1
|
Bassani CL, van Anders G, Banin U, Baranov D, Chen Q, Dijkstra M, Dimitriyev MS, Efrati E, Faraudo J, Gang O, Gaston N, Golestanian R, Guerrero-Garcia GI, Gruenwald M, Haji-Akbari A, Ibáñez M, Karg M, Kraus T, Lee B, Van Lehn RC, Macfarlane RJ, Mognetti BM, Nikoubashman A, Osat S, Prezhdo OV, Rotskoff GM, Saiz L, Shi AC, Skrabalak S, Smalyukh II, Tagliazucchi M, Talapin DV, Tkachenko AV, Tretiak S, Vaknin D, Widmer-Cooper A, Wong GCL, Ye X, Zhou S, Rabani E, Engel M, Travesset A. Nanocrystal Assemblies: Current Advances and Open Problems. ACS NANO 2024; 18:14791-14840. [PMID: 38814908 DOI: 10.1021/acsnano.3c10201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
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.
Collapse
Affiliation(s)
- Carlos L Bassani
- Institute for Multiscale Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Greg van Anders
- Department of Physics, Engineering Physics, and Astronomy, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Uri Banin
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Dmitry Baranov
- Division of Chemical Physics, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden
| | - Qian Chen
- University of Illinois, Urbana, Illinois 61801, USA
| | - Marjolein Dijkstra
- Soft Condensed Matter & Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Michael S Dimitriyev
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - Efi Efrati
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Jordi Faraudo
- Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, E-08193 Bellaterra, Barcelona, Spain
| | - Oleg Gang
- Department of Chemical Engineering, Columbia University, New York, New York 10027, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Nicola Gaston
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Physics, The University of Auckland, Auckland 1142, New Zealand
| | - Ramin Golestanian
- Max Planck Institute for Dynamics and Self-Organization (MPI-DS), 37077 Göttingen, Germany
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3PU, UK
| | - G Ivan Guerrero-Garcia
- Facultad de Ciencias de la Universidad Autónoma de San Luis Potosí, 78295 San Luis Potosí, México
| | - Michael Gruenwald
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, USA
| | - Maria Ibáñez
- Institute of Science and Technology Austria (ISTA), 3400 Klosterneuburg, Austria
| | - Matthias Karg
- Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Tobias Kraus
- INM - Leibniz-Institute for New Materials, 66123 Saarbrücken, Germany
- Saarland University, Colloid and Interface Chemistry, 66123 Saarbrücken, Germany
| | - Byeongdu Lee
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Reid C Van Lehn
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53717, USA
| | - Robert J Macfarlane
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Bortolo M Mognetti
- Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Arash Nikoubashman
- Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Germany
- Institut für Theoretische Physik, Technische Universität Dresden, 01069 Dresden, Germany
| | - Saeed Osat
- Max Planck Institute for Dynamics and Self-Organization (MPI-DS), 37077 Göttingen, Germany
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| | - Grant M Rotskoff
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Leonor Saiz
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - An-Chang Shi
- Department of Physics & Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Sara Skrabalak
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | - Ivan I Smalyukh
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, Colorado 80309, USA
- International Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Higashi-Hiroshima City 739-0046, Japan
| | - Mario Tagliazucchi
- Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA Ciudad Autónoma de Buenos Aires, Buenos Aires 1428 Argentina
| | - Dmitri V Talapin
- Department of Chemistry, James Franck Institute and Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, USA
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Alexei V Tkachenko
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Sergei Tretiak
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - David Vaknin
- Iowa State University and Ames Lab, Ames, Iowa 50011, USA
| | - Asaph Widmer-Cooper
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
- The University of Sydney Nano Institute, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Gerard C L Wong
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
| | - Xingchen Ye
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | - Shan Zhou
- Department of Nanoscience and Biomedical Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701, USA
| | - Eran Rabani
- Department of Chemistry, University of California and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- The Raymond and Beverly Sackler Center of Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michael Engel
- Institute for Multiscale Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Alex Travesset
- Iowa State University and Ames Lab, Ames, Iowa 50011, USA
| |
Collapse
|
2
|
Baek H, Kang S, Heo J, Choi S, Kim R, Kim K, Ahn N, Yoon YG, Lee T, Chang JB, Lee KS, Park YG, Park J. Insights into structural defect formation in individual InP/ZnSe/ZnS quantum dots under UV oxidation. Nat Commun 2024; 15:1671. [PMID: 38396037 PMCID: PMC10891109 DOI: 10.1038/s41467-024-45944-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
InP/ZnSe/ZnS quantum dots (QDs) stand as promising candidates for advancing QD-organic light-emitting diodes (QLED), but low emission efficiency due to their susceptibility to oxidation impedes applications. Structural defects play important roles in the emission efficiency degradation of QDs, but the formation mechanism of defects in oxidized QDs has been less investigated. Here, we investigated the impact of diverse structural defects formation on individual QDs and propagation during UV-facilitated oxidation using high-resolution (scanning) transmission electron microscopy. UV-facilitated oxidation of the QDs alters shell morphology by the formation of surface oxides, leaving ZnSe surfaces poorly passivated. Further oxidation leads to the formation of structural defects, such as dislocations, and induces strain at the oxide-QD interfaces, facilitating In diffusion from the QD core. These changes in the QD structures result in emission quenching. This study provides insight into the formation of structural defects through photo-oxidation, and their effects on emission properties of QDs.
Collapse
Grants
- IBS-R006-D1 Institute for Basic Science (IBS)
- This work was supported by the Institute for Basic Science (IBS-R006-D1) (H.B., S.K., and J.P.) and Samsung Display Co., Ltd (H.B., S.K., J.H., S.C., R.K., K.K., N.A., Y.-G.Y., T.L., J.B.C., K.S.L., Y.-G.P., and J.P.). H.B. and J.P. acknowledge support from Samsung Research Funding & Incubation Center of Samsung Electronics under Project Number SRFC-MA2002-3. H.B. and S.K.
Collapse
Affiliation(s)
- Hayeon Baek
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, Republic of Korea
| | - Sungsu Kang
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, Republic of Korea
| | - Junyoung Heo
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Soonmi Choi
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Ran Kim
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Kihyun Kim
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Nari Ahn
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Yeo-Geon Yoon
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Taekjoon Lee
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Jae Bok Chang
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Kyung Sig Lee
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea
| | - Young-Gil Park
- Samsung Display Co., Ltd., Yongin-si, Gyeonggi-do, Republic of Korea.
| | - Jungwon Park
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea.
