1
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Johst F, Rebmann J, Werners H, Klemeyer L, Kopula Kesavan J, Koziej D, Strelow C, Bester G, Mews A, Kipp T. Exciton-Phonon Coupling in Single ZnCdSe-Dot/CdS-Rod Nanocrystals with Engineered Band Gaps from Type-II to Type-I. ACS PHOTONICS 2024; 11:3741-3749. [PMID: 39310298 PMCID: PMC11413927 DOI: 10.1021/acsphotonics.4c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 08/29/2024] [Accepted: 08/29/2024] [Indexed: 09/25/2024]
Abstract
Exciton-phonon coupling limits the homogeneous emission line width of nanocrystals. Hence, a full understanding of this is crucial. In this work, we statistically investigate exciton-phonon coupling by performing single-particle spectroscopy on colloidal Zn1-x Cd x Se/CdS and CdSe/CdS dot-in-rod nanocrystals at cryogenic temperatures (T ≈ 10 K). In situ cation exchange enables us to analyze different band alignments and, thereby, different charge-carrier distributions. We find that the relative intensities of the longitudinal optical S- and Se-type phonon replicas correlate with the charge-carrier distribution. Our experimental findings are complemented with quantum mechanical calculations within the effective mass approximation that hint at the relevance of surface charges.
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Affiliation(s)
- Florian Johst
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
| | - Jannik Rebmann
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
| | - Hans Werners
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
| | - Lars Klemeyer
- Institute
of Nanostructure and Solid State Physics, University of Hamburg, Luruper Chaussee 149, Hamburg D-22761, Germany
| | - Jagadesh Kopula Kesavan
- Institute
of Nanostructure and Solid State Physics, University of Hamburg, Luruper Chaussee 149, Hamburg D-22761, Germany
| | - Dorota Koziej
- Institute
of Nanostructure and Solid State Physics, University of Hamburg, Luruper Chaussee 149, Hamburg D-22761, Germany
| | - Christian Strelow
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
| | - Gabriel Bester
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
- The
Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Alf Mews
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
| | - Tobias Kipp
- Institute
of Physical Chemistry, University of Hamburg, Grindelallee 117, Hamburg D-20416, Germany
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2
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Su Y, Ye K, Hu J, Zhang Z, Wang Y, Geng B, Pan D, Shen L. Graphene Quantum Dots Eradicate Resistant and Metastatic Cancer Cells by Enhanced Interfacial Inhibition. Adv Healthc Mater 2024; 13:e2304648. [PMID: 38597827 DOI: 10.1002/adhm.202304648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/07/2024] [Indexed: 04/11/2024]
Abstract
Drug-resistant and metastatic cancer cells such as a small population of cancer stem cells (CSCs) play a crucial role in metastasis and relapse. Conventional small-molecule chemotherapeutics, however, are unable to eradicate drug-resistant CSCs owing to limited interface inhibitory effects. Herein, it is reported that enhanced interfacial inhibition leading to eradication of drug-resistant CSCs can be dramatically induced by self-insertion of bioactive graphene quantum dots (GQDs) into DNA major groove (MAG) sites in cancer cells. Since transcription factors regulate gene expression at the MAG site, MAG-targeted GQDs exert greatly enhanced interfacial inhibition, downregulating the expression of a collection of cancer stem genes such as ALDH1, Notch1, and Bmi1. Moreover, the nanoscale interface inhibition mechanism reverses cancer multidrug resistance (MDR) by inhibiting MDR1 gene expression when GQDs are used at a nontoxic concentration (1/4 × half-maximal inhibitory concentration (IC50)) as the MDR reverser. Given their high efficacy in interfacial inhibition, CSC-mediated migration, invasion, and metastasis of cancer cells can be substantially blocked by MAG-targeted GQDs, which can also be harnessed to sensitize clinical cytotoxic agents for improved efficacy in combination chemotherapy. These findings elucidate the inhibitory effects of the enhanced nano-bio interface at the MAG site on eradicating CSCs, thus preventing cancer metastasis and recurrence.
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Affiliation(s)
- Yan Su
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Kai Ye
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Jinyan Hu
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Zhenlin Zhang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Yang Wang
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Bijiang Geng
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Dengyu Pan
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Longxiang Shen
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Department of Orthopedic Surgery, Sheyang County People's Hospital, Yancheng, Jiangsu, 224300, China
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3
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Yorov KE, Nematulloev S, Saidzhonov BM, Skorotetcky MS, Karluk AA, Hasanov BE, Mir WJ, Sheikh T, Gutiérrez-Arzaluz L, Phielepeit MEM, Ashraf N, Blick RH, Mohammed OF, Bayindir M, Bakr OM. Controlled Synthesis of Terbium-Doped Colloidal Gd 2O 2S Nanoplatelets Enables High-Performance X-ray Scintillators. ACS NANO 2024. [PMID: 38951541 DOI: 10.1021/acsnano.4c01652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb3+), commonly referred to as Gadox, is a widely used scintillator material due to its exceptional X-ray attenuation efficiency and high light yield. However, Gadox-based scintillators suffer from low X-ray spatial resolution due to their large particle size, which causes significant light scattering. To address this limitation, we report the synthesis of terbium-doped colloidal Gadox nanoplatelets (NPLs) with near-unity photoluminescence quantum yield (PLQY) and high radioluminescence light yield (LY). In particular, our investigation reveals a strong correlation between PLQY, LY, particle size, and Tb3+concentration. Our synthetic approach allows precise control over the lateral size and thickness of the Gadox NPLs, resulting in a LY of 50,000 photons/MeV. Flexible scintillating screens fabricated with the solution-processable Gadox NPLs exhibited a 20 lp/mm X-ray spatial resolution, surpassing commercial Gadox scintillators. These high-performance and flexible Gadox NPL-based scintillators enable enhanced X-ray imaging capabilities in medicine and security. Our work provides a framework for designing nanomaterial scintillators with superior spatial resolution and efficiency through precise control of dimensions and dopant concentration.
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Affiliation(s)
- Khursand E Yorov
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Saidkhodzha Nematulloev
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Bedil M Saidzhonov
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Maxim S Skorotetcky
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Azimet A Karluk
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Bashir E Hasanov
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Wasim J Mir
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Tariq Sheikh
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Luis Gutiérrez-Arzaluz
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | | | - Nawal Ashraf
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Robert H Blick
- Center for Hybrid Nanostructures, University of Hamburg, 22761 Hamburg, Germany
| | - Omar F Mohammed
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
- Division of Physical Sciences and Engineering, Advanced Membranes and Porous Materials Center (AMPM), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Mehmet Bayindir
- Center for Hybrid Nanostructures, University of Hamburg, 22761 Hamburg, Germany
| | - Osman M Bakr
- Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
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4
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Purcell-Milton F, Kuznetsova VA, Bai X, Coogan Á, Martínez-Carmona M, Garcia JA, Bradley AL, Gun'ko YK. Chiroptically active quantum nanonails. NANOSCALE HORIZONS 2024; 9:1013-1022. [PMID: 38597212 DOI: 10.1039/d4nh00015c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
In recent years, extensive research efforts have been dedicated to the investigation of CdSe/CdS-based quantum-confined nanostructures, driven by their distinctive properties. The morphologies of these nanostructures have been shown to directly affect their properties, an area which has proven to be an important field of study. Herein, we report a new morphology of CdSe/CdS core-shell heterostructures in the form of a 'nanonail' - a modified nanorod-like morphology, in which a distinctive triangular head can be observed at one end of the structure. In-depth studies of this morphology reveal a material with tuneable rod length and width, as well as exceptional photoluminescent properties. Following this, we have demonstrated the ability to induce chiroptical activity via ligand exchange, revealing the important role of the specific morphology, shell thickness and chiral ligand concentration in the effect of ligand induced chirality. In addition, the cellular uptake and cytotoxicity of obtained chiral nanostructures were evaluated on human lung-derived A549 cancer cells, revealing a significant enantioselectivity in biological activity. Finally, analysis on monolayers of the material demonstrate the complete absence of FRET processes. Overall, this CdSe/CdS heterostructure is another tuneable morphology of a very important nanomaterial, one which shows great advantages and a range of potential applications.
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Affiliation(s)
- Finn Purcell-Milton
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, Dublin, Ireland.
- School of Chemical & BioPharmaceutical Sciences, Technological University Dublin, Grangegorman, Dublin, Ireland
| | - Vera A Kuznetsova
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, Dublin, Ireland.
| | - Xue Bai
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, Dublin, Ireland.
| | - Áine Coogan
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, Dublin, Ireland.
| | - Marina Martínez-Carmona
- Departamento de Didáctica de las Ciencias Experimentales, Universidad de Murcia, 30100 Murcia, Spain
| | - Jorge A Garcia
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | | | - Yurii K Gun'ko
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, Dublin, Ireland.
