2023
logo, Taejong Paik ORCID; Greybush, Nicholas J.; Najmr, Stan; Woo, Ho Young; Hong, Seong Vin; Kim, Seung Hyeon; Lee, Jennifer D.; Kagan, Cherie R.; Murray, Christopher B.
Shape-controlled synthesis and self-assembly of highly uniform upconverting calcium fluoride nanocrystals Journal Article
In: Inorganic Chemistry Frontiers, vol. 11, pp. 278-285, 2023.
@article{logologo2023,
title = {Shape-controlled synthesis and self-assembly of highly uniform upconverting calcium fluoride nanocrystals},
author = {Taejong Paik ORCID logo and Nicholas J. Greybush and Stan Najmr and Ho Young Woo and Seong Vin Hong and Seung Hyeon Kim and Jennifer D. Lee and Cherie R. Kagan and Christopher B. Murray},
url = {https://pubs-rsc-org.proxy.library.upenn.edu/en/content/articlehtml/2023/qi/d3qi01864d},
doi = {10.1039/D3QI01864D},
year = {2023},
date = {2023-11-13},
journal = {Inorganic Chemistry Frontiers},
volume = {11},
pages = {278-285},
abstract = {Herein, the size- and shape-controlled synthesis of nearly-monodisperse, lanthanide-doped calcium fluoride (CaF2) nanocrystals (NCs) is reported. The sizes and shapes of CaF2 NCs are controlled by tailoring the reaction conditions, such as the concentration of lithium fluoride precursors, reaction time and temperature, and the procedure for adding the calcium trifluoroacetate precursors in the reaction mixture. Highly uniform CaF2 NCs are synthesized with several morphologies, such as nanospheres, truncated octahedra, nanoplates, and nanowires. The shape-controlled CaF2 NCs self-assemble into NC superlattices with long-range orientational and positional order forming crystalline and liquid crystalline structures. The near-infrared-to-visible upconversion luminescence properties are investigated by varying the types of dopants as well as the sizes and shapes of the CaF2 NCs.},
keywords = {nanoparticle assembly, self-assembly, synthesis, upconverting nanophosphors},
pubstate = {published},
tppubtype = {article}
}
Herein, the size- and shape-controlled synthesis of nearly-monodisperse, lanthanide-doped calcium fluoride (CaF2) nanocrystals (NCs) is reported. The sizes and shapes of CaF2 NCs are controlled by tailoring the reaction conditions, such as the concentration of lithium fluoride precursors, reaction time and temperature, and the procedure for adding the calcium trifluoroacetate precursors in the reaction mixture. Highly uniform CaF2 NCs are synthesized with several morphologies, such as nanospheres, truncated octahedra, nanoplates, and nanowires. The shape-controlled CaF2 NCs self-assemble into NC superlattices with long-range orientational and positional order forming crystalline and liquid crystalline structures. The near-infrared-to-visible upconversion luminescence properties are investigated by varying the types of dopants as well as the sizes and shapes of the CaF2 NCs.
Choi, Yun Chang; Lee, Jaeyoung; Ng, Jonah J.; Kagan, Cherie R.
Surface Engineering of Metal and Semiconductor Nanocrystal Assemblies and Their Optical and Electronic Devices Journal Article
In: Accounts of Chemical Research, vol. 56, no. 13, pp. 1791–1802, 2023.
@article{Choi2023,
title = {Surface Engineering of Metal and Semiconductor Nanocrystal Assemblies and Their Optical and Electronic Devices},
author = {Yun Chang Choi and Jaeyoung Lee and Jonah J. Ng and Cherie R. Kagan},
url = {https://doi.org/10.1021/acs.accounts.3c00147},
doi = {10.1021/acs.accounts.3c00147},
year = {2023},
date = {2023-06-21},
urldate = {2023-06-21},
journal = {Accounts of Chemical Research},
volume = {56},
number = {13},
pages = {1791–1802},
abstract = {Colloidal nanocrystals (NCs) are composed of inorganic cores and organic or inorganic ligand shells and serve as building blocks of NC assemblies. Metal and semiconductor NCs are well known for the size-dependent physical properties of their cores. The large NC surface-to-volume ratio and the space between NCs in assemblies places significant importance on the composition of the NC surface and ligand shell. Nonaqueous colloidal NC syntheses use relatively long organic ligands to control NC size and uniformity during growth and to prepare stable NC dispersions. However, these ligands create large interparticle distances that dilute the metal and semiconductor NC properties of their assemblies. In this Account, we describe postsynthesis chemical treatments to engineer the NC surface and design the optical and electronic properties of NC assemblies. In metal NC assemblies, compact ligand exchange reduces the interparticle distance and drives an insulator-to-metal transition tuning the dc resistivity over a 1010 range and the real part of the optical dielectric function from positive to negative across the visible-to-IR region. Juxtaposing NC and bulk metal thin films in bilayers allows the differential chemical and thermal addressability of the NC surface to be exploited in device fabrication. Ligand exchange and thermal annealing densifies the NC layer, creating interfacial misfit strain that triggers folding of the bilayers and is used to fabricate, with only one lithography step, large-area 3D chiral metamaterials. In semiconductor NC assemblies, chemical treatments such as ligand exchange, doping, and cation exchange control the interparticle distance and composition to add impurities, tailor stoichiometry, or make entirely new compounds. These treatments are employed in longer studied II–VI and IV–VI materials and are being developed as interest in III–V and I–III–VI2 NC materials grows. NC surface engineering is used to design NC assemblies with tailored carrier energy, type, concentration, mobility, and lifetime. Compact ligand exchange increases the coupling between NCs but can introduce intragap states that scatter and reduce the lifetime of carriers. Hybrid ligand exchange with two different chemistries can enhance the mobility-lifetime product. Doping increases carrier concentration, shifts the Fermi energy, and increases carrier mobility, creating n- and p-type building blocks for optoelectronic and electronic devices and circuits. Surface engineering of semiconductor NC assemblies is also important to modify device interfaces to allow the stacking and patterning of NC layers and to realize excellent device performance. It is used to construct NC-integrated circuits, exploiting the library of metal, semiconductor, and insulator NCs, to achieve all-NC, solution-fabricated transistors.},
keywords = {gold, ligand exchange, ligands, nanocrystal, nanoparticle assembly, Noble metal nanoparticles, optical metamaterials, optical properties, quantum dots, semiconductors, surface modification},
pubstate = {published},
tppubtype = {article}
}
Colloidal nanocrystals (NCs) are composed of inorganic cores and organic or inorganic ligand shells and serve as building blocks of NC assemblies. Metal and semiconductor NCs are well known for the size-dependent physical properties of their cores. The large NC surface-to-volume ratio and the space between NCs in assemblies places significant importance on the composition of the NC surface and ligand shell. Nonaqueous colloidal NC syntheses use relatively long organic ligands to control NC size and uniformity during growth and to prepare stable NC dispersions. However, these ligands create large interparticle distances that dilute the metal and semiconductor NC properties of their assemblies. In this Account, we describe postsynthesis chemical treatments to engineer the NC surface and design the optical and electronic properties of NC assemblies. In metal NC assemblies, compact ligand exchange reduces the interparticle distance and drives an insulator-to-metal transition tuning the dc resistivity over a 1010 range and the real part of the optical dielectric function from positive to negative across the visible-to-IR region. Juxtaposing NC and bulk metal thin films in bilayers allows the differential chemical and thermal addressability of the NC surface to be exploited in device fabrication. Ligand exchange and thermal annealing densifies the NC layer, creating interfacial misfit strain that triggers folding of the bilayers and is used to fabricate, with only one lithography step, large-area 3D chiral metamaterials. In semiconductor NC assemblies, chemical treatments such as ligand exchange, doping, and cation exchange control the interparticle distance and composition to add impurities, tailor stoichiometry, or make entirely new compounds. These treatments are employed in longer studied II–VI and IV–VI materials and are being developed as interest in III–V and I–III–VI2 NC materials grows. NC surface engineering is used to design NC assemblies with tailored carrier energy, type, concentration, mobility, and lifetime. Compact ligand exchange increases the coupling between NCs but can introduce intragap states that scatter and reduce the lifetime of carriers. Hybrid ligand exchange with two different chemistries can enhance the mobility-lifetime product. Doping increases carrier concentration, shifts the Fermi energy, and increases carrier mobility, creating n- and p-type building blocks for optoelectronic and electronic devices and circuits. Surface engineering of semiconductor NC assemblies is also important to modify device interfaces to allow the stacking and patterning of NC layers and to realize excellent device performance. It is used to construct NC-integrated circuits, exploiting the library of metal, semiconductor, and insulator NCs, to achieve all-NC, solution-fabricated transistors.
Cai, Yi-Yu; Fallah, Asma; Yang, Shengsong; Choi, Yun Chang; Xu, Jun; Stein, Aaron; Kikkawa, James M.; Murray, Christopher B.; Engheta, Nader; Kagan, Cherie R.
Open- and Close-Packed, Shape-engineered Polygonal Nanoparticle Metamolecules with Tailorable Fano Resonances Journal Article
In: Advanced Materials, 2023.
