| 1. |
- Ermolaev, Georgy A., et al.
(författare)
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Broadband optical properties of monolayer and bulk MoS 2
- 2020
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Ingår i: npj 2D Materials and Applications. - : Springer Science and Business Media LLC. - 2397-7132. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Layered semiconductors such as transition metal dichalcogenides (TMDs) offer endless possibilities for designing modern photonic and optoelectronic components. However, their optical engineering is still a challenging task owing to multiple obstacles, including the absence of a rapid, contactless, and the reliable method to obtain their dielectric function as well as to evaluate in situ the changes in optical constants and exciton binding energies. Here, we present an advanced approach based on ellipsometry measurements for retrieval of dielectric functions and the excitonic properties of both monolayer and bulk TMDs. Using this method, we conduct a detailed study of monolayer MoS2 and its bulk crystal in the broad spectral range (290–3300 nm). In the near- and mid-infrared ranges, both configurations appear to have no optical absorption and possess an extremely high dielectric permittivity making them favorable for lossless subwavelength photonics. In addition, the proposed approach opens a possibility to observe a previously unreported peak in the dielectric function of monolayer MoS2 induced by the use of perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) seeding promoters for MoS2 synthesis and thus enables its applications in chemical and biological sensing. Therefore, this technique as a whole offers a state-of-the-art metrological tool for next-generation TMD-based devices.
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| 2. |
- Baluchová, Simona, et al.
(författare)
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Getting to Know Editors and Authors: The Humans Behind the Screen
- 2024
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Ingår i: Chemistry Views. - 2190-3735.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Fourteen guests from all over Europe and editors of Chemistry Europe journals met for two days to discuss trends and challenges in publishing and to get to know each other during networking breaks and a social evening. The third Chemistry Europe Early Career Researchers Meeting was held on invitation by the Chemistry Europe societies at the Wiley-VCH offices in Weinheim, Germany. It was a great success and a very fruitful exchange, as some of the participants described below.The idea of the meeting was to connect the next generation of chemists with the editors of Chemistry Europe journals and ChemistryViews, Chemistry Europe’s science news magazine. The goal was to discuss challenges in publishing and science communication, exchange ideas and best practices, and clarify expectations for editors, authors, and reviewers, and how mutual support can work. The meeting featured a combination of workshops and talks covering topics such as society publishing, peer review, advanced writing, open access, AI, and the promotion of one’s own research.
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| 3. |
- Bassani, Carlos L., et al.
(författare)
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Nanocrystal Assemblies : Current Advances and Open Problems
- 2024
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Ingår i: ACS Nano. - 1936-0851. ; 18:23, s. 14791-14840
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Forskningsöversikt (refereegranskat)abstract
- We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.
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| 4. |
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| 5. |
- Li, Zhanzhao, et al.
(författare)
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Exogenous Metal Cations in the Synthesis of CsPbBr3 Nanocrystals and Their Interplay with Tertiary Amines
- 2024
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Ingår i: Journal of the American Chemical Society. - 0002-7863. ; 146:30, s. 20636-20648
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Tidskriftsartikel (refereegranskat)abstract
- Current syntheses of CsPbBr3 halide perovskite nanocrystals (NCs) rely on overstoichiometric amounts of Pb2+ precursors, resulting in unreacted lead ions at the end of the process. In our synthesis scheme of CsPbBr3 NCs, we replaced excess Pb2+ with different exogenous metal cations (M) and investigated their effect on the synthesis products. These cations can be divided into two groups: group 1 delivers monodisperse CsPbBr3 cubes capped with oleate species (as for the case when Pb2+ is used in excess) and with a photoluminescence quantum yield (PLQY) as high as 90% with some cations (for example with M = In3+); group 2 yields irregularly shaped CsPbBr3 NCs with broad size distributions. In both cases, the addition of a tertiary ammonium cation (didodecylmethylammonium, DDMA+) during the synthesis, after the nucleation of the NCs, reshapes the NCs to monodisperse truncated cubes. Such NCs feature a mixed oleate/DDMA+ surface termination with PLQY values of up to 97%. For group 1 cations this happens only if the ammonium cation is directly added as a salt (DDMA-Br), while for group 2 cations this happens even if the corresponding tertiary amine (DDMA) is added, instead of DDMA-Br. This is attributed to the fact that only group 2 cations can facilitate the protonation of DDMA by the excess oleic acid present in the reaction environment. In all cases studied, the incorporation of M cations is marginal, and the reshaping of the NCs is only transient: if the reactions are run for a long time, the truncated cubes evolve to cubes.
