@article{nokey,

title = {One-pot heat-up synthesis of short-wavelength infrared, colloidal InAs quantum dots},

author = {J Lee and T Zhao and S Yang and M Muduli and CB Murray and CR Kagan},

url = {https://pubs.aip.org/aip/jcp/article/160/7/071103/3266823},

doi = {10.1063/5.0187162},

year  = {2024},

date = {2024-02-21},

urldate = {2024-02-21},

journal = {The Journal of Chemical Physics},

volume = {160},

pages = {071103},

abstract = {III–V colloidal quantum dots (QDs) promise Pb and Hg-free QD compositions with which to build short-wavelength infrared (SWIR) optoelectronic devices. However, their synthesis is limited by the availability of group-V precursors with controllable reactivities to prepare monodisperse, SWIR-absorbing III–V QDs. Here, we report a one-pot heat-up method to synthesize ∼8 nm edge length (∼6.5 nm in height) tetrahedral, SWIR-absorbing InAs QDs by increasing the [In3+]:[As3+] ratio introduced using commercially available InCl3 and AsCl3 precursors and by decreasing the concentration and optimizing the volume of the reducing reagent superhydride to control the concentration of In(0) and As(0) intermediates through QD nucleation and growth. InAs QDs are treated with NOBF4, and their deposited films are exchanged with Na2S to yield n-type InAs QD films. We realize the only colloidal InAs QD photoconductors with responsivity at the technologically important wavelength of 1.55 μm.},

keywords = {colloids, nanocrystal, nanocrystal electronics, optical properties, quantum dots, semiconductors, spectroscopy, surface modification, synthesis, TEM, thin films, transport},

pubstate = {published},

tppubtype = {article}

}

@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{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}

}

@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}

}

@article{Zhao2019,

title = {General Synthetic Route to High-Quality Colloidal III–V Semiconductor Quantum Dots Based on Pnictogen Chlorides},

author = {Tianshuo Zhao and Nuri Oh and Davit Jishkariani and Mingliang Zhang and Han Wang and Na Li and Jennifer D. Lee and Chenjie Zeng and Manisha Muduli and Hak-Jong Choi and Dong Su and Christopher B. Murray and Cherie R. Kagan},

url = {https://pubs.acs.org/doi/abs/10.1021/jacs.9b06652},

doi = {10.1021/jacs.9b06652},

year  = {2019},

date = {2019-09-07},

journal = {Journal of the American Chemical Society},

volume = {141},

number = {38},

pages = {15145-15152},

abstract = {The synthesis of colloidal III–V quantum dots (QDs), particularly of the arsenides and antimonides, has been limited by the lack of stable and available group V precursors. In this work, we exploit accessible InCl3- and pnictogen chloride-oleylamine as precursors to synthesize III–V QDs. Through coreduction reactions of the precursors, we achieve size- and stoichiometry-tunable binary InAs and InSb as well as ternary alloy InAs1–xSbx QDs. On the basis of structural, analytical, optical, and electrical characterization of the QDs and their thin-film assemblies, we study the effects of alloying on their particle formation and optoelectronic properties. We introduce a hydrazine-free hybrid ligand-exchange process to improve carrier transport in III–V QD thin films and realize InAs QD field-effect transistors with electron mobility > 5 cm2/(V s). We demonstrate that III–V QD thin films are promising candidate materials for infrared devices and show InAs1–xSbx QD photoconductors with superior short-wavelength infrared (SWIR) photoresponse than those of the binary QD devices.},

keywords = {quantum dots, synthesis},

pubstate = {published},

tppubtype = {article}

}

@article{Wang2019,

title = {Air-Stable CuInSe2 Nanocrystal Transistors and Circuits via Post-Deposition Cation Exchange},

author = {Han Wang and Derrick J. Butler and Daniel B. Straus and Nuri Oh and Fengkai Wu and Jiacen Guo and Kun Xue and Jennifer D. Lee and Christopher B. Murray and Cherie R. Kagan},