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5
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Drake GA, Keating LP, Huang C, Shim M. Colloidal Multi-Dot Nanorods. J Am Chem Soc 2024; 146:9074-9083. [PMID: 38517010 DOI: 10.1021/jacs.3c14115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Colloidal nanorod heterostructures consisting of multiple quantum dots within a nanorod (n-DNRs, where n is the number of quantum dots within a nanorod) are synthesized with alternating segments of CdSe "dot" and CdS "rod" via solution heteroepitaxy. The reaction temperature, time dependent ripening, and asymmetry of the wurtzite lattice and the resulting anisotropy of surface ligand steric hindrance are exploited to vary the morphology of the growing quantum dot segments. The alternating CdSe and CdS growth steps can be easily repeated to increment the dot number in unidirectional or bidirectional growth regimes. As an initial exploration of electron occupation effects on their optical properties, asymmetric 2-DNRs consisting of two dots of different lengths and diameters are synthesized and are shown to exhibit a change in color and an unusual photoluminescence quantum yield increase upon photochemical doping.
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Affiliation(s)
- Gryphon A Drake
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Logan P Keating
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Conan Huang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Moonsub Shim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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6
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Liz-Marzán LM, Artzi N, Bals S, Buriak JM, Chan WCW, Chen X, Hersam MC, Kim ID, Millstone JE, Mulvaney P, Parak WJ, Rogach A, Schaak RE. Celebrating a Nobel Prize to the "Discovery of Quantum Dots, an Essential Milestone in Nanoscience". ACS NANO 2023; 17:19474-19475. [PMID: 37847312 DOI: 10.1021/acsnano.3c09671] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
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7
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Shulenberger KE, Jilek MR, Sherman SJ, Hohman BT, Dukovic G. Electronic Structure and Excited State Dynamics of Cadmium Chalcogenide Nanorods. Chem Rev 2023; 123:3852-3903. [PMID: 36881852 DOI: 10.1021/acs.chemrev.2c00676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The cylindrical quasi-one-dimensional shape of colloidal semiconductor nanorods (NRs) gives them unique electronic structure and optical properties. In addition to the band gap tunability common to nanocrystals, NRs have polarized light absorption and emission and high molar absorptivities. NR-shaped heterostructures feature control of electron and hole locations as well as light emission energy and efficiency. We comprehensively review the electronic structure and optical properties of Cd-chalcogenide NRs and NR heterostructures (e.g., CdSe/CdS dot-in-rods, CdSe/ZnS rod-in-rods), which have been widely investigated over the last two decades due in part to promising optoelectronic applications. We start by describing methods for synthesizing these colloidal NRs. We then detail the electronic structure of single-component and heterostructure NRs and follow with a discussion of light absorption and emission in these materials. Next, we describe the excited state dynamics of these NRs, including carrier cooling, carrier and exciton migration, radiative and nonradiative recombination, multiexciton generation and dynamics, and processes that involve trapped carriers. Finally, we describe charge transfer from photoexcited NRs and connect the dynamics of these processes with light-driven chemistry. We end with an outlook that highlights some of the outstanding questions about the excited state properties of Cd-chalcogenide NRs.
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Affiliation(s)
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Benjamin T Hohman
- 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.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States.,Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
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8
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Abstract
Anisotropic heterostructures of colloidal nanocrystals embed size-, shape-, and composition-dependent electronic structure within variable three-dimensional morphology, enabling intricate design of solution-processable materials with high performance and programmable functionality. The key to designing and synthesizing such complex materials lies in understanding the fundamental thermodynamic and kinetic factors that govern nanocrystal growth. In this review, nanorod heterostructures, the simplest of anisotropic nanocrystal heterostructures, are discussed with respect to their growth mechanisms. The effects of crystal structure, surface faceting/energies, lattice strain, ligand sterics, precursor reactivity, and reaction temperature on the growth of nanorod heterostructures through heteroepitaxy and cation exchange reactions are explored with currently known examples. Understanding the role of various thermodynamic and kinetic parameters enables the controlled synthesis of complex nanorod heterostructures that can exhibit unique tailored properties. Selected application prospects arising from such capabilities are then discussed.
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Affiliation(s)
- Gryphon A Drake
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
| | - Logan P Keating
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
| | - Moonsub Shim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
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9
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Kim D, Shcherbakov-Wu W, Ha SK, Lee WS, Tisdale WA. Uniaxial Strain Engineering via Core Position Control in CdSe/CdS Core/Shell Nanorods and Their Optical Response. ACS NANO 2022; 16:14713-14722. [PMID: 36044017 DOI: 10.1021/acsnano.2c05427] [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
Anisotropic strain engineering has emerged as a powerful strategy for enhancing the optoelectronic performance of semiconductor nanocrystals. Here, we show that CdSe/CdS dot-in-rod structures offer a platform for fine-tuning the optical response of CdSe quantum dots through anisotropic strain. By controlling the spatial position of the CdSe core within a growing CdS nanorod shell, varying degrees of uniaxial strain can be introduced. Placing CdSe cores at the end of the CdS nanorod induces strong asymmetric compression along the c-axis of the wurtzite CdSe core, dramatically altering its absorption and emission characteristics, whereas CdSe cores located near the middle of the nanorod experience a comparatively weak uniaxial strain field. The change in absorption and emission spectra and dynamics for highly strained end-position CdSe/CdS nanorods is explained by (1) relative shifting of the valence band light hole and heavy hole levels and (2) introduction of a strong piezoelectric potential, which spatially separates the electron and hole wave functions. The ability to tune the degree of uniaxial strain through core position control in a nanorod structure creates opportunities for precisely modulating the electronic properties of CdSe nanocrystals while simultaneously taking advantage of dielectric and optical anisotropies intrinsic to 1D nanostructures.
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Affiliation(s)
- Dahin Kim
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wenbi Shcherbakov-Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Seung Kyun Ha
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Woo Seok Lee
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - William A Tisdale
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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10
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Rosner T, Pavlopoulos NG, Shoyhet H, Micheel M, Wächtler M, Adir N, Amirav L. The Other Dimension-Tuning Hole Extraction via Nanorod Width. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12193343. [PMID: 36234471 PMCID: PMC9565346 DOI: 10.3390/nano12193343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/14/2022] [Accepted: 09/21/2022] [Indexed: 05/10/2023]
Abstract
Solar-to-hydrogen generation is a promising approach to generate clean and renewable fuel. Nanohybrid structures such as CdSe@CdS-Pt nanorods were found favorable for this task (attaining 100% photon-to-hydrogen production efficiency); yet the rods cannot support overall water splitting. The key limitation seems to be the rate of hole extraction from the semiconductor, jeopardizing both activity and stability. It is suggested that hole extraction might be improved via tuning the rod's dimensions, specifically the width of the CdS shell around the CdSe seed in which the holes reside. In this contribution, we successfully attain atomic-scale control over the width of CdSe@CdS nanorods, which enables us to verify this hypothesis and explore the intricate influence of shell diameter over hole quenching and photocatalytic activity towards H2 production. A non-monotonic effect of the rod's diameter is revealed, and the underlying mechanism for this observation is discussed, alongside implications towards the future design of nanoscale photocatalysts.
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Affiliation(s)
- Tal Rosner
- Schulich Faculty of Chemistry, The Russell Berrie Nanotechnology Institute, The Nancy and Stephen Grand Technion Energy Program, Technion−Israel Institute of Technology, Haifa 32000, Israel
| | - Nicholas G. Pavlopoulos
- Schulich Faculty of Chemistry, The Russell Berrie Nanotechnology Institute, The Nancy and Stephen Grand Technion Energy Program, Technion−Israel Institute of Technology, Haifa 32000, Israel
| | - Hagit Shoyhet
- Schulich Faculty of Chemistry, The Russell Berrie Nanotechnology Institute, The Nancy and Stephen Grand Technion Energy Program, Technion−Israel Institute of Technology, Haifa 32000, Israel
| | - Mathias Micheel
- Department Functional Interfaces, Leibniz Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745 Jena, Germany
| | - Maria Wächtler
- Department Functional Interfaces, Leibniz Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Correspondence: (M.W.); (N.A.); (L.A.)
| | - Noam Adir
- Schulich Faculty of Chemistry, The Russell Berrie Nanotechnology Institute, The Nancy and Stephen Grand Technion Energy Program, Technion−Israel Institute of Technology, Haifa 32000, Israel
- Correspondence: (M.W.); (N.A.); (L.A.)
| | - Lilac Amirav
- Schulich Faculty of Chemistry, The Russell Berrie Nanotechnology Institute, The Nancy and Stephen Grand Technion Energy Program, Technion−Israel Institute of Technology, Haifa 32000, Israel
- Correspondence: (M.W.); (N.A.); (L.A.)