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Institute of Engineering Research, College of Engineering, Seoul National University, Seoul, Republic of Korea.
- Advanced Institute of Convergence Technology, Seoul National University, Suwon, Republic of Korea.
| |
Collapse
|
3
|
Levi A, Hou B, Alon O, Ossia Y, Verbitsky L, Remennik S, Rabani E, Banin U. The Effect of Monomer Size on Fusion and Coupling in Colloidal Quantum Dot Molecules. NANO LETTERS 2023; 23:11307-11313. [PMID: 38047748 PMCID: PMC11145643 DOI: 10.1021/acs.nanolett.3c03903] [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: 11/24/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
The fusion step in the formation of colloidal quantum dot molecules, constructed from two core/shell quantum dots, dictates the coupling strength and hence their properties and enriched functionalities compared to monomers. Herein, studying the monomer size effect on fusion and coupling, we observe a linear relation of the fusion temperature with the inverse nanocrystal radius. This trend, similar to that in nanocrystal melting, emphasizes the role of the surface energy. The suggested fusion mechanism involves intraparticle ripening where atoms diffuse to the reactive connecting neck region. Moreover, the effect of monomer size and neck filling on the degree of electronic coupling is studied by combined atomistic-pseudopotential calculations and optical measurements, uncovering strong coupling effects in small QD dimers, leading to significant optical changes. Understanding and controlling the fusion and hence coupling effect allows tailoring the optical properties of these nanoscale structures, with potential applications in photonic and quantum technologies.
Collapse
Affiliation(s)
- Adar Levi
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Bokang Hou
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Omer Alon
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Yonatan Ossia
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Lior Verbitsky
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Sergei Remennik
- The
Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem,
Edmond J. Safra Campus, Jerusalem 9190401, Israel
| | - Eran Rabani
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- The
Raymond and Beverly Sackler Center of Computational Molecular and
Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Uri Banin
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
| |
Collapse
|
4
|
Cao W, Yakimov A, Qian X, Li J, Peng X, Kong X, Copéret C. Surface Sites and Ligation in Amine-capped CdSe Nanocrystals. Angew Chem Int Ed Engl 2023; 62:e202312713. [PMID: 37869935 DOI: 10.1002/anie.202312713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 10/24/2023]
Abstract
Converting colloidal nanocrystals (NCs) into devices for various applications is facilitated by designing and controlling their surface properties. One key strategy for tailoring surface properties is thus to choose tailored surface ligands. In that context, amines have been universally used, with the goal to improve NCs synthesis, processing and performances. However, understanding the nature of surface sites in amine-capped NCs remains challenging, due to the complex surface compositions as well as surface ligands dynamic. Here, we investigate both surface sites and amine ligation in CdSe NCs by combining advanced NMR spectroscopy and computational modelling. Notably, dynamic nuclear polarization (DNP) enhanced 113 Cd and 77 Se 1D NMR helps to identify both bulk and surface sites of NCs, while 113 Cd 2D NMR spectroscopy enables to resolve amines terminated sites on both Se-rich and nonpolar surfaces. In addition to directly bonding to surface sites, amines are shown to also interact through hydrogen-bonding with absorbed water as revealed by 15 N NMR, augmented with computations. The characterization methodology developed for this work provides unique molecular-level insight into the surface sites of a range of amine-capped CdSe NCs, and paves the way to identify structure-function relationships and rational approaches towards colloidal NCs with tailored properties.
Collapse
Affiliation(s)
- Weicheng Cao
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
- Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou, 310058, China
| | - Alexander Yakimov
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - Xudong Qian
- Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou, 310058, China
| | - Jiongzhao Li
- Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou, 310058, China
| | - Xiaogang Peng
- Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou, 310058, China
| | - Xueqian Kong
- Institute of Translational Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou, 310058, China
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| |
Collapse
|
5
|
Chaturvedi J, Munthasir ATM, Nayak AK, Tripathi LN, Thilagar P, Jagirdar BR. Shape and Phase-Controlled One-Pot Synthesis of Air Stable Cationic AgCdS Nanocrystals, Optoelectronic and Electrochemical Hydrogen Evolution Studies. SMALL METHODS 2023:e2300907. [PMID: 37849238 DOI: 10.1002/smtd.202300907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/24/2023] [Indexed: 10/19/2023]
Abstract
CdS-based materials are extensively studied for photocatalytic water splitting. By incorporating Ag+ into CdS nanomaterials, the catalyst's charge carrier dynamic can be tuned for photo-electrochemical devices. However, photo-corrosion and air-stability of the heterostructures limit the photocatalytic device's performance. Here, a one-pot, single molecular source synthesis of the air-stable AgCdS ternary semiconductor alloy nanostructures by heat-up method is reported. Monoclinic and hexagonal phases of the alloy are tuned by judicious choice of dodecane thiol (DDT), octadecyl amine (ODA), and oleyl amine (OLA) as capping agents. Transmission electron microscope (TEM) and powder X-ray diffraction characterization of the AgCdS alloy confirm the monoclinic and hexagonal phase (wurtzite) formation. The high-resolution TEM studies confirm the formation of AgCdS@DDT alloy nanorods and their shape transformation into nano-triangles. The nanoparticle coalescence is observed for ODA-capped alloys in the wurtzite phase. Moreover, OLA directs mixed crystal phases and anisotropic growth of alloy. Optical processes in AgCdS@DDT nano-triangles show mono-exponential decay (3.97 ± 0.01 ns). The monoclinic phase of the AgCdS@DDT nanorods exhibits higher electrochemical hydrogen evolution activity in neutral media as compared to the AgCdS@ODA/OLA alloy nanocrystals. DDT and OLA-capped alloys display current densities of 14.1 and 14.7 mA cm-2 , respectively, at 0.8 V (vs RHE).
