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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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Kini GC, Yu J, Wang L, Kan AT, Biswal SL, Tour JM, Tomson MB, Wong MS. Salt- and temperature-stable quantum dot nanoparticles for porous media flow. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.11.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Rukenstein P, Jen-La Plante I, Diab M, Chockler E, Flomin K, Moshofsky B, Mokari T. Selective growth of metal sulfide tips onto cadmium chalcogenide nanostructures. CrystEngComm 2012. [DOI: 10.1039/c2ce25795e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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4
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Sitt A, Salant A, Menagen G, Banin U. Highly emissive nano rod-in-rod heterostructures with strong linear polarization. NANO LETTERS 2011; 11:2054-2060. [PMID: 21480584 DOI: 10.1021/nl200519b] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report the synthesis of CdSe/CdS rod in rod core/shell heterostructures. These rods, synthesized using a seeded-growth approach, show narrow distributions of rod diameters and lengths and exhibit high emission quantum efficiencies and highly polarized emission. The degree of polarization is controlled by the inner core rod dimensions, and it is equal or up to 1.5 times higher than the polarization of equivalent sphere in rod systems. Using the method of photoselection we measure the polarization anisotropy at different excitation wavelengths and study the interplay between electronic contribution and dielectric effects in determining the absorption and emission polarization.
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Affiliation(s)
- Amit Sitt
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University , Jerusalem 91904, Israel
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Royo M, Climente JI, Movilla JL, Planelles J. Dielectric confinement of excitons in type-I and type-II semiconductor nanorods. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:015301. [PMID: 21406821 DOI: 10.1088/0953-8984/23/1/015301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We theoretically study the effect of the dielectric environment on the exciton ground state of CdSe and CdTe/CdSe/CdTe nanorods. We show that insulating environments enhance the exciton recombination rate and blueshift the emission peak by tens of meV. These effects are particularly pronounced for type-II nanorods. In these structures, the dielectric confinement may even modify the spatial distribution of the electron and hole charges. A critical electric field is required to separate electrons from holes, whose value increases with the insulating strength of the surroundings.
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Affiliation(s)
- M Royo
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080, Castelló, Spain
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Lo SS, Mirkovic T, Chuang CH, Burda C, Scholes GD. Emergent properties resulting from type-II band alignment in semiconductor nanoheterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:180-197. [PMID: 21069886 DOI: 10.1002/adma.201002290] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The development of elegant synthetic methodologies for the preparation of monocomponent nanocrystalline particles has opened many possibilities for the preparation of heterostructured semiconductor nanostructures. Each of the integrated nanodomains is characterized by its individual physical properties, surface chemistry, and morphology, yet, these multicomponent hybrid particles present ideal systems for the investigation of the synergetic properties that arise from the material combination in a non-additive fashion. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole following photoexcitation, a highly desirable property for photovoltaic applications. This article highlights recent progress in both synthetic strategies, which allow for material and architectural modulation of novel nanoheterostructures, as well as the experimental work that provides insight into the photophysical properties of type-II heterostructures. The effects of external factors, such as electric fields, temperature, and solvent are explored in conjunction with exciton and multiexciton dynamics and charge transfer processes typical for type-II semiconductor heterostructures.
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Affiliation(s)
- Shun S Lo
- Department of Chemistry, Institute for Optical Science, and Center for Quantum Information and Quantum Contro, l80 St. George Street, University of Toronto, Ontario M5S 3H6, Canada
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Costi R, Saunders AE, Banin U. Colloidal hybrid nanostructures: a new type of functional materials. Angew Chem Int Ed Engl 2010; 49:4878-97. [PMID: 20544758 DOI: 10.1002/anie.200906010] [Citation(s) in RCA: 677] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
One key goal of nanocrystal research is the development of experimental methods to selectively control the composition and shape of nanocrystals over a wide range of material combinations. The ability to selectively arrange nanosized domains of metallic, semiconducting, and magnetic materials into a single hybrid nanoparticle offers an intriguing route to engineer nanomaterials with multiple functionalities or the enhanced properties of one domain. In this Review, we focus on recent strategies used to create semiconductor-metal hybrid nanoparticles, present the emergent properties of these multicomponent materials, and discuss their potential applicability in different technologies.