url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.8b09055},

doi = {10.1021/acsnano.8b09055},

year  = {2019},

date = {2019-02-01},

journal = {ACS Nano},

volume = {13},

number = {2},

pages = {2324–2333},

abstract = {Colloidal semiconductor nanocrystals (NCs) are a promising materials class for solution-processable, next-generation electronic devices. However, most high-performance devices and circuits have been achieved using NCs containing toxic elements, which may limit their further device development. We fabricate high mobility CuInSe2 NC field-effect transistors (FETs) using a solution-based, post-deposition, sequential cation exchange process that starts with electronically coupled, thiocyanate (SCN)-capped CdSe NC thin films. First Cu+ is substituted for Cd2+ transforming CdSe NCs to Cu-rich Cu2Se NC films. Next, Cu2Se NC films are dipped into a Na2Se solution to Se-enrich the NCs, thus compensating the Cu-rich surface, promoting fusion of the Cu2Se NCs, and providing sites for subsequent In-dopants. The liquid-coordination-complex trioctylphosphine–indium chloride (TOP–InCl3) is used as a source of In3+ to partially exchange and n-dope CuInSe2 NC films. We demonstrate Al2O3-encapsulated, air-stable CuInSe2 NC FETs with linear (saturation) electron mobilities of 8.2 ± 1.8 cm2/(V s) (10.5 ± 2.4 cm2/(V s)) and with current modulation of 105, comparable to that for high-performance Cd-, Pb-, and As-based NC FETs. The CuInSe2 NC FETs are used as building blocks of integrated inverters to demonstrate their promise for low-cost, low-toxicity NC circuits.},

keywords = {nanocrystal electronics, synthesis},

pubstate = {published},

tppubtype = {article}

}

@article{Najmr2018,

title = {Preparation of silica coated and 90Y-radiolabeled β-NaYF4 upconverting nanophosphors for multimodal tracing},

author = {Stan Najmr and Tianfeng Lu and Austin W Keller and Mingyue Zhang and Jennifer D Lee and Mehran Makvandi and Daniel A Pryma and Cherie R Kagan and Christopher B Murray},

url = {https://iopscience.iop.org/article/10.1088/2399-1984/aab947/meta},

year  = {2018},

date = {2018-04-18},

journal = {Nano Futures},

volume = {2},

number = {2},

pages = {025002},

abstract = {Rare-earth (RE) compounds have been actively pursued for therapeutic and diagnostic applications due to their ability to upconvert near infrared light into the UV–vis range. Through nanoengineering and bottom-up synthesis, additional functionality can be added to these upconverting systems. Herein, we report the synthesis of 90Y-doped β-NaYF4:Er, Yb upconverting nanophosphors (UCNPs) to enable β-particle emission and upconversion by the same UCNP. To homogenously incorporate the radionuclides, we employ a hydroxide metathesis method to produce the RE precursor required for the solvothermal synthesis of monodisperse UCNPs. Once incorporated, we find that the β-emitting 90Y dopants do not influence the energy pathways required for upconversion, enabling simultaneous radio- and optical-tracing. The resulting large (>100 nm in height and width), anisotropic, 90Y-radiolabeled β-NaYF4 UCNPs are then coated with silica using a modified, micelle-driven Stöber process to enable their dispersion in polar solvents. Doing so highlights the importance of surfactant (Igepal CO-520) and silica source (tetraethyl orthosilicate) interactions to the continuity of the silica shell and makes the vast library of silica surface chemistry and functionality accessible to upconverting radiotracers.},

keywords = {multifunctional nanomaterials, synthesis, upconverting nanophosphors},

pubstate = {published},

tppubtype = {article}

}

@article{Zhang2018b,

title = {3D Nanofabrication via Chemo‐Mechanical Transformation of Nanocrystal/Bulk Heterostructures},

author = {Mingliang Zhang and Jiacen Guo and Yao Yu and Yaoting Wu and Hongseok Yun and Davit Jishkariani and Wenxiang Chen and Nicholas J. Greybush and Christian Kübel and Aaron Stein and Christopher B. Murray and Cherie R. Kagan},