@article{Cai2023,
title = {Open- and Close-Packed, Shape-engineered Polygonal Nanoparticle Metamolecules with Tailorable Fano Resonances},
author = {Yi-Yu Cai and Asma Fallah and Shengsong Yang and Yun Chang Choi and Jun Xu and Aaron Stein and James M. Kikkawa and Christopher B. Murray and Nader Engheta and Cherie R. Kagan},
url = { https://doi.org/10.1002/adma.202301323},
doi = {10.1002/adma.202301323},
year = {2023},
date = {2023-05-11},
urldate = {2023-05-11},
journal = {Advanced Materials},
abstract = {A top-down lithographic patterning and deposition process is reported for producing nanoparticles (NPs) with well-defined sizes, shapes, and compositions that are often not accessible by wet-chemical synthetic methods. These NPs are ligated and harvested from the substrate surface to prepare colloidal NP dispersions. Using a template-assisted assembly technique, fabricated NPs are driven by capillary forces to assemble into size- and shape-engineered templates and organize into open or close-packed multi-NP structures or NP metamolecules. The sizes and shapes of the NPs and of the templates control the NP number, coordination, interparticle gap size, disorder, and location of defects such as voids in the NP metamolecules. The plasmonic resonances of polygonal-shaped Au NPs are exploited to correlate the structure and optical properties of assembled NP metamolecules. Comparing open- and close-packed architectures highlights that introduction of a center NP to form closed-packed assemblies supports collective interactions, altering magnetic optical modes and multipolar interactions in Fano resonances. Decreasing the distance between NPs strengthens the plasmonic coupling, and the structural symmetries of the NP metamolecules determine the orientation-dependent scattering response.},
keywords = {nanoparticle assembly, optical properties, plasmonic, templated assembly},
pubstate = {published},
tppubtype = {article}
}
A top-down lithographic patterning and deposition process is reported for producing nanoparticles (NPs) with well-defined sizes, shapes, and compositions that are often not accessible by wet-chemical synthetic methods. These NPs are ligated and harvested from the substrate surface to prepare colloidal NP dispersions. Using a template-assisted assembly technique, fabricated NPs are driven by capillary forces to assemble into size- and shape-engineered templates and organize into open or close-packed multi-NP structures or NP metamolecules. The sizes and shapes of the NPs and of the templates control the NP number, coordination, interparticle gap size, disorder, and location of defects such as voids in the NP metamolecules. The plasmonic resonances of polygonal-shaped Au NPs are exploited to correlate the structure and optical properties of assembled NP metamolecules. Comparing open- and close-packed architectures highlights that introduction of a center NP to form closed-packed assemblies supports collective interactions, altering magnetic optical modes and multipolar interactions in Fano resonances. Decreasing the distance between NPs strengthens the plasmonic coupling, and the structural symmetries of the NP metamolecules determine the orientation-dependent scattering response.
Yang, Shengsong; LaCour, R. Allen; Cai, Yi-Yu; Xu, Jun; Rosen, Daniel J.; Zhang, Yugang; Kagan, Cherie R.; Glotzer, Sharon C.; Murray, Christopher B.
Self-Assembly of Atomically Aligned Nanoparticle Superlattices from Pt–Fe3O4 Heterodimer Nanoparticles Journal Article
In: Journal of the American Chemical Society, vol. 145, iss. 11, pp. 6280–6288, 2023.
@article{Yang2023,
title = {Self-Assembly of Atomically Aligned Nanoparticle Superlattices from Pt–Fe3O4 Heterodimer Nanoparticles},
author = {Shengsong Yang and R. Allen LaCour and Yi-Yu Cai and Jun Xu and Daniel J. Rosen and Yugang Zhang and Cherie R. Kagan and Sharon C. Glotzer and Christopher B. Murray},
url = {https://pubs.acs.org/doi/full/10.1021/jacs.2c12993},
doi = {10.1021/jacs.2c12993},
year = {2023},
date = {2023-03-13},
urldate = {2023-03-13},
journal = {Journal of the American Chemical Society},
volume = {145},
issue = {11},
pages = {6280–6288},
abstract = {Multicomponent nanoparticle superlattices (SLs) promise the integration of nanoparticles (NPs) with remarkable electronic, magnetic, and optical properties into a single structure. Here, we demonstrate that heterodimers consisting of two conjoined NPs can self-assemble into novel multicomponent SLs with a high degree of alignment between the atomic lattices of individual NPs, which has been theorized to lead to a wide variety of remarkable properties. Specifically, by using simulations and experiments, we show that heterodimers composed of larger Fe3O4 domains decorated with a Pt domain at one vertex can self-assemble into an SL with long-range atomic alignment between the Fe3O4 domains of different NPs across the SL. The SLs show an unanticipated decreased coercivity relative to nonassembled NPs. In situ scattering of the self-assembly reveals a two-stage mechanism of self-assembly: translational ordering between NPs develops before atomic alignment. Our experiments and simulation indicate that atomic alignment requires selective epitaxial growth of the smaller domain during heterodimer synthesis and specific size ratios of the heterodimer domains as opposed to specific chemical composition. This composition independence makes the self-assembly principles elucidated here applicable to the future preparation of multicomponent materials with fine structural control.},
keywords = {nanocrystal, nanoparticle assembly, self-assembly},
pubstate = {published},
tppubtype = {article}
}
Multicomponent nanoparticle superlattices (SLs) promise the integration of nanoparticles (NPs) with remarkable electronic, magnetic, and optical properties into a single structure. Here, we demonstrate that heterodimers consisting of two conjoined NPs can self-assemble into novel multicomponent SLs with a high degree of alignment between the atomic lattices of individual NPs, which has been theorized to lead to a wide variety of remarkable properties. Specifically, by using simulations and experiments, we show that heterodimers composed of larger Fe3O4 domains decorated with a Pt domain at one vertex can self-assemble into an SL with long-range atomic alignment between the Fe3O4 domains of different NPs across the SL. The SLs show an unanticipated decreased coercivity relative to nonassembled NPs. In situ scattering of the self-assembly reveals a two-stage mechanism of self-assembly: translational ordering between NPs develops before atomic alignment. Our experiments and simulation indicate that atomic alignment requires selective epitaxial growth of the smaller domain during heterodimer synthesis and specific size ratios of the heterodimer domains as opposed to specific chemical composition. This composition independence makes the self-assembly principles elucidated here applicable to the future preparation of multicomponent materials with fine structural control.
2022
Nguyen, Hao A.; Sharp, David; Johannes E. Fröch,; Cai, Yi-Yu; Wu, Shenwei; Monahan, Madison; Munley, Christopher; Manna, Arnab; Majumdar, Arka; Kagan, Cherie R.; Cossairt*, Brandi M.
Deterministic Quantum Light Arrays from Giant Silica-Shelled Quantum Dots Journal Article
In: ACS Applied Materials & Interfaces, vol. 15, iss. 3, pp. 4294–4302, 2022.
@article{Nguyen2022,
title = {Deterministic Quantum Light Arrays from Giant Silica-Shelled Quantum Dots},
author = {Hao A. Nguyen and David Sharp and Johannes E. Fröch, and Yi-Yu Cai and Shenwei Wu and Madison Monahan and Christopher Munley and Arnab Manna and Arka Majumdar and Cherie R. Kagan and Brandi M. Cossairt*},
url = {https://pubs.acs.org/doi/full/10.1021/acsami.2c18475},
doi = {10.1021/acsami.2c18475},
year = {2022},
date = {2022-12-12},
urldate = {2022-12-12},
journal = {ACS Applied Materials & Interfaces},
volume = {15},
issue = {3},
pages = {4294–4302},
abstract = {Colloidal quantum dots (QDs) are promising candidates for single-photon sources with applications in photonic quantum information technologies. Developing practical photonic quantum devices with colloidal materials, however, requires scalable deterministic placement of stable single QD emitters. In this work, we describe a method to exploit QD size to facilitate deterministic positioning of single QDs into large arrays while maintaining their photostability and single-photon emission properties. CdSe/CdS core/shell QDs were encapsulated in silica to both increase their physical size without perturbing their quantum-confined emission and enhance their photostability. These giant QDs were then precisely positioned into ordered arrays using template-assisted self-assembly with a 75% yield for single QDs. We show that the QDs before and after assembly exhibit antibunching behavior at room temperature and their optical properties are retained after an extended period of time. Together, this bottom-up synthetic approach via silica shelling and the robust template-assisted self-assembly offer a unique strategy to produce scalable quantum photonics platforms using colloidal QDs as single-photon emitters.},
keywords = {colloids, nanoparticle assembly, organic compounds, quantum dots, silica},
pubstate = {published},
tppubtype = {article}
}
Colloidal quantum dots (QDs) are promising candidates for single-photon sources with applications in photonic quantum information technologies. Developing practical photonic quantum devices with colloidal materials, however, requires scalable deterministic placement of stable single QD emitters. In this work, we describe a method to exploit QD size to facilitate deterministic positioning of single QDs into large arrays while maintaining their photostability and single-photon emission properties. CdSe/CdS core/shell QDs were encapsulated in silica to both increase their physical size without perturbing their quantum-confined emission and enhance their photostability. These giant QDs were then precisely positioned into ordered arrays using template-assisted self-assembly with a 75% yield for single QDs. We show that the QDs before and after assembly exhibit antibunching behavior at room temperature and their optical properties are retained after an extended period of time. Together, this bottom-up synthetic approach via silica shelling and the robust template-assisted self-assembly offer a unique strategy to produce scalable quantum photonics platforms using colloidal QDs as single-photon emitters.
Keller, Austin W.; Marino, Emanuele; An, Di; Neuhaus, Steven J.; Elbert, Katherine C.; Murray, Christopher B.; Kagan, Cherie R.
Sub-5 nm Anisotropic Pattern Transfer via Colloidal Lithography of a Self-Assembled GdF3 Nanocrystal Monolayer Journal Article
In: Nano Letters, vol. 22, iss. 5, pp. 1992–2000, 2022.
@article{Keller2022,
title = {Sub-5 nm Anisotropic Pattern Transfer via Colloidal Lithography of a Self-Assembled GdF3 Nanocrystal Monolayer},
author = {Austin W. Keller and Emanuele Marino and Di An and Steven J. Neuhaus and Katherine C. Elbert and Christopher B. Murray and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.1c04761},
doi = {10.1021/acs.nanolett.1c04761},
year = {2022},
date = {2022-02-28},
urldate = {2022-02-28},
journal = {Nano Letters},
volume = {22},
issue = {5},
pages = {1992–2000},
abstract = {Patterning materials with nanoscale features opens many research opportunities ranging from fundamental science to technological applications. However, current nanofabrication methods are ill-suited for sub-5 nm patterning and pattern transfer. We demonstrate the use of colloidal lithography to transfer an anisotropic pattern of discrete features into substrates with a critical dimension below 5 nm. The assembly of monodisperse, anisotropic nanocrystals (NCs) with a rhombic-plate morphology spaced by dendrimer ligands results in a well-ordered monolayer that serves as a 2D anisotropic hard mask pattern. This pattern is transferred into the underlying substrate using dry etching followed by removal of the NC mask. We exemplify this approach by fabricating an array of pillars with a rhombic cross-section and edge-to-edge spacing of 4.4 ± 1.1 nm. The fabrication approach enables broader access to patterning materials at the deep nanoscale by implementing innovative processes into well-established fabrication methods while minimizing process complexity.},
keywords = {lithography, manufacturing, nanocrystal, nanoparticle assembly, nanoscience, nanotechnology, patterning, self-assembly},
pubstate = {published},
tppubtype = {article}
}
Patterning materials with nanoscale features opens many research opportunities ranging from fundamental science to technological applications. However, current nanofabrication methods are ill-suited for sub-5 nm patterning and pattern transfer. We demonstrate the use of colloidal lithography to transfer an anisotropic pattern of discrete features into substrates with a critical dimension below 5 nm. The assembly of monodisperse, anisotropic nanocrystals (NCs) with a rhombic-plate morphology spaced by dendrimer ligands results in a well-ordered monolayer that serves as a 2D anisotropic hard mask pattern. This pattern is transferred into the underlying substrate using dry etching followed by removal of the NC mask. We exemplify this approach by fabricating an array of pillars with a rhombic cross-section and edge-to-edge spacing of 4.4 ± 1.1 nm. The fabrication approach enables broader access to patterning materials at the deep nanoscale by implementing innovative processes into well-established fabrication methods while minimizing process complexity.