Collapse
Affiliation(s)
- Jyotsna Chaturvedi
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | | | - Arpan Kumar Nayak
- Department of Physics, School of Advance Sciences, Vellore Institute of Technology, Vellore, 632014, India
| | - Laxmi Narayan Tripathi
- Department of Physics, School of Advance Sciences, Vellore Institute of Technology, Vellore, 632014, India
| | - Pakkirisamy Thilagar
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Balaji R Jagirdar
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India
| |
Collapse
|
6
|
Yan C, Byrne D, Ondry JC, Kahnt A, Moreno-Hernandez IA, Kamat GA, Liu ZJ, Laube C, Crook MF, Zhang Y, Ercius P, Alivisatos AP. Facet-selective etching trajectories of individual semiconductor nanocrystals. SCIENCE ADVANCES 2022; 8:eabq1700. [PMID: 35947667 DOI: 10.1126/sciadv.abq1700] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The size and shape of semiconductor nanocrystals govern their optical and electronic properties. Liquid cell transmission electron microscopy (LCTEM) is an emerging tool that can directly visualize nanoscale chemical transformations and therefore inform the precise synthesis of nanostructures with desired functions. However, it remains difficult to controllably investigate the reactions of semiconductor nanocrystals with LCTEM, because of the highly reactive environment formed by radiolysis of liquid. Here, we harness the radiolysis processes and report the single-particle etching trajectories of prototypical semiconductor nanomaterials with well-defined crystalline facets. Lead selenide nanocubes represent an isotropic structure that retains the cubic shape during etching via a layer-by-layer mechanism. The anisotropic arrow-shaped cadmium selenide nanorods have polar facets terminated by either cadmium or selenium atoms, and the transformation trajectory is driven by etching the selenium-terminated facets. LCTEM trajectories reveal how nanoscale shape transformations of semiconductors are governed by the reactivity of specific facets in liquid environments.
Collapse
Affiliation(s)
- Chang Yan
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Dana Byrne
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Justin C Ondry
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Axel Kahnt
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, D-04318 Leipzig, Germany
| | | | - Gaurav A Kamat
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Zi-Jie Liu
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Christian Laube
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, D-04318 Leipzig, Germany
| | - Michelle F Crook
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ye Zhang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Peter Ercius
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| |
Collapse
|
7
|
Jasrasaria D, Weinberg D, Philbin JP, Rabani E. Simulations of nonradiative processes in semiconductor nanocrystals. J Chem Phys 2022; 157:020901. [PMID: 35840368 DOI: 10.1063/5.0095897] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The description of carrier dynamics in spatially confined semiconductor nanocrystals (NCs), which have enhanced electron-hole and exciton-phonon interactions, is a great challenge for modern computational science. These NCs typically contain thousands of atoms and tens of thousands of valence electrons with discrete spectra at low excitation energies, similar to atoms and molecules, that converge to the continuum bulk limit at higher energies. Computational methods developed for molecules are limited to very small nanoclusters, and methods for bulk systems with periodic boundary conditions are not suitable due to the lack of translational symmetry in NCs. This perspective focuses on our recent efforts in developing a unified atomistic model based on the semiempirical pseudopotential approach, which is parameterized by first-principle calculations and validated against experimental measurements, to describe two of the main nonradiative relaxation processes of quantum confined excitons: exciton cooling and Auger recombination. We focus on the description of both electron-hole and exciton-phonon interactions in our approach and discuss the role of size, shape, and interfacing on the electronic properties and dynamics for II-VI and III-V semiconductor NCs.
Collapse
Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - John P Philbin
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| |
Collapse
|
8
|
Zhou Y, Garoufalis CS, Baskoutas S, Zeng Z, Jia Y. Twisting Enabled Charge Transfer Excitons in Epitaxially Fused Quantum Dot Molecules. NANO LETTERS 2022; 22:4912-4918. [PMID: 35639504 DOI: 10.1021/acs.nanolett.2c01459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A heterojunction with type-II band alignment has long been considered as a prerequisite to realize charge transfer (CT) excitons which are highly appealing for exploration of quantum many-body phenomena, such as excitonic Bose-Einstein condensation and superfluidity. Herein, we have shown CT excitons can be activated via twisting in epitaxially fused heterodimer quantum dot (QD) molecules with quasi type-II band alignment, and even in QD homodimer molecules, therefore breaking the constraint of band alignment. The enabling power of twisting has been revealed. It modulates the orbital spatial localization toward charge separation that is mandatory for CT excitons. Meanwhile, it manifests an effective band offset that counterbalances the distinct many-body effects felt by excitons of different nature, thus ensuring the successful generation of CT excitons. The present work extends the realm of twistroincs into zero-dimensional materials and opens a novel pathway of manipulating the properties of QD materials and closely related molecular systems.
Collapse
Affiliation(s)
- Yamei Zhou
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, and School of Materials Science and Engineering, Henan University, Kaifeng, Henan 475001, China
| | | | - Sotirios Baskoutas
- Materials Science Department, University of Patras, 26504 Patras, Greece
| | - Zaiping Zeng
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, and School of Materials Science and Engineering, Henan University, Kaifeng, Henan 475001, China
| | - Yu Jia
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, and School of Materials Science and Engineering, Henan University, Kaifeng, Henan 475001, China
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan 450001, China
| |
Collapse
|
9
|
Ondry JC, Frechette LB, Geissler PL, Alivisatos AP. Trade-offs between Translational and Orientational Order in 2D Superlattices of Polygonal Nanocrystals with Differing Edge Count. NANO LETTERS 2022; 22:389-395. [PMID: 34935383 DOI: 10.1021/acs.nanolett.1c04058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The goal of this work is to identify factors which modulate structural order in 2D self-assembled superlattices of polygon-shaped colloidal nanocrystals. Using combined experimental and simulation techniques, we quantify order in superlattices of hexagonal prism-shaped CdSe/CdS nanocrystals and cube-shaped CsPbBr3 nanocrystals. Superlattices derived from cube-shaped nanocrystals display less translational order compared to hexagonal prism-shaped nanocrystals both experimentally and in simulations. This effect can be attributed to geometric considerations inherent to the combined rotational and translational symmetries of different polygonal shapes and their superlattices. Cubes form a simple cubic lattice where nanocrystals can slide without steric overlap, whereas hexagonal prisms interlock, preventing translation. Regarding orientational order, cube assemblies display a narrower orientation distribution. Intuitively, hexagonal prisms are a more "spherical" shape compared to cubes. The results presented here outline a conceptual framework for identifying superlattice structures which favor translationally and orientationally ordered self-assembled superlattices.