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11
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Ratnaweera RJ, Rodríguez Ortiz FA, Gripp NJ, Sheldon MT. Quantifying Order during Field-Driven Alignment of Colloidal Semiconductor Nanorods. ACS NANO 2022; 16:3834-3842. [PMID: 35188744 DOI: 10.1021/acsnano.1c08488] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Aligning large populations of colloidal nanorods (NRs) into ordered assemblies provides a strategy for engineering macroscopic functional materials with strong optical anisotropy. The bulk optical properties of such systems depend not only on the individual NR building blocks but also on their meso- and macroscale ordering, in addition to more complex interparticle coupling effects. Here, we investigate the dynamic alignment of colloidal CdSe/CdS NRs in the presence of AC electric fields by measuring concurrent changes in optical transmission. Our work identifies two distinct scales of interaction that give rise to the field-driven optical response: (1) the spontaneous mesoscale self-assembly of colloidal NRs into structures with increased optical anisotropy and (2) the macroscopic ordering of NR assemblies along the direction of the applied AC field. By modeling the alignment of NR ensembles using directional statistics, we experimentally quantify the maximum degree of order in terms of the average deviation angle relative to the field axis. Results show a consistent improvement in alignment as a function of NR concentration─with a minimum average deviation of 36.2°─indicating that mesoscale assembly helps facilitate field-driven alignment of colloidal NRs.
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Affiliation(s)
- Rivi J Ratnaweera
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
| | | | - Nicholas J Gripp
- Department of Materials Science & Engineering, Texas A&M University, College Station, Texas 77843-3255, United States
| | - Matthew T Sheldon
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
- Department of Materials Science & Engineering, Texas A&M University, College Station, Texas 77843-3255, United States
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12
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Liu G, Liang W, Xue X, Rosei F, Wang Y. Atomic Identification of Interfaces in Individual Core@shell Quantum Dots. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2102784. [PMID: 34647434 PMCID: PMC8596122 DOI: 10.1002/advs.202102784] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/22/2021] [Indexed: 05/29/2023]
Abstract
CdSe@CdS Core@shell quantum dots (QDs) have been widely studied in recent years, due to their architecture which allows to tailor properties by controlling structure and composition. However, since CdSe and CdS have the same crystal structure, same cations, and similar lattice parameters, it is very challenging to image the interface. Herein, high-resolution transmission electron microscopy, high-angle annular dark-field imaging, and energy-dispersive X-ray spectroscopy elemental mapping are combined to characterize the core@shell structure and identify the interface in the CdSe@CdS QDs with different CdS shell thicknesses. By examining changes in lattice spacing in an individual CdSe@CdS quantum dot, the atomic core@shell interface is identified. For thin-shelled QDs, an ideal coherent interface forms between core and shell due to the small lattice mismatch, and the lattice spacing remains unchanged at the core and shell regions. For thick-shelled QDs, the lattice spacing is different at the core and shell regions, while the heterostructured interface is still coherent and cannot be clearly imaged. As the shell thickness further increases, a sharp core@shell interface appears. The results define an approach to characterize the heterostructure of two materials with the same crystalline structure and cations.
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Affiliation(s)
- Guiju Liu
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Wenshuang Liang
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Xuyan Xue
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Federico Rosei
- Centre Énergie Matériaux et TélécommunicationsInstitut National de la Recherche Scientifique1650 Boulevard Lionel‐BouletVarennesQuébecJ3X 1S2Canada
| | - Yiqian Wang
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
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13
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Ibrahim SA, Chan Y. Fluorescent Semiconductor Nanorods for the Solid-Phase Polymerase Chain Reaction-Based, Multiplexed Gene Detection of Mycobacterium tuberculosis. ACS APPLIED MATERIALS & INTERFACES 2021; 13:35294-35305. [PMID: 34313114 DOI: 10.1021/acsami.1c05312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The spread of infectious diseases with significantly high mortality rates can wreak devastating damage on global health systems and economies, underscoring the need for better disease diagnostic platforms. Solid-phase polymerase chain reaction (SP-PCR) potentially combines the advantages of conventional PCR-based diagnostics with the capability of multiplexed detection, given that the spatial separation between primers circumvents unwanted primer-primer interactions. However, the generally low efficiency of solid-phase amplification results in poor sensitivity and limits its use in detection schemes. We present an SP-PCR-based, multiplexed pulldown fluorescence assay for the detection of Mycobacterium tuberculosis (MTB), utilizing highly fluorescent oligonucleotide-functionalized CdSe/CdS and CdSe1-xSx/CdS nanorods (NRs) as multicolor hybridization probes. The large surface area of the NRs allows for their easy capture and pulldown, but without contributing significantly to the interparticle photon reabsorption when clustered at the pulldown sites. The NR nanoprobes were specifically designed to target the hotspot regions of the rpoB gene of MTB, which have been implicated in resistance to standard rifampicin treatment. The implementation of the semiconductor NRs as photostable multicolor fluorophores in a multiplexed SP-PCR-based detection scheme allowed for the identification of multiple hotspot regions with sub-picomolar levels of sensitivity and high specificity in artificial sputum. While this work demonstrates the utility of semiconductor NRs as highly fluorescent chromophores that can enable SP-PCR as a sensitive and accurate technique for multipathogen diagnostics, the flexible surface chemistry of the NRs should allow them to be applicable to a wide variety of detection motifs.
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Affiliation(s)
- Salwa Ali Ibrahim
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- National Institute of Laser Enhanced Sciences, Cairo University, Giza 12613, Egypt
| | - Yinthai Chan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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14
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Liu X, Xu Y, Li J, Ong X, Ali Ibrahim S, Buonassisi T, Wang X. A robust low data solution: Dimension prediction of semiconductor nanorods. Comput Chem Eng 2021. [DOI: 10.1016/j.compchemeng.2021.107315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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15
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Combining HR-TEM and XPS to elucidate the core-shell structure of ultrabright CdSe/CdS semiconductor quantum dots. Sci Rep 2020; 10:20712. [PMID: 33244030 PMCID: PMC7692488 DOI: 10.1038/s41598-020-77530-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/11/2020] [Indexed: 12/17/2022] Open
Abstract
Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the application-relevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties.
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16
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Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods. Catalysts 2020. [DOI: 10.3390/catal10101143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this study, the impact of the type of ligand at the surface of colloidal CdSe@CdS dot-in-rod nanostructures on the basic exciton relaxation and charge localization processes is closely examined. These systems have been introduced into the field of artificial photosynthesis as potent photosensitizers in assemblies for light driven hydrogen generation. Following photoinduced exciton generation, electrons can be transferred to catalytic reaction centers while holes localize into the CdSe seed, which can prevent charge recombination and lead to the formation of long-lived charge separation in assemblies containing catalytic reaction centers. These processes are in competition with trapping processes of charges at surface defect sites. The density and type of surface defects strongly depend on the type of ligand used. Here we report on a systematic steady-state and time-resolved spectroscopic investigation of the impact of the type of anchoring group (phosphine oxide, thiols, dithiols, amines) and the bulkiness of the ligand (alkyl chains vs. poly(ethylene glycol) (PEG)) to unravel trapping pathways and localization efficiencies. We show that the introduction of the widely used thiol ligands leads to an increase of hole traps at the surface compared to trioctylphosphine oxide (TOPO) capped rods, which prevent hole localization in the CdSe core. On the other hand, steric restrictions, e.g., in dithiolates or with bulky side chains (PEG), decrease the surface coverage, and increase the density of electron trap states, impacting the recombination dynamics at the ns timescale. The amines in poly(ethylene imine) (PEI) on the other hand can saturate and remove surface traps to a wide extent. Implications for catalysis are discussed.
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17
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Hao J, Li Y, Miao J, Liu R, Li J, Liu H, Wang Q, Liu H, Delville MH, He T, Wang K, Zhu X, Cheng J. Ligand-Induced Chirality in Asymmetric CdSe/CdS Nanostructures: A Close Look at Chiral Tadpoles. ACS NANO 2020; 14:10346-10358. [PMID: 32806030 DOI: 10.1021/acsnano.0c03909] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ligand-induced chirality in asymmetric CdSe/CdS core-shell nanocrystals (NCs) has been extensively applied in chiral biosensors, regioselective syntheses and assemblies, circularly polarized luminescence (CPL), and chiroptic-based devices due to their excellent physiochemical properties, such as the tunable quantum confinement effects, surface functionality, and chemical stability. Herein, we present CdSe/CdS NCs with various morphologies such as nanoflowers, tadpoles, and dot/rods (DRs) with chirality induced by surface chiral ligands. The observed circular dichroism (CD) and CPL activities are closely associated with the geometrical characteristics of the nanostructures, such as the shell thickness and the aspect ratio of the CdSe/CdS NCs. Furthermore, in situ observations of the growth of tadpoles with a single tail indicate that the CD response is mainly attributed to the CdS shell, which has a maximum tail length of ∼45 nm (approximately λ/10 of the incident light wavelength). On the other hand, the CPL activity is only related to the CdSe core, and the activity benefits from a thin CdS shell with a relatively high photoluminescence quantum yield (QY). Further theoretical models demonstrated the aspect-ratio-dependent g-factor and QY variations in these asymmetric nanostructures. These findings provide insights into not only the asymmetric synthesis of CdSe/CdS NCs, but also the rational design of CdSe/CdS nanostructures with tunable CD and CPL activities.
