Control over faceting in nanocrystals (NCs) is pivotal for many applications, but most notably when investigating catalytic reactions which occur on the surfaces of nanostructures. Anatase titanium dioxide (TiO(2)) one studied photocatalysts, shape dependence its activity has not yet been satisfactorily investigated and questions still remain unanswered. We report nonaqueous surfactant-assisted synthesis highly uniform anatase TiO(2) NCs with tailorable morphology 10-100 nm size regime,...

Synthetic methods produce libraries of colloidal nanocrystals with tunable physical properties by tailoring the nanocrystal size, shape, and composition. Here, we exploit diversity design materials, interfaces, processes to construct all-nanocrystal electronic devices using solution-based processes. Metallic silver semiconducting cadmium selenide are deposited form high-conductivity high-mobility thin-film electrodes channel layers field-effect transistors. Insulating aluminum oxide...

We investigate the effects of stoichiometric imbalance on electronic properties lead chalcogenide nanocrystal films by introducing excess (Pb) or selenium (Se) through thermal evaporation. Hall-effect and capacitance-voltage measurements show that carrier type, concentration, Fermi level in solids may be precisely controlled their stoichiometry. By manipulating only stoichiometry solids, we engineer characteristics optoelectronic devices. Lead field-effect transistors (FETs) are fabricated...

The influence of particle shape on plasmonic response and local electric field strength is well-documented in metallic nanoparticles. Morphologies such as rods, plates, octahedra are readily synthesized exhibit drastically different extinction spectra than spherical particles. Despite this fact, the composition optical properties semiconductor nanocrystals, which free electrons result from heavy doping, has not been well-studied. Here, we report first observation resonance indium-doped...

We report direct photocatalytic hydrogen evolution from substoichiometric highly reduced tungsten oxide (WOx) nanowires (NWs) using sacrificial alcohol. WOx NWs are synthesized via nonaqueous colloidal synthesis with a diameter of about 4 nm and an average length 250 nm. As-synthesized exhibit broad absorption across the visible to infrared regions attributed presence oxygen vacancies. The optical band gap is increased in these compared stoichiometric bulk (WO3) powders as result...

We report a simple, solution-based, postsynthetic colloidal, atomic layer deposition (PS-cALD) process to engineer stepwise the surface stoichiometry and therefore electronic properties of lead chalcogenide nanocrystal (NC) thin films integrated in devices. found that unlike chalcogen-enriched NC surfaces are structurally, optically, electronically unstable, chloride treatment creates well-passivated shell stabilizes NCs. Using PS-cALD we demonstrate high electron field-effect mobilities...

We present a generalized cation–anion codoping methodology for the synthesis of monodisperse, doped metal-oxide nanocrystals (NCs) that exhibit near-infrared localized surface plasmon resonance (LSPR) with highest reported quality factors. demonstrate that, in addition to use common cation dopants, incorporation fluorine into lattice as an anion dopant can further increase free-carrier concentration within individual NCs; this supports cooperative effects mixed doping shifting LSPR higher...

We demonstrate thermally switchable VO2 metamaterials fabricated using solution-processable colloidal nanocrystals (NCs). Vanadium oxide (VOx) NCs are synthesized through a nonhydrolytic reaction and deposited from stable dispersions to form NC thin films. Rapid thermal annealing transforms the VOx films into monoclinic, nanocrystalline that show sharp, reversible metal-insulator phase transition. Introduction of precise concentrations tungsten dopings enables still sharp transition be tuned...

Self-assembly of multicomponent anisotropic nanocrystals with controlled orientation and spatial distribution allows the design novel metamaterials unique shape- orientation-dependent collective properties. Although many phases binary structures are theoretically proposed, examples assemblies, which experimentally realized colloidal nanocrystals, still limited. In this report, we demonstrate formation ternary superlattices from two-dimensional LaF3 nanodisks one-dimensional CdSe/CdS nanorods...

Here, we report the shape-controlled synthesis of tripodal and triangular gadolinium oxide (Gd2O3) nanoplates. In presence lithium ions, shape nanocrystals is readily controlled by tailoring reaction parameters such as temperature time. We observe that morphology transforms from an initial to a with increasing time or elevated temperatures. Highly uniform Gd2O3 nanoplates are self-assembled into nanofibril-like liquid-crystalline superlattices long-range orientational positional order....

