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Lee HC, Bootharaju MS, Lee K, Chang H, Kim SY, Ahn E, Li S, Kim BH, Ahn H, Hyeon T, Yang J. Revealing Two Distinct Formation Pathways of 2D Wurtzite-CdSe Nanocrystals Using In Situ X-Ray Scattering. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307600. [PMID: 38072639 PMCID: PMC10853705 DOI: 10.1002/advs.202307600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/21/2023] [Indexed: 02/10/2024]
Abstract
Understanding the mechanism underlying the formation of quantum-sized semiconductor nanocrystals is crucial for controlling their synthesis for a wide array of applications. However, most studies of 2D CdSe nanocrystals have relied predominantly on ex situ analyses, obscuring key intermediate stages and raising fundamental questions regarding their lateral shapes. Herein, the formation pathways of two distinct quantum-sized 2D wurtzite-CdSe nanocrystals - nanoribbons and nanosheets - by employing a comprehensive approach, combining in situ small-angle X-ray scattering techniques with various ex situ characterization methods is studied. Although both nanostructures share the same thickness of ≈1.4 nm, they display contrasting lateral dimensions. The findings reveal the pivotal role of Se precursor reactivity in determining two distinct synthesis pathways. Specifically, highly reactive precursors promote the formation of the nanocluster-lamellar assemblies, leading to the synthesis of 2D nanoribbons with elongated shapes. In contrast, mild precursors produce nanosheets from a tiny seed of 2D nuclei, and the lateral growth is regulated by chloride ions, rather than relying on nanocluster-lamellar assemblies or Cd(halide)2 -alkylamine templates, resulting in 2D nanocrystals with relatively shorter lengths. These findings significantly advance the understanding of the growth mechanism governing quantum-sized 2D semiconductor nanocrystals and offer valuable guidelines for their rational synthesis.
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Affiliation(s)
- Hyo Cheol Lee
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Megalamane S. Bootharaju
- Center for Nanoparticle ResearchInstitute for Basic Science (IBS)Seoul08826Republic of Korea
- School of Chemical and Biological Engineeringand Institute of Chemical ProcessesSeoul National UniversitySeoul08826Republic of Korea
| | - Kyunghoon Lee
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Hogeun Chang
- Center for Nanoparticle ResearchInstitute for Basic Science (IBS)Seoul08826Republic of Korea
- School of Chemical and Biological Engineeringand Institute of Chemical ProcessesSeoul National UniversitySeoul08826Republic of Korea
- Samsung Advanced Institute of TechnologySamsung ElectronicsSuwon16678Republic of Korea
| | - Seo Young Kim
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Eonhyoung Ahn
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Shi Li
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Byung Hyo Kim
- Center for Nanoparticle ResearchInstitute for Basic Science (IBS)Seoul08826Republic of Korea
- Department of Material Science and EngineeringSoongsil UniversitySeoul06978Republic of Korea
| | - Hyungju Ahn
- Pohang Accelerator LaboratoryPohang37673Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle ResearchInstitute for Basic Science (IBS)Seoul08826Republic of Korea
- School of Chemical and Biological Engineeringand Institute of Chemical ProcessesSeoul National UniversitySeoul08826Republic of Korea
| | - Jiwoong Yang
- Department of Energy Science and EngineeringDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
- Energy Science and Engineering Research CenterDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
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2
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Saenz N, Hamachi LS, Wolock A, Goodge BH, Kuntzmann A, Dubertret B, Billinge I, Kourkoutis LF, Muller DA, Crowther AC, Owen JS. Synthesis of graded CdS 1-xSe x nanoplatelet alloys and heterostructures from pairs of chalcogenoureas with tailored conversion reactivity. Chem Sci 2023; 14:12345-12354. [PMID: 37969574 PMCID: PMC10631235 DOI: 10.1039/d3sc03384h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/13/2023] [Indexed: 11/17/2023] Open
Abstract
A mixture of N,N,N'-trisubstituted thiourea and cyclic N,N,N',N'-tetrasubstituted selenourea precursors were used to synthesize three monolayer thick CdS1-xSex nanoplatelets in a single synthetic step. The microstructure of the nanoplatelets could be tuned from homogeneous alloys, to graded alloys to core/crown heterostructures depending on the relative conversion reactivity of the sulfur and selenium precursors. UV-visible absorption and photoluminescence spectroscopy and scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) images demonstrate that the elemental distribution is governed by the relative precursor conversion kinetics. Slow conversion kinetics produced nanoplatelets with larger lateral dimensions, behavior that is characteristic of precursor conversion limited growth kinetics. Across a 10-fold range of reactivity, CdS nanoplatelets have 4× smaller lateral dimensions than CdSe nanoplatelets grown under identical conversion kinetics. The difference in size is consistent with a rate of CdSe growth that is 4× greater than the rate of CdS. The influence of the relative sulfide and selenide growth rates, the duration of the nucleation phase, and the solute composition on the nanoplatelet microstructure are discussed.