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Affiliation(s)
- Junjie Hao
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- CNRS, Univ. Bordeaux, Bordeaux INP, ICMCB, UMR 5026, Pessac F-33608, France
| | - Yiwen Li
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jun Miao
- Institute of Energy and Climate Research (IEK) Photovoltaics, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rulin Liu
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Jiagen Li
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Haochen Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qiushi Wang
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
| | - Huan Liu
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | | | - Tingchao He
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Kai Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xi Zhu
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Jiaji Cheng
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
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18
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Miethe JF, Luebkemann F, Schlosser A, Dorfs D, Bigall NC. Revealing the Correlation of the Electrochemical Properties and the Hydration of Inkjet-Printed CdSe/CdS Semiconductor Gels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4757-4765. [PMID: 32122127 PMCID: PMC7203843 DOI: 10.1021/acs.langmuir.9b03708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/02/2020] [Indexed: 05/31/2023]
Abstract
The mobility of charge carriers across a semiconductor-nanoparticle-based 3D network (i.e., a gel) and the interfacial transfer of the charge carriers across the nanoparticle network/electrolyte boundary are elementary processes for applications in the fields of sensing and energy harvesting. The automated manufacturing of electrodes coated with porous networks can be realized by inkjet printing. By simultaneous printing of CdSe/CdS dot-in-rod-shaped nanorods (NRs) and the destabilization reagent, CdSe/CdS gel-network-coated electrodes can be obtained. In this work, the charge carrier mobility of the electrons and the holes within the porous CdSe/CdS nanorod gel network is investigated via photoelectrochemistry. Using linear sweep voltammograms (LSVs) and intensity-modulated photocurrent spectroscopy (IMPS), it is shown that the electron is moving within the tip-to-tip-connected CdSe/CdS NR gel structure, while the holes are trapped in the CdSe seed of the semiconductor heterostructures. Furthermore, the preparation process of gel structures is related to the elementary mechanism of hydration, which can be shown via photoelectrochemical long-term studies.
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Affiliation(s)
- Jan F. Miethe
- Institute
of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, D-30167 Hannover, Germany
- Laboratory
of Nano and Quantum Engineering, Leibniz
Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany
| | - Franziska Luebkemann
- Institute
of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, D-30167 Hannover, Germany
- Laboratory
of Nano and Quantum Engineering, Leibniz
Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany
| | - Anja Schlosser
- Institute
of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, D-30167 Hannover, Germany
- Laboratory
of Nano and Quantum Engineering, Leibniz
Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany
| | - Dirk Dorfs
- Institute
of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, D-30167 Hannover, Germany
- Laboratory
of Nano and Quantum Engineering, Leibniz
Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany
- Cluster
of Excellence PhoenixD, (Photonics, Optics, and Engineering—Innovation
Across Disciplines), 30167 Hannover, Germany
| | - Nadja C. Bigall
- Institute
of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, D-30167 Hannover, Germany
- Laboratory
of Nano and Quantum Engineering, Leibniz
Universität Hannover, Schneiderberg 39, D-30167 Hannover, Germany
- Cluster
of Excellence PhoenixD, (Photonics, Optics, and Engineering—Innovation
Across Disciplines), 30167 Hannover, Germany
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19
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Khan AH, Bertrand GHV, Teitelboim A, Sekhar M. C, Polovitsyn A, Brescia R, Planelles J, Climente JI, Oron D, Moreels I. CdSe/CdS/CdTe Core/Barrier/Crown Nanoplatelets: Synthesis, Optoelectronic Properties, and Multiphoton Fluorescence Upconversion. ACS NANO 2020; 14:4206-4215. [PMID: 32275814 PMCID: PMC7199781 DOI: 10.1021/acsnano.9b09147] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Colloidal two-dimensional (2D) nanoplatelet heterostructures are particularly interesting as they combine strong confinement of excitons in 2D materials with a wide range of possible semiconductor junctions due to a template-free, solution-based growth. Here, we present the synthesis of a ternary 2D architecture consisting of a core of CdSe, laterally encapsulated by a type-I barrier of CdS, and finally a type-II outer layer of CdTe as so-called crown. The CdS acts as a tunneling barrier between CdSe- and CdTe-localized hole states, and through strain at the CdS/CdTe interface, it can induce a shallow electron barrier for CdTe-localized electrons as well. Consequently, next to an extended fluorescence lifetime, the barrier also yields emission from CdSe and CdTe direct transitions. The core/barrier/crown configuration further enables two-photon fluorescence upconversion and, due to a high nonlinear absorption cross section, even allows to upconvert three near-infrared photons into a single green photon. These results demonstrate the capability of 2D heterostructured nanoplatelets to combine weak and strong confinement regimes to engineer their optoelectronic properties.
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Affiliation(s)
- Ali Hossain Khan
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | | | - Ayelet Teitelboim
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 7610001, Israel
| | - Chandra Sekhar M.
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | | | - Rosaria Brescia
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Josep Planelles
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Juan Ignacio Climente
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Dan Oron
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 7610001, Israel
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
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20
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Cunningham PD, Coropceanu I, Mulloy K, Cho W, Talapin DV. Quantized Reaction Pathways for Solution Synthesis of Colloidal ZnSe Nanostructures: A Connection between Clusters, Nanowires, and Two-Dimensional Nanoplatelets. ACS NANO 2020; 14:3847-3857. [PMID: 32105062 DOI: 10.1021/acsnano.9b09051] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The morphology of nanocrystals serves as a powerful handle to modulate their functional properties. For semiconducting nanostructures, the shape is no less important than the size and composition, in terms of determining the electronic structure. For example, in the case of nanoplatelets (NPLs), their two-dimensional (2D) electronic structure and atomic precision along the axis of quantum confinement makes them well-suited as pure color emitters and optical gain media. In this study, we describe synthetic efforts to develop ZnSe NPLs emitting in the ultraviolet part of the spectrum. We focus on two populations of NPLs, the first having a sharp absorption onset at 345 nm and a previously unreported species with an absorption onset at 380 nm. Interestingly, we observe that the nanoplatelets are one step in a quantized reaction pathway that starts with (zero-dimensional (0D)) magic-sized clusters, then proceeds through the formation of (one-dimensional (1D)) nanowires toward the (2D) "345 nm" species of NPLs, which finally interconvert into the "380 nm" NPL species. We seek to rationalize this evolution of the morphology, in terms of a general free-energy landscape, which, under reaction control, allows for the isolation of well-defined structures, while thermodynamic control leads to the formation of three-dimensional (3D) nanocrystals.
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Affiliation(s)
- Patrick D Cunningham
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Igor Coropceanu
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Kavan Mulloy
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Wooje Cho
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Dmitri V Talapin
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
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21
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Wang J, Shao X, Liu J, Ji X, Ma J, Tian G. Fabrication of CdS-SBA-15 nanomaterials and their photocatalytic activity for degradation of salicylic acid under visible light. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 190:110139. [PMID: 31901808 DOI: 10.1016/j.ecoenv.2019.110139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/24/2019] [Accepted: 12/26/2019] [Indexed: 06/10/2023]
Abstract
CdS-SBA-15 nanomaterials were synthesized by solvothermal method using cadmium nitrate as cadmium source and thiourea as sulfur source. The properties of as-prepared materials were characterized by means of XRD, FTIR, TEM, XPS, N2 physisorption, UV-Vis DRS and PL spectra, etc. The results show as-synthesized materials have partially ordered mesoporous structure, larger specific surface area, and higher content of CdS and good crystallinity. The combination of SBA-15 and CdS did almost no reduction in the absorption light range of CdS, but greatly increased the photocapacity of the composite. The synergistic effect of CdS and SBA-15 leads to improving the photocatalytic degradation activity of salicylic acid under visible light. When the photocatalyst was 30 mg (0.75 g/L) and the concentration of salicylic acid was 10 mg/L, the maximum degradation efficiency of salicylic acid was 84.93% after 6 h of light. Photocatalytic reaction has a lower activation energy (2.90 kJ/mol), activation enthalpy (3.13 kJ/mol) and activation entropy (-281.00 J/(mol K)). The photocatalytic mechanism study demonstrates that superoxide radicals (O2•-) are the most key active species, e- and h+ have something to do with the photocatalytic reaction, while ·OH has little to do with the photocatalytic reaction. In sum, the protection effect of SBA-15 on CdS nanomaterials makes the composite have a higher photolumination intensity and a higher photocatalytic activity.