We study charge injection and transport in PbSe nanocrystal thin films. By engineering the contact metallurgy ligand exchange chemistry surface passivation, we demonstrate partial Fermi-level pinning at metal–nanocrystal interface an insulator-to-metal transition with increased coupling doping, allowing us to design high conductivity mobility construct complementary circuits from n-type p-type transistors realized a single material by selecting metallurgy.

Enhancement of the charge transfer rate in CdSe quantum dot (QD) sensitized solar cells is one most important criteria determining cell efficiency. We report a novel strategy for enhancing by exchanging native, long organic chain to an atomic ligand, S(2-), with simple solid exchange process. S(2-)-ligand easily executed dipping QDs photoanode into formamide solution K2S. The results show that this process leads enhancement electronic coupling between QD and TiO2 removing insulating barrier...

We demonstrate optical metamaterial design using colloidal gold nanocrystal building blocks. In the solid state, chemically exchanging nanocrystals' surface-capping molecules provides a tailorable dielectric-to-metal transition exhibiting 10(10) range in DC conductivity and dielectric permittivity ranging from everywhere positive to negative throughout visible-to-near-IR. Direct, wide-area nanoimprinting of subwavelength superstructures at room temperature, on plastic glass substrates,...

Directed self-assembly of colloidal nanocrystals into ordered superlattices enables the preparation novel metamaterials with diverse functionalities. Structural control and precise characterization these allow interactions between individual nanocrystal building blocks origin their collective properties to be understood. Here, we report directed liquid interfacial assembly gadolinium trifluoride (GdF(3)) nanoplates crystalline assemblies displaying long-range orientational positional order....

We present the binary self-assembly of two anisotropic nanoplate building blocks mediated by shape complementarity. use rhombic GdF3 and tripodal Gd2O3 nanoplates as in which size are designed to be optimal for complementary organization. A liquid interfacial assembly technique allows formation self-assembled superlattices from over a micrometer length scale. Shape-directed guides position each superlattices, allowing long-range orientational positional order block. The design offers...

We have developed a generalized seeded-growth methodology for the synthesis of monodisperse metal-doped plasmonic oxide heterodimer nanocrystals (NCs) with near-unity morphological yield. Using indium-doped cadmium (ICO) as an example, we show that wide variety preformed metal NCs (Au, Pt, Pd, FePt, etc.) can serve seeds tailored metal-ICO heterodimers exquisite size, shape, and composition control, facilitated by delayed nucleation mechanism CdO phase. The exhibit broadly tunable...

Light absorption and electron injection are important criteria determining solar energy conversion efficiency. In this research, monodisperse CdSe quantum dots (QDs) synthesized with five different diameters, the size-dependent efficiency of dot sensitized cell (QDSSCs) is investigated by employing atomic inorganic ligand, S(2-). Absorbance measurements transmission microscopy show that diameters uniform QDs 2.5, 3.2, 4.2, 6.4, 7.8 nm. Larger generate a larger amount charge under irradiation...

We present a general synthesis for family of n-type transparent conducting oxide nanocrystals through doping with aliovalent cations. These monodisperse exhibit localized surface plasmon resonances tunable in the mid- and near-infrared increasing dopant concentration. employ battery electrical measurements to demonstrate that plasmonic resonance isolated particles is consistent electronic properties nanocrystal thin films. Hall Seebeck show form degenerately doped solids free electron...

We investigate the size- and composition-dependent ac magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency (RF) applications. The are obtained through high-temperature decomposition synthesis, their stoichiometry is determined by Mössbauer spectroscopy. Two sets oxides studied: (a) as-synthesized magnetite-rich (b) aged maghemite nanocrystals. All nanocrystalline samples confirmed to be in state at room temperature SQUID magnetometry. Through one-turn...

Monodisperse 3.1 nm Ag2Te NCs show a sharp optical absorption feature at 1154 with large linear temperature dependence and the photoconductive response consistent semiconducting character in NCs. The wavelength of resonance is within window transparency for biological tissue making it potential vivo marker or transducer situ heating deep-penetrating near-infrared radiation.