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Affiliation(s)
- Natalie Saenz
- Department of Chemistry, Columbia University New York NY USA
| | | | - Anna Wolock
- Department of Chemistry, Barnard College, Columbia University New York NY USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
| | - Alexis Kuntzmann
- Ecole Supérieure de Physique et de Chimie Industrielle Paris France
| | - Benoit Dubertret
- Ecole Supérieure de Physique et de Chimie Industrielle Paris France
| | - Isabel Billinge
- Department of Chemistry, Columbia University New York NY USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University Ithaca NY 14853 USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University Ithaca NY 14853 USA
| | - Andrew C Crowther
- Department of Chemistry, Barnard College, Columbia University New York NY USA
| | - Jonathan S Owen
- Department of Chemistry, Columbia University New York NY USA
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3
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Diroll BT, Guzelturk B, Po H, Dabard C, Fu N, Makke L, Lhuillier E, Ithurria S. 2D II-VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration. Chem Rev 2023; 123:3543-3624. [PMID: 36724544 DOI: 10.1021/acs.chemrev.2c00436] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II-VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II-VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II-VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron-hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Burak Guzelturk
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Hong Po
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Corentin Dabard
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Ningyuan Fu
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Lina Makke
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
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4
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Montanarella F, Akkerman QA, Bonatz D, van der Sluijs MM, van der Bok JC, Prins PT, Aebli M, Mews A, Vanmaekelbergh D, Kovalenko MV. Growth and Self-Assembly of CsPbBr 3 Nanocrystals in the TOPO/PbBr 2 Synthesis as Seen with X-ray Scattering. NANO LETTERS 2023; 23:667-676. [PMID: 36607192 PMCID: PMC9881167 DOI: 10.1021/acs.nanolett.2c04532] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Despite broad interest in colloidal lead halide perovskite nanocrystals (LHP NCs), their intrinsic fast growth has prevented controlled synthesis of small, monodisperse crystals and insights into the reaction mechanism. Recently, a much slower synthesis of LHP NCs with extreme size control has been reported, based on diluted TOPO/PbBr2 precursors and a diisooctylphosphinate capping ligand. We report new insights into the nucleation, growth, and self-assembly in this reaction, obtained by in situ synchrotron-based small-angle X-ray scattering and optical absorption spectroscopy. We show that dispersed 3 nm Cs[PbBr3] agglomerates are the key intermediate species: first, they slowly nucleate into crystals, and then they release Cs[PbBr3] monomers for further growth of the crystals. We show the merits of a low Cs[PbBr3] monomer concentration for the reaction based on oleate ligands. We also examine the spontaneous superlattice formation mechanism occurring when the growing nanocrystals in the solvent reach a critical size of 11.6 nm.
