In this Letter, we report on a new nanofabrication technology to yield highly arrayed nanoelectrodes for organic–inorganic solar cells that promise new levels of performance and efficiency. This technology efficiently controls the effective area of highly arrayed nanoelectrodes and allows for the maximum incorporation of organic materials within the voids. Particularly the 3D parameters such as thickness, spacing, and height of the nanostructures are controlled non‐lithographically by atomic layer deposition technology.
We present the synthesis of highly crystalline metallic rhenium trioxide (ReO3) nanowires via a simple physical vapor transport at 300 °C for the first time. Based on HRTEM, the ReO3 nanowires exhibit a core of perfect cubic perovskite‐type single crystal structure with a shell of thin amorphous and disordered structures of less than 2 nm in the near surface layers. Possibly this is due to proton intercalation induced by the surface reaction of single crystal ReO3 with water.
Light‐induced degradation of charge carrier lifetime was observed in indium‐doped silicon. After defect formation, an annealing step at 200 °C for 10 min deactivates the defect and the initial charge carrier lifetime is fully recovered. The observed time range of the defect kinetics is similar to the well known defect kinetics of the light‐induced degradation in boron‐doped samples. Differences between defect formation in boron‐ and indium‐doped silicon are detected and discussed. A new model based on an acceptor self‐interstitial ASi–Sii defect is proposed and established with experimental findings and existing ab‐initio simulations.
We demonstrated important changes produced on the modulation frequency of hybrid organic–inorganic light‐emitting diodes to examine the applicability as a light source for visible optical communications. The fabricated device structure was 4,4′‐bis[N ‐(1‐napthyl)‐N ‐phenyl‐amino]biphenyl/4,4′‐(bis(9‐ethyl‐3‐carbazovinylene)‐1,1′‐biphenyl:4,4′‐bis[9‐dicarbazolyl]‐2,2′‐biphenyl/ZnS/LiF/MgAg. This device showed an improvement in the modulation frequency using ZnS instead of an organic material, tris(8‐hydroxyquinoline)aluminum. A maximum cutoff frequency of 20.6 MHz was achieved.
We have fabricated multi‐peak and chromaticity‐stable top‐emitting white organic light‐emitting diodes (TEWOLEDs) using single blue emitter. Besides the intrinsic emission of blue emitter, the additional emission can be well realized by simply adjusting the thickness of hole transporting layer (HTL), thus modifying the optical cavity length to obtain different resonant wavelengths. The detailed variation process for multi‐peak spectra with the increase of HTL thickness is studied, which provides a guidance for the design of microcavity TEWOLEDs.
We report on the photoconductance in two‐dimensional arrays of gold nanorods. The arrays are formed by a combination of droplet deposition and stamping methods. We find that the plasmon induced photoconductance is sensitive to the linear polarization of the exciting photons consistent with the excitation of the longitudinal surface plasmon resonance of the nanorods.
A new method for fabricating carbon nanotube‐conducting polymer (CNT‐CP) composite single nanowires is reported. The method developed is highly efficient, reliable, and economical because it obviates the time consuming process of template fabrication and the post‐synthesis task of positioning nanowires. Single nanowires with diameters of 50‐500 nm are fabricated between electrodes, self‐templated by dielectrophoresis and electropolymerization. Fabrication of an individually addressed nanowire array with cantilever electrodes on a microchip is demonstrated.
The growth, structural and optical characterisation of dilute nitride alloys of InSb grown by plasma‐assisted molecular beam epitaxy is presented. The layers were characterised by high‐resolution X‐ray diffraction indicating high crystalline quality and nitrogen incorporations up to 0.68%. Fourier‐transform infrared absorption measurements reveal the position of the absorption edge to be a result of the competing effects of bandgap reduction (due to nitrogen incorporation and bandgap renormalisation) and Moss–Burstein band filling.
We report on solution‐processible polymer solar cells (PSCs) fabricated on a papery substrate using carton. Highly conductive PEDOT:PSS was used as a bottom anode and planarization layer, and a semi‐transparent top cathode was applied. This research could be an important approach to the development of all‐solution‐processible papery PSCs as well as paper electronics.