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Affiliation(s)
- Junhong Wang
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China.
| | - Xianzhao Shao
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China
| | - Junhai Liu
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China
| | - Xiaohui Ji
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China
| | - Jianqi Ma
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China
| | - Guanghui Tian
- Shaanxi Key Laboratory of Catalysis, College of Chemical and Environment Science, Shaanxi University of Technology, Hanzhong, 723000, PR China
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22
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Wang B, Liu L, Zhang Y, Deng Y, Dong A. A novel strategy for boosting the photoluminescence quantum efficiency of CdSe nanocrystals at room temperature. CHINESE CHEM LETT 2020. [DOI: 10.1016/j.cclet.2019.03.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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23
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van der Stam W, Grimaldi G, Geuchies JJ, Gudjonsdottir S, van Uffelen PT, van Overeem M, Brynjarsson B, Kirkwood N, Houtepen AJ. Electrochemical Modulation of the Photophysics of Surface-Localized Trap States in Core/Shell/(Shell) Quantum Dot Films. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2019; 31:8484-8493. [PMID: 31666761 PMCID: PMC6814269 DOI: 10.1021/acs.chemmater.9b02908] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/23/2019] [Indexed: 05/03/2023]
Abstract
In this work, we systematically study the spectroelectrochemical response of CdSe quantum dots (QDs), CdSe/CdS core/shell QDs with varying CdS shell thicknesses, and CdSe/CdS/ZnS core/shell/shell QDs in order to elucidate the influence of localized surface trap states on the optoelectronic properties. By correlating the differential absorbance and the photoluminescence upon electrochemically raising the Fermi level, we reveal that trap states near the conduction band (CB) edge give rise to nonradiative recombination pathways regardless of the CdS shell thickness, evidenced by quenching of the photoluminescence before the CB edge is populated with electrons. This points in the direction of shallow trap states localized on the CdS shell surface that give rise to nonradiative recombination pathways. We suggest that these shallow trap states reduce the quantum yield because of enhanced hole trapping when the Fermi level is raised electrochemically. We show that these shallow trap states are removed when additional wide band gap ZnS shells are grown around the CdSe/CdS core/shell QDs.
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24
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Drake GA, Flanagan JC, Shim M. Highly luminescent double-heterojunction nanorods. J Chem Phys 2019; 151:134706. [DOI: 10.1063/1.5121159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Gryphon A. Drake
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - Joseph C. Flanagan
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - Moonsub Shim
- Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
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25
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Yang L, Zhou Z, Song J, Chen X. Anisotropic nanomaterials for shape-dependent physicochemical and biomedical applications. Chem Soc Rev 2019; 48:5140-5176. [PMID: 31464313 PMCID: PMC6768714 DOI: 10.1039/c9cs00011a] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review contributes towards a systematic understanding of the mechanism of shape-dependent effects on nanoparticles (NPs) for elaborating and predicting their properties and applications based on the past two decades of research. Recently, the significance of shape-dependent physical chemistry and biomedicine has drawn ever increasing attention. While there has been a great deal of effort to utilize NPs with different morphologies in these fields, so far research studies are largely localized in particular materials, synthetic methods, or biomedical applications, and have ignored the interactional and interdependent relationships of these areas. This review is a comprehensive description of the NP shapes from theory, synthesis, property to application. We figure out the roles that shape plays in the properties of different kinds of nanomaterials together with physicochemical and biomedical applications. Through systematic elaboration of these shape-dependent impacts, better utilization of nanomaterials with diverse morphologies would be realized and definite strategies would be expected for breakthroughs in these fields. In addition, we have proposed some critical challenges and open problems that need to be addressed in nanotechnology.
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Affiliation(s)
- Lijiao Yang
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, P. R. China. and Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Zijian Zhou
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jibin Song
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, P. R. China.
| | - Xiaoyuan Chen
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
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26
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Rabouw F, Antolinez FV, Brechbühler R, Norris DJ. Microsecond Blinking Events in the Fluorescence of Colloidal Quantum Dots Revealed by Correlation Analysis on Preselected Photons. J Phys Chem Lett 2019; 10:3732-3738. [PMID: 31204809 PMCID: PMC6614792 DOI: 10.1021/acs.jpclett.9b01348] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 06/15/2019] [Indexed: 05/24/2023]
Abstract
Nearly all colloidal quantum dots, when measured at the single-emitter level, exhibit fluorescence "blinking". However, despite over 20 years of research on this phenomenon, its microscopic origins are still debated. One reason is a gap in available experimental information, specifically for dynamics at short (submillisecond) time scales. Here, we use photon-correlation analysis to investigate microsecond blinking events in individual quantum dots. While the strongly distributed kinetics of blinking normally makes such events difficult to study, we show that they can be analyzed by excluding photons emitted during long bright or dark periods. Moreover, we find that submillisecond blinking events are more common than one might expect from extrapolating the power-law blinking statistics observed on longer (millisecond) time scales. This result provides important experimental data for developing a microscopic understanding of blinking. More generally, our method offers a simple strategy for analyzing microsecond switching dynamics in the fluorescence of quantum emitters.
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27
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Jia G, Pang Y, Ning J, Banin U, Ji B. Heavy-Metal-Free Colloidal Semiconductor Nanorods: Recent Advances and Future Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900781. [PMID: 31063615 DOI: 10.1002/adma.201900781] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/26/2019] [Indexed: 05/10/2023]
Abstract
Quasi-1D colloidal semiconductor nanorods (NRs) are at the forefront of nanoparticle (NP) research owing to their intriguing size-dependent and shape-dependent optical and electronic properties. The past decade has witnessed significant advances in both fundamental understanding of the growth mechanisms and applications of these stimulating materials. Herein, the state-of-the-art of colloidal semiconductor NRs is reviewed, with special emphasis on heavy-metal-free materials. The main growth mechanisms of heavy-metal-free colloidal semiconductor NRs are first elaborated, including anisotropic-controlled growth, oriented attachment, solution-liquid-solid method, and cation exchange. Then, structural engineering and properties of semiconductor NRs are discussed, with a comprehensive overview of core/shell structures, alloying, and doping, as well as semiconductor-metal hybrid nanostructures, followed by highlighted practical applications in terms of photocatalysis, photodetectors, solar cells, and biomedicine. Finally, challenges and future opportunities in this fascinating research area are proposed.
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Affiliation(s)
- Guohua Jia
- Curtin Institute of Functional Molecules and Interfaces, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, WA, 6845, Australia
| | - Yingping Pang
- Curtin Institute of Functional Molecules and Interfaces, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, WA, 6845, Australia
| | - Jiajia Ning
- Department of Materials Science and Engineering & Centre for Functional Photonics (CFP), City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Uri Banin
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Botao Ji
- School of Engineering, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, China
- Institute of Advanced Technology Westlake Institute for Advanced Study, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, China
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28
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Yang G, Zhong H. Multi‐Dimensional Quantum Nanostructures with Polarization Properties for Display Applications. Isr J Chem 2019. [DOI: 10.1002/ijch.201900001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Gaoling Yang
- Department of Physics of Complex SystemsWeizmann Institute of Science Rehovot 76100 Israel
| | - Haizheng Zhong
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic SystemsSchool of Materials Science & EngineeringBeijing Institute of Technology Beijing China
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29
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Lin ML, Miscuglio M, Polovitsyn A, Leng YC, Martín-García B, Moreels I, Tan PH, Krahne R. Giant-Shell CdSe/CdS Nanocrystals: Exciton Coupling to Shell Phonons Investigated by Resonant Raman Spectroscopy. J Phys Chem Lett 2019; 10:399-405. [PMID: 30626187 DOI: 10.1021/acs.jpclett.8b03211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The interaction between excitons and phonons in semiconductor nanocrystals plays a crucial role in the exciton energy spectrum and dynamics, and thus in their optical properties. We investigate the exciton-phonon coupling in giant-shell CdSe/CdS core-shell nanocrystals via resonant Raman spectroscopy. The Huang-Rhys parameter is evaluated by the intensity ratio of the longitudinal-optical (LO) phonon of CdS with its first multiscattering (2LO) replica. We used four different excitation wavelengths in the range from the onset of the CdS shell absorption to well above the CdS shell band edge to get insight into resonance effects of the CdS LO phonon with high-energy excitonic transitions. The isotropic spherical giant-shell nanocrystals show consistently stronger exciton-phonon coupling as compared to the anisotropic rod-shaped dot-in-rod (DiR) architecture, and the 2LO/LO intensity ratio decreases for excitation wavelengths approaching the CdS band edge. The strong exciton-phonon coupling in the spherical giant-shell nanocrystals can be related to the delocalization of the electronic wave functions. Furthermore, we observe the radial breathing modes of the GS nanocrystals and their overtones by ultralow frequency Raman spectroscopy with nonresonant excitation, using laser energies well below the band gap of the heteronanocrystals, and highlight the differences between higher-order optical and acoustic phonon modes.