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Affiliation(s)
- Federico Montanarella
- Laboratory
of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093Zürich, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600Dübendorf, Switzerland
- Email
for F.M.:
| | - Quinten A. Akkerman
- Laboratory
of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093Zürich, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600Dübendorf, Switzerland
| | - Dennis Bonatz
- Institute
of Physical Chemistry, University of Hamburg, 20146Hamburg, Germany
| | | | - Johanna C. van der Bok
- Debye
Institute for Nanomaterials Science, Utrecht
University, 3584 CCUtrecht, The Netherlands
| | - P. Tim Prins
- Debye
Institute for Nanomaterials Science, Utrecht
University, 3584 CCUtrecht, The Netherlands
| | - Marcel Aebli
- Laboratory
of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093Zürich, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600Dübendorf, Switzerland
| | - Alf Mews
- Institute
of Physical Chemistry, University of Hamburg, 20146Hamburg, Germany
| | - Daniel Vanmaekelbergh
- Debye
Institute for Nanomaterials Science, Utrecht
University, 3584 CCUtrecht, The Netherlands
| | - Maksym V. Kovalenko
- Laboratory
of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093Zürich, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600Dübendorf, Switzerland
- Email for M.V.K.:
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5
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Nguyen KA, Pachter R, Day PN. Theoretical Investigation of the Electronic Spectra of Cadmium Chalcogenide 2D Nanoplatelets. J Phys Chem A 2022; 126:8818-8825. [DOI: 10.1021/acs.jpca.2c05253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Kiet A. Nguyen
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio45433, United States
- UES, Inc., Dayton, Ohio45432, United States
| | - Ruth Pachter
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio45433, United States
| | - Paul N. Day
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio45433, United States
- UES, Inc., Dayton, Ohio45432, United States
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6
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Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission. Nat Commun 2022; 13:5094. [PMID: 36042249 PMCID: PMC9427944 DOI: 10.1038/s41467-022-32713-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Nanocrystals (NCs) are now established building blocks for optoelectronics and their use as down converters for large gamut displays has been their first mass market. NC integration relies on a combination of green and red NCs into a blend, which rises post-growth formulation issues. A careful engineering of the NCs may enable dual emissions from a single NC population which violates Kasha’s rule, which stipulates that emission should occur at the band edge. Thus, in addition to an attentive control of band alignment to obtain green and red signals, non-radiative decay paths also have to be carefully slowed down to enable emission away from the ground state. Here, we demonstrate that core/crown/crown 2D nanoplatelets (NPLs), made of CdSe/CdTe/CdSe, can combine a large volume and a type-II band alignment enabling simultaneously red and narrow green emissions. Moreover, we demonstrate that the ratio of the two emissions can be tuned by the incident power, which results in a saturation of the red emission due to non-radiative Auger recombination that affects this emission much stronger than the green one. Finally, we also show that dual-color, power tunable, emission can be obtained through an electrical excitation. Nanocrystals are desirable light sources for advanced display technologies. Here, the authors report on double-crowned 2D semiconductor nanoplatelets as light downconverters that offer both green and red emissions to achieve a wide color gamut.
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7
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van der Bok JC, Prins PT, Montanarella F, Maaskant DN, Brzesowsky FA, van der Sluijs MM, Salzmann BBV, Rabouw FT, Petukhov AV, De Mello Donega C, Vanmaekelbergh D, Meijerink A. In Situ Optical and X-ray Spectroscopy Reveals Evolution toward Mature CdSe Nanoplatelets by Synergetic Action of Myristate and Acetate Ligands. J Am Chem Soc 2022; 144:8096-8105. [PMID: 35482030 PMCID: PMC9100465 DOI: 10.1021/jacs.2c00423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The growth of two-dimensional platelets of the CdX family (X = S, Se, or Te) in an organic solvent requires the presence of both long- and short-chain ligands. This results in nanoplatelets of atomically precise thickness and long-chain ligand-stabilized Cd top and bottom surfaces. The platelets show a bright and spectrally pure luminescence. Despite the enormous interest in CdX platelets for optoelectronics, the growth mechanism is not fully understood. Riedinger et al. studied the reaction without a solvent and showed the favorable role for short-chain carboxylates for growth in two dimensions. Their model, based on the total energy of island nucleation, shows favored side facet growth versus growth on the top and bottom surfaces. However, several aspects of the synthesis under realistic conditions are not yet understood: Why are both short- and long-chain ligands required to obtain platelets? Why does the synthesis result in both isotropic nanocrystals and platelets? At which stage of the reaction is there bifurcation between isotropic and 2D growth? Here, we report an in situ study of the CdSe nanoplatelet reaction under practical synthesis conditions. We show that without short-chain ligands, both isotropic and mini-nanoplatelets form in the early stage of the process. However, most remaining precursors are consumed in isotropic growth. Addition of acetate induces a dramatic shift toward nearly exclusive 2D growth of already existing mini-nanoplatelets. Hence, although myristate stabilizes mini-nanoplatelets, mature nanoplatelets only grow by a subtle interplay between myristate and acetate, the latter catalyzes fast lateral growth of the side facets of the mini-nanoplatelets.