Shulevitz, Henry J.; Huang, Tzu-Yung; Xu, Jun; Neuhaus, Steven; Patel, Raj N.; Lee C. Bassett, Cherie R. Kagan
Template-Assisted Self Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies Journal Article
In: ACS Nano, vol. 16, iss. 2, pp. 1847–1856, 2022.
@article{Shulevitz2021,
title = {Template-Assisted Self Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies},
author = {Henry J. Shulevitz and Tzu-Yung Huang and Jun Xu and Steven Neuhaus and Raj N. Patel and Lee C. Bassett, Cherie R. Kagan},
url = {https://pubs.acs.org/doi/10.1021/acsnano.1c09839
https://arxiv.org/abs/2111.14921},
year = {2022},
date = {2022-01-13},
urldate = {2022-01-13},
journal = {ACS Nano},
volume = {16},
issue = {2},
pages = {1847–1856},
abstract = {Milled nanodiamonds containing nitrogen-vacancy (NV) centers provide an excellent platform for sensing applications as they are optically robust, have nanoscale quantum sensitivity, and form colloidal dispersions which enable bottom-up assembly techniques for device integration. However, variations in their size, shape, and surface chemistry limit the ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self assembly. This method enables the precise spatial arrangement of isolated nanodiamonds with diameters below 50 nm across millimeter-scale areas. Measurements of over 200 assembled nanodiamonds yield a statistical understanding of their structural, optical, and quantum properties. The NV centers' spin and charge properties are uncorrelated with nanodiamond size, but rather are consistent with heterogeneity in their nanoscale environment. This flexible assembly method, together with improved understanding of the material, will enable the integration of nanodiamonds into future quantum photonic and electronic devices.},
keywords = {nanoparticle assembly, nanotechnology, quantum information science, self-assembly, TEM, templated assembly},
pubstate = {published},
tppubtype = {article}
}
Milled nanodiamonds containing nitrogen-vacancy (NV) centers provide an excellent platform for sensing applications as they are optically robust, have nanoscale quantum sensitivity, and form colloidal dispersions which enable bottom-up assembly techniques for device integration. However, variations in their size, shape, and surface chemistry limit the ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self assembly. This method enables the precise spatial arrangement of isolated nanodiamonds with diameters below 50 nm across millimeter-scale areas. Measurements of over 200 assembled nanodiamonds yield a statistical understanding of their structural, optical, and quantum properties. The NV centers' spin and charge properties are uncorrelated with nanodiamond size, but rather are consistent with heterogeneity in their nanoscale environment. This flexible assembly method, together with improved understanding of the material, will enable the integration of nanodiamonds into future quantum photonic and electronic devices.
2021
Cai, Yi-Yu; Choi, Yun Chang; Kagan, Cherie R.
Chemical and Physical Properties of Photonic Noble-metal Nanomaterials Journal Article
In: Advanced Materials, pp. 2108104, 2021.
@article{Cai2021,
title = {Chemical and Physical Properties of Photonic Noble-metal Nanomaterials},
author = {Yi-Yu Cai and Yun Chang Choi and Cherie R. Kagan},
url = {https://onlinelibrary.wiley.com/doi/10.1002/adma.202108104},
doi = {10.1002/adma.202108104},
year = {2021},
date = {2021-12-12},
urldate = {2021-12-12},
journal = {Advanced Materials},
pages = {2108104},
abstract = {Colloidal noble metal nanoparticles are composed of metal cores and organic or inorganic ligand shells. These nanoparticles support size- and shape-dependent plasmonic resonances. They can be assembled from dispersions into artificial metamolecules which have collective plasmonic resonances originating from coupled bright and dark optical electric and magnetic modes that form depending on the size and shape of the constituent nanoparticles and their number, arrangement, and interparticle distance. Nanoparticles can also be assembled into extended two- and three-dimensional metamaterials that are glassy thin films or ordered thin films or crystals, also known as superlattices and supercrystals. The metamaterials have tunable optical properties that depend on the size, shape, and composition of the nanoparticles, and on the number of nanoparticle layers and their interparticle distance. Interestingly, strong light-matter interactions in superlattices form plasmon polaritons. Tunable interparticle distances allow designer materials with dielectric functions tailorable from that characteristic of an insulator to that of a metal, and serve as strong optical absorbers or scatterers, respectively. In combination with lithography techniques, these extended assemblies can be patterned to create subwavelength nanoparticle superstructures and form large-area 2D and 3D metamaterials that manipulate the amplitude, phase, and polarization of transmitted or reflected light.},
keywords = {chiral, metamolecule, nanoparticle assembly, Noble metal nanoparticles, optical metamaterials, plasmonic},
pubstate = {published},
tppubtype = {article}
}
Colloidal noble metal nanoparticles are composed of metal cores and organic or inorganic ligand shells. These nanoparticles support size- and shape-dependent plasmonic resonances. They can be assembled from dispersions into artificial metamolecules which have collective plasmonic resonances originating from coupled bright and dark optical electric and magnetic modes that form depending on the size and shape of the constituent nanoparticles and their number, arrangement, and interparticle distance. Nanoparticles can also be assembled into extended two- and three-dimensional metamaterials that are glassy thin films or ordered thin films or crystals, also known as superlattices and supercrystals. The metamaterials have tunable optical properties that depend on the size, shape, and composition of the nanoparticles, and on the number of nanoparticle layers and their interparticle distance. Interestingly, strong light-matter interactions in superlattices form plasmon polaritons. Tunable interparticle distances allow designer materials with dielectric functions tailorable from that characteristic of an insulator to that of a metal, and serve as strong optical absorbers or scatterers, respectively. In combination with lithography techniques, these extended assemblies can be patterned to create subwavelength nanoparticle superstructures and form large-area 2D and 3D metamaterials that manipulate the amplitude, phase, and polarization of transmitted or reflected light.
2020
Kagan, Cherie R.; Bassett, Lee C.; Murray, Christopher B.; Thompson, Sarah M.
Colloidal Quantum Dots as Platforms for Quantum Information Science Journal Article
In: Chemical Reviews, vol. 121, no. 5, pp. 3186–3233, 2020.
@article{Kagan2020,
title = {Colloidal Quantum Dots as Platforms for Quantum Information Science},
author = {Cherie R. Kagan and Lee C. Bassett and Christopher B. Murray and Sarah M. Thompson},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.chemrev.0c00831},
doi = {10.1021/acs.chemrev.0c00831},
year = {2020},
date = {2020-12-29},
journal = {Chemical Reviews},
volume = {121},
number = {5},
pages = {3186–3233},
abstract = {Colloidal quantum dots (QDs) are nanoscale semiconductor crystals with surface ligands that enable their dispersion in solvents. Quantum confinement effects facilitate wave function engineering to sculpt the spatial distribution of charge and spin states and thus the energy and dynamics of QD optical transitions. Colloidal QDs can be integrated in devices using solution-based assembly methods to position single QDs and to create ordered QD arrays. Here, we describe the synthesis, assembly, and photophysical properties of colloidal QDs that have captured scientific imagination and have been harnessed in optical applications. We focus especially on the current understanding of their quantum coherent effects and opportunities to exploit QDs as platforms for quantum information science. Freedom in QD design to isolate and control the quantum mechanical properties of charge, spin, and light presents various approaches to create systems with robust, addressable quantum states. We consider the attributes of QDs for optically addressable qubits in emerging quantum computation, sensing, simulation, and communication technologies, e.g., as robust sources of indistinguishable, single photons that can be integrated into photonic structures to amplify, direct, and tune their emission or as hosts for isolated, coherent spin states that can be coupled to light or to other spins in QD arrays.},
keywords = {nanoparticle assembly, quantum dots, quantum information science, synthesis},
pubstate = {published},
tppubtype = {article}
}
Colloidal quantum dots (QDs) are nanoscale semiconductor crystals with surface ligands that enable their dispersion in solvents. Quantum confinement effects facilitate wave function engineering to sculpt the spatial distribution of charge and spin states and thus the energy and dynamics of QD optical transitions. Colloidal QDs can be integrated in devices using solution-based assembly methods to position single QDs and to create ordered QD arrays. Here, we describe the synthesis, assembly, and photophysical properties of colloidal QDs that have captured scientific imagination and have been harnessed in optical applications. We focus especially on the current understanding of their quantum coherent effects and opportunities to exploit QDs as platforms for quantum information science. Freedom in QD design to isolate and control the quantum mechanical properties of charge, spin, and light presents various approaches to create systems with robust, addressable quantum states. We consider the attributes of QDs for optically addressable qubits in emerging quantum computation, sensing, simulation, and communication technologies, e.g., as robust sources of indistinguishable, single photons that can be integrated into photonic structures to amplify, direct, and tune their emission or as hosts for isolated, coherent spin states that can be coupled to light or to other spins in QD arrays.
Kagan, Cherie R.; Hyeon, Taeghwan; Kim, Dae-Hyeong; Ruiz, Ricardo; Tung, Maryann C.; Wong, H. -S. Philip
Self-assembly for electronics Journal Article
In: MRS Bulletin, vol. 45, pp. 807–814, 2020.
