The interface structure of graphene with thermally evaporated metal oxide layers, in particular molybdenum trioxide (MoO3), is studied combining photoemission spectroscopy, sheet resistance measurements and organic light emitting diode (OLED) characterization. Thin (<5 nm) MoO3 layers give rise to an 1.9 eV large interface dipole and a downwards bending of the MoO3 conduction band towards the Fermi level of graphene, leading to a near ideal alignment of the transport levels. The surface charge transfer manifests itself also as strong and stable p-type doping of the graphene layers, with the Fermi level downshifted by 0.25 eV and sheet resistance values consistently below 50 Ω/sq for few-layer graphene films. The combination of stable doping and highly efficient charge extraction/injection allows the demonstration of simplified graphene-based OLED device stacks with efficiencies exceeding those of standard ITO reference devices.

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The primary objective of this work is to demonstrate a novel sensor system as a convenient vehicle for scaled-up repeatability and the kinetic analysis of a pixelated testbed. This work presents a sensor system capable of measuring hundreds of functionalized graphene sensors in a rapid and convenient fashion. The sensor system makes use of a novel array architecture requiring only one sensor per pixel and no selector transistor. The sensor system is employed specifically for the evaluation of Co(tpfpp)ClO functionalization of graphene sensors for the detection of ammonia as an extension of previous work. Co(tpfpp)ClO treated graphene sensors were found to provide 4-fold increased ammonia sensitivity over pristine graphene sensors. Sensors were also found to exhibit excellent selectivity over interfering compounds such as water and common organic solvents. The ability to monitor a large sensor array with 160 pixels provides insights into performance variations and reproducibility-critical factors in the development of practical sensor systems. All sensors exhibit the same linearly related responses with variations in response exhibiting Gaussian distributions, a key finding for variation modeling and quality engineering purposes. The mean correlation coefficient between sensor responses was found to be 0.999 indicating highly consistent sensor responses and excellent reproducibility of Co(tpfpp)ClO functionalization. A detailed kinetic model is developed to describe sensor response profiles. The model consists of two adsorption mechanisms-one reversible and one irreversible-and is shown capable of fitting experimental data with a mean percent error of 0.01%.

The energy and power requirements of portable electronic devices and electric vehicles are ever increasing, driving research into novel battery structures with increased volumetric energy and power densities.Existing energy storage technologies cannot satisfy both of these requirements. There are many reports on the application of graphene in batteries and supercapacitors with enhanced power and energy densities; however, few results were shown on the performance of an electrochemical energy storage device made of monolayer graphene. The energy storage capability of monolayer graphene is investigated in this paper and it can contribute an understanding of the application of graphene materials in high energy and power density batteries. In parallel, flexible solid-state batteries will relax design constraints, giving the freedom to create new device form factors. A mechanically flexible allsolid state battery can be made of monolayer graphene grown by chemical vapour deposition (CVD) directly onto copper (Cu) foil. The total thickness of the resulting battery was $50 mm. Such an ultrathin battery showed the highest energy density of 10 W h L À1 and the highest power density of 300 W L À1 .It also shows excellent cyclic stability and sustains a discharge current density of 100 mA cm À2 over 100 cycles, maintaining energy capacity over 0.02 mA h cm À2 .

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