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Affiliation(s)
- Johanna C van der Bok
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - P Tim Prins
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Federico Montanarella
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - D Nicolette Maaskant
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Floor A Brzesowsky
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Maaike M van der Sluijs
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Bastiaan B V Salzmann
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Andrei V Petukhov
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands.,Laboratory of Physical Chemistry, Eindhoven University of Technology, AZ Eindhoven 5612, The Netherlands
| | - Celso De Mello Donega
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Daniel Vanmaekelbergh
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
| | - Andries Meijerink
- Debye Institute for Nanomaterials Science, Utrecht University, CS Utrecht 3584, The Netherlands
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8
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Cao Z, Zhu J, Peng J, Meng N, Bian F, Luan C, Zhang M, Li Y, Yu K, Zeng J. Transformation Pathway from CdSe Nanoplatelets with Absorption Doublets at 373/393 nm to Nanoplatelets at 434/460 nm. JOURNAL OF PHYSICAL CHEMISTRY LETTERS 2022; 13:3983-3989. [PMID: 35481745 DOI: 10.1021/acs.jpclett.2c00844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
For those colloidal semiconductor CdSe nanospecies that exhibit sharp optical absorption doublets, different explanations have appeared in the literature regarding their morphological nature and formation, with no consensus reached. Here, we discuss the transformation pathway in two types of CdSe nanoplatelets (NPLs), from NPL-393 to NPL-460, exhibiting absorption doublets at 373/393 and 433/460 nm, respectively. Synchrotron-based small/wide-angle X-ray scattering (SAXS/WAXS) was performed to monitor the in situ transformation associated with the temperature. Combining the results of SAXS/WAXS, optical spectroscopy, and transmission electron microscopy, we propose that the transformation pathway experiences corresponding magic-sized clusters (MSCs), which display similar optical properties but with zero-dimensional structure. From stacked NPL-393 to stacked NPL-460, the transformation goes through sequentially individual NPL-393, MSC-393, MSC-460, and individual NPL-460 at their corresponding characteristic temperature. The present findings provide compelling evidence that both MSCs and their assembled NPLs exhibit similar optical absorption.
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Affiliation(s)
- Zhaopeng Cao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jinming Zhu
- School of Basic Medicine, Guizhou Medical University, Guiyang, Guizhou 550025, People's Republic of China.,Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Jun Peng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Nan Meng
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fenggang Bian
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Chaoran Luan
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China.,Laboratory of Ethnopharmacology, Tissue-Orientated Property of Chinese Medicine Key Laboratory of Sichuan Province, West China School of Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China
| | - Meng Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Yan Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Kui Yu
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China.,Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Jianrong Zeng
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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9
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Guillemeney L, Lermusiaux L, Landaburu G, Wagnon B, Abécassis B. Curvature and self-assembly of semi-conducting nanoplatelets. Commun Chem 2022; 5:7. [PMID: 36697722 PMCID: PMC9814859 DOI: 10.1038/s42004-021-00621-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/21/2021] [Indexed: 01/28/2023] Open
Abstract
Semi-conducting nanoplatelets are two-dimensional nanoparticles whose thickness is in the nanometer range and controlled at the atomic level. They have come up as a new category of nanomaterial with promising optical properties due to the efficient confinement of the exciton in the thickness direction. In this perspective, we first describe the various conformations of these 2D nanoparticles which display a variety of bent and curved geometries and present experimental evidences linking their curvature to the ligand-induced surface stress. We then focus on the assembly of nanoplatelets into superlattices to harness the particularly efficient energy transfer between them, and discuss different approaches that allow for directional control and positioning in large scale assemblies. We emphasize on the fundamental aspects of the assembly at the colloidal scale in which ligand-induced forces and kinetic effects play a dominant role. Finally, we highlight the collective properties that can be studied when a fine control over the assembly of nanoplatelets is achieved.
