Post-synthetic oriented attachment of CsPbBr<sub>3</sub> perovskite nanocrystal building blocks: from first principle calculation to experimental demonstration of size and dimensionality (0D/1D/2D)

Jeon, Sanghyun; Jung, Myung-Chul; Ahn, Jungkyu; Woo, Ho Kun; Bang, Junsung; Kim, Dong-Gyu; Lee, Sang Yeop; Woo, Ho Young; Jeon, Jongchul; Han, Myung Joon; Paik, Taejong; Oh, Soong Ju

doi:10.1039/d0nh00029a

Cited by 26 publications

(21 citation statements)

References 61 publications

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“…Previously, multiple reports have documented the propensity of CsPbX 3 nanocrystals to coalesce under external stimuli such as light − or heat, − ,, from the destabilizing action of polar solvents, − or spontaneously due to aging in dispersion or on a solid substrate . To gain insight into the transformations of CsPbBr 3 nanocrystals as they age in a vacuum, a series of wide-angle XRD patterns were collected from the sample stored under medium vacuum (∼0.4–0.7 mbar) at room temperature for more than a month.…”

Section: Resultsmentioning

confidence: 99%

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

et al. 2020

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Excitonic/electronic coupling and cooperative interactions in self-assembled lead halide perovskite nanocrystals were reported to give rise to a collective low energy emission peak with accelerated dynamics. Here we report that similar spectroscopic features could appear as a result of the nanocrystal reactivity within the self-assembled superlattices. This is demonstrated by using CsPbBr3 nanocrystal superlattices under room temperature and cryogenic micro-photoluminescence spectroscopy. It is shown that keeping such structures under vacuum, a gradual contraction of the superlattices and subsequent coalescence of the nanocrystals occurs over several days. As a result, a narrow, low energy emission peak is observed at 4 K with a concomitant shortening of the photoluminescence lifetime due to the energy transfer between nanocrystals. When exposed to air, self-assembled CsPbBr3 nanocrystals develop bulk-like CsPbBr3 particles on top of the superlattices. At 4 K, these particles produce a distribution of narrow, low energy emission peaks with short lifetimes and excitation fluence-dependent, oscillatory decays, resembling the features of superfluorescence. Overall, the reactivity of CsPbBr3 nanocrystals dramatically alters the emission of their assemblies, which should not be overlooked when studying collective optoelectronic properties nor confused with superfluorescence effects.

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Section: Resultsmentioning

confidence: 99%

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

et al. 2020

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“…The absence of a clear mechanism of directional growth suggests that either these lead halide perovskites do not follow any facet-directive growth or their true mechanism is still hidden. The common observation for all reported 1D structures suggests that the major axis or the presumed growth direction remained along the [001] (or [110]) direction of their orthorhombic phase. ,,,− However, except for oriented attachments of cubes/platelets, ,− ,, no other mechanism leading to the specific [001] directional growth/formation of these 1D structures has been properly explained. Hence, achieving anisotropy in these nanocrystals by design has remained difficult, and it needs further investigation.…”

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confidence: 99%

Introducing B-Site Cations by Ion Exchange and Shape Anisotropy in CsPbBr₃ Perovskite Nanostructures

et al. 2021

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Lead halide perovskite nanocrystals, whether formed by their own nucleation and growth or by ion diffusion into the lattice of others, are still under investigation. Moreover, beyond isotropic nanocrystals, fabricating anisotropic perovskite nanocrystals by design has remained difficult. Exploring the lattice of orthorhombic-phase Cs 2 ZnBr 4 with the complete replacement of Zn tetrahedra by Pb octahedra, dimension-tunable anisotropic nanocrystals of CsPbBr 3 are reported. This B-site ion introduction led to CsPbBr 3 nanorods having [100] as major axis, in contrast with all reports on rods/wires where the lengths were along the [001] direction. This was possible by using derivatives of α-bromo ketones, which helped in tuning the shape of Cs 2 ZnBr 4 and also the facets of transformed CsPbBr 3 . While similar experiments are extended to orthorhombic Cs 2 HgBr 4 , standard nanorods with [001] as the major axis were observed. From these results, it is further concluded that anisotropic perovskite nanocrystals might not follow any specific rules for directional growth and instead might depend on the structure of the parent lattice.

