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Micro-supercapacitors (MSCs) are one of the most promising electronic circuit elements in electronic devices as they are designed for use as energy storage components, decoupling capacitors, ripple current filter elements, and in many other applications. The materials used for MSCs have been greatly restricted since only a few materials or material combinations are capable of operating at the required high frequencies with high power and sufficient stability for long-term operation [1]. By using graphene and its derivatives as electrodes, here we demonstrate that MSCs with ultrahigh power density will push further the monolithic integration and the realization of smart multifunctional autonomous system-on-a-chip.

In this work, we present hybrid nanostructured core-shell solar cells based on patterned GaAs nanopillars grown by MOCVD, coated with electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. The patterns are photolithographically defined and center-to-center pitch, hole size and mask arrangement can be precisely predetermined at nanometric resolution. Our inherently catalyst-free growth mode eliminates any metal (i.e. Au) diffusion into the nanopillars that could hinder the electron-hole pair extraction, paramount in photovoltaics. Hybrid devices [1–3] are normally obtained by spin-coating conjugated polymers on top of inorganic semiconducting surfaces. Spin-coating techniques allow to achieve only non-conformal thin films on planar substrates, yet it offers scarce controllability for 3-D structures where the polymer needs to be coated uniformly along the sides of the nanostructures too. Electrolytic deposition approaches, on the other hand, offer a simple, versatile route to high quality, conformal coatings to conductive surfaces regardless of the device structure. In addition, it possesses exquisite selectivity over the deposition position and precise control of the coating thickness and morphology, representing an attractive technique for fabricating core-shell inorganic-organic structured devices. This study demonstrates the rational design of a hybrid photovoltaic device through the careful tuning of the thickness, morphology, and physical/chemical properties of the polymer layer by electrodeposition, in conjunction with the manipulation over the size and properties of the patterned GaAs nanopillar arrays via MOCVD, in order to achieve optimized device configuration and performance. Device characterization is carried out in terms of photocurrent density-voltage (J-V) characteristics (under dark and standard AM 1.5 conditions), external quantum efficiency (EQE), and transient open-circuit voltage decay (TOCVD), standard figures of merit in the photovoltaic field.

In this paper, we report the development of a novel Pt/MoO 3 nano-flower/SiC Schottky diode based device for hydrogen gas sensing applications. The MoO 3 nanostructured thin films were deposited on SiC substrates via thermal evaporation. Morphological characterization of the nanostructured MoO 3 by scanning electron microscopy revealed randomly orientated thin nanoplatelets in a densely packed formation of nano-flowers with dimensions ranging from 250 nm to 1 µm. Current-voltage characteristics of the sensor were measured at temperatures from 25°C to 250°C. The sensor showed greater sensitivity in a reverse bias condition than in forward bias. Dynamic response of the sensor was investigated towards different concentrations of hydrogen gas in a synthetic air mixture at 250°C and a large voltage shift of 5.7 V was recorded upon exposure to 1% hydrogen.

In this paper, we present gas sensing properties of Pt/graphene-like nano-sheets towards hydrogen gas. The graphene-like nano-sheets were produced via the reduction of spray-coated graphite oxide deposited on SiC substrates by hydrazine vapor. Structural and morphological characterizations of the graphene sheets were analyzed by scanning electron and atomic force microscopy. Current-voltage and dynamic responses of the sensors were investigated towards different concentrations of hydrogen gas in a synthetic air mixture at 100°C. A voltage shift of 100 mV was recorded at 1 mA reverse bias current.

Presented is the material and gas sensing properties of graphene-like nano-sheets deposited on 36deg YX lithium tantalate (LiTaO3) surface acoustic wave (SAW) transducers. The graphene-like nano-sheets were characterized via scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The graphenelike nano-sheet/SAW sensors were exposed to different concentrations of hydrogen (H2) gas in a synthetic air at room temperature. The developed sensors exhibit good sensitivity towards low concentrations of H2 in ambient conditions, as well as excellent dynamic performance towards H2 at room temperature.