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Affiliation(s)
- Lilian Guillemeney
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Laurent Lermusiaux
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Guillaume Landaburu
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benoit Wagnon
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benjamin Abécassis
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
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10
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Hu Z, O’Neill R, Lesyuk R, Klinke C. Colloidal Two-Dimensional Metal Chalcogenides: Realization and Application of the Structural Anisotropy. Acc Chem Res 2021; 54:3792-3803. [PMID: 34623803 DOI: 10.1021/acs.accounts.1c00209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ConspectusDue to the spatial confinement, two-dimensional metal chalcogenides display an extraordinary optical response and carrier transport ability. Solution-based synthesis techniques such as colloidal hot injection and ion exchange provide a cost-effective way to fabricate such low-dimensional semiconducting nanocrystals. Over the years, developments in colloidal chemistry made it possible to synthesize various kinds of ultrathin colloidal nanoplatelets, including wurtzite- and zinc blende-type CdSe, rock salt PbS, black phosphorus-like SnX (X = S or Se), hexagonal copper sulfides, selenides, and even transition metal dichalcogenides like MoS2. By altering experimental conditions and applying capping ligands with specific functional groups, it is possible to accurately tune the dimensionality, geometry, and consequently the optical properties of these colloidal metal chalcogenide crystals. Here, we review recent progress in the syntheses of two-dimensional colloidal metal chalcogenides (CMCs) and property characterizations based on optical spectroscopy or device-related measurements. The discoveries shine a light on their huge prospect for applications in areas such as photovoltaics, optoelectronics, and spintronics. In specific, the formation mechanisms of two-dimensional CMCs are discussed. The growth of colloidal nanocrystals into a two-dimensional shape is found to require either an intrinsic structural asymmetry or the assist of coexisted ligand molecules, which act as lamellar double-layer templates or "facet" the crystals via selective adsorption. By performing optical characterizations and especially ultrafast spectroscopic measurements on these two-dimensional CMCs, their unique electronic and excitonic features are revealed. A strong dependence of optical transition energies linked to both interband and inter-subband processes on the crystal geometry can be verified, highlighting a tremendous confinement effect in such nanocrystals. With the self-assembly of two-dimensional nanocrystals or coupling of different phases by growing heterostructures, unconventional optical performances such as charge transfer state generation or efficient Förster resonance energy transfer are discovered. The growth of large-scale individualized PbS and SnS nanosheets can be realized by facile hot injection techniques, which gives the opportunity to investigate the charge carrier behavior within a single nanocrystal. According to the results of the device-based measurements on these individualized crystals, structure asymmetry-induced anisotropic electrical responses and Rashba effects caused by a splitting of spin-resolved bands in the momentum space due to strong spin-orbit-coupling are demonstrated. It is foreseen that such geometry-controlled, large-scale two-dimensional CMCs can be the ideal materials used for designing high-efficiency photonics and electronics.
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Affiliation(s)
- Ziyi Hu
- Chemistry Department, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Ryan O’Neill
- Chemistry Department, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom
| | - Rostyslav Lesyuk
- Institute of Physics, University of Rostock, Albert-Einstein-Strasse 23, 18059 Rostock, Germany
- Pidstryhach Institute for Applied Problems of Mechanics and Mathematics, National Academy of Sciences of Ukraine, 79060 Lviv, Ukraine
- Department of Photonics, Lviv Polytechnic National University, 79000 Lviv, Ukraine
| | - Christian Klinke
- Chemistry Department, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom
- Institute of Physics, University of Rostock, Albert-Einstein-Strasse 23, 18059 Rostock, Germany
- Department “Life, Light & Matter”, University of Rostock, Albert-Einstein-Strasse 25, 18059 Rostock, Germany
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Zhu J, Cao Z, Zhu Y, Rowell N, Li Y, Wang S, Zhang C, Jiang G, Zhang M, Zeng J, Yu K. Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Jinming Zhu
- Institute of Atomic and Molecular Physics Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Zhaopeng Cao
- Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 P. R. China
- School of Physical Science and Technology ShanghaiTech University Shanghai 201210 P. R. China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Yongcheng Zhu
- Institute of Atomic and Molecular Physics Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Nelson Rowell
- Metrology Research Centre National Research Council Canada Ottawa Ontario K1A 0R6 Canada
| | - Yan Li
- Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 P. R. China
- School of Physical Science and Technology ShanghaiTech University Shanghai 201210 P. R. China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Shanling Wang
- Analytical & Testing Center Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Chunchun Zhang
- Analytical & Testing Center Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Gang Jiang
- Institute of Atomic and Molecular Physics Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Meng Zhang
- Institute of Atomic and Molecular Physics Sichuan University Chengdu Sichuan 610065 P. R. China
| | - Jianrong Zeng
- Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 P. R. China
- Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201204 P. R. China
| | - Kui Yu
- Institute of Atomic and Molecular Physics Sichuan University Chengdu Sichuan 610065 P. R. China
- Engineering Research Center in Biomaterials Sichuan University Chengdu Sichuan 610065 P. R. China
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12