Collapse
Affiliation(s)
- Justin C Ondry
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| | - Layne B Frechette
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Phillip L Geissler
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| |
Collapse
|
10
|
Wang M, Park C, Woehl TJ. Real-time imaging of metallic supraparticle assembly during nanoparticle synthesis. NANOSCALE 2022; 14:312-319. [PMID: 34928292 DOI: 10.1039/d1nr05416c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Observations of nanoparticle superlattice formation over minutes during colloidal nanoparticle synthesis elude description by conventional understanding of self-assembly, which theorizes superlattices require extended formation times to allow for diffusively driven annealing of packing defects. It remains unclear how nanoparticle position annealing occurs on such short time scales despite the rapid superlattice growth kinetics. Here we utilize liquid phase transmission electron microscopy to directly image the self-assembly of platinum nanoparticles into close packed supraparticles over tens of seconds during nanoparticle synthesis. Electron-beam induced reduction of an aqueous platinum precursor formed monodisperse 2-3 nm platinum nanoparticles that simultaneously self-assembled over tens of seconds into 3D supraparticles, some of which showed crystalline ordered domains. Experimentally varying the interparticle interactions (e.g., electrostatic, steric interactions) by changing precursor chemistry revealed that supraparticle formation was driven by weak attractive van der Waals forces balanced by short ranged repulsive steric interactions. Growth kinetic measurements and an interparticle interaction model demonstrated that nanoparticle surface diffusion rates on the supraparticles were orders of magnitude faster than nanoparticle attachment, enabling nanoparticles to find high coordination binding sites unimpeded by incoming particles. These results reconcile rapid self-assembly of supraparticles with the conventional self-assembly paradigm in which nanocrystal position annealing by surface diffusion occurs on a significantly shorter time scale than nanocrystal attachment.
Collapse
Affiliation(s)
- Mei Wang
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.
| | - Chiwoo Park
- Department of Industrial and Manufacturing Engineering, Florida State University, Tallahassee, FL, USA
| | - Taylor J Woehl
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.
| |
Collapse
|
11
|
Cui J, Koley S, Panfil YE, Levi A, Ossia Y, Waiskopf N, Remennik S, Oded M, Banin U. Neck Barrier Engineering in Quantum Dot Dimer Molecules via Intraparticle Ripening. J Am Chem Soc 2021; 143:19816-19823. [PMID: 34791875 DOI: 10.1021/jacs.1c08863] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Coupled colloidal quantum dot (CQD) dimers represent a new class of artificial molecules composed of fused core/shell semiconductor nanocrystals. The electronic coupling and wave function hybridization are enabled by the formation of an epitaxial connection with a coherent lattice between the shells of the two neighboring quantum dots where the shell material and its dimensions dictate the quantum barrier characteristics for the charge carriers. Herein we introduce a colloidal approach to control the neck formation at the interface between the two CQDs in such artificial molecular constructs. This allows the tailoring of the neck barrier in prelinked homodimers formed via fusion of multifaceted wurtzite CdSe/CdS CQDs. The effects of reaction time, temperature, and excess ligands are studied. The neck filling process follows an intraparticle ripening mechanism at relatively mild reaction conditions while avoiding interparticle ripening. The degree of surface ligand passivation plays a key role in activating the surface atom diffusion to the neck region. The degree of neck filling strongly depends also on the initial relative orientation of the two CQDs, where homonymous plane attachment allows for facile neck growth, unlike the case of heteronymous plane attachment. Upon neck filling, the observed red-shift of the absorption and fluorescence measured both for ensemble and single dimers is assigned to enhanced hybridization of the confined wave function in CQD dimer molecules, as supported by quantum calculations. The fine-tuning of the particle interface introduced herein provides therefore a powerful tool to further control the extent of hybridization and coupling in CQD molecules.
Collapse
Affiliation(s)
- Jiabin Cui
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Somnath Koley
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yossef E Panfil
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Adar Levi
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yonatan Ossia
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Nir Waiskopf
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Sergei Remennik
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Meirav Oded
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Uri Banin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| |
Collapse
|
12
|
Cui J, Koley S, Panfil YE, Levi A, Waiskopf N, Remennik S, Oded M, Banin U. Semiconductor Bow‐Tie Nanoantenna from Coupled Colloidal Quantum Dot Molecules. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jiabin Cui
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Somnath Koley
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Yossef E. Panfil
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Adar Levi
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Nir Waiskopf
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Sergei Remennik
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Meirav Oded
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| | - Uri Banin
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 91904 Israel
- The Center for Nanoscience and Nanotechnology The Hebrew University of Jerusalem Jerusalem 91904 Israel
| |
Collapse
|
13
|
Cui J, Koley S, Panfil YE, Levi A, Waiskopf N, Remennik S, Oded M, Banin U. Semiconductor Bow-Tie Nanoantenna from Coupled Colloidal Quantum Dot Molecules. Angew Chem Int Ed Engl 2021; 60:14467-14472. [PMID: 33793047 DOI: 10.1002/anie.202101155] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/09/2021] [Indexed: 11/06/2022]
Abstract
Top-down fabricated nanoantenna architectures of both metallic and dielectric materials show powerful functionalities for Raman and fluorescence enhancement with relevance to single molecule sensing while inducing directionality of chromophore emission with implications for single photon sources. We synthesize the smallest bow-tie nanoantenna by selective tip-to-tip fusion of two tetrahedral colloidal quantum dots (CQDs) forming a dimer. While the tetrahedral monomers emit non-polarized light, the bow-tie architecture manifests nanoantenna functionality of enhanced emission polarization along the bow-tie axis, as predicted theoretically and revealed by single-particle spectroscopy. Theory also predicts the formation of an electric-field hotspot at the bow-tie epicenter. This is utilized for selective light-induced photocatalytic metal growth at that location, unlike growth on the free tips in dark conditions, thus demonstrating bow-tie dimer functionality as a photochemical reaction center.
Collapse
Affiliation(s)
- Jiabin Cui
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Somnath Koley
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Yossef E Panfil
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Adar Levi
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Nir Waiskopf
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Sergei Remennik
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Meirav Oded
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Uri Banin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| |
Collapse
|
14
|
Chen Y, Dorn RW, Hanrahan MP, Wei L, Blome-Fernández R, Medina-Gonzalez AM, Adamson MAS, Flintgruber AH, Vela J, Rossini AJ. Revealing the Surface Structure of CdSe Nanocrystals by Dynamic Nuclear Polarization-Enhanced 77Se and 113Cd Solid-State NMR Spectroscopy. J Am Chem Soc 2021; 143:8747-8760. [PMID: 34085812 DOI: 10.1021/jacs.1c03162] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) spectroscopy was used to obtain detailed surface structures of zinc blende CdSe nanocrystals (NCs) with plate or spheroidal morphologies which are capped by carboxylic acid ligands. 1D 113Cd and 77Se cross-polarization magic angle spinning (CPMAS) NMR spectra revealed distinct signals from Cd and Se atoms on the surface of the NCs, and those residing in bulk-like environments, below the surface. 113Cd cross-polarization magic-angle-turning (CP-MAT) experiments identified CdSe3O, CdSe2O2, and CdSeO3 Cd coordination environments on the surface of the NCs, where the oxygen atoms are presumably from coordinated carboxylate ligands. The sensitivity gain from DNP enabled natural isotopic abundance 2D homonuclear 113Cd-113Cd and 77Se-77Se and heteronuclear 113Cd-77Se scalar correlation solid-state NMR experiments which revealed the connectivity of the Cd and Se atoms. Importantly, 77Se{113Cd} scalar heteronuclear multiple quantum coherence (J-HMQC) experiments were used to selectively measure one-bond 77Se-113Cd scalar coupling constants (1J(77Se, 113Cd)). With knowledge of 1J(77Se, 113Cd), heteronuclear 77Se{113Cd} spin echo (J-resolved) NMR experiments were used to determine the number of Cd atoms bonded to Se atoms and vice versa. The J-resolved experiments directly confirmed that major Cd and Se surface species have CdSe2O2 and SeCd4 stoichiometries, respectively. Considering the crystal structure of zinc blende CdSe and the similarity of the solid-state NMR data for the platelets and spheroids, we conclude that the surface of the spheroidal CdSe NCs is primarily composed of {100} facets. The methods outlined here will generally be applicable to obtain detailed surface structures of various main group semiconductor nanoparticles.