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“…While the size distributions of our CsPbX 3 samples are too broad to perform Rietveld refinement and measure changes in the octahedral tilt angles, the mean size of our initial CsPbI 3 NCs (11.9 nm) falls within the range where surface strain is expected to induce changes to their structure. Thus, the octahedral tilt angles likely change during anion exchange both due to differences in bulk structure along with the different surface energies associated with CsPbBr 3 and CsPbI 3 . − …”

Section: Resultsmentioning

confidence: 99%

Irreversibility in Anion Exchange Between Cesium Lead Bromide and Iodide Nanocrystals Imaged by Single-Particle Fluorescence

2020

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Anion exchange is a powerful method to tune the emission wavelength of perovskite CsPbX 3 (X = Cl, Br, or I) nanocrystals across the visible spectrum. CsPbX 3 nanocrystals can possess a number of crystal structures that depend on both their composition and size. Understanding the role these structural variations play during anion exchange is important for their future application in optoelectronic devices. In this work, we used fluorescence microscopy to monitor reaction trajectories of individual nanocrystals as they undergo anion exchange between CsPbBr 3 and CsPbI 3 . By varying the concentration of substitutional ion used to induce anion exchange, we quantify differences in reaction times for exchange in opposite directions. CsPbI 3 nanocrystals undergo more abrupt shifts in their emission characteristics as they transform to CsPbBr 3 , while CsPbBr 3 nanocrystals exhibit a smoother transition during their transformation to CsPbI 3 . Simulations of anion exchange using Monte Carlo trajectories are consistent with a larger degree of structural reorganization when CsPbI 3 nanocrystals undergo anion exchange. Together, these results reveal that there are structural differences between CsPbI 3 nanocrystals synthesized by the hot-injection method and those produced by anion exchange. The narrower distribution of reaction times when CsPbI 3 nanocrystals transform to CsPbBr 3 may produce better compositional homogeneity when this reaction is scaled-up to incorporate these materials into optoelectronic devices.

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Post-synthetic oriented attachment of CsPbBr₃ perovskite nanocrystal building blocks: from first principle calculation to experimental demonstration of size and dimensionality (0D/1D/2D)

Abstract: Immiscible solvent treatment induced oriented attachment of perovskite nanocrystal, resulting in change of size and dimensionality (0D/1D/2D).

Cited by 26 publications

References 61 publications

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

Introducing B-Site Cations by Ion Exchange and Shape Anisotropy in CsPbBr₃ Perovskite Nanostructures

Irreversibility in Anion Exchange Between Cesium Lead Bromide and Iodide Nanocrystals Imaged by Single-Particle Fluorescence

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Post-synthetic oriented attachment of CsPbBr3 perovskite nanocrystal building blocks: from first principle calculation to experimental demonstration of size and dimensionality (0D/1D/2D)

Abstract: Immiscible solvent treatment induced oriented attachment of perovskite nanocrystal, resulting in change of size and dimensionality (0D/1D/2D).

Cited by 26 publications

References 61 publications

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

Introducing B-Site Cations by Ion Exchange and Shape Anisotropy in CsPbBr3 Perovskite Nanostructures

Irreversibility in Anion Exchange Between Cesium Lead Bromide and Iodide Nanocrystals Imaged by Single-Particle Fluorescence

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Resources

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Post-synthetic oriented attachment of CsPbBr₃ perovskite nanocrystal building blocks: from first principle calculation to experimental demonstration of size and dimensionality (0D/1D/2D)

Introducing B-Site Cations by Ion Exchange and Shape Anisotropy in CsPbBr₃ Perovskite Nanostructures