Superstructures by Dynamics Simulations

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