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Affiliation(s)
- Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Mario Miscuglio
- Istituto Italiano di Tecnologia (IIT) , Via Morego 30 , 16163 Genoa , Italy
| | - Anatolii Polovitsyn
- Department of Chemistry , Ghent University , Krijgslaan 281-S3 , 9000 Gent , Belgium
| | - Yu-Chen Leng
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | | | - Iwan Moreels
- Department of Chemistry , Ghent University , Krijgslaan 281-S3 , 9000 Gent , Belgium
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Roman Krahne
- Istituto Italiano di Tecnologia (IIT) , Via Morego 30 , 16163 Genoa , Italy
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30
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Abstract
Semiconductor heterostructure nanocrystals, especially with core/shell architectures, are important for numerous applications. Here we show that by decreasing the shell growth rate the morphology of ZnS shells on ZnSe quantum rods can be tuned from flat to islands-like, which decreases the interfacial strain energy. Further reduced growth speed, approaching the thermodynamic limit, leads to coherent shell growth forming unique helical-shell morphology. This reveals a template-free mechanism for induced chirality at the nanoscale. The helical morphology minimizes the sum of the strain and surface energy and maintains band gap emission due to its coherent core/shell interface without traps, unlike the other morphologies. Reaching the thermodynamic controlled growth regime for colloidal semiconductor core/shell nanocrystals thus offers morphologies with clear impact on their applicative potential. Core/shell semiconductor nanocrystals have advantageous optoelectronic properties, which depend on the shell architecture. Here the authors show that by reducing the growth rate of ZnS shells on ZnSe nanorods the shell morphology can be tuned from flat to islands-like to helical
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31
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Molaei MJ. A review on nanostructured carbon quantum dots and their applications in biotechnology, sensors, and chemiluminescence. Talanta 2018; 196:456-478. [PMID: 30683392 DOI: 10.1016/j.talanta.2018.12.042] [Citation(s) in RCA: 204] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/11/2018] [Accepted: 12/13/2018] [Indexed: 12/22/2022]
Abstract
Carbon quantum dots (CQDs) are a member of carbon nanostructures family which have received increasing attention for their photoluminescence (PL), physical and chemical stability and low toxicity. The classical semiconductor quantum dots (QDs) are semiconductor particles that are able to emit fluorescence by excitation. The CQDs is mainly referred to photoluminescent carbon nanoparticles less than 10 nm, with surface modification or functionalization. Contrary to other carbon nanostructures, CQDs can be synthesized and functionalized fast and easily. The fluorescence origin of the CQDs is a controversial issue which depends on carbon source, experimental conditions, and functional groups. However, PL emissions originated from conjugated π-domains and surface defects have been proposed for the PL emission mechanisms of the CQDs. These nanostructures have been used as nontoxic alternatives to the classical heavy metals containing semiconductor QDs in some applications such as in-vivo and in-vitro bio-imaging, drug delivery, photosensors, chemiluminescence (CL), and etc. This paper will introduce CQDs, their structure, and PL characteristics. Recent advances of the application of CQDs in biotechnology, sensors, and CL is comprehensively discussed.
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Affiliation(s)
- Mohammad Jafar Molaei
- Faculty of Chemical and Materials Engineering, Shahrood University of Technology, Shahrood 3619995161, Iran.
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Reid KR, McBride JR, La Croix AD, Freymeyer NJ, Click SM, Macdonald JE, Rosenthal SJ. Role of Surface Morphology on Exciton Recombination in Single Quantum Dot-in-Rods Revealed by Optical and Atomic Structure Correlation. ACS NANO 2018; 12:11434-11445. [PMID: 30403844 DOI: 10.1021/acsnano.8b06472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The physical structure of colloidal quantum dot (QD) nanostructures strongly influences their optical and electronic behavior. A fundamental understanding of this interplay between structure and function is crucial to fully tailor the performance of QDs and their assemblies. Here, by directly correlating the atomic and chemical structure of single CdSe-CdS quantum dot-in-rods with time-resolved fluorescence measurements on the same structures, we identify morphological irregularities at their surfaces that moderate photoluminescence efficiencies. We find that two nonradiative exciton recombination mechanisms are triggered by these imperfections: charging and trap-assisted nonradiative processes. Furthermore, we show that the proximity of the surface defects to the CdSe core of the core-shell structures influences whether the charging or trap-assisted nonradiative channel dominates exciton recombination. Our results extend to other QD nanostructures and emphasize surface roughness as a crucial parameter when designing colloidal QDs with specific excitonic fates.
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Chakrabarty A, Raffy G, Maity M, Gartzia-Rivero L, Marre S, Aymonier C, Maitra U, Del Guerzo A. Nanofiber-Directed Anisotropic Self-Assembly of CdSe-CdS Quantum Rods for Linearly Polarized Light Emission Evidenced by Quantum Rod Orientation Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1802311. [PMID: 30112796 DOI: 10.1002/smll.201802311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/24/2018] [Indexed: 06/08/2023]
Abstract
Hybrid soft materials composed of CdSe-CdS nanorods or "quantum rods" (QRs) and the fluorescent 2,3-didecyloxyanthracene (DDOA) low molecular weight organogelator are obtained through self-assembly. Spectroscopy, microscopy, and rheology studies show that the QRs and DDOA coassemble, thereby stabilizing the organogels. Depending on the QR load and excitation wavelength, single nanofibers (NFs) of the hybrid gel display either sharp polarized red luminescence (under green excitation), or dual perpendicularly polarized blue and red emissions (under UV excitation). Transmission electron microscopy, microspectroscopy, and quantum rod orientation microscopy (QROM) reveal that QRs align along the organogel NFs with order parameters reaching 76% and 87%. This paves the way for obtaining surfaces of QR/NF assemblies yielding sharp red linearly polarized emission. In addition, this work demonstrates that QRs can be used more generally to probe nanostructured soft materials, even nonemissive ones. QROM allows to establish maps of the orientation of single QRs dispersed onto or within a gel network by measuring the polarization of the emission of the individual QRs. As occurs within this work in which QRs and NFs interact, the orientation of each QR reveals information on the underlying nanostructure (such as surface striation, bundle formation, and helicity).
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Affiliation(s)
- Arkajyoti Chakrabarty
- Institut des Sciences Moléculaires, UMR 5255, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33400, Talence, France
- ICMCB, Bordeaux INP, UMR 5026, Université de Bordeaux, CNRS, 87 av. du Dr. Schweitzer, 33600, Pessac, France
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Guillaume Raffy
- Institut des Sciences Moléculaires, UMR 5255, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33400, Talence, France
| | - Mitasree Maity
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Leire Gartzia-Rivero
- Institut des Sciences Moléculaires, UMR 5255, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33400, Talence, France
- Department of Physical Chemistry, University of the Basque Country (UPV/EHU), Apartado 644, 48080, Bilbao, Spain
| | - Samuel Marre
- ICMCB, Bordeaux INP, UMR 5026, Université de Bordeaux, CNRS, 87 av. du Dr. Schweitzer, 33600, Pessac, France
| | - Cyril Aymonier
- ICMCB, Bordeaux INP, UMR 5026, Université de Bordeaux, CNRS, 87 av. du Dr. Schweitzer, 33600, Pessac, France
| | - Uday Maitra
- Department of Organic Chemistry, Indian Institute of Science, Bangalore, 560012, India
| | - André Del Guerzo
- Institut des Sciences Moléculaires, UMR 5255, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33400, Talence, France
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Palei M, Caligiuri V, Kudera S, Krahne R. Robust and Bright Photoluminescence from Colloidal Nanocrystal/Al 2O 3 Composite Films Fabricated by Atomic Layer Deposition. ACS APPLIED MATERIALS & INTERFACES 2018; 10:22356-22362. [PMID: 29893110 DOI: 10.1021/acsami.8b03769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Colloidal nanocrystals are a promising fluorescent class of materials whose spontaneous emission features can be tuned over a broad spectral range via their composition, geometry, and size. However, toward embedding nanocrystal films in elaborated device geometries, one significant drawback is the sensitivity of their emission properties on further fabrication processes like lithography, metal or oxide deposition, etc. In this work, we demonstrate how bright-emitting and robust thin films can be obtained by combining nanocrystal deposition from solutions via spin coating with subsequent atomic layer deposition of alumina. For the resulting composite films, the layer thickness can be controlled on the nanoscale and their refractive index can be finely tuned by the amount of deposited alumina. Ellipsometry is used to measure the real and imaginary part of the dielectric permittivity, which gives direct access to the wavelength dependent refractive index and absorbance of the film. Detailed analysis of the photophysics of thin films of core-shell nanocrystals with different shapes and different shell thicknesses allows to correlate the behavior of the photoluminescence and of the decay lifetime to the changes in the nonradiative rate that are induced by the alumina deposition. We show that the photoemission properties of such composite films are stable in wavelength and intensity over several months and that the photoluminescence completely recovers from heating processes up to 240 °C. The latter is particularly interesting since it demonstrates robustness to the typical heat treatment that is needed in several process steps like resist-based lithography and deposition by thermal or electron beam evaporation of metals or oxides.
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Affiliation(s)
- Milan Palei
- Nanochemistry Department , Istituto Italiano di Tecnologia , 16163 Genova , Italy
- Dipartimento di Chimica e Chimica Industriale , Universita di Genova , 16146 Genova , Italy
| | - Vincenzo Caligiuri
- Nanochemistry Department , Istituto Italiano di Tecnologia , 16163 Genova , Italy
| | - Stefan Kudera
- Nanochemistry Department , Istituto Italiano di Tecnologia , 16163 Genova , Italy
| | - Roman Krahne
- Nanochemistry Department , Istituto Italiano di Tecnologia , 16163 Genova , Italy
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35
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Hong YK, Cho G, Park Y, Oh SJ, Ha DH. Trioctylphosphine-assisted morphology control of ZnO nanoparticles. NANOTECHNOLOGY 2018; 29:225602. [PMID: 29513266 DOI: 10.1088/1361-6528/aab4c6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study investigates the morphological change in colloidal ZnO nanoparticles (NPs) synthesized with trioctylphosphine (TOP). The addition of TOP to the synthesis causes an evolution in the shape of ZnO NPs to tadpole-like particles from quasi-spherical particles at 300 °C. The total length of the tadpole-like ZnO NPs can be modified by controlling the molar ratio of TOP to oleylamine (OLAM). The tadpole-like particles are elongated as the concentration of TOP increased but decreased when the addition of TOP is excessive. These tadpole-like ZnO NPs transform to quasi-spherical NPs regardless of the amount of TOP at a reaction time of 3 h at 300 °C. At 200 °C, the effect of TOP on the ZnO NP synthesis differs from that at 300 °C. The ZnO NPs synthesized by controlling the molar ratios of surfactant ligands (TOP:OLAM = 2:100 and 70:100) at 200 °C share similar amorphous structures, while a crystalline ZnO phase is formed when the reaction time is 3 h. X-ray photoelectron spectroscopy analysis shows that TOP influences the oxidation of ZnO and suggests that a combination of OLAM and TOP plays a role in controlling the shape of ZnO NPs. These results provide critical insights to the utilization of TOP for a shape controlling ligand in ZnO NPs and suggest a new route to design oxide NPs.