@article{Kagan2020b,
title = {Self-assembly for electronics},
author = {Cherie R. Kagan and Taeghwan Hyeon and Dae-Hyeong Kim and Ricardo Ruiz and Maryann C. Tung and H.-S. Philip Wong },
url = {https://link.springer.com/article/10.1557/mrs.2020.248},
doi = {10.1557/mrs.2020.248},
year = {2020},
date = {2020-12-24},
journal = {MRS Bulletin},
volume = {45},
pages = {807–814},
abstract = {Self-assembly, a process in which molecules, polymers, and particles are driven by local interactions to organize into patterns and functional structures, is being exploited in advancing silicon electronics and in emerging, unconventional electronics. Silicon electronics has relied on lithographic patterning of polymer resists at progressively smaller lengths to scale down device dimensions. Yet, this has become increasingly difficult and costly. Assembly of block copolymers and colloidal nanoparticles allows resolution enhancement and the definition of essential shapes to pattern circuits and memory devices. As we look to a future in which electronics are integrated at large numbers and in new forms for the Internet of Things and wearable and implantable technologies, we also explore a broader material set. Semiconductor nanoparticles and biomolecules are prized for their size-, shape-, and composition-dependent properties and for their solution-based assembly and integration into devices that are enabling unconventional manufacturing and new device functions.},
keywords = {nanocrystal electronics, nanoparticle assembly},
pubstate = {published},
tppubtype = {article}
}
Self-assembly, a process in which molecules, polymers, and particles are driven by local interactions to organize into patterns and functional structures, is being exploited in advancing silicon electronics and in emerging, unconventional electronics. Silicon electronics has relied on lithographic patterning of polymer resists at progressively smaller lengths to scale down device dimensions. Yet, this has become increasingly difficult and costly. Assembly of block copolymers and colloidal nanoparticles allows resolution enhancement and the definition of essential shapes to pattern circuits and memory devices. As we look to a future in which electronics are integrated at large numbers and in new forms for the Internet of Things and wearable and implantable technologies, we also explore a broader material set. Semiconductor nanoparticles and biomolecules are prized for their size-, shape-, and composition-dependent properties and for their solution-based assembly and integration into devices that are enabling unconventional manufacturing and new device functions.
Marino, Emanuele; Keller, Austin W.; Di An, Sjoerd van Dongen; Kodger, Thomas E.; MacArthur, Katherine E.; Heggen, Marc; Kagan, Cherie R.; Murray, Christopher B.; Schall, Peter
Favoring the Growth of High-Quality, Three-Dimensional Supercrystals of Nanocrystals Journal Article
In: The Journal of Physical Chemistry C, vol. 124, no. 20, pp. 11256–11264, 2020.
@article{Marino2020,
title = {Favoring the Growth of High-Quality, Three-Dimensional Supercrystals of Nanocrystals},
author = {Emanuele Marino and Austin W. Keller and Di An, Sjoerd van Dongen and Thomas E. Kodger and Katherine E. MacArthur and Marc Heggen and Cherie R. Kagan and Christopher B. Murray and Peter Schall},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.0c02805},
doi = {abs/10.1021/acs.jpcc.0c02805},
year = {2020},
date = {2020-04-28},
journal = {The Journal of Physical Chemistry C},
volume = {124},
number = {20},
pages = {11256–11264},
abstract = {A recently developed emulsion-templated assembly method promises the scalable, low-cost, and reproducible fabrication of hierarchical nanocrystal (NC) superstructures. These superstructures derive properties from the unique combination of choices of NC building blocks and superstructure morphology and therefore realize the concept of “artificial solids”. To control the final properties of these superstructures, it is essential to control the assembly conditions that yield distinct architectural morphologies. Here, we explore the phase-space of experimental parameters describing the emulsion-templated assembly including temperature, interfacial tension, and NC polydispersity and demonstrate which conditions lead to the growth of the most crystalline NC superstructures or supercrystals. By using a combination of electron microscopy and small-angle X-ray scattering, we show that slower assembly kinetics, softer interfaces, and lower NC polydispersity contribute to the formation of supercrystals with grain sizes up to 600 nm, while reversing these trends yields glassy solids. These results provide a clear path to the realization of higher-quality supercrystals, necessary to many applications.},
keywords = {multifunctional nanomaterials, nanoparticle assembly, synthesis},
pubstate = {published},
tppubtype = {article}
}
A recently developed emulsion-templated assembly method promises the scalable, low-cost, and reproducible fabrication of hierarchical nanocrystal (NC) superstructures. These superstructures derive properties from the unique combination of choices of NC building blocks and superstructure morphology and therefore realize the concept of “artificial solids”. To control the final properties of these superstructures, it is essential to control the assembly conditions that yield distinct architectural morphologies. Here, we explore the phase-space of experimental parameters describing the emulsion-templated assembly including temperature, interfacial tension, and NC polydispersity and demonstrate which conditions lead to the growth of the most crystalline NC superstructures or supercrystals. By using a combination of electron microscopy and small-angle X-ray scattering, we show that slower assembly kinetics, softer interfaces, and lower NC polydispersity contribute to the formation of supercrystals with grain sizes up to 600 nm, while reversing these trends yields glassy solids. These results provide a clear path to the realization of higher-quality supercrystals, necessary to many applications.
2019
Chen, Wenxiang; Guo, Jiacen; Zhao, Qinghua; Gopalan, Prashanth; Fafarman, Aaron T.; Keller, Austin; Zhang, Mingliang; Wu, Yaoting; Murray, Christopher B.; Kagan, Cherie R.
Designing Strong Optical Absorbers via Continuous Tuning of Interparticle Interaction in Colloidal Gold Nanocrystal Assemblies Journal Article
In: ACS Nano, vol. 13, no. 7, pp. 7493-7501, 2019.
@article{Chen2019,
title = {Designing Strong Optical Absorbers via Continuous Tuning of Interparticle Interaction in Colloidal Gold Nanocrystal Assemblies},
author = {Wenxiang Chen and Jiacen Guo and Qinghua Zhao and Prashanth Gopalan and Aaron T. Fafarman and Austin Keller and Mingliang Zhang and Yaoting Wu and Christopher B. Murray and Cherie R. Kagan},
doi = {10.1021/acsnano.9b02818},
year = {2019},
date = {2019-05-28},
journal = {ACS Nano},
volume = {13},
number = {7},
pages = {7493-7501},
abstract = {We program the optical properties of colloidal Au nanocrystal (NC) assemblies via an unconventional ligand hybridization (LH) strategy to precisely engineer interparticle interactions and design materials with optical properties difficult or impossible to achieve in bulk form. Long-chain hydrocarbon ligands used in NC synthesis are partially exchanged, from 0% to 100%, with compact thiocyanate ligands by controlling the reaction time for exchange. The resulting NC assemblies show transmittance, reflectance, optical permittivity, and direct-current (DC) resistivity that continuously traverse a dielectric-metal transition, providing analog tuning of their physical properties, unlike the digital control realized by complete exchange with ligands of varying length. Exploiting this LH strategy, we create Au NC assemblies that are strong, ultrathin film optical absorbers, as seen by a 6× increase in the extinction of infrared light compared to that in bulk Au thin films and by a temperature rise of 20 °C upon illumination with 808 nm light. Our LH strategy may be applied to the design of materials constructed from NCs of different size, shape, and composition for specific applications.},
keywords = {nanoparticle assembly},
pubstate = {published},
tppubtype = {article}
}
We program the optical properties of colloidal Au nanocrystal (NC) assemblies via an unconventional ligand hybridization (LH) strategy to precisely engineer interparticle interactions and design materials with optical properties difficult or impossible to achieve in bulk form. Long-chain hydrocarbon ligands used in NC synthesis are partially exchanged, from 0% to 100%, with compact thiocyanate ligands by controlling the reaction time for exchange. The resulting NC assemblies show transmittance, reflectance, optical permittivity, and direct-current (DC) resistivity that continuously traverse a dielectric-metal transition, providing analog tuning of their physical properties, unlike the digital control realized by complete exchange with ligands of varying length. Exploiting this LH strategy, we create Au NC assemblies that are strong, ultrathin film optical absorbers, as seen by a 6× increase in the extinction of infrared light compared to that in bulk Au thin films and by a temperature rise of 20 °C upon illumination with 808 nm light. Our LH strategy may be applied to the design of materials constructed from NCs of different size, shape, and composition for specific applications.
2017
Jishkariani, Davit; Lee, Jennifer D.; Yun, Hongseok; Paik, Taejong; Kikkawa, James M.; Kagan, Cherie R.; Murray, Bertrand Donnioand Christopher B.
The dendritic effect and magnetic permeability in dendron coated nickel and manganese zinc ferrite nanoparticles Journal Article
In: Nanoscale, vol. 9, no. 37, pp. 13922-13928, 2017.
@article{Jishkariani2017,
title = {The dendritic effect and magnetic permeability in dendron coated nickel and manganese zinc ferrite nanoparticles},
author = {Davit Jishkariani and Jennifer D. Lee and Hongseok Yun and Taejong Paik and James M. Kikkawa and Cherie R. Kagan and Bertrand Donnioand Christopher B. Murray},
url = {https://pubs.rsc.org/en/content/articlelanding/2017/nr/c7nr05769e#!divAbstract},
doi = {10.1039/C7NR05769E},
year = {2017},
date = {2017-08-21},
journal = {Nanoscale},
volume = {9},
number = {37},
pages = {13922-13928},
abstract = {The collective magnetic properties of nanoparticle (NP) solid films are greatly affected by inter-particle dipole–dipole interactions and therefore the proximity of the neighboring particles. In this study, a series of dendritic ligands (generations 0 to 3, G0–G3) have been designed and used to cover the surface of magnetic NPs to control the spacings between the NP components in single lattices. The dendrons of different generations introduced here were based on the 2,2-bis(hydroxymethyl)propionic acid (Bis-MPA) scaffold and equipped with an appropriate surface binding group at one end and several fatty acid segments at the other extremity. The surface of the NPs was then modified by partial ligand exchange between the primary stabilizing surfactants and the new dendritic wedges. It was shown that this strategy permitted very precise tuning of inter-particle spacings in the range of 2.9–5.0 nm. As expected, the increase in the inter-particle spacings reduced the dipole–dipole interactions between magnetic NPs and therefore allowed changes in their magnetic permeability. The dendron size and inter-particle distance dependence was studied to reveal the dendritic effect and identify the optimal geometry and generation.},
keywords = {nanoparticle assembly, synthesis},
pubstate = {published},
tppubtype = {article}
}
The collective magnetic properties of nanoparticle (NP) solid films are greatly affected by inter-particle dipole–dipole interactions and therefore the proximity of the neighboring particles. In this study, a series of dendritic ligands (generations 0 to 3, G0–G3) have been designed and used to cover the surface of magnetic NPs to control the spacings between the NP components in single lattices. The dendrons of different generations introduced here were based on the 2,2-bis(hydroxymethyl)propionic acid (Bis-MPA) scaffold and equipped with an appropriate surface binding group at one end and several fatty acid segments at the other extremity. The surface of the NPs was then modified by partial ligand exchange between the primary stabilizing surfactants and the new dendritic wedges. It was shown that this strategy permitted very precise tuning of inter-particle spacings in the range of 2.9–5.0 nm. As expected, the increase in the inter-particle spacings reduced the dipole–dipole interactions between magnetic NPs and therefore allowed changes in their magnetic permeability. The dendron size and inter-particle distance dependence was studied to reveal the dendritic effect and identify the optimal geometry and generation.