Single sheet graphite oxide films are synthesized by intercalation and exfoliation routes of graphite. Those insulating graphite oxide films were deposited on SiO2/Si substrates and reduced to semiconducting graphene. Field effect transistors of these graphite oxide and graphene films were fabricated. The transport properties of the devices were studied before and after the reduction reaction. Such method opens up the possibility of preparing high quality, large area and manufacturable graphene films with low cost.

A Polyaniline/In2O3 nanofiber composite based surface acoustic wave (SAW) gas sensor has been developed. Chemical oxidative polymerization of aniline was employed to synthesize polyaniline nanofibers with lIn2O3 nanoparticles. The nanocomposite was deposited onto a layered ZnO/64deg YX LiNbo3 SAW transducer. The sensor was exposed to various concentrations of H2 gas and operated at room temperature. The sensor response was found to be 11 kHz towards 1% of H2 in synthetic air. A fast response and recovery with good repeatability in a stable baseline condition were observed at room temperature.

Electro-conductive polyaniline (PANI) nanofiber based surface acoustic wave (SAW) gas sensors have been investigated with hydrogen (H 2) gas. A template-free, rapidly mixed method was employed to synthesize polyaniline nanofibers using chemical oxidative polymerization of aniline. The nanofibers were deposited onto a layered ZnO/64deg YX LiNbO3 SAW transducer for gas sensing applications. The novel sensor was exposed to various concentrations of H2 gas at room temperature. The sensor response, defined as the relative variation in operating frequency of oscillation due to the introduction of the gas, was 3.04 kHz towards a 1% H2 concentration. A relatively fast response time of 8 sec and a recovery time of 60 sec with good repeatability were observed at room temperature. Due to room temperature operation, the novel gas sensor is promising for environmental and industrial applications

Polyaniline (PANI) nanofiber and PANI/semi-conducting metal oxide nanofiber composites based layered surface acoustic wave (SAW) and conductometric sensors have been developed and investigated towards hydrogen (H2) gas. Chemical oxidative polymerization of aniline was employed to synthesize pure PANI nanofibers as well as PANI/semi-conducting metal oxide composites. The nano-materials were deposited onto layered ZnO/64deg YX LiNbO3 SAW and conductometric transducers. The novel sensors were exposed to H2 gas. Fast response and recovery with good repeatability were observed at room temperature.

A polyaniline (PANI) nanofiber based surface acoustic wave (SAW) gas sensor, has been developed and investigated towards hydrogen (H2) gas. A template-free, rapidly-mixed reaction approach was employed to synthesize polyaniline nanofibers, which utilized chemical oxidative polymerization of aniline. Hydrochloric acid (HCl) was used as the dopant acid in the synthesis of the polyaniline nanofibers. Polystyrene sulfonic acid (PSSA) was used to re-dope PANI nanofibers after dialyzing with ammonium hydroxide. Then PSSA doped nanofibers were deposited onto a ZnO/64 YX LiNbO3 SAW transducer. The sensor was exposed to various concentrations of H2 gas in an ambient of synthetic air, and operated at room temperature.

Summary form only given, as follows. We will report on our optical investigations on the alkali-doped C60 superconductors over a broad energy spectral range (i.e., from 10 cm-1 up to 105 cm-1) and at temperatures below and above T c· The samples were in form of pressed pellet and single crystal. The normal state response (T >> Tc) is characterized by various interband transitions at high frequencies (v > 5x103 cm-1) and by a broad excitation in the mid-IR, superimposed to a Drude contribution. Below Tc a clear enhancement of the reflectivity is observed in the FIR at frequencies below 100 cm-1, with an onset as a function of temperature coincident with Tc. A superconducting gap of about 73 and 48 cm-1 is inferred for the Rb- and K-doped C60 single crystals, respectively. This is in full agreement with a weak coupling limit of a BCS singlet superconductor and also suggests that the relevant excitation, responsible for the superconducting pairing, is significantly larger than the single particle gap energy. Moreover, we present our calculation of the electrodynamic response above and below Tc with the standard Eliashberg electron - phonon theory of superconductivity, which strongly supports a pairing mechanism mediated by high frequency intramolecular phonon modles.