Collapse
Affiliation(s)
- Yunhua Chen
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Rick W Dorn
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Michael P Hanrahan
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Lin Wei
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | | | | | - Marquix A S Adamson
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Anne H Flintgruber
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States
| | - Javier Vela
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Aaron J Rossini
- U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| |
Collapse
|
15
|
Zhao Q, Gouget G, Guo J, Yang S, Zhao T, Straus DB, Qian C, Oh N, Wang H, Murray CB, Kagan CR. Enhanced Carrier Transport in Strongly Coupled, Epitaxially Fused CdSe Nanocrystal Solids. NANO LETTERS 2021; 21:3318-3324. [PMID: 33792310 DOI: 10.1021/acs.nanolett.1c00860] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Strongly coupled, epitaxially fused colloidal nanocrystal (NC) solids are promising solution-processable semiconductors to realize optoelectronic devices with high carrier mobilities. Here, we demonstrate sequential, solid-state cation exchange reactions to transform epitaxially connected PbSe NC thin films into Cu2Se nanostructured thin-film intermediates and then successfully to achieve zinc-blende, CdSe NC solids with wide epitaxial necking along {100} facets. Transient photoconductivity measurements probe carrier transport at nanometer length scales and show a photoconductance of 0.28(1) cm2 V-1 s-1, the highest among CdSe NC solids reported. Atomic-layer deposition of a thin Al2O3 layer infiltrates and protects the structure from fusing into a polycrystalline thin film during annealing and further improves the photoconductance to 1.71(5) cm2 V-1 s-1 and the diffusion length to 760 nm. We fabricate field-effect transistors to study carrier transport at micron length scales and realize high electron mobilities of 35(3) cm2 V-1 s-1 with on-off ratios of 106 after doping.
Collapse
|
16
|
Ondry JC, Alivisatos AP. Application of Dislocation Theory to Minimize Defects in Artificial Solids Built with Nanocrystal Building Blocks. Acc Chem Res 2021; 54:1419-1429. [PMID: 33576596 DOI: 10.1021/acs.accounts.0c00719] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
ConspectusOriented atomic attachment of colloidal inorganic nanocrystals represents a powerful synthetic method for preparing complex inorganic superstructures. Examples include fusion of nanocrystals into dimer and superlattice structures. If the attachment were perfect throughout, then the resulting materials would have single crystal-like alignment of the individual nanocrystals' atomic lattices. While individual colloidal nanocrystals typically are free of many defects, there are a multitude of pathways that can generate defects upon nanocrystal attachment. These attachment generated defects are typically undesirable, and thus developing strategies to favor defect-free attachment or heal defective interfaces are essential. There may also be some cases where attachment-derived defects are desirable. In this Account, we summarize our current understanding of how these defects arise, in order to offer guidance to those who are designing nanocrystal derived solids.The small size of inorganic nanocrystals means short diffusion lengths to the surface, which favor the formation of nanocrystal building blocks with pristine atomic structures. Upon attachment, however, there are numerous pathways that can lead to atomic scale defects, and bulk crystal dislocation theory provides an invaluable guide to understanding these phenomena. As an example, an atomic step edge can be incorporated into the interface leading to an extra half-plane of atoms, known as an edge dislocation. These dislocations can be well described by the Burgers vector description of dislocations, which geometrically identifies planes in which a dislocation can move. Our in situ measurements have verified that bulk dislocation theory predictions for 1D defects hold true at few-nanometer length scales in PbTe and CdSe nanocrystal interfaces. Ultimately, the applicability of dislocation theory to nanocrystal attachment enables the predictive design of attachment to prevent or facilitate healing of defects upon nanocrystal attachment. We applied similar logic to understand formation of planar (2D) defects such as stacking faults upon nanocrystal attachment. Again concepts from bulk crystal defect crystallography can identify attachment pathways that can prevent or deterministically form planar defects upon nanocrystal attachment. The concepts we discuss work well for identifying favorable attachment geometries for nanocrystal pairs; however it is currently unclear how to translate these ideas to near-simultaneous multiparticle attachment. Geometric frustration, which prevents nanocrystal rotation, and yet-to-be considered defect generation pathways unique to multiparticle attachment complicate defect-free superlattice attachment. New imaging methods now allow for the direct observation of local attachment trajectories and may enable improved understanding of such multiparticle phenomena. With further refinement, a unified framework for understanding and ultimately eliminating structural defects in fused nanocrystal superstructures may well be achievable in coming years.