Ashkar, Rana; Hore, Michael J. A.; Ye, Xingchen; Natarajan, Bharath; Greybush, Nicholas J.; Thomas,; Kagan, Cherie R.; Murray, Christopher B.
Rapid Large-Scale Assembly and Pattern Transfer of One-Dimensional Gold Nanorod Superstructures Journal Article
In: ACS Applied Materials & Interfaces, vol. 9, no. 30, pp. 25513–25521, 2017.
@article{Ashkar2017,
title = {Rapid Large-Scale Assembly and Pattern Transfer of One-Dimensional Gold Nanorod Superstructures},
author = {Rana Ashkar and Michael J. A. Hore and Xingchen Ye and Bharath Natarajan and Nicholas J. Greybush and Thomas and Cherie R. Kagan and Christopher B. Murray},
url = {https://pubs.acs.org/doi/abs/10.1021/acsami.7b06273},
doi = {abs/10.1021/acsami.7b06273},
year = {2017},
date = {2017-07-07},
journal = {ACS Applied Materials & Interfaces},
volume = {9},
number = {30},
pages = {25513–25521},
abstract = {The utility of gold nanorods for plasmonic applications largely depends on the relative orientation and proximity of the nanorods. Though side-by-side or chainlike nanorod morphologies have been previously demonstrated, a simple reliable method to obtain high-yield oriented gold nanorod assemblies remains a significant challenge. We present a facile, scalable approach which exploits meniscus drag, evaporative self-assembly, and van der Waals interactions to precisely position and orient gold nanorods over macroscopic areas of 1D nanostructured substrates. By adjusting the ratio of the nanorod diameter to the width of the nanochannels, we demonstrate the formation of two highly desired translationally ordered nanorod patterns. We further demonstrate a method to transfer the aligned nanorods into a polymer matrix which exhibits anisotropic optical properties, allowing for rapid fabrication and deployment of flexible optical and electronic materials in future nanoscale devices.},
keywords = {nanoparticle assembly, plasmonic, templated assembly},
pubstate = {published},
tppubtype = {article}
}
The utility of gold nanorods for plasmonic applications largely depends on the relative orientation and proximity of the nanorods. Though side-by-side or chainlike nanorod morphologies have been previously demonstrated, a simple reliable method to obtain high-yield oriented gold nanorod assemblies remains a significant challenge. We present a facile, scalable approach which exploits meniscus drag, evaporative self-assembly, and van der Waals interactions to precisely position and orient gold nanorods over macroscopic areas of 1D nanostructured substrates. By adjusting the ratio of the nanorod diameter to the width of the nanochannels, we demonstrate the formation of two highly desired translationally ordered nanorod patterns. We further demonstrate a method to transfer the aligned nanorods into a polymer matrix which exhibits anisotropic optical properties, allowing for rapid fabrication and deployment of flexible optical and electronic materials in future nanoscale devices.
Greybush, Nicholas J.; Libera, Iñigo; Malassis, Ludivine; Kikkawa, James M.; Engheta, Nader; Murray, Christopher B.; Kagan, Cherie R.
Plasmon Resonances in Self-Assembled Two-Dimensional Au Nanocrystal Metamolecules Journal Article
In: ACS Nano, vol. 11, no. 3, pp. 2917–2927, 2017.
@article{Greybush2017,
title = {Plasmon Resonances in Self-Assembled Two-Dimensional Au Nanocrystal Metamolecules},
author = {Nicholas J. Greybush and Iñigo Libera and Ludivine Malassis and James M. Kikkawa and Nader Engheta and Christopher B. Murray and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.6b08189},
doi = {10.1021/acsnano.6b08189},
year = {2017},
date = {2017-02-12},
journal = {ACS Nano},
volume = {11},
number = {3},
pages = {2917–2927},
abstract = {We explore the evolution of plasmonic modes in two-dimensional nanocrystal oligomer “metamolecules” as the number of nanocrystals is systematically varied. Precise, hexagonally ordered Au nanocrystal oligomers with 1–31 members are assembled via capillary forces into polygonal topographic templates defined using electron-beam lithography. The visible and near-infrared scattering response of individual oligomers is measured by spatially resolved, polarized darkfield scattering spectroscopy. The response is highly sensitive to in-plane versus out-of-plane incident polarization, and we observe an exponentially saturating red shift in plasmon resonance wavelength as the number of nanocrystals per oligomer increases, in agreement with theoretical predictions. Simulations further elucidate the modes supported by the oligomers, including electric dipole and magnetic dipole resonances and their Fano interference. The single-oligomer sensitivity of our measurements also reveals the role of positional disorder in determining the wavelength and character of the plasmonic response. The progression of oligomer metamolecule structures studied here advances our understanding of fundamental plasmonic interactions in the transition regime between few-member plasmonic clusters and extended two-dimensional arrays.},
keywords = {nanoparticle assembly, optical metamaterials, plasmonic, templated assembly},
pubstate = {published},
tppubtype = {article}
}
We explore the evolution of plasmonic modes in two-dimensional nanocrystal oligomer “metamolecules” as the number of nanocrystals is systematically varied. Precise, hexagonally ordered Au nanocrystal oligomers with 1–31 members are assembled via capillary forces into polygonal topographic templates defined using electron-beam lithography. The visible and near-infrared scattering response of individual oligomers is measured by spatially resolved, polarized darkfield scattering spectroscopy. The response is highly sensitive to in-plane versus out-of-plane incident polarization, and we observe an exponentially saturating red shift in plasmon resonance wavelength as the number of nanocrystals per oligomer increases, in agreement with theoretical predictions. Simulations further elucidate the modes supported by the oligomers, including electric dipole and magnetic dipole resonances and their Fano interference. The single-oligomer sensitivity of our measurements also reveals the role of positional disorder in determining the wavelength and character of the plasmonic response. The progression of oligomer metamolecule structures studied here advances our understanding of fundamental plasmonic interactions in the transition regime between few-member plasmonic clusters and extended two-dimensional arrays.
Wu, Yaoting; Siming,; Gogotsi, Natalie; Zhao, Tianshuo; Fleury, Blaise; Kagan, Cherie R.; Murray, Christopher B.; Baxter, Jason B.
Directional Carrier Transfer in Strongly Coupled Binary Nanocrystal Superlattice Films Formed by Assembly and in Situ Ligand Exchange at a Liquid–Air Interface Journal Article
In: The Journal of Physical Chemistry C, vol. 121, no. 8, pp. 4146–4157, 2017.
@article{Wu2017,
title = {Directional Carrier Transfer in Strongly Coupled Binary Nanocrystal Superlattice Films Formed by Assembly and in Situ Ligand Exchange at a Liquid–Air Interface},
author = {Yaoting Wu and Siming and Natalie Gogotsi and Tianshuo Zhao and Blaise Fleury and Cherie R. Kagan and Christopher B. Murray and Jason B. Baxter},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b12327},
doi = {abs/10.1021/acs.jpcc.6b12327},
year = {2017},
date = {2017-02-05},
journal = {The Journal of Physical Chemistry C},
volume = {121},
number = {8},
pages = {4146–4157},
abstract = {Two species of monodisperse nanocrystals (NCs) can self-assemble into a variety of complex 2D and 3D periodic structures, or binary NC superlattice (BNSL) films, based on the relative number and size of the NCs. BNSL films offer great promise for both fundamental scientific studies and optoelectronic applications; however, the utility of as-assembled structures has been limited by the insulating ligands that originate from the synthesis of NCs. Here we report the application of an in situ ligand exchange strategy at a liquid–air interface to replace the long synthesis ligands with short ligands while preserving the long-range order of BNSL films. This approach is demonstrated for BNSL structures consisting of PbSe NCs of different size combinations and ligands of interest for photovoltaic devices, infrared detectors, and light-emitting diodes. To confirm enhanced coupling introduced by ligand exchange, we show ultrafast (∼1 ps) directional carrier transfer across the type-I heterojunction formed by NCs of different sizes within ligand-exchanged BNSL films. This approach shows the potential promise of functional BNSL films, where the local and long-range energy landscape and electronic coupling can be adjusted by tuning NC composition, size, and interparticle spacing.},
keywords = {nanoparticle assembly, transport},
pubstate = {published},
tppubtype = {article}
}
Two species of monodisperse nanocrystals (NCs) can self-assemble into a variety of complex 2D and 3D periodic structures, or binary NC superlattice (BNSL) films, based on the relative number and size of the NCs. BNSL films offer great promise for both fundamental scientific studies and optoelectronic applications; however, the utility of as-assembled structures has been limited by the insulating ligands that originate from the synthesis of NCs. Here we report the application of an in situ ligand exchange strategy at a liquid–air interface to replace the long synthesis ligands with short ligands while preserving the long-range order of BNSL films. This approach is demonstrated for BNSL structures consisting of PbSe NCs of different size combinations and ligands of interest for photovoltaic devices, infrared detectors, and light-emitting diodes. To confirm enhanced coupling introduced by ligand exchange, we show ultrafast (∼1 ps) directional carrier transfer across the type-I heterojunction formed by NCs of different sizes within ligand-exchanged BNSL films. This approach shows the potential promise of functional BNSL films, where the local and long-range energy landscape and electronic coupling can be adjusted by tuning NC composition, size, and interparticle spacing.
