Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating

Tang, Yingying; Gómez, Leyre; Lesage, Arnon; Marino, Emanuele; Kodger, Thomas E.; Meijer, Janne‐Mieke; Kolpakov, Paul; Meng, Jie; Zheng, Kaibo; Gregorkiewicz, T.; Schall, Peter

doi:10.1021/acs.nanolett.0c02005

Cited by 26 publications

(44 citation statements)

References 33 publications

(77 reference statements)

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“… 12 , 68 , 69 Recently, a carrier solvent–surfactant pair suitable for dispersing perovskite NC colloidal droplets (in toluene) was developed, namely, fluorinated solvents FC-40 or HFE-750 and fluorinated surfactant 008-FS, yielding single-component perovskite supraparticles. 70 Here, we extend the method to binary SLs with perovskite NCs ( Figure 16 ). Supraparticles with b-ABO 3 -type structures can be obtained from the emulsions of 8.6 nm CsPbBr 3 and 18.6 nm NaGdF 4 NCs ( Figure 16 b).…”

Section: Results and Discussionmentioning

confidence: 99%

Structural Diversity in Multicomponent Nanocrystal Superlattices Comprising Lead Halide Perovskite Nanocubes

et al. 2022

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Nanocrystal (NC) self-assembly is a versatile platform for materials engineering at the mesoscale. The NC shape anisotropy leads to structures not observed with spherical NCs. This work presents a broad structural diversity in multicomponent, long-range ordered superlattices (SLs) comprising highly luminescent cubic CsPbBr 3 NCs (and FAPbBr 3 NCs) coassembled with the spherical, truncated cuboid, and disk-shaped NC building blocks. CsPbBr 3 nanocubes combined with Fe 3 O 4 or NaGdF 4 spheres and truncated cuboid PbS NCs form binary SLs of six structure types with high packing density; namely, AB 2 , quasi-ternary ABO 3 , and ABO 6 types as well as previously known NaCl, AlB 2 , and CuAu types. In these structures, nanocubes preserve orientational coherence. Combining nanocubes with large and thick NaGdF 4 nanodisks results in the orthorhombic SL resembling CaC 2 structure with pairs of CsPbBr 3 NCs on one lattice site. Also, we implement two substrate-free methods of SL formation. Oil-in-oil templated assembly results in the formation of binary supraparticles. Self-assembly at the liquid–air interface from the drying solution cast over the glyceryl triacetate as subphase yields extended thin films of SLs. Collective electronic states arise at low temperatures from the dense, periodic packing of NCs, observed as sharp red-shifted bands at 6 K in the photoluminescence and absorption spectra and persisting up to 200 K.

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Section: Results and Discussionmentioning

confidence: 99%

Structural Diversity in Multicomponent Nanocrystal Superlattices Comprising Lead Halide Perovskite Nanocubes

et al. 2022

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“…This process likely is also largely responsible for the decrease of the photoluminescence quantum yield from 50.8 to 28.2% upon the formation of SBs that was observed in our previous work. 17 …”

Section: Resultsmentioning

confidence: 99%

“…A 12 or 60 μL aliquot of 008-FS in FC-40 (5 wt %) was injected into 588 or 540 μL of neat FC-40, forming 0.1 or 2 wt % 008-FS in FC-40, respectively. 17 …”

Section: Methodsmentioning

confidence: 99%

“…Here, we investigate the ultrafast carrier dynamics of SCs of perovskite NCs by femtosecond transient optical absorption (TA), and steady-state PL and absorption measurements, to characterize the excited states of the assembled NCs and their time-dependent occupation after photoexcitation. We focus on spherical SCs, which we term superballs (SBs), 17 and employ TA measurements in the low-excitation regime, where the average number of absorbed photons per nanocrystal, ⟨ N ⟩, is below 0.10 to limit multiple exciton processes. We find a lower band gap energy and faster carrier cooling than that of the dispersed NCs, which we attribute to the increased density of states in the ordered NC assemblies, i.e., the SBs.…”

Section: Introductionmentioning

confidence: 99%

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Electronic Coupling of Highly Ordered Perovskite Nanocrystals in Supercrystals

Tang

Poonia

Laan

et al. 2022

ACS Appl. Energy Mater.

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Assembled perovskite nanocrystals (NCs), known as supercrystals (SCs), can have many exotic optical and electronic properties different from the individual NCs due to energy transfer and electronic coupling in the dense superstructures. We investigate the optical properties and ultrafast carrier dynamics of highly ordered SCs and the dispersed NCs by absorption, photoluminescence (PL), and femtosecond transient absorption (TA) spectroscopy to determine the influence of the assembly on the excitonic properties. Next to a red shift of absorption and PL peak with respect to the individual NCs, we identify signatures of the collective band-like states in the SCs. A smaller Stokes shift, decreased biexciton binding energy, and increased carrier cooling rates support the formation of delocalized states as a result of the coupling between the individual NC states. These results open perspectives for assembled perovskite NCs for application in optoelectronic devices, with design opportunities exceeding the level of NCs and bulk materials.

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“…Eq. ( 4) with z = 0, Tang et al [35] found that N ≈ 2.65 for freshly synthesized and N ≈ 1.8 for aged samples, respectively.…”

Section: Governing Equationsmentioning

confidence: 98%

Deep learning in physics: a study of dielectric quasi-cubic particles in a uniform electric field

Wang

Guet

2021

Preprint

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Solving physics problems for which we know the equations, boundary conditions and symmetries can be done by deep learning. The constraints can be either imposed as terms in a loss function or used to formulate a neural ansatz. In the present case study, we calculate the induced field inside and outside a dielectric cube placed in a uniform electric field, wherein the dielectric mismatch at edges and corners of the cube makes accurate calculations numerically challenging. The electric potential is expressed as an ansatz incorporating neural networks with known leading order behaviors and symmetries and the Laplace's equation is then solved with boundary conditions at the dielectric interface by minimizing a loss function. The loss function ensures that both Laplace's equation and boundary conditions are satisfied everywhere inside a large solution domain. We study how the electric potential inside and outside a quasi-cubic particle evolves through a sequence of shapes from a sphere to a cube. The neural network being differentiable, it is straightforward to calculate the electric field over the whole domain, the induced surface charge distribution and the polarizability. The neural network being retentive, one can efficiently follow how the field changes upon particle's shape or dielectric constant by iterating from any previously converged solution. The present work's objective is two-fold, first to show how an a priori knowledge can be incorporated into neural networks to achieve efficient learning and second to apply the method and study how the induced field and polarizability change when a dielectric particle progressively changes its shape from a sphere to a cube.

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Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating

Cited by 26 publications

References 33 publications

Structural Diversity in Multicomponent Nanocrystal Superlattices Comprising Lead Halide Perovskite Nanocubes

Structural Diversity in Multicomponent Nanocrystal Superlattices Comprising Lead Halide Perovskite Nanocubes

Electronic Coupling of Highly Ordered Perovskite Nanocrystals in Supercrystals

Deep learning in physics: a study of dielectric quasi-cubic particles in a uniform electric field

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