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Zhu J, Cao Z, Zhu Y, Rowell N, Li Y, Wang S, Zhang C, Jiang G, Zhang M, Zeng J, Yu K. Transformation Pathway from CdSe Magic-Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm. Angew Chem Int Ed Engl 2021; 60:20358-20365. [PMID: 33960093 DOI: 10.1002/anie.202104986] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Indexed: 12/13/2022]
Abstract
Divergent interpretations have appeared in the literature regarding the structural nature and evolutionary behavior for photoluminescent CdSe nanospecies with sharp doublets in optical absorption. We report a comprehensive description of the transformation pathway from one CdSe nanospecies displaying an absorption doublet at 373/393 nm to another species with a doublet at 433/460 nm. These two nanospecies are zero-dimensional (0D) magic-size clusters (MSCs) with 3D quantum confinement, and are labeled dMSC-393 and dMSC-460, respectively. Synchrotron-based small-angle X-ray scattering (SAXS) returns a radius of gyration of 0.92 nm for dMSC-393 and 1.14 nm for dMSC-460, and indicates that both types are disc shaped with the exponent of the SAXS form factor equal to 2.1. The MSCs develop from their unique counterpart precursor compounds (PCs), which are labeled PC-393 and PC-460, respectively. For the dMSC-393 to dMSC-460 transformation, the proposed PC-enabled pathway is comprised of three key steps, dMSC-393 to PC-393 (Step 1), PC-393 to PC-460 (Step 2 involving monomer addition), and PC-460 to dMSC-460 (Step 3). The present study provides a framework for understanding the PC-based evolution of MSCs and how PCs enable transformations between MSCs.
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Affiliation(s)
- Jinming Zhu
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Zhaopeng Cao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P. R. China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yongcheng Zhu
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Nelson Rowell
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, K1A 0R6, Canada
| | - Yan Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P. R. China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Shanling Wang
- Analytical & Testing Center, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Chunchun Zhang
- Analytical & Testing Center, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Gang Jiang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Meng Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
| | - Jianrong Zeng
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P. R. China.,Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, P. R. China
| | - Kui Yu
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, P. R. China.,Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan, 610065, P. R. China
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13
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Pun AB, Mazzotti S, Mule AS, Norris DJ. Understanding Discrete Growth in Semiconductor Nanocrystals: Nanoplatelets and Magic-Sized Clusters. Acc Chem Res 2021; 54:1545-1554. [PMID: 33660971 DOI: 10.1021/acs.accounts.0c00859] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
ConspectusSemiconductor nanocrystals (NCs) fluoresce with a color that strongly depends on their size and shape. Thus, to obtain homogeneous optical properties, researchers have strived to synthesize particles that are uniform. However, because NCs typically grow through continuous, incremental addition of material, slight differences in the growth process between individual crystallites yield statistical distributions in size and shape, leading to inhomogeneities in their optical characteristics. Much work has focused on improving synthetic protocols to control these distributions and enhance performance. Interestingly, during these efforts, several syntheses were discovered that exhibit a different type of growth process. The NCs jump from one discrete size to the next. Through purification methods, one of these sizes can then be isolated, providing a different approach to uniform NCs. Unfortunately, the fundamental mechanism behind such discrete growth and how it differs from the conventional continuous process have remained poorly understood.Discrete growth has been observed in two major classes of NCs: semiconductor nanoplatelets (NPLs) and magic-sized clusters (MSCs). NPLs are quasi-two-dimensional crystallites that exhibit a precise thickness of only a few atomic layers but much larger lateral dimensions. During growth, NPLs slowly appear with an increasing number of monolayers. By halting this process at a specific time, NPLs with a desired thickness can then be isolated (e.g., four monolayers). Because the optical properties are primarily governed by this thickness, which is uniform, NPLs exhibit improved optical properties such as narrower fluorescence line widths.While NPLs have highly anisotropic shapes and show discrete growth only in one dimension (thickness), MSCs are isotropic particles. The name "magic" arose because a specific set of NC sizes appear during synthesis. They have been believed to represent special atomic arrangements that possess enhanced structural stability. Historically, they were very small, hence molecular-scale "clusters." Isolation of one of the MSC sizes can then, in principle, provide a uniform sample of NCs. More recently, MSC growth has been extended to larger sizes, beyond what is commonly considered to be the "cluster" regime, challenging the conventional explanation for these materials.This Account summarizes recent work by our group to understand the mechanism that governs discrete growth in semiconductor NCs. We begin by describing the synthesis of NPLs. Next, we discuss the mechanism behind the highly anisotropic shape of NPLs. We build on this by examining the ripening process in NPLs. We show that NPLs slowly appear with increasing thickness, counterintuitively through lateral growth. Then, we turn to the synthesis of MSCs, in particular focusing on their growth mechanism. Our findings indicate a strong connection between NPLs and MSCs. Finally, we review several remaining challenges for the growth of NPLs and MSCs and give a brief outlook on the future of discrete growth. By understanding the underlying process, we believe that it can be exploited more broadly, potentially moving us toward more uniform nanomaterials.