Paik, Taejong; Hongseok,; Fleury, Blaise; Hong, Sung-Hoon; Jo, Pil Sung; Wu, Yaoting; Oh, Soong-Ju; Cargnello, Matteo; Yang, Haoran; Murray, Christopher B.; Kagan, Cherie R.
Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices Journal Article
In: Nano Letters, vol. 17, no. 3, pp. 1387–1394, 2017.
@article{Paik2017,
title = {Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices},
author = {Taejong Paik and Hongseok and Blaise Fleury and Sung-Hoon Hong and Pil Sung Jo and Yaoting Wu and Soong-Ju Oh and Matteo Cargnello and Haoran Yang and Christopher B. Murray and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.6b04279},
doi = {abs/10.1021/acs.nanolett.6b04279},
year = {2017},
date = {2017-02-01},
journal = {Nano Letters},
volume = {17},
number = {3},
pages = {1387–1394},
abstract = {We demonstrate the fabrication of hierarchical materials by controlling the structure of highly ordered binary nanocrystal superlattices (BNSLs) on multiple length scales. Combinations of magnetic, plasmonic, semiconducting, and insulating colloidal nanocrystal (NC) building blocks are self-assembled into BNSL membranes via the liquid–interfacial assembly technique. Free-standing BNSL membranes are transferred onto topographically structured poly(dimethylsiloxane) molds via the Langmuir–Schaefer technique and then deposited in patterns onto substrates via transfer printing. BNSLs with different structural motifs are successfully patterned into various meso- and microstructures such as lines, circles, and even three-dimensional grids across large-area substrates. A combination of electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) measurements confirm the ordering of NC building blocks in meso- and micropatterned BNSLs. This technique demonstrates structural diversity in the design of hierarchical materials by assembling BNSLs from NC building blocks of different composition and size by patterning BNSLs into various size and shape superstructures of interest for a broad range of applications.},
keywords = {multifunctional nanomaterials, nanoparticle assembly, self-assembly, TEM},
pubstate = {published},
tppubtype = {article}
}
We demonstrate the fabrication of hierarchical materials by controlling the structure of highly ordered binary nanocrystal superlattices (BNSLs) on multiple length scales. Combinations of magnetic, plasmonic, semiconducting, and insulating colloidal nanocrystal (NC) building blocks are self-assembled into BNSL membranes via the liquid–interfacial assembly technique. Free-standing BNSL membranes are transferred onto topographically structured poly(dimethylsiloxane) molds via the Langmuir–Schaefer technique and then deposited in patterns onto substrates via transfer printing. BNSLs with different structural motifs are successfully patterned into various meso- and microstructures such as lines, circles, and even three-dimensional grids across large-area substrates. A combination of electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) measurements confirm the ordering of NC building blocks in meso- and micropatterned BNSLs. This technique demonstrates structural diversity in the design of hierarchical materials by assembling BNSLs from NC building blocks of different composition and size by patterning BNSLs into various size and shape superstructures of interest for a broad range of applications.
2016
Zhang, Mingliang; Magagnosc, Daniel J.; Liberal, Iñigo; Yu, Yao; Yun, Hongseok; Yang, Haoran; Wu, Yaoting; Guo, Jiacen; Chen, Wenxiang; Shin, Young Jae; Stein, Aaron; Kikkawa, James M.; Engheta, Nader; Gianola, Daniel S.; Murray, Christopher B.; Kagan, Cherie R.
High-strength magnetically switchable plasmonic nanorods assembled from a binary nanocrystal mixture Journal Article
In: Nature Nanotechnology, vol. 12, pp. 228–232, 2016.
@article{Zhang2016,
title = {High-strength magnetically switchable plasmonic nanorods assembled from a binary nanocrystal mixture},
author = {Mingliang Zhang and Daniel J. Magagnosc and Iñigo Liberal and Yao Yu and Hongseok Yun and Haoran Yang and Yaoting Wu and Jiacen Guo and Wenxiang Chen and Young Jae Shin and Aaron Stein and James M. Kikkawa and Nader Engheta and Daniel S. Gianola and Christopher B. Murray and Cherie R. Kagan},
url = {https://www.nature.com/articles/nnano.2016.235},
doi = {10.1038/nnano.2016.235},
year = {2016},
date = {2016-11-07},
journal = {Nature Nanotechnology},
volume = {12},
pages = {228–232},
abstract = {Next-generation ‘smart’ nanoparticle systems should be precisely engineered in size, shape and composition to introduce multiple functionalities, unattainable from a single material1,2,3. Bottom-up chemical methods are prized for the synthesis of crystalline nanoparticles, that is, nanocrystals, with size- and shape-dependent physical properties4,5,6, but they are less successful in achieving multifunctionality7,8,9. Top-down lithographic methods can produce multifunctional nanoparticles with precise size and shape control2,3,10,11, yet this becomes increasingly difficult at sizes of ∼10 nm. Here, we report the fabrication of multifunctional, smart nanoparticle systems by combining top-down fabrication and bottom-up self-assembly methods. Particularly, we template nanorods from a mixture of superparamagnetic Zn0.2Fe2.8O4 and plasmonic Au nanocrystals. The superparamagnetism of Zn0.2Fe2.8O4 prevents these nanorods from spontaneous magnetic-dipole-induced aggregation, while their magnetic anisotropy makes them responsive to an external field. Ligand exchange drives Au nanocrystal fusion and forms a porous network, imparting the nanorods with high mechanical strength and polarization-dependent infrared surface plasmon resonances. The combined superparamagnetic and plasmonic functions enable switching of the infrared transmission of a hybrid nanorod suspension using an external magnetic field.},
keywords = {nanoparticle assembly, optical metamaterials},
pubstate = {published},
tppubtype = {article}
}
Next-generation ‘smart’ nanoparticle systems should be precisely engineered in size, shape and composition to introduce multiple functionalities, unattainable from a single material1,2,3. Bottom-up chemical methods are prized for the synthesis of crystalline nanoparticles, that is, nanocrystals, with size- and shape-dependent physical properties4,5,6, but they are less successful in achieving multifunctionality7,8,9. Top-down lithographic methods can produce multifunctional nanoparticles with precise size and shape control2,3,10,11, yet this becomes increasingly difficult at sizes of ∼10 nm. Here, we report the fabrication of multifunctional, smart nanoparticle systems by combining top-down fabrication and bottom-up self-assembly methods. Particularly, we template nanorods from a mixture of superparamagnetic Zn0.2Fe2.8O4 and plasmonic Au nanocrystals. The superparamagnetism of Zn0.2Fe2.8O4 prevents these nanorods from spontaneous magnetic-dipole-induced aggregation, while their magnetic anisotropy makes them responsive to an external field. Ligand exchange drives Au nanocrystal fusion and forms a porous network, imparting the nanorods with high mechanical strength and polarization-dependent infrared surface plasmon resonances. The combined superparamagnetic and plasmonic functions enable switching of the infrared transmission of a hybrid nanorod suspension using an external magnetic field.
2014
Diroll, Benjamin T.; Doan-Nguyen, Vicky V. T.; Cargnello, Matteo; Gaulding, E. Ashley; Kagan, Cherie R.; Murray, Christopher B.
X-ray Mapping of Nanoparticle Superlattice Thin Films Journal Article
In: ACS Nano, vol. 8, no. 12, pp. 12843–12850, 2014.
@article{Diroll2014,
title = {X-ray Mapping of Nanoparticle Superlattice Thin Films},
author = {Benjamin T. Diroll and Vicky V. T. Doan-Nguyen and Matteo Cargnello and E. Ashley Gaulding and Cherie R. Kagan and Christopher B. Murray},
url = {https://pubs.acs.org/doi/full/10.1021/nn5062832},
doi = {10.1021/nn5062832},
year = {2014},
date = {2014-12-05},
urldate = {2014-12-05},
journal = {ACS Nano},
volume = {8},
number = {12},
pages = {12843–12850},
abstract = {We combine grazing-incidence and transmission small-angle X-ray diffraction with electron microscopy studies to characterize the structure of nanoparticle films with long-range order. Transmission diffraction is used to collect in-plane diffraction data from single grains and locally aligned nanoparticle superlattice films. Systematic mapping of samples can be achieved by translating the sample in front of the X-ray beam with a spot size selected to be on the order of superlattice grain features. This allows a statistical determination of superlattice grain size and size distribution over much larger areas than typically accessible with electron microscopy. Transmission X-ray measurements enables spatial mapping of the grain size, orientation, uniformity, strain, or crystal projections and polymorphs. We expand this methodology to binary nanoparticle superlattice and nanorod superlattice films. This study provides a framework for characterization of nanoparticle superlattices over large areas which complements or expands microstructure information from real-space imaging.},
keywords = {nanocrystal, nanoparticle assembly, superlattices, thin films},
pubstate = {published},
tppubtype = {article}
}
We combine grazing-incidence and transmission small-angle X-ray diffraction with electron microscopy studies to characterize the structure of nanoparticle films with long-range order. Transmission diffraction is used to collect in-plane diffraction data from single grains and locally aligned nanoparticle superlattice films. Systematic mapping of samples can be achieved by translating the sample in front of the X-ray beam with a spot size selected to be on the order of superlattice grain features. This allows a statistical determination of superlattice grain size and size distribution over much larger areas than typically accessible with electron microscopy. Transmission X-ray measurements enables spatial mapping of the grain size, orientation, uniformity, strain, or crystal projections and polymorphs. We expand this methodology to binary nanoparticle superlattice and nanorod superlattice films. This study provides a framework for characterization of nanoparticle superlattices over large areas which complements or expands microstructure information from real-space imaging.