Collapse
Affiliation(s)
- Justin C. Ondry
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| | - A. Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| |
Collapse
|
17
|
Abstract
![]()
Electronic
coupling and hence hybridization of atoms serves as
the basis for the rich properties for the endless library of naturally
occurring molecules. Colloidal quantum dots (CQDs) manifesting quantum
strong confinement possess atomic-like characteristics with s and p electronic levels, which popularized
the notion of CQDs as artificial atoms. Continuing this analogy, when
two atoms are close enough to form a molecule so that their orbitals
start overlapping, the orbitals energies start to split into bonding
and antibonding states made out of hybridized orbitals. The same concept
is also applicable for two fused core–shell nanocrystals in
close proximity. Their band edge states, which dictate the emitted
photon energy, start to hybridize, changing their electronic and optical
properties. Thus, an exciting direction of “artificial molecules”
emerges, leading to a multitude of possibilities for creating a library
of new hybrid nanostructures with novel optoelectronic properties
with relevance toward diverse applications including quantum technologies. The controlled separation and the barrier height between two adjacent
quantum dots are key variables for dictating the magnitude of the
coupling energy of the confined wave functions. In the past, coupled
double quantum dot architectures prepared by molecular beam epitaxy
revealed a coupling energy of few millielectron volts, which limits
the applications to mostly cryogenic operation. The realization of
artificial quantum molecules with sufficient coupling energy detectable
at room temperature calls for the use of colloidal semiconductor nanocrystal
building blocks. Moreover, the tunable surface chemistry widely opens
the predesigned attachment strategies as well as the solution processing
ability of the prepared artificial molecules, making the colloidal
nanocrystals as an ideal candidate for this purpose. Despite several
approaches that demonstrated enabling of the coupled structures, a
general and reproducible method applicable to a broad range of colloidal
quantum materials is needed for systematic tailoring of the coupling
strength based on a dictated barrier This Account addresses
the development of nanocrystal chemistry to create
coupled colloidal quantum dot molecules and to study the
controlled electronic coupling and their emergent properties. The
simplest nanocrystal molecule, a homodimer formed from two core/shell
nanocrystal monomers, in analogy to homonuclear diatomic molecules,
serves as a model system. The shell material of the two CQDs is structurally
fused, resulting in a continuous crystal. This lowers the potential
energy barrier, enabling the hybridization of the electronic wave
functions. The direct manifestation of the hybridization reflects
on the band edge transition shifting toward lower energy and is clearly
resolved at room temperature. The hybridization energy within the
single homodimer molecule is strongly correlated with the extent of
structural continuity, the delocalization of the exciton wave function,
and the barrier thickness as calculated numerically. The hybridization
impacts the emitted photon statistics manifesting faster radiative
decay rate, photon bunching effect, and modified Auger recombination
pathway compared to the monomer artificial atoms. Future perspectives
for the nanocrystals chemistry paradigm are also highlighted.
Collapse
Affiliation(s)
- Somnath Koley
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Jiabin Cui
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yossef E. Panfil
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Uri Banin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| |
Collapse
|
18
|
Yan C, Weinberg D, Jasrasaria D, Kolaczkowski MA, Liu ZJ, Philbin JP, Balan AD, Liu Y, Schwartzberg AM, Rabani E, Alivisatos AP. Uncovering the Role of Hole Traps in Promoting Hole Transfer from Multiexcitonic Quantum Dots to Molecular Acceptors. ACS NANO 2021; 15:2281-2291. [PMID: 33336575 DOI: 10.1021/acsnano.0c08158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding electronic dynamics in multiexcitonic quantum dots (QDs) is important for designing efficient systems useful in high power scenarios, such as solar concentrators and multielectron charge transfer. The multiple charge carriers within a QD can undergo undesired Auger recombination events, which rapidly annihilate carriers on picosecond time scales and generate heat from absorbed photons instead of useful work. Compared to the transfer of multiple electrons, the transfer of multiple holes has proven to be more difficult due to slower hole transfer rates. To probe the competition between Auger recombination and hole transfer in CdSe, CdS, and CdSe/CdS QDs of varying sizes, we synthesized a phenothiazine derivative with optimized functionalities for binding to QDs as a hole accepting ligand and for spectroscopic observation of hole transfer. Transient absorption spectroscopy was used to monitor the photoinduced absorption features from both trapped holes and oxidized ligands under excitation fluences where the averaged initial number of excitons in a QD ranged from ∼1 to 19. We observed fluence-dependent hole transfer kinetics that last around 100 ps longer than the predicted Auger recombination lifetimes, and the transfer of up to 3 holes per QD. Theoretical modeling of the kinetics suggests that binding of hole acceptors introduces trapping states significantly different from those in native QDs passivated with oleate ligands. Holes in these modified trap states have prolonged lifetimes, which promotes the hole transfer efficiency. These results highlight the beneficial role of hole-trapping states in devising hole transfer pathways in QD-based systems under multiexcitonic conditions.
Collapse
Affiliation(s)
- Chang Yan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew A Kolaczkowski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zi-Jie Liu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John P Philbin
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Arunima D Balan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Yi Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| |
Collapse
|
19
|
Ondry JC, Philbin JP, Lostica M, Rabani E, Alivisatos AP. Colloidal Synthesis Path to 2D Crystalline Quantum Dot Superlattices. ACS NANO 2021; 15:2251-2262. [PMID: 33377761 DOI: 10.1021/acsnano.0c07202] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
By combining colloidal nanocrystal synthesis, self-assembly, and solution phase epitaxial growth techniques, we developed a general method for preparing single dot thick atomically attached quantum dot (QD) superlattices with high-quality translational and crystallographic orientational order along with state-of-the-art uniformity in the attachment thickness. The procedure begins with colloidal synthesis of hexagonal prism shaped core/shell QDs (e.g., CdSe/CdS), followed by liquid subphase self-assembly and immobilization of superlattices on a substrate. Solution phase epitaxial growth of additional semiconductor material fills in the voids between the particles, resulting in a QD-in-matrix structure. The photoluminescence emission spectra of the QD-in-matrix structure retains characteristic 0D electronic confinement. Importantly, annealing of the resulting structures removes inhomogeneities in the QD-QD inorganic bridges, which our atomistic electronic structure calculations demonstrate would otherwise lead to Anderson-type localization. The piecewise nature of this procedure allows one to independently tune the size and material of the QD core, shell, QD-QD distance, and the matrix material. These four choices can be tuned to control many properties (degree of quantum confinement, quantum coupling, band alignments, etc.) depending on the specific applications. Finally, cation exchange reactions can be performed on the final QD-in-matrix, as demonstrated herein with a CdSe/CdS to HgSe/HgS conversion.