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| 6. |
- Milloch, Alessandra, et al.
(författare)
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Halide Perovskite Artificial Solids as a New Platform to Simulate Collective Phenomena in Doped Mott Insulators
- 2023
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Ingår i: Nano Letters. - 1530-6992. ; 23:22, s. 10617-10624
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Tidskriftsartikel (refereegranskat)abstract
- The development of quantum simulators, artificial platforms where the predictions of many-body theories of correlated quantum materials can be tested in a controllable and tunable way, is one of the main challenges of condensed matter physics. Here we introduce artificial lattices made of lead halide perovskite nanocubes as a new platform to simulate and investigate the physics of correlated quantum materials. We demonstrate that optical injection of quantum confined excitons in this system realizes the two main features that ubiquitously pervade the phase diagram of many quantum materials: collective phenomena, in which long-range orders emerge from incoherent fluctuations, and the excitonic Mott transition, which has one-to-one correspondence with the insulator-to-metal transition described by the repulsive Hubbard model in a magnetic field. Our results demonstrate that time-resolved experiments provide a quantum simulator that is able to span a parameter range relevant for a broad class of phenomena, such as superconductivity and charge-density waves.
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| 7. |
- Milloch, Alessandra, et al.
(författare)
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Halide perovskite artificial solids as a new platform to simulate collective phenomena in doped Mott insulators
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The development of Quantum Simulators, artificial platforms where the predictions of many-body theories of correlated quantum materials can be tested in a controllable and tunable way, is one of the main challenges of condensed matter physics. We introduce artificial lattices made of lead halide perovskite nanocubes as a new platform to simulate and investigate the physics of correlated quantum materials. The ultrafast optical injection of quantum-confined excitons plays a similar role to doping in real materials. We show that, at large photo-doping, the exciton gas undergoes an excitonic Mott transition, which can be mapped on the insulator-to-metal transition of the Hubbard model in a magnetic field. At lower photo-doping, the long-range interactions drive the formation of a collective superradiant state, in which the phases of the excitons generated in each single perovskite nanocube are coherently locked. Our results demonstrate that time-resolved experiments span a parameter region of the Hubbard model in which long-range and phase-coherent orders emerge out of a doped Mott insulating phase. This physics is relevant for a broad class of phenomena, such as superconductivity and charge-density waves in correlated materials whose properties are captured by doped Hubbard models.
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| 8. |
- Nguyen, T. P.Tan, et al.
(författare)
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Tuning perovskite nanocrystal superlattices for superradiance in the presence of disorder
- 2023
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Ingår i: Journal of Chemical Physics. - 0021-9606. ; 159:20
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Tidskriftsartikel (refereegranskat)abstract
- The cooperative emission of interacting nanocrystals is an exciting topic fueled by recent reports of superfluorescence and superradiance in assemblies of perovskite nanocubes. Several studies estimated that coherent coupling is localized to a small fraction of nanocrystals (10−7-10−3) within the assembly, raising questions about the origins of localization and ways to overcome it. In this work, we examine single-excitation superradiance by calculating radiative decays and the distribution of superradiant wave function in two-dimensional CsPbBr3 nanocube superlattices. The calculations reveal that the energy disorder caused by size distribution and large interparticle separations reduces radiative coupling and leads to the excitation localization, with the energy disorder being the dominant factor. The single-excitation model clearly predicts that, in the pursuit of cooperative effects, having identical nanocubes in the superlattice is more important than achieving a perfect spatial order. The monolayers of large CsPbBr3 nanocubes (LNC = 10-20 nm) are proposed as model systems for experimental tests of superradiance under conditions of non-negligible size dispersion, while small nanocubes (LNC = 5-10 nm) are preferred for realizing the Dicke state under ideal conditions.
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