We report the growth and characterization of core/multishell nanowire radial heterostructures, their implementation as efficient synthetically tunable multicolor nanophotonic sources. Core/multishell nanowires were prepared by metal-organic chemical vapor deposition with an n-GaN core InxGa1-xN/GaN/p-AlGaN/p-GaN shells, where variation indium mole fraction is used to tune emission wavelength. Cross-sectional transmission electron microscopy studies reveal that are dislocation-free single...

We report a new and general strategy for efficient injection of carriers in active nanophotonic devices involving the synthesis well-defined doped core/shell/shell (CSS) nanowire heterostructures. n-GaN/InGaN/p-GaN CSS structures were grown by metal-organic chemical vapor deposition. Electron microscopy images reveal that nanowires are defect-free single crystalline structures, while energy-dispersive X-ray linescan profile studies confirm shell thickness composition can be well controlled...

We report optically pumped room-temperature lasing in GaN nanowires grown by metalorganic chemical vapor deposition (MOCVD). Electron microscopy images reveal that the grow along a nonpolar ⟨11-20⟩ direction, have single-crystal structures and triangular cross sections. The function as free-standing Fabry–Pérot cavities with cavity mode spacings depend inversely on length. Optical excitation studies demonstrate thresholds for stimulated emission of 22kW∕cm2 are substantially lower than other...

Quantum dots show great promise for fabrication of hybrid bulk heterojunction solar cells with enhanced power conversion efficiency, yet controlling the morphology and interface structure on nanometer length scale is challenging. Here, we demonstrate quantum dot-based improved electronic interaction between donor acceptor components, resulting in significant improvement short-circuit current open-circuit voltage. CdS were bound onto crystalline P3HT nanowires through solvent-assisted...

We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire heterostructures and their implementation as high electron mobility transistors (HEMTs). The were prepared by sequential shell growth immediately following elongation using metal−organic chemical vapor deposition (MOCVD). Transmission microscopy (TEM) studies reveal that are dislocation-free single crystals. In addition, thicknesses compositions individual AlN AlGaN shells unambiguously identified cross-sectional...

Vertical arrays of ZnO nanowires can decouple light absorption from carrier collection in PbS quantum dot solar cells and increase power conversion efficiencies by 35%. The resulting ordered bulk heterojunction devices achieve short-circuit current densities excess 20 mA cm(-2) up to 4.9%.

Advancements in the field of flexible high-efficiency solar cells and other optoelectronic devices will strongly depend on development electrode materials with good conductivity flexibility. To address chemical mechanical instability currently used indium tin oxide (ITO), graphene has been suggested as a promising transparent but challenges remain achieving high efficiency graphene-based polymer (PSCs) compared to their ITO-based counterparts. Here we demonstrate anode- cathode-based PSCs...

Hydrogen embrittlement (HE) causes engineering alloys to fracture unexpectedly, often at considerable economic or environmental cost. Inaccurate predictions of component lifetimes arise from inadequate understanding how alloy microstructure affects HE. Here we investigate hydrogen-assisted a Ni-base superalloy and identify coherent twin boundaries (CTBs) as the microstructural features most susceptible crack initiation. This is surprising result considering renowned beneficial effect CTBs on...

A general approach for the synthesis of manganese-doped II−VI and III−V nanowires based on metal nanocluster-catalyzed chemical vapor deposition has been developed. High-resolution transmission electron microscopy energy-dispersive X-ray spectroscopy studies Mn-doped CdS, ZnS, GaN demonstrate that are single-crystal structures homogeneously doped with controllable concentrations manganese ions. Photoluminescence measurements individual CdS ZnS show characteristic pseudo-tetrahedral Mn2+ (4T1...

Growth of semiconducting nanostructures on graphene would open up opportunities for the development flexible optoelectronic devices, but challenges remain in preserving structural and electrical properties during this process. We demonstrate growth highly uniform well-aligned ZnO nanowire arrays by modifying surface with conductive polymer interlayers. On basis structure, we then cathode-based hybrid solar cells using two different photoactive materials, PbS quantum dots conjugated P3HT, AM...

We demonstrate single-walled carbon nanotube (SWCNT)/P3HT polymer bulk heterojunction solar cells with an AM1.5 efficiency of 0.72%, significantly higher than previously reported (0.05%). A key step in achieving high is the utilization semiconducting SWCNTs coated ordered P3HT layer to enhance charge separation and transport device active layer. Electrical characteristics devices SWCNT concentrations up 40 wt % were measured are shown be strongly dependent on loading. maximum open circuit...