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Affiliation(s)
- Ronny Costi
- Institute of Chemistry and Center for Nanoscience & Nanotechnology, The Hebrew University, Jerusalem, 91904 Israel
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Gaponik N, Hickey SG, Dorfs D, Rogach AL, Eychmüller A. Progress in the light emission of colloidal semiconductor nanocrystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:1364-1378. [PMID: 20564480 DOI: 10.1002/smll.200902006] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Some 25 years ago it was found that semiconductor nanocrystals emitted light. Since then tremendous progress has been made with respect to increasing the emission quantum yields, extending the spectral range that may be addressed, from the UV across to the near infrared, and improving the color purity. Here some major lines in these developments are reviewed, touching on milestones as well as on the principles of the most successful preparative approaches.
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Affiliation(s)
- Nikolai Gaponik
- Physical Chemistry TU Dresden Bergstrasse 66b, 01062 Dresden, Germany
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Fabrication and Characteristics of β-Bi[sub 2]O[sub 3] Nanowires Prepared by Heating a Mixture of In and Bi Powders. ACTA ACUST UNITED AC 2010. [DOI: 10.1149/1.3387710] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Nonoguchi Y, Nakashima T, Kawai T. Tuning band offsets of core/shell CdS/CdTe nanocrystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:2403-2406. [PMID: 19634186 DOI: 10.1002/smll.200900571] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Yoshiyuki Nonoguchi
- Graduate School of Materials Science Nara Institute of Science and Technology, NAIST, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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Lo SS, Khan Y, Jones M, Scholes GD. Temperature and solvent dependence of CdSe/CdTe heterostructure nanorod spectra. J Chem Phys 2009; 131:084714. [DOI: 10.1063/1.3212693] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Costi R, Cohen G, Salant A, Rabani E, Banin U. Electrostatic force microscopy study of single Au-CdSe hybrid nanodumbbells: evidence for light-induced charge separation. NANO LETTERS 2009; 9:2031-2039. [PMID: 19435381 DOI: 10.1021/nl900301v] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electrostatic force microscopy is used to study light-induced charging in single hybrid Au-CdSe nanodumbbells. Upon illumination, nanodumbbells show negative charging, which is in contrast with CdSe rods and Au particles that show positive charging. This different behavior is attributed to charge separation in the nanodumbbells, where after excitation the electron is transferred to the gold tips and the hole is subsequently filled through tunneling interactions with the substrate. The process of light-induced charge separation at the metal-semiconductor interface is key for the photocatalytic activity of such hybrid metal-semiconductor nanostructures.
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Affiliation(s)
- Ronny Costi
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel
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Koo B, Korgel BA. Coalescence and interface diffusion in linear CdTe/CdSe/CdTe heterojunction nanorods. NANO LETTERS 2008; 8:2490-2496. [PMID: 18616330 DOI: 10.1021/nl8015126] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Colloidal nanorods with linear CdTe/CdSe/CdTe heterojunctions were synthesized by sequential reactant injection. After CdTe deposition at the ends of initially formed CdSe nanorods, continued heating in solution leads to Se-Te interdiffusion across the heterojunctions and coalescence to decreased aspect ratio. The Se-Te interdiffusion rates were measured by mapping the composition profile using nanobeam energy dispersive X-ray spectroscopy (EDS) along the lengths of individual nanorods aged in hot solvent for different amounts of time. The rate of nanorod coalescence was also measured and compared to model predictions using a continuum viscous flow model, which appears to provide a reasonable estimate of the coalescence rate.
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Affiliation(s)
- Bonil Koo
- Department of Chemical Engineering, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712-1062, USA
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