MgZnO‐based ultraviolet avalanche photodetectors (APDs) have been fabricated from Au/MgO/Mg0.44Zn0.56O/MgO/Au Schottky structures. The carrier avalanche multiplication is realized via an impact ionization process occurring in the MgO layer under relatively large electric field. The APDs exhibit an avalanche gain of 587 at 31 V bias, and the response speed of the APDs is in the order of microseconds.
Epitaxial TiC/SiC multilayers were grown by magnetron sputtering at a substrate temperature of 550 °C, where SiC is normally amorphous. The epitaxial TiC template induced growth of cubic SiC up to a thickness of ～2 nm. Thicker SiC layers result in a direct transition to growth of the metastable amorphous SiC followed by renucleation of nanocrystalline TiC layers.
We present a computational study based on time‐dependent density functional theory of the optical absorption spectra of TiO2 nanowires sensitized with organic dye molecules. We concentrate on catechol and squaraine dyes. For those molecules, we compute adsorption geometries and energies and investigate the optical properties of the combined dye– nanowire system. We find that although the molecules have qualitatively different optical spectra in the gas phase, both lead to an enhancement of the absorption in the visible frequency range when adsorbed on a nanowire.
By means of first‐principles calculations we predict the stability of silicene as buckled honeycomb lattice on passivated substrates of group‐IV(111)1 × 1 surfaces. The weak van‐der‐Waals interaction between silicene and substrates does not destroy its linear bands forming Dirac cones at the Brillouin zone corners. Only very small fundamental gaps are opened around the Fermi level.
Write‐once–read‐many‐times memory (WORM) devices were fabricated using Ti/Au and Au as top contacts on ZnO thin films on Si. Electrical characterization shows that both types of WORM devices have large resistance OFF/ON ratio (R ratio), small resistance distribution range, long retention and good endurance. WORM devices with Au top contact have better performance of higher R ratio because of a larger work function of Au compared to Ti.
This Letter reports on the assembly on the tip of an optical fibre of a metamaterial film fabricated by a self‐assembly bottom‐up method, composed of silver nanowires embedded in an alumina matrix. By illuminating the film through the fibre in a reflection configuration, we observe experimentally the optical response of the metamaterial in agreement with theoretical predictions and interpreted as the excitation of surface plasmon‐polaritons in the cylindrical surface of the nanowires. These results pave the way for low‐cost optical fibre devices that incorporate metamaterial films.
We study the spin ordering of a quantum dot defined via magnetic barriers in an interacting quantum spin Hall edge. The spin‐resolved density–density correlation functions are computed. We show that strong electron interactions induce a ground state with a highly correlated spin pattern. The crossover from the liquid‐type correlations at weak interactions to the ground state spin texture found at strong interactions parallels the formation of a one‐dimensional Wigner molecule in an ordinary strongly interacting quantum dot.
We report the fabrication procedure and the characterization of an Al0.3Ga0.7As solar cell containing high‐density GaAs strain‐free quantum dots grown by droplet epitaxy. The production of photocurrent when two sub‐bandgap energy photons are absorbed simultaneously is demonstrated. The high quality of the quantum dot/barrier pair, allowed by the high quality of nanostructured strain‐free materials, opens new opportunities for quantum dot based solar cells.
Using silver and gold, we have measured the size‐dependence of the yield strength of atomic‐sized samples as small as a single‐atom bridge, with pico‐level resolution in the applied force and displacement. The strength approaches theoretical values as the diameter of the sample becomes comparable to the Fermi wavelength of electrons (～0.5 nm); in the limit of a single‐atom bridge, the strength is over four orders of magnitude higher than in bulk single crystals. Results provide direct evidence for Pauling's prediction of bond stiffening with reduced atomic coordination. Beginning with a single‐atom bridge, strength evolves in a staircase manner in Ag, instead of the intuitively assumed continuous approach to a saturating bulk value.
A facile metal catalyst free route to synthesize boron doped (0.6%–1.0%) carbon nanotubes via ceramic nanowires in which the formation of the nanowires (probably serving as templates), the carbon nanotubes and their doping all occur unanimously in the reaction, is presented.