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Affiliation(s)
- Yun-Kun Hong
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
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36
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Rastogi P, Palazon F, Prato M, Di Stasio F, Krahne R. Enhancing the Performance of CdSe/CdS Dot-in-Rod Light-Emitting Diodes via Surface Ligand Modification. ACS APPLIED MATERIALS & INTERFACES 2018; 10:5665-5672. [PMID: 29355299 DOI: 10.1021/acsami.7b18780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface ligands on colloidal nanocrystals (NCs) play an important role in the performance of NC-based optoelectronic devices such as photovoltaic cells, photodetectors, and light-emitting diodes (LEDs). On one hand, the NC emission depends critically on the passivation of the surface to minimize trap states that can provide nonradiative recombination channels. On the other hand, the electrical properties of NC films are dominated by the ligands that constitute the barriers for charge transport from one NC to its neighbor. Therefore, surface modifications via ligand exchange have been employed to improve the conductance of NC films. However, in LEDs, such surface modifications are more critical because of their possible detrimental effects on the emission properties. In this work, we study the role of surface ligand modifications on the optical and electrical properties of CdSe/CdS dot-in-rods (DiRs) in films and investigate their performance in all-solution-processed LEDs. The DiR films maintain high photoluminescence quantum yield, around 40-50%, and their electroluminescence in the LED preserves the excellent color purity of the photoluminescence. In the LEDs, the ligand exchange boosted the luminance, reaching a fourfold increase from 2200 cd/m2 for native surfactants to 8500 cd/m2 for the exchanged aminoethanethiol (AET) ligands. Moreover, the efficiency roll-off, operational stability, and shelf life are significantly improved, and the external quantum efficiency is modestly increased from 5.1 to 5.4%. We relate these improvements to the increased conductivity of the emissive layer and to the better charge balance of the electrically injected carriers. In this respect, we performed ultraviolet photoelectron spectroscopy (UPS) to obtain a deeper insight into the band alignment of the LED structure. The UPS data confirm similar flat-band offsets of the emitting layer to the electron- and hole-transport layers in the case of AET ligands, which translates to more symmetric barriers for charge injection of electrons and holes. Furthermore, the change in solubility of the NCs induced by the ligand exchange allows for a layer-by-layer deposition process of the DiR films, which yields excellent homogeneity and good thickness control and enables the fabrication of all the LED layers (except for cathode and anode) by spin-coating.
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Affiliation(s)
- Prachi Rastogi
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso 31, 16146 Genova, Italy
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37
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Enright MJ, Cossairt BM. Synthesis of tailor-made colloidal semiconductor heterostructures. Chem Commun (Camb) 2018; 54:7109-7122. [DOI: 10.1039/c8cc03498b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This feature article provides an account of the various bottom-up and top-down methods that have been developed to prepare colloidal heterostructures and highlights the benefits of a seeded assembly approach for greater control and customizability.
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38
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Kim D, Lee YK, Lee D, Kim WD, Bae WK, Lee DC. Colloidal Dual-Diameter and Core-Position-Controlled Core/Shell Cadmium Chalcogenide Nanorods. ACS NANO 2017; 11:12461-12472. [PMID: 29131591 DOI: 10.1021/acsnano.7b06542] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
To capitalize on shape- and structure-dependent properties of semiconductor nanorods (NRs), high-precision control and exquisite design of their growth are desired. Cadmium chalcogenide (CdE; E = S or Se) NRs are the most studied class of such, whose growth exhibits axial anisotropy, i.e., different growth rates along the opposite directions of {0001} planes. However, the mechanism behind asymmetric axial growth of NRs remains unclear because of the difficulty in instant analysis of growth surfaces. Here, we design colloidal dual-diameter semiconductor NRs (DDNRs) under the quantum confinement regime, which have two sections along the long axis with different diameters. The segmentation of the DDNRs allows rigorous assessment of the kinetics of NR growth at a molecular level. The reactivity of a terminal facet passivated by an organic ligand is governed by monomer diffusivity through the surface ligand monolayer. Therefore, the growth rate in two polar directions can be finely tuned by controlling the strength of ligand-ligand attraction at end surfaces. Building on these findings, we report the synthesis of single-diameter CdSe/CdS core/shell NRs with CdSe cores of controllable position, which reveals a strong structure-optical polarization relationship. The understanding of the NR growth mechanism with controllable anisotropy will serve as a cornerstone for the exquisite design of more complex anisotropic nanostructures.
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Affiliation(s)
- Dahin Kim
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Young Kuk Lee
- Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, Korea
| | - Dongkyu Lee
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Whi Dong Kim
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Wan Ki Bae
- Photoelectronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 02792, Korea
| | - Doh C Lee
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
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Srivastava AK, Zhang W, Schneider J, Rogach AL, Chigrinov VG, Kwok HS. Photoaligned Nanorod Enhancement Films with Polarized Emission for Liquid-Crystal-Display Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1701091. [PMID: 28657203 DOI: 10.1002/adma.201701091] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/28/2017] [Indexed: 05/27/2023]
Abstract
Semiconductor nanorods (NR) emit polarized light, which is expected to bring manifold benefits, in terms of brightness and color enhancement, for modern liquid-crystal displays (LCD). In this regard, photoaligned nanorod enhancement films (NREF) for color and polarization conversion for LCD backlights are introduced here. The photoinduced anchoring forces, by the photoalignment layer, stimulate well-ordered self-assembly of NR in the thin polymer films. Green and red emitting NR with a quantum yield of ≈80% are aligned unidirectionally and in-plane, showing a polarization ratio of >7:1 and a degree of polarization of >0.81. The photoalignment technique facilitates the fabrication of mixed and multiple stacked NREF for LCDs, which improves the color gamut and polarization efficiency, and is thus expected to increase the optical efficiency of conventional LCDs by ≈60%.
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Affiliation(s)
- Abhishek K Srivastava
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Wanlong Zhang
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Julian Schneider
- Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Andrey L Rogach
- Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Vladimir G Chigrinov
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Hoi-Sing Kwok
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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40
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Qiao F, Wang X, Wang Q, He G, Xie Y. Functionalized self-assembly of colloidal CdX (X = S, Se) nanorods on solid substrates for device applications. NANOSCALE 2017; 9:8066-8079. [PMID: 28585959 DOI: 10.1039/c7nr01974b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In comparison to randomly oriented nanorods (NRs), self-assembly of the colloidal CdX (X = S, Se) NRs into well-organized large-scale structures results in unique collective properties. Moreover, the anisotropic structural features of self-assemblies preserved from colloidal CdX (X = S, Se) NRs have opened up exciting opportunities in the field of nanotechnology applications. We present the latest strategies for the self-assembly of colloidal NRs on solid substrates, and further focus on the self-assembled NRs for applications in devices. Advanced progress in the preparation of NR building blocks on the basis of nanofabrication techniques and comprehensive studies on the interactions of NRs with substrates will remarkably expand the application of colloidal semiconductor NRs. Understanding and mastering the driving forces behind the assembly of the NRs is the key goal of engineering future functional structures based on NRs.
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Affiliation(s)
- Fen Qiao
- School of Energy & Power Engineering, Jiangsu University, Zhenjiang, 212013, P R China.
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41
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Schneider J, Zhang W, Srivastava AK, Chigrinov VG, Kwok HS, Rogach AL. Photoinduced Micropattern Alignment of Semiconductor Nanorods with Polarized Emission in a Liquid Crystal Polymer Matrix. NANO LETTERS 2017; 17:3133-3138. [PMID: 28394620 DOI: 10.1021/acs.nanolett.7b00563] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Photoalignment technology provides high alignment quality with an exceptional control over the local director of liquid crystals. Because of the reorientation ability of sulfonic azo dye molecules, they offer high azimuthal and polar anchoring energy with a low pretilt angle for the orientation of liquid crystals and liquid crystal composites. In this work, we make use of this approach to align thin film composites of light-emitting semiconductor nanorods dispersed in a liquid crystal polymer into both one-dimensional and two-dimensional microscale patterns. After unidirectional alignment, the patterns are fabricated by a second irradiation with different polarization azimuth and the employment of a photomask. Fluorescence micrographs reveal the nanorod pattern alignment in domain sizes down to 2 μm. Apart from demonstrating the possibility of controlling the orientation of anisotropic nanocrystals with strongly polarized emission on microscopic scale, our results are promising for the fabrication of complex nanostructures for photonic applications.