url = {https://onlinelibrary.wiley.com/doi/10.1002/adma.201800233},

doi = {10.1002/adma.201800233},

year  = {2018},

date = {2018-04-15},

journal = {Advanced Materials},

volume = {30},

number = {22},

pages = {1800233},

abstract = {Planar nanocrystal/bulk heterostructures are transformed into 3D architectures by taking advantage of the different chemical and mechanical properties of nanocrystal and bulk thin films. Nanocrystal/bulk heterostructures are fabricated via bottom‐up assembly and top‐down fabrication. The nanocrystals are capped by long ligands introduced in their synthesis, and therefore their surfaces are chemically addressable, and their assemblies are mechanically “soft,” in contrast to the bulk films. Chemical modification of the nanocrystal surface, exchanging the long ligands for more compact chemistries, triggers large volume shrinkage of the nanocrystal layer and drives bending of the nanocrystal/bulk heterostructures. Exploiting the differential chemo‐mechanical properties of nanocrystal and bulk materials, the scalable fabrication of designed 3D, cell‐sized nanocrystal/bulk superstructures is demonstrated, which possess unique functions derived from nanocrystal building blocks.},

keywords = {chiral, multifunctional nanomaterials, optical metamaterials, synthesis},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@article{Oh2016,

title = {Engineering the surface chemistry of lead chalcogenide nanocrystal solids to enhance carrier mobility and lifetime in optoelectronic devices},

author = {S. J. Oh and D. B. Straus and T. Zhao and J.-H. Choi and S.-W. Lee and A. Gaulding and C. B. Murray and C. R. Kagan},

url = {https://pubs.rsc.org/en/content/articlelanding/2016/cc/c6cc07916d#!divAbstract},

year  = {2016},

date = {2016-12-12},

journal = {Chemical Communications},

volume = {53},

number = {4},

pages = {728-731},

abstract = {We introduce a stepwise, hybrid ligand-exchange method for lead chalcogenide nanocrystal (NC) thin films using the compact-inorganic ligand thiocyanate and the short organic ligand benzenediothiolate. Spectroscopic and device measurements show that hybrid exchange enhances both carrier mobility and lifetime in NC thin films. The increased mobility-lifetime product achieved by this method enables demonstration of optoelectronic devices with enhanced power conversion and quantum efficiency.},

keywords = {nanocrystal electronics, synthesis, transport},

pubstate = {published},

tppubtype = {article}

}

@article{Yun2016,

title = {Alternate current magnetic property characterization of nonstoichiometric zinc ferrite nanocrystals for inductor fabrication via a solution based process},

author = {Hongseok Yun and Jungkwun Kim and Taejong Paik and Lingyao Meng and Pil Sung Jo and James M. Kikkawa and Cherie R. Kagan and Mark G. Allen and Christopher B. Murray},

url = {https://aip.scitation.org/doi/full/10.1063/1.4942865},

doi = {10.1063/1.4942865},

year  = {2016},

date = {2016-03-17},

journal = {Journal of Applied Physics},

volume = {119},

pages = {113901 },

abstract = {We investigate the ac magnetic behavior of solution processable, non-stoichiometric zinc ferrite nanocrystals with a series of sizes and zinc concentrations. Nearly monodisperse ZnxFe3−xO4 nanocrystals (x = 0–0.25) with an average size ranging from 7.4 nm to 13.8 nm are synthesized by using a solvothermal method. All the nanocrystals are in a superparamagnetic state at 300 K, which is confirmed by Superconductive Quantum Interference Device magnetometry. Due to the doping of non-magnetic Zn2+ into A site of ferrite, the saturation magnetization of nanocrystals increases as the size and Zn concentration increases. The ac magnetic permeability measurements at radio frequencies reveal that the real part of the magnetic permeability of similarly sized ferrite nanocrystals can be enhanced by almost twofold as the Zn2+ doping level increases from 0 to 0.25. The integration of 12.3 nm Zn0.25Fe2.75O4 nanocrystals into a toroidal inductor and a solenoid inductor prepared via a simple solution cast process yields a higher quality factors than air core inductors with the same geometries up to 5 MHz and 9 MHz, respectively, which is in the regime of the switching frequencies for the advanced integrated power converters.},

keywords = {magnetic nanocrystals, synthesis},

pubstate = {published},

tppubtype = {article}

}