@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@article{Paik2015,

title = {Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods},

author = {Taejong Paik and Benjamin T. Diroll and Cherie R. Kagan and Christopher B. Murray},

url = {https://pubs.acs.org/doi/abs/10.1021/jacs.5b03234},

doi = {10.1021/jacs.5b03234},

year  = {2015},

date = {2015-04-30},

journal = {Journal of the American Chemical Society},

volume = {137},

number = {20},

pages = {6662–6669},

abstract = {Self-assembly of multicomponent anisotropic nanocrystals with controlled orientation and spatial distribution allows the design of novel metamaterials with unique shape- and orientation-dependent collective properties. Although many phases of binary structures are theoretically proposed, the examples of multicomponent assemblies, which are experimentally realized with colloidal anisotropic nanocrystals, are still limited. In this report, we demonstrate the formation of binary and ternary superlattices from colloidal two-dimensional LaF3 nanodisks and one-dimensional CdSe/CdS nanorods via liquid interfacial assembly. The colloidal nanodisks and nanorods are coassembled into AB-, AB2-, and AB6-type binary arrays determined by their relative size ratio and concentration to maximize their packing density. The position and orientation of anisotropic nanocrystal building blocks are tightly controlled in the self-assembled binary and ternary lattices. The macroscopic orientation of the superlattices is further tuned by changing the liquid subphase used for self-assembly, resulting in the formation of lamellar-type binary liquid crystalline superlattices. In addition, we demonstrate a novel ternary superlattice self-assembled from two different sizes of nanodisks and a nanorod, which offers the unique opportunity to design multifunctional metamaterials.},

keywords = {colloids, liquid crystals, nanodisks, nanorods, self-assembly, superlattices},

pubstate = {published},

tppubtype = {article}

}

@article{Diroll2015,

title = {Smectic Nanorod Superlattices Assembled on Liquid Subphases: Structure, Orientation, Defects, and Optical Polarization},

author = {Benjamin T. Diroll and Nicholas J. Greybush and Cherie R. Kagan and Christopher B. Murray},

url = {https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.5b00355},

doi = {10.1021/acs.chemmater.5b00355},

year  = {2015},

date = {2015-03-10},

urldate = {2015-03-10},

journal = {Chemistry of Materials},

volume = {27},

issue = {8},

pages = {2998–3008},

abstract = {Directing the orientation of anisotropic nanocrystal assemblies is important for harnessing the shape-dependent properties of nanocrystal solids in devices. We control the orientation of smectic B superlattices of CdSe/CdS dot-in-rod nanocrystals through assembly on different polar interfaces and quantify the superlattice orientation through correlated small- and wide-angle grazing-incidence diffraction. Small-angle scattering is used to determine the phase of the nanorod superlattices and their preferential growth directions from the subphase. Wide-angle diffraction is used to quantify the orientations of nanorods within the superlattices and with respect to the substrate. Not only are the nanorod long axes aligned within the structures, but truncation of the short axes also coaligns the crystal axes of the nanorods with the zone axes in assembled smectic B crystals. Three dimensional orientational alignment of nanocrystals in superlattices is highly desirable in device applications. Depending on the subphase used for self-assembly, the films range from nearly quantitative vertical to horizontal alignment. Controlling for other variables, we find that the surface tension of the subphase is strongly correlated with the orientational ordering of the nanorod superlattices. The microstructure of nanorod superlattices shows many classic defects of atomic and liquid crystalline systems. The nature of defect structures supports a mechanism of nuclei formation on the subphase–solvent interface rather than in solution. Last, we demonstrate the relationship between optical absorption polarization and superlattice structure using correlated optical spectroscopy and electron microscopy.},

keywords = {defects, liquid crystals, nanorods, optical properties, self-assembly, superlattices},

pubstate = {published},

tppubtype = {article}

}

@article{Cativo2014,

title = {Air–Liquid Interfacial Self-Assembly of Conjugated Block Copolymers into Ordered Nanowire Arrays},

author = {Ma. Helen M. Cativo and David K. Kim and Robert A. Riggleman and Kevin G. Yager and Stephen S. Nonnenmann and Huikuan Chao and Dawn A. BonnellvCharles T. Black and Cherie R. Kagan and So-Jung Park},

url = {https://pubs.acs.org/doi/full/10.1021/nn505871b},

doi = {10.1021/nn505871b},

year  = {2014},

date = {2014-12-08},

urldate = {2014-12-08},

journal = {ACS Nano},

volume = {8},

number = {12},

pages = {12755–12762},

abstract = {The ability to control the molecular packing and nanoscale morphology of conjugated polymers is important for many of their applications. Here, we report the fabrication of well-ordered nanoarrays of conjugated polymers, based on the self-assembly of conjugated block copolymers at the air–liquid interface. We demonstrate that the self-assembly of poly(3-hexylthiophene)-block-poly(ethylene glycol) (P3HT-b-PEG) at the air–water interface leads to large-area free-standing films of well-aligned P3HT nanowires. Block copolymers with high P3HT contents (82–91%) formed well-ordered nanoarrays at the interface. The fluidic nature of the interface, block copolymer architecture, and rigid nature of P3HT were necessary for the formation of well-ordered nanostructures. The free-standing films formed at the interface can be readily transferred to arbitrary solid substrates. The P3HT-b-PEG films are integrated in field-effect transistors and show orders of magnitude higher charge carrier mobility than spin-cast films, demonstrating that the air–liquid interfacial self-assembly is an effective thin film fabrication tool for conjugated block copolymers.},

keywords = {copolymers, interfaces, organic compounds, self-assembly, self-organization, thin films},

pubstate = {published},

tppubtype = {article}

}