Collapse
Affiliation(s)
- Justin C Ondry
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| | - John P Philbin
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Michael Lostica
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel 69978
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| |
Collapse
|
20
|
Salzmann BV, van der Sluijs MM, Soligno G, Vanmaekelbergh D. Oriented Attachment: From Natural Crystal Growth to a Materials Engineering Tool. Acc Chem Res 2021; 54:787-797. [PMID: 33502844 PMCID: PMC7893701 DOI: 10.1021/acs.accounts.0c00739] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 12/18/2022]
Abstract
ConspectusIntuitively, chemists see crystals grow atom-by-atom or molecule-by-molecule, very much like a mason builds a wall, brick by brick. It is much more difficult to grasp that small crystals can meet each other in a liquid or at an interface, start to align their crystal lattices and then grow together to form one single crystal. In analogy, that looks more like prefab building. Yet, this is what happens in many occasions and can, with reason, be considered as an alternative mechanism of crystal growth. Oriented attachment is the process in which crystalline colloidal particles align their atomic lattices and grow together into a single crystal. Hence, two aligned crystals become one larger crystal by epitaxy of two specific facets, one of each crystal. If we simply consider the system of two crystals, the unifying attachment reduces the surface energy and results in an overall lower (free) energy of the system. Oriented attachment often occurs with massive numbers of crystals dispersed in a liquid phase, a sol or crystal suspension. In that case, oriented attachment lowers the total free energy of the crystal suspension, predominantly by removal of the nanocrystal/liquid interface area. Accordingly, we should start by considering colloidal suspensions with crystals as the dispersed phase, i.e., "sols", and discuss the reasons for their thermodynamic (meta)stability and how this stability can be lowered such that oriented attachment can occur as a spontaneous thermodynamic process. Oriented attachment is a process observed both for charge-stabilized crystals in polar solvents and for ligand capped nanocrystal suspensions in nonpolar solvents. In this last system different facets can develop a very different reactivity for oriented attachment. Due to this facet selectivity, crystalline structures with very specific geometries can be grown in one, two, or three dimensions; controlled oriented attachment suddenly becomes a tool for material scientists to grow architectures that cannot be reached by any other means. We will review the work performed with PbSe and CdSe nanocrystals. The entire process, i.e., the assembly of nanocrystals, atomic alignment, and unification by attachment, is a very complex and intriguing process. Researchers have succeeded in monitoring these different steps with in situ wave scattering methods and real-space (S)TEM studies. At the same time coarse-grained molecular dynamics simulations have been used to further study the forces involved in self-assembly and attachment at an interface. We will briefly come back to some of these results in the last sections of this review.
Collapse
Affiliation(s)
| | | | - Giuseppe Soligno
- Condensed Matter and Interfaces,
Debye Institute for Nanomaterials Science, Utrecht University, P. O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Daniel Vanmaekelbergh
- Condensed Matter and Interfaces,
Debye Institute for Nanomaterials Science, Utrecht University, P. O. Box 80000, 3508 TA Utrecht, The Netherlands
| |
Collapse
|
21
|
Smeaton MA, El Baggari I, Balazs DM, Hanrath T, Kourkoutis LF. Mapping Defect Relaxation in Quantum Dot Solids upon In Situ Heating. ACS NANO 2021; 15:719-726. [PMID: 33444506 DOI: 10.1021/acsnano.0c06990] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Epitaxially connected quantum dot solids have emerged as an interesting class of quantum confined materials with the potential for highly tunable electronic structures. Realization of the predicted emergent electronic properties has remained elusive due in part to defective interdot epitaxial connections. Thermal annealing has shown potential to eliminate such defects, but a direct understanding of this mechanism hinges on determining the nature of defects in the connections and how they respond to heating. Here, we use in situ heating in the scanning transmission electron microscope to probe the effect of heating on distinct defect types. We apply a real space, local strain mapping technique, which allows us to identify tensile and shear strain in the atomic lattice, highlighting tensile, shear, and bending defects in interdot connections. We also track the out-of-plane orientation of individual QDs and infer the prevalence of out-of-plane twisting and bending defects as a function of annealing. We find that tensile and shear defects are fully relaxed upon mild thermal annealing, while bending defects persist. Additionally, out-of-plane orientation tracking reveals an increase in correctly oriented QDs, pointing to a relaxation of either twisting defects or out-of-plane bending defects. While bending defects remain, highlighting the need for further study of orientational ordering during the preattachment phase of superlattice formation, these atomic-scale insights show that annealing can effectively eliminate tensile and shear defects, a promising step toward delocalization of charge carriers and tunable electronic properties.
Collapse
Affiliation(s)
- Michelle A Smeaton
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Ismail El Baggari
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Daniel M Balazs
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Tobias Hanrath
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| |
Collapse
|
22
|
Hartley CL, Kessler ML, Dempsey JL. Molecular-Level Insight into Semiconductor Nanocrystal Surfaces. J Am Chem Soc 2021; 143:1251-1266. [PMID: 33442974 DOI: 10.1021/jacs.0c10658] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Semiconductor nanocrystals exhibit attractive photophysical properties for use in a variety of applications. Advancing the efficiency of nanocrystal-based devices requires a deep understanding of the physical defects and electronic states that trap charge carriers. Many of these states reside at the nanocrystal surface, which acts as an interface between the semiconductor lattice and the molecular capping ligands. While a detailed structural and electronic understanding of the surface is required to optimize nanocrystal properties, these materials are at a technical disadvantage: unlike molecular structures, semiconductor nanocrystals lack a specific chemical formula and generally must be characterized as heterogeneous ensembles. Therefore, in order for the field to improve current nanocrystal-based technologies, a creative approach to gaining a "molecular-level" picture of nanocrystal surfaces is required. To this end, an expansive toolbox of experimental and computational techniques has emerged in recent years. In this Perspective, we critically evaluate the insight into surface structure and reactivity that can be gained from each of these techniques and demonstrate how their strategic combination is already advancing our molecular-level understanding of nanocrystal surface chemistry.
Collapse
Affiliation(s)
- Carolyn L Hartley
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Melody L Kessler
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| |
Collapse
|
23
|
Utterback JK, Cline RP, Shulenberger KE, Eaves JD, Dukovic G. The Motion of Trapped Holes on Nanocrystal Surfaces. J Phys Chem Lett 2020; 11:9876-9885. [PMID: 33170725 DOI: 10.1021/acs.jpclett.0c02618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This Perspective discusses the phenomenon of trapped-hole diffusion in colloidal semiconductor nanocrystals. Surface charge-carrier traps are ubiquitous in nanocrystals and often dictate the fate of photoexcited carriers. New measurements and calculations are unveiling the nature of the nanocrystal surface, but many challenges to understanding the dynamics of trapped carriers remain. In contrast to the view that trapped holes are stationary, we have put forward a series of reports demonstrating that trapped holes on the surfaces of CdS and CdSe nanocrystals are mobile and move between traps in a sequence of hops. We summarize how these findings advance the understanding of carrier dynamics in colloidal nanocrystals and how they may impact a broad set of excited-state behaviors in these materials.