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Affiliation(s)
- Julian Schneider
- Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Hong Kong SAR
| | - Wanlong Zhang
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology , Hong Kong SAR
| | - Abhishek K Srivastava
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology , Hong Kong SAR
| | - Vladimir G Chigrinov
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology , Hong Kong SAR
| | - Hoi-Sing Kwok
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology , Hong Kong SAR
| | - Andrey L Rogach
- Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Hong Kong SAR
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42
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Pavlopoulos NG, Dubose JT, Liu Y, Huang X, Pinna N, Willinger MG, Lian T, Char K, Pyun J. Type I vs. quasi-type II modulation in CdSe@CdS tetrapods: ramifications for noble metal tipping. CrystEngComm 2017. [DOI: 10.1039/c7ce01558e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on noble metal tipping of heterostructured nanocrystals (NCs) of CdSe@CdS tetrapods (TPs) as a chemical reaction to manifest energetic differences between type I and quasi-type II heterojunctions.
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Affiliation(s)
| | - Jeffrey T. Dubose
- Department of Chemistry and Biochemistry
- University of Arizona
- Tucson
- USA
| | - Yawei Liu
- Department of Chemistry
- Emory University
- Atlanta
- USA
| | - Xing Huang
- Institut fur Chemie
- Humboldt-Universitat zu Berlin
- 12489 Berlin
- Germany
| | - Nicola Pinna
- Department of Inorganic Chemistry
- Fritz Haber Institute of the Max Planck Society
- Berlin
- Germany
| | | | | | - Kookheon Char
- World Class University Program for Chemical Convergence for Energy and Environment
- School of Chemical and Biological Engineering
- Seoul National University
- Seoul 151-744
- Korea
| | - Jeffrey Pyun
- Department of Chemistry and Biochemistry
- University of Arizona
- Tucson
- USA
- World Class University Program for Chemical Convergence for Energy and Environment
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43
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Geißler D, Würth C, Wolter C, Weller H, Resch-Genger U. Excitation wavelength dependence of the photoluminescence quantum yield and decay behavior of CdSe/CdS quantum dot/quantum rods with different aspect ratios. Phys Chem Chem Phys 2017; 19:12509-12516. [DOI: 10.1039/c7cp02142a] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Our results reveal a strong λexc-dependence of PL quantum yields and decay times, particularly for longer quantum dot-quantum rods with high aspect ratios.
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Affiliation(s)
- D. Geißler
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
| | - C. Würth
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
| | - C. Wolter
- University of Hamburg
- Institute of Physical Chemistry
- Hamburg
- Germany
| | - H. Weller
- University of Hamburg
- Institute of Physical Chemistry
- Hamburg
- Germany
| | - U. Resch-Genger
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
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44
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Rossinelli AA, Riedinger A, Marqués-Gallego P, Knüsel PN, Antolinez FV, Norris DJ. High-temperature growth of thick-shell CdSe/CdS core/shell nanoplatelets. Chem Commun (Camb) 2017; 53:9938-9941. [DOI: 10.1039/c7cc04503d] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a simple high-temperature protocol to add uniform CdS shells to CdSe nanoplatelets, yielding improved fluorescence efficiency and stability.
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Affiliation(s)
- Aurelio A. Rossinelli
- 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
| | - Patricia Marqués-Gallego
- Optical Materials Engineering Laboratory
- Department of Mechanical and Process Engineering
- ETH Zurich
- 8092 Zurich
- Switzerland
| | - Philippe N. Knüsel
- Optical Materials Engineering Laboratory
- Department of Mechanical and Process Engineering
- ETH Zurich
- 8092 Zurich
- Switzerland
| | - Felipe V. Antolinez
- 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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45
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Ramasamy P, Kim B, Lee MS, Lee JS. Beneficial effects of water in the colloidal synthesis of InP/ZnS core-shell quantum dots for optoelectronic applications. NANOSCALE 2016; 8:17159-17168. [PMID: 27540861 DOI: 10.1039/c6nr04713k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We demonstrate that the presence of a small amount of water as an impurity during the hot-injection synthesis can significantly decrease the emission lines full width at half-maximum (FWHM) and improve the quantum yield (QY) of InP/ZnS quantum dots (QDs). By utilizing the water present in the indium precursor and solvent, we obtained InP/ZnS QDs emitting around 530 nm with a FWHM as narrow as 46 nm and a QY up to 45%. Without water, the synthesized QDs have emission around 625 nm with a FWHM of 66 nm and a QY of about 33%. Absorption spectra, XRD and XPS analyses revealed that when water is present, an amorphous phosphate layer is formed over the InP QDs and inhibits the QD growth. This amorphous layer favors the formation of a very thick ZnS shell by decreasing the lattice mismatch between the InP core and the ZnS shell. We further show the possibility to tune the emission wavelengths of InP/ZnS QDs by simply adjusting the amount of water present in the system while keeping all the other reaction parameters (i.e., precursor concentration, reaction temperature and time) constant. As an example of their application in light-emitting diodes (LEDs), the green and red InP/ZnS QDs are combined with a blue LED chip to produce white light.
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Affiliation(s)
- Parthiban Ramasamy
- Department of Energy Systems Engineering, DGIST, Daegu 711-873, Republic of Korea.
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46
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Cunningham PD, Souza JB, Fedin I, She C, Lee B, Talapin DV. Assessment of Anisotropic Semiconductor Nanorod and Nanoplatelet Heterostructures with Polarized Emission for Liquid Crystal Display Technology. ACS NANO 2016; 10:5769-81. [PMID: 27203222 DOI: 10.1021/acsnano.5b07949] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Semiconductor nanorods can emit linear-polarized light at efficiencies over 80%. Polarization of light in these systems, confirmed through single-rod spectroscopy, can be explained on the basis of the anisotropy of the transition dipole moment and dielectric confinement effects. Here we report emission polarization in macroscopic semiconductor-polymer composite films containing CdSe/CdS nanorods and colloidal CdSe nanoplatelets. Anisotropic nanocrystals dispersed in polymer films of poly butyl-co-isobutyl methacrylate (PBiBMA) can be stretched mechanically in order to obtain unidirectionally aligned arrays. A high degree of alignment, corresponding to an orientation factor of 0.87, was achieved and large areas demonstrated polarized emission, with the contrast ratio I∥/I⊥ = 5.6, making these films viable candidates for use in liquid crystal display (LCD) devices. To some surprise, we observed significant optical anisotropy and emission polarization for 2D CdSe nanoplatelets with the electronic structure of quantum wells. The aligned nanorod arrays serve as optical funnels, absorbing unpolarized light and re-emitting light from deep-green to red with quantum efficiencies over 90% and high degree of linear polarization. Our results conclusively demonstrate the benefits of anisotropic nanostructures for LCD backlighting. The polymer films with aligned CdSe/CdS dot-in-rod and rod-in-rod nanostructures show more than 2-fold enhancement of brightness compared to the emitter layers with randomly oriented nanostructures. This effect can be explained as the combination of linearly polarized luminescence and directional emission from individual nanostructures.
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Affiliation(s)
- Patrick D Cunningham
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - João B Souza
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
- Instituto de Química de São Carlos, Universidade de São Paulo-USP, Colloidal Materials Group , CP 780, 13566-590 São Carlos, São Paulo, Brazil
| | - Igor Fedin
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - Chunxing She
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - Byeongdu Lee
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Dmitri V Talapin
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
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47
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Segarra C, Climente JI, Polovitsyn A, Rajadell F, Moreels I, Planelles J. Piezoelectric Control of the Exciton Wave Function in Colloidal CdSe/CdS Nanocrystals. J Phys Chem Lett 2016; 7:2182-2188. [PMID: 27225599 DOI: 10.1021/acs.jpclett.6b00622] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using multiband k·p calculations, we show that strain-engineered piezoelectricity is a powerful tool to modulate the electron-hole spatial separation in a wide class of wurtzite CdSe/CdS nanocrystals. The inherent anisotropy of the hexagonal crystal structure leads to anisotropic strain and, consequently, to a pronounced piezoelectric field along the c axis, which can be amplified or quenched through a proper design of the core-shell structure. The use of large cores and thick shells promotes a gradual departure from quantum confined nanocrystals to a regime dominated by piezoelectric confinement. This allows excitons to evolve from the usual type-I and quasi-type-II behavior to a type-II behavior in dot-in-dots, dot-in-rods, rod-in-rods, and dot-in-plates. Piezoelectric fields explain experimental observations for giant-shell nanocrystals, whose time-resolved photoluminescence reveals long exciton lifetimes for large cores, contrary to the expectations of standard quantum confinement models. They also explain the large differences in exciton lifetimes reported for different classes of CdSe/CdS nanocrystals.
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Affiliation(s)
- Carlos Segarra
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | | | - Fernando Rajadell
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Iwan Moreels
- Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
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