2014
“Designing High-Performance PbS and PbSe Nanocrystal Electronic Devices through Stepwise, Post-Synthesis, Colloidal Atomic Layer Deposition,” Soong Ju Oh, Nathaniel E. Berry, Ji-Hyuk Choi, E. Ashley Gaulding, Hangfei Lin, Taejong Paik, Benjamin. T. Diroll, Shin Muramoto, Christopher B. Murray, and Cherie R. Kagan NANO Letters, 14 (3) 1559-1566 (2014)
“Air-Stable, Nanostructured Electronic and Plasmonic Materials from Solution-Processable, Silver Nanocrystal Building Blocks,” Aaron T. Fafarman, Sung-Hoon Hong, Soong Ju Oh, Humeyra Caglayan, Xingchen Ye, Benjamin T. Diroll, Nader Engheta, Christopher B. Murray, and Cherie R. Kagan ACS NANO, 8 (3) 2746-2754 (2014)
“Solution-Processed Phase-Change VO2 Metamaterials from Colloidal Vanadium Oxide (VOx) Nanocrystals,” Taejong Paik, Sung-Hoon Hong, E. Ashley Gaulding, Humeyra Caglayan, Thomas R. Gordon, Nader Engheta, Cherie R. Kagan, and Christopher B. Murray ACS NANO, 8 (1) 797-806 (2014)
2013
“Solution-Based Stoichiometric Control over Charge Transport in Nanocrystalline CdSe Devices,” David K. Kim, Aaron T. Fafarman, Benjamin T. Diroll, Silvia H Chan, Thomas R. Gordon, Christopher B. Murray, and Cherie R. Kagan ACS NANO, 7 (10) 8760-8770 (2013)
“Crystallographic anisotropy of the resistivity size effect in single crystal tungsten nanowires,” Dooho Choi, Matthew Moneck, Xuan Liu, Soong Ju Oh, Cherie R. Kagan, Kevin R. Coffey, & Katayun Barmak Scientific Reports, 3 (2591) 1-4 (2013)
“In-situ Repair of High-Performance, Flexible Nanocrystal Electronics for Large-Area Fabrication and Operation in Air,” Ji-Hyuk Choi, Soong Ju Oh, Yuming Lai, David K. Kim, Tianshuo Zhao, Aaron T. Fafarman, Benjamin T. Diroll, Christopher B. Murray, and Cherie R. Kagan ACS Nano, 7 (9) 8275-8283 (2013)
“Near-Infrared Metatronic Nanocircuits by Design,” Humeyra Caglayan*, Sung-Hoon Hong*, Brian Edwards, Cherie R. Kagan, and Nader Engheta Physical Review Letters, 111 073904 (2013)
* Indicates equal contribution
“Plasmonic Enhancement of Nanophosphor Upconversion Luminescence in Au Nanohole Arrays,” Marjan Saboktakin, Xingchen Ye, Uday K. Chettiar, Nader Engheta , Christopher B. Murray, and Cherie R. Kagan ACS Nano, 7 (8) 7186-7192 (2013)
“Competition of shape and interaction patchiness for self-assembling nanoplates,” Xingchen Ye, Jun Chen, Michael Engel, Jaime A. Millan, Wenbin Li, Liang Qi, Guozhong Xing, Joshua E. Collins, Cherie R. Kagan, Ju Li, Sharon C. Glotzer & Christopher B. Murray Nature Chemistry, 5 466-473 (2013)
“Stoichiometric Control of Lead Chalcogenide Nanocrystal Solids to Enhance Their Electronic and Optoelectronic Device Performance,” Soong Ju Oh, Nathaniel E. Berry, Ji-Hyuk Choi, E. Ashley Gaulding, Taejong Paik, Sung-Hoon Hong, Christopher B. Murray, and Cherie R. Kagan ACS Nano, 7 (3) 2413-2421 (2013)
“Engineering Catalytic Contacts and Thermal Stability: Gold/Iron Oxide Binary Nanocrystal Superlattices for CO Oxidation,” Yijin Kang, Xingchen Ye, Jun Chen, Liang Qi, Rosa E. Diaz, Vicky Doan-Nguyen, Guozhong Xing, Cherie R. Kagan, Ju Li, Raymond J. Gorte, Eric A. Stach, and Christopher B. Murray JACS, 135 4 1499-1505 (2013)
“Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing,” Jun Chen, Xingchen Ye, Soong Ju Oh, James M. Kikkawa, Cherie R. Kagan, and Christopher B. Murray ACS Nano, 7(2) 1478-1486 (2013)
“Chemically Tailored Dielectric-to-Metal Transition for the Design of Metamaterials from Nanoimprinted Colloidal Nanocrystals,” Aaron T. Fafarman*, Sung-Hoon Hong*, Humeyra Caglayan, Xingchen Ye, Benjamin T. Diroll, Taejong Paik, Nader Engheta, Christopher B. Murray & Cherie R. Kagan Nano Letters, 13 (2) 350-357 (2013)
*=Equal Contributors
2012
“Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors,” David K. Kim*, Yuming Lai*, Benjamin T. Diroll, Christopher B. Murray & Cherie R. Kagan Nature Communications, 3 (1216) 1-6 (2012)
*=Equal Contributors
“The State of Nanoparticle-Based Nanoscience and Biotechnology: Progress, Promises, and Challenges,” Beatriz Pelaz, Sarah Jaber, Dorleta Jimenez de Aberasturi, Verena Wulf, Takuzo Aida, Jesus M. de la Fuente, Jochen Feldmann, Hermann E. Gaub, Lee Josephson, Cherie R. Kagan, Nicholas A. Kotov, Luis M. Liz-Marzan, Hedi Mattoussi, Paul Mulvaney, Christopher B. Murray, Andrey L. Rogach, Paul S. Weiss, Itamar Willner, and Wolfgang J. Parak, ACS Nano, 6 (10) 8468-8483 (2012)
“Metal Enhanced Upconversion Luminescence Tunable through Metal Nanoparticle-Nanophosphor Separation,” Marjan Saboktakin, Xingchen Ye, Soong Ju Oh, Sung-Hoon Hong, Aaron T. Fafarman, Uday K. Chettiar, Nader Engheta, Christopher B. Murray, and Cherie R. Kagan, ACS Nano, 6 (10) 8758-8766 (2012)
“Bandlike Transport in Strongly Coupled and Doped Quantum Dot Solids: A Route to High-Performance Thin-Film Electronics,” Ji-Hyuk Choi, Aaron T. Fafarman, Soong Ju Oh, Dong-Kyun Ko, David K. Kim, Benjamin T. Diroll, Shin Muramoto, J. Greg Gillen, Christopher B. Murray, and Cherie R. Kagan, Nano Letters, 12 (5) 2631-2638 (2012)
“Remote Doping and Schottky Barrier Formation in Strongly Quantum Confined Single PbSe Nanowire Field-Effect Transistors,” Soong Ju Oh, David K. Kim, and Cherie. R. Kagan, ACS Nano, 6 (5) 4328-4334 (2012)
“Wrinkles and deep folds as photonic structures in photovoltaics,” Jong Bok Kim, Pilnam Kim, Nicolas C. Pgard, Soong Ju Oh, Cherie R. Kagan, Jason W. Fleischer, Howard A. Stone and Yueh-Lin Loo, Nature Photonics, 6 327-332 (2012)
“An Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives,” Xingchen Ye, Linghua Jin, Humeyra Caglayan, Jun Chen, Guozhong Xing, Chen Zheng, Vicky Doan-Nguyen, Yijin Kang, Nader Engheta, Cherie R. Kagan, and Christopher B. Murray, ACS Nano, 6 2804-2817 (2012)
“Molecular Monolayers as Semiconducting Channels in Field Effect Transistors,” Cherie R. Kagan, Topics in Current Chemistry, 312 213-237, (2012)
2011
“Flexible, Low-Voltage, and Low-Hysteresis PbSe Nanowire Field-Effect Transistors,” David K. Kim, Yuming Lai, Tarun R. Vemulkar, and Cherie R. Kagan, ACS Nano, 5 (12) 10074-10083, (2011)
“Thiocyanate-capped PbS nanocubes: ambipolar transport enables quantum dot-based circuits on a flexible substrate,” Weon-kyu Koh , Sangameshwar R Saudari , Aaron T. Fafarman , Cherie R. Kagan , and Christopher B. Murray, Nano Letters, 11 (11) 4764-4767, (2011)
“Near-Infrared Absorption of Monodisperse Silver Telluride (Ag2Te) Nanocrystals and Photoconductive Response of Their Self-Assembled Superlattices,” Yu-Wen Liu, Dong-Kyun Ko, Soong Ju Oh, Thomas R. Gordon, Vicky Doan-Nguyen, Taejong Paik, Yijin Kang, Xingchen Ye, Linghua Jin, Cherie R. Kagan, and Christopher B. Murray, ACS Chemistry of Materials, 23 (21) 4657-4659, (2011)
“Diketopyrrolopyrrole-based p-bridged Donor-Acceptor Polymer for Photovoltaic Applications,” Wenting Li, Taegweon Lee, Soong Ju Oh, and Cherie R. Kagan, ACS Applied Materials and Interfaces, 3 (10) 3874-3883 (2011)
“Flexible Organic Electronics for Use in Neural Sensing,” Hank Bink*, Yuming Lai*, Sangamweshwar Rao Saudari, Brian Helfer, Jonathan Viventi, Jan Van der Spiegel, Brian Litt, Cherie Kagan, IEEE EMBC 2011 5400-5403 (2011)
* = Equal Contributors
“Thiocyanate Capped Nanocrystal Colloids: A Vibrational Reporter of Surface Chemistry and a Solution-based Route to Enhanced Coupling in Nanocrystal Solids,” Aaron T. Fafarman, Weon-kyu Koh, Benjamin T. Diroll, David K. Kim, Dong-Kyun Ko, Soong Ju Oh, Xingchen Ye, Vicky Doan-Nguyen, Michael R. Crump, Danielle C. Reifsnyder, Christopher B. Murray, and Cherie R. Kagan, Journal of the American Chemical Society, 133 (39), 15753-15761, (2011)
“Ambipolar and Unipolar PbSe Nanowire Field-Effect Transistors,” David K. Kim, Tarun R. Vemulkar, Soong-Ju Oh, Weon-kyu Koh, Christopher B. Murray and Cherie R. Kagan, ACS Nano, 5 (4), 3230-3236, (2011)
“Multiscale Periodic Assembly of Striped Nanocrystal Superlattice Films on a Liquid Surface,” Angang Dong, Jun Chen, Soong Ju Oh, Weon-kyu Koh, Faxian Xiu, Xingchen Ye, Dong-Kyun Ko, Kang L. Wang, Cherie R. Kagan, and Christopher B. Murray, Nano Letters, 11 (2), 841-846, (2011)
2010
“Comparison of the Energy-level Alignment of Thiolate- and Carbodithiolate-Bound Self-Assembled Monolayers on Gold,” Philip Schulz, Christopher D. Zangmeister, Yi-Lei Zhao, Paul R. Frail, Sangameshwar R. Saudari, Carlos A. Gonzalez, Cherie R. Kagan, Matthias Wuttig, and Roger D. van Zee, Journal of Physical Chemistry C, 114 (48), 20843-20851, (2010)
“Device Configurations for Ambipolar Transport in Flexible, Pentacene Transistors,” Sangameshwar Rao Saudari, Yu Jen Lin, Yuming Lai and Cherie R. Kagan, Advanced Materials, 44, 5063-5068, (2010)
“Small-Molecule Thiophene-C60 Dyads As Compatibilizers in Inverted Polymer Solar Cells,” Jong Bok Kim, Kathryn Allen, Soong Ju Oh, Stephanie Lee, Michael F. Toney, Youn Sang Kim, Cherie R. Kagan, Colin Nuckolls, and Yueh-Lin Loo, Chemistry of Materials, 22 (20), pp 5762-5773 (2010)
2009
“Ambipolar transport in solution-deposited pentacene transistors enhanced by molecular engineering of device contacts,” Sangameshwar Rao Saudari, Paul R. Frail, Cherie R. Kagan , Appl. Phys. Lett, 95, 023301 (2009)
2007
“Chemically Assisted Directed Assembly of Carbon Nanotubes for the Fabrication of Large-Scale Device Arrays,” G. S. Tulevski, J. Hannon, A. Afzali, Z. Chen, Ph. Avouris, C. R. Kagan, J. American Chemical Society, 129 (39), 11964 (2007)
“Alignment, Electronic Properties, Doping, and On-Chip Growth of Colloidal PbSe Nanowires,” D. V. Talapin, C. T. Black, C. R. Kagan, E. V. Shevchenko, A. Afzali, C. B. Murray, J. Phys. Chem. C, 111 (35), 13244 (2007)
“Synergistic Effects in Binary Nanocrystal Superlattices: Enhanced p-Type Conductivity in Self-Assembled PbTe/Ag2Te Thin Films,” J. J. Urban, D. V. Talapin, E. V. Shevchenko, C. R. Kagan, C. B. Murray, Nature Materials, 6 (2), 115 (2007).