Collapse
Affiliation(s)
- James K Utterback
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - R Peyton Cline
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | | | - Joel D Eaves
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| |
Collapse
|
24
|
Zhao J, Chen B, Wang F. Shedding Light on the Role of Misfit Strain in Controlling Core-Shell Nanocrystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004142. [PMID: 33051904 DOI: 10.1002/adma.202004142] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/21/2020] [Indexed: 05/17/2023]
Abstract
Heteroepitaxial modification of nanomaterials has become a powerful means to create novel functionalities for various applications. One of the most elementary factors in heteroepitaxial nanostructures is the misfit strain arising from mismatched lattices of the constituent parts. Misfit strain not only dictates epitaxy kinetics for diversifying nanocrystal morphologies but also provides rational control over materials properties. In recent years, advances in chemical synthesis along with the rapid development of electron microscopy and X-ray diffraction techniques have enabled a substantial understanding of strain-related processes, which offers theoretical foundation and experimental guidance for researchers to refine heteroepitaxial nanostructures and their properties. Herein, recent investigations on heterogeneous core-shell nanocrystals containing misfit strains are summarized, with a focus on the mechanistic understanding of strain and strain-induced effects such as tuning the epitaxial habit, modulating the optical emission, and enhancing the catalytic activity and magnetic coercivity.
Collapse
Affiliation(s)
- Jianxiong Zhao
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| | - Bing Chen
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| | - Feng Wang
- Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| |
Collapse
|
25
|
Chen IY, Cimada daSilva J, Balazs DM, Smeaton MA, Kourkoutis LF, Hanrath T, Clancy P. The Role of Dimer Formation in the Nucleation of Superlattice Transformations and Its Impact on Disorder. ACS NANO 2020; 14:11431-11441. [PMID: 32804472 DOI: 10.1021/acsnano.0c03800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The formation of defect-free two-dimensional nanocrystal (NC) superstructures remains a challenge as persistent defects hinder charge delocalization and related device performance. Understanding defect formation is an important step toward developing strategies to mitigate their formation. However, specific mechanisms of defect formation are difficult to determine, as superlattice phase transformations that occur during fabrication are quite complex and there are a variety of factors influencing the disorder in the final structure. Here, we use Molecular Dynamics (MD) and electron microscopy in concert to investigate the nucleation of the epitaxial attachment of lead chalcogenide (PbX, where X = S, Se) NC assemblies. We use an updated implementation of an existing reactive force field in an MD framework to investigate how initial orientational (mis)alignment of the constituent building blocks impacts the final structure of the epitaxially connected superlattice. This Simple Molecular Reactive Force Field (SMRFF) captures both short-range covalent forces and long-range electrostatic forces and allows us to follow orientational and translational changes of NCs during superlattice transformation. Our simulations reveal how robust the oriented attachment is with regard to the initial configuration of the NCs, measuring its sensitivity to both in-plane and out-of-plane misorientation. We show that oriented attachment nucleates through the initial formation of dimers, which corroborate experimentally observed structures. We present high-resolution structural analysis of dimers at early stages of the superlattice transformation and rationalize their contribution to the formation of defects in the final superlattice. Collectively, the simulations and experiments presented in this paper provide insights into the nucleation of NC oriented attachment, the impact of the initial configuration of NCs on the structural fidelity of the final epitaxially connected superlattice, and the propensity to form commonly observed defects, such as missing bridges and atomic misalignment in the superlattice due to the formation of dimers. We present potential strategies to mitigate the formation of superlattice defects.
Collapse
Affiliation(s)
- Isaiah Y Chen
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | | | | | | | | | | | - Paulette Clancy
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| |
Collapse
|
26
|
|
27
|
Lee YS, Ito T, Shimura K, Watanabe T, Bu HB, Hyeon-Deuk K, Kim D. Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands. NANOSCALE 2020; 12:7124-7133. [PMID: 32191241 DOI: 10.1039/d0nr00194e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Semiconductor quantum dot superlattices (QDSLs) have attracted much attention as key materials for realizing new optoelectronic devices such as solar cells with high conversion efficiency and thermoelectric elements with high electrical conductivity. To improve the charge transport properties of QDSL-based optoelectronic devices, it is important that the QD structures form minibands, which are the coupled electronic states between QDs. A shorter inter-QD distance and a periodic arrangement of QDs are the essential conditions for the formation of minibands. In this study, we use CdTe QDs capped with short ligands of N-acetyl-l cysteine (NAC) to fabricate three-dimensional QD assemblies by utilizing chemical bonding between NACs. Absorption spectra clearly display the quantum resonance phenomenon originating from the coupling of the wave functions between the adjacent QDs in CdTe QD assemblies. Furthermore, we demonstrate the formation of minibands in CdTe QD assemblies by examining both, the excitation energy dependence of photoluminescence (PL) spectra and the detection energy dependence of PL excitation spectra. The fabrication method of QD assemblies utilizing chemical bonding between NACs can be applied to all QDs capped with NAC as a ligand.
Collapse
Affiliation(s)
- Yong-Shin Lee
- Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan.
| | | | | | | | | | | | | |
Collapse
|
28
|
Woehl T. Refocusing in Situ Electron Microscopy: Moving beyond Visualization of Nanoparticle Self-Assembly To Gain Practical Insights into Advanced Material Fabrication. ACS NANO 2019; 13:12272-12279. [PMID: 31738051 DOI: 10.1021/acsnano.9b08281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Despite incredible progress in preparing extended nanoparticle superlattices by self-assembly, theoretically predicted collective properties of extended nanoparticle superlattices are rarely correlated to observations due to the presence of defects. Enhanced fundamental understanding of the kinetics involved in nanoparticle superlattice self-assembly, specifically defect formation and annealing kinetics and mechanisms, is needed to prepare defect-free nanoparticle superlattices. In situ transmission electron microscopy (TEM) enables direct visualization of nanoparticle self-assembly phenomena in real time and at atomic spatial resolution; however, effective translation of in situ TEM data into new predictive models and material synthesis design rules remains a persistent challenge. Recent work by Ondry et al. in this issue of ACS Nano utilized atomic resolution in situ TEM to establish defect removal kinetics in epitaxially attached CdSe nanocrystal pairs, revealing a set of practical guidelines for minimizing defect formation in extended nanoparticle solids. Motivated by this work, in this Perspective, I explore and discuss the most effective and impactful uses of in situ TEM for nanoscience research and the associated technical barriers for performing in situ TEM measurements that are meaningful to bulk-scale self-assembly experiments.
Collapse
Affiliation(s)
- Taylor Woehl
- Department of Chemical and Biomolecular Engineering , University of Maryland , College Park , Maryland 20740 , United States
| |
Collapse
|