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Affiliation(s)
- Andrew B. Pun
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Sergio Mazzotti
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Aniket S. Mule
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - David J. Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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14
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Mule AS, Mazzotti S, Rossinelli AA, Aellen M, Prins PT, van der Bok JC, Solari SF, Glauser YM, Kumar PV, Riedinger A, Norris DJ. Unraveling the Growth Mechanism of Magic-Sized Semiconductor Nanocrystals. J Am Chem Soc 2021; 143:2037-2048. [DOI: 10.1021/jacs.0c12185] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aniket S. Mule
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Sergio Mazzotti
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Aurelio A. Rossinelli
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Marianne Aellen
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - P. Tim Prins
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508 TA Utrecht, The Netherlands
| | - Johanna C. van der Bok
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508 TA Utrecht, The Netherlands
| | - Simon F. Solari
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Yannik M. Glauser
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Priyank V. Kumar
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Andreas Riedinger
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - David J. Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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15
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Nguyen KA, Pachter R, Day PN. Systematic Study of the Properties of CdS Clusters with Carboxylate Ligands Using a Deep Neural Network Potential Developed with Data from Density Functional Theory Calculations. J Phys Chem A 2020; 124:10472-10481. [PMID: 33271016 DOI: 10.1021/acs.jpca.0c06965] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although structures of the inorganic core of CdS atomically precise quantum dots were reported, characterizing the nature of the metal-carboxylate coordination in these materials remains a challenge due to the large number of possible isomers. The computational cost imposed by first-principles methods is prohibitive for such a configurational search, and empirical potentials are not available. In this work, we applied deep neural network algorithms to train a potential for CdS clusters with carboxylate ligands using a database of energies and gradients obtained from density functional theory calculations. The derived potential provided energies and gradients based on a set of reference structures. Our trained potential was then used to accelerate genetic algorithm and molecular dynamics simulations searches of low-energy structures, which in turn, were used to compute the X-ray diffraction and electronic absorption spectra. Our results for CdS clusters with carboxylate ligands, analyzed and compared with experimental findings, demonstrated that the structure of a cluster whose properties agree better with experiment may deviate from the one previously assumed.
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Affiliation(s)
- Kiet A Nguyen
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,UES, Inc. Dayton, Ohio 45432, United States
| | - Ruth Pachter
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Paul N Day
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,UES, Inc. Dayton, Ohio 45432, United States
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16
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Di Giacomo A, Rodà C, Khan AH, Moreels I. Colloidal Synthesis of Laterally Confined Blue-Emitting 3.5 Monolayer CdSe Nanoplatelets. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2020; 32:9260-9267. [PMID: 33191978 PMCID: PMC7659369 DOI: 10.1021/acs.chemmater.0c03066] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/09/2020] [Indexed: 05/03/2023]
Abstract
The typical synthesis protocol for blue-emitting CdSe nanoplatelets (NPLs) yields particles with extended lateral dimensions and large surface areas, resulting in NPLs with poor photoluminescence quantum efficiency. We have developed a synthesis protocol that achieves an improved control over the lateral size, by exploiting a series of long-chained carboxylate precursors that vary from cadmium octanoate (C8) to cadmium stearate (C18). The length of this metallic precursor is key to tune the width and aspect ratio of the final NPLs, and for the shorter chain lengths, the synthesis yield is improved. NPLs prepared with our procedure possess significantly enhanced photoluminescence quantum efficiencies, up to 30%. This is likely due to their reduced lateral dimensions, which also grant them good colloidal stability. As the NPL width can be tuned below the bulk exciton Bohr radius, the band edge blue-shifts, and we constructed a sizing curve relating the NPL absorption position and width. Further adjusting the synthesis protocol, we were able to obtain even thinner NPLs, emitting in the near-UV region, with a band-edge quantum efficiency of up to 11%. Results pave the way to stable and efficient light sources for applications such as blue and UV light-emitting devices and lasers.
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