“Molecular Assemblies: Briding the Gap to Form Molecular Junctions,” C. R. Kagan, C. Lin, in Multifunctional Conducting Molecular Materials, eds. G. Saito, F. Wudl, R. C. Haddon, K. Tanigaki, T. Enoki, H. E. Katz, M. Maesato, Royal Society of Chemistry, London 306, 248, (2007).
2006
“The Role of Chemical Contacts in Molecular Conductance,” N. D. Lang, C. R. Kagan, Nano Letters, 6, 2955 (2006).
“Enforced One-Dimensional Photoconductivity in Core-Cladding Hexabenzocorenenes,” Y. S. Cohen, S. Xiao, C. Nuckolls, C. R. Kagan, Nano Letters, 6, 2838 (2006).
“Organic and Organic-Inorganic Hybrid Molecular Devices,” Proceedings of the 12th International Micromachine/Nanotech Symposium, 31 (2006).
“Device Scaling in Sub-100 nm Pentacene FETs,” G. S. Tulevski, A. Afzali, T. O Graham, C. Nuckolls, C. R. Kagan, Applied Physics Letters, 89, 183101 (2006).
“Chemical Complementarity in the Contacts for Nanoscale Organic Field-Effect Transistors,” G. S. Tulevski, Q. Miao, A. Afzali, T. O. Graham, C. R. Kagan, C. Nuckolls, Journal of the American Chemical Society, 128, 1788 (2006).
2005
“Self-assembly and Oligomerization of Alkyne-Terminated Molecules on Metal and Oxide Surfaces,” L. Vyklicky, A. Afzali, C. R. Kagan, Langmuir, 21, 11574 (2005).
“Operational and Environmental Stability of Pentacene Thin Film Transistors,” C. R. Kagan, A. Afzali, T. O. Graham, Applied Physics Letters, 86, 193505 (2005).
“N-Sulfinylcarbamate-Pentacene Adduct; a Novel Pentacene Precursor Soluble in Alcohols,” A. Afzali, C. R. Kagan, G. Traub, Synthetic Metals, 155, 490 (2005).
“Electrostatic Field and Partial Fermi Level Pinning at the Pentacene-SiO2 Interface,” L. Chen, R. Ludeke, X. Cui, A. G. Schrott, C. R. Kagan, L. E. Brus, Journal of Physical Chemistry B, 109, 1834 (2005).
2004
“Molecular Transport Junctions: An Introduction,” C. R. Kagan, M. A. Ratner, MRS Bulletin, edited by C. R. Kagan, M. A. Ratner, 29, 376 (2004).
“Direct Assembly of Organic Semiconductors on Gate Oxides,” G. S. Tulevski, Q. Miao, M. Fukuto, R. Abram, B. Ocko, R. Pindak, C. R. Kagan, C. Nuckolls, Journal of the American Chemical Society, 126, 15048 (2004).
“Understanding the Molecular Transistor,” P. Solomon, C. R. Kagan in Future Trends in Microelectronics: The Nano, the Giga, and the Ultra, edited by S. Luryi, J. Xu, A. Zaslavsky, Wiley, NY (2004), p.168.
2003
“Evaluations and Considerations for Self-Assembled Monolayer Field-Effect Transistors,” C. R. Kagan, A. Afzali, R. Martel, L. M. Gignac, P. M. Solomon, A. Schrott, B. Ek, Nano Letters, 3, 119 (2003).
“Layer-by-Layer Growth of Metal-Metal Bonded Supramolecular Thin Films and Its Use in the Fabrication of Lateral Nanoscale Devices,” C. Lin and C. R. Kagan, Journal of the American Chemical Society, 125, 336 (2003).
“Organic-Inorganic Thin Film Transistors,” D. B. Mitzi, C. R. Kagan in Thin Film Transistors, edited by C. R. Kagan, P. S. Andry, Marcell-Dekker, NY, (2003), p. 475.
“Charge Transport on the Nanoscale,” D. Adams, L. Brus, C. E. D. Chidsey, S. Creager, C. Creutz, C. R. Kagan, P. Kamat, M. Lieberman, S. Lindsay, R. A. Marcus, R. M. Metzger, M. E. Michel-Beyerle, J. R. Miller, M. D. Newton, D. R. Rolison, O. Sankey, K. S. Schanze, J. Yardley, X. Zhu, Journal of Physical Chemistry B, 107, 6668 (2003).
2002
“An efficient synthesis of symmetrical oligothiophenes: Synthesis and transport properties of a soluble sexithiophene derivative,” A. Afzali, T. L. Breen, C. R. Kagan, Chemistry of Materials, 14(4), 1742 (2002) .
2001
“Patterning Organic-Inorganic Thin-Film Transistors Using Microcontact Printed Templates,” C. R. Kagan, T. L Breen, L. L. Kosbar, Applied Physics Letters 79 (21), 3536 (2001).
“Organic-Inorganic Electronics,” D. B. Mitzi, K. Chondroudis, C. R. Kagan, IBM Journal of Research and Development, 45, 29 (2001).
“Colloidal Synthesis of Nanocrystals and Nanocrystal Superlattices,” C. B. Murray, S. Sun, W. Gaschler, H. Doyle, T. Betley, C. R. Kagan, IBM Journal of Research and Development, 45, 47 (2001).
2000
“Synthesis and Characterization of Monodisperse Nanocrystals and Close Packed Nanocrystal Assemblies,” C. B. Murray, C. R. Kagan, M. G. Bawendi, Annual Review of Materials Science 30, 545, (2000).
“Photoconductivity in CdSe Quantum Dot Solids,” C. A. Leatherdale, C. R. Kagan, N. Y. Morgan, S. A. Empedocles, M. A. Kastner, and M. G. Bawendi, Physical Review B, 62, 2669 (2000).
1999
“Organic-Inorganic Hybrid Materials as Semiconducting Channels in Thin-Film Field-Effect Transistors,” C. R. Kagan, D. B. Mitzi, C. D. Dimitrakopoulos, Science, 286, 945 (1999).
“Design, Structure, and Optical Properties of Organic-Inorganic Perovskites Containing an Oligothiophene Chromophore,” David B. Mitzi, Konstantinos Chondroudis, Cherie R. Kagan, Inorganic Chemistry 38, 6246 (1999).
“Charge Generation and Transport in CdSe Semiconductor Quantum Dot Solids,” C. A. Leatherdale, N. Y. Morgan, C. R. Kagan, S. A. Empedocles, M. G. Bawendi, M. A. Kastner, MRS Proceedings 571, 191 (1999).
1998
“Submicron Confocal Raman Imaging of Holograms in Multicomponent Photopolymers,” C. R. Kagan, T. D. Harris, A. L. Harris, and M. L. Schilling, Journal of Chemical Physics, 108, 6892 (1998).
1996
“Long Range Resonance Transfer of Electronic Excitations in Close Packed CdSe Quantum Dot Solids,” C. R. Kagan, C. B. Murray, and M. G. Bawendi, Physical Review B, 54, 8633 (1996).
“Electronic Energy Transfer in CdSe Quantum Dot Solids,” C. R. Kagan, C. B. Murray, M. Nirmal, M. G. Bawendi, Physical Review Letters, 76, 1517 (1996).
1995
“Self Organization of CdSe Nanocrystallites into Three Dimensional Quantum Dot Superlattices,” C. B. Murray, C. R. Kagan, and M. G. Bawendi, Science, 270, 1335 (1995).
“Synthesis, Structural Characterization, and Optical Spectroscopy of Close Packed CdSe Nanocrystallites,” C. R. Kagan, C. B. Murray, M. G. Bawendi, MRS Proceedings, 358, 219 (1995).
1993
“Solution Precipitation of CdSe Quantum Dots,” C. R. Kagan, M. J. Cima, MRS Proceedings, 283, 841 (1993).
1992
“Ion-Exchange Reactions of Potassium Brannerite, K0.8(V0.8Mo1.2)O6,” Peter K. Davies and Cherie R. Kagan, Solid State Ionics, 53-56, 546-552 (1992).
Books and Journals Edited
“Molecular Transport Junctions,” edited by C. R. Kagan, M. A. Ratner, MRS Bulletin, Materials Research Society, PA, (2004).
“Thin Film Transistors,” edited by C. R. Kagan, P. S. Andry, Marcell-Dekker, NY, (2003).