Portable electronic devices have become increasingly widespread. Because these cannot always be tethered to a central grid, powering them will require low‐cost energy harvesting technologies. As response this anticipated demand, study demonstrates transparent organic solar cells fabricated on flexible substrates, including plastic and paper, using graphene as both the anode cathode. Optical transmittance of up 69% at 550 nm is achieved by combining highly electrodes with polymers that...

Controlled growth of two-dimensional transition metal dichalcogenide (TMD) lateral heterostructures would enable on-demand tuning electronic and optoelectronic properties in this new class materials. Prior to work, compositional modulations TMD have been considered depend solely on the chronology. We show that in-plane diffusion can play a significant role chemical vapor deposition MoS2/WS2 leading variety nontrivial structures whose composition does not necessarily follow order. Optical,...

We demonstrate an organic/inorganic solar cell architecture based on a blend of poly(3-hexylthiophene) (P3HT) and narrow bandgap GaAs nanowires. The measured increase device photocurrent with increased nanowire loading is correlated structural ordering within the active layer that enhances charge transport. Coating nanowires TiO(x) shells passivates surface states further improves photovoltaic performance. find P3HT/nanowire cells yield power conversion efficiencies 2.36% under white LED...

Direct correlation of structural and optical properties on the nanoscale is essential for rational synthesis nanomaterials with predefined structure functionality. We study single III-V nitride nanowire radial heterostructures measured spatial resolution <20 nm using cathodoluminescence (CL) technique coupled scanning transmission electron microscopy (STEM). Enhanced carrier recombination in quantum wells reduced light emission from regions containing defects were directly observed. Using...

Silicon hyperdoped with chalcogens via femtosecond-laser irradiation exhibits unique near-unity sub-bandgap absorptance extending into the infrared region. The intense light-matter interactions that occur during doping produce pressure waves sufficient to induce phase transformations in silicon, resulting formation of metastable polymorphic phases, but their exact mechanism and influence on process are still unknown. We report direct observations these describe distribution, consider...

The high transparency of graphene, together with its good electrical conductivity and mechanical robustness, enable use as transparent electrodes in optoelectronic devices such solar cells. While initial demonstrations graphene-based organic photovoltaics (OPV) have been promising, realization scalable technologies remains challenging due to their performance and, critically, poor device reproducibility yield. In this work, we demonstrate by engineering the interface between graphene layers,...

Despite the recent astronomical success of organic-inorganic perovskite solar cells (PSCs), impact microscale film inhomogeneities on device performance remains poorly understood. In this work, we study CH3NH3PbI3 films using cathodoluminescence in scanning transmission electron microscopy and show that localized regions with increased intensity correspond to iodide-enriched regions. These observations constitute direct evidence nanoscale stoichiometric variations produce corresponding...

Hydrothermally synthesized ZnO nanowire arrays are critical components in a range of nanostructured semiconductor devices. The device performance is governed by relevant morphological parameters that cannot be fully controlled during bulk hydrothermal synthesis due to its transient nature. Here, we maintain homeostatic zinc concentration, pH, and temperature employing continuous flow demonstrate independent tailoring array dimensions including areal density, length, diameter on...

Lead sulfide quantum dot (QD) solar cells employing an ordered bulk heterojunction with ZnO nanowires and band alignment engineering of the QD film achieve photocurrent density greater than 30 mA cm−2, highest reported for a photovoltaic (PV) device ideal gap 1.3 eV. This record performance is shown to be result simultaneous improvement in light harvesting carrier collection efficiency, these effects are generalizable other PV absorber materials. As service our authors readers, this journal...

Abstract Hydrogen embrittlement (HE) causes sudden, costly failures of metal components across a wide range industries. Yet, despite over century research, the physical mechanisms HE are too poorly understood to predict HE-induced with confidence. We use non-destructive, synchrotron-based techniques investigate relationship between crystallographic character grain boundaries and their susceptibility hydrogen-assisted fracture in nickel superalloy. Our data lead us identify class striking...

Spin–orbit torque provides a highly efficient way to achieve current-induced magnetization switching, which relies on charge-to-spin conversion of the spin source layer. However, in conventional heavy metal/ferromagnetic layer, generated spin–orbit is limited in-plane, cannot deterministically switch perpendicularly magnetized ferromagnets, and thus impedes practical application for high-density magnetic memory. In this work, deterministic switching perpendicular achieved SrRuO3/WTe2 bilayer...