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Addressing the oxidation state of functional materials such as transition metal oxides is a current critical challenge and requires new methodologies to characterize their electronic structure within surface to bulk resolution at the nanometer scale. One approach to this issue is the combination of co‐localized soft and hard X‐ray photoelectron spectroscopies for a non‐destructive depth profiling. In this work, we demonstrate the capability to characterize the oxidation state of cobalt in LiCoO2 thin films, a model electrode material in the Li‐ion battery field, within the first 15 nm. The capability of the methodology to address the surface evolution of the cobalt oxidation state is tested through a proof of concept surface modification introduced by Ar‐ion sputtering. To address the cobalt local electronic structure at different depths from the extreme surface, we exploited Auger‐free Hard X‐ray photoelectron spectroscopy (HAXPES) spectra to fit the Co 2p core‐level features in the X‐ray photoelectron spectroscopy (XPS) spectra. This approach may pave the way for a better understanding of the surface electronic structure changes in transition metal oxides driven by their applications in a broad range of technologies. [ABSTRACT FROM AUTHOR]

Lithium metal electrodes have been submitted to a long-term storage in contact with carbonated-based electrolyte at different temperatures, with the aim of gaining more understanding on the impact of aging conditions on the lithium metal surface. To do so, the evolution of lithium surface∣electrolyte interface has been monitored via electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and FE-SEM techniques, to correlate the change of the interface properties with the chemical and morphological modifications at the electrode’s surface. After this aging, lithium electrodes were galvanostatically cycled in symmetric Li∣Li coin cell configuration at 10, 25 and 45 °C. Through this approach, a better cycling stability was observed in those cells stored at 45 °C, which can be ascribed to the more compact lithium electrodeposition than that observed in the rest of cells previously aged at lower temperatures. These results indicate that calendar at high temperature condition benefits lithium electrode performance, which can be attributed to a homogeneous passivation of the metal surface with fluorine and/or phosphate-based compounds, following XPS measurements, which can improve the behaviour of the solid electrolyte interface. [ABSTRACT FROM AUTHOR]

Carbon black (CB) filled elastomers are structurally complex materials that offer unique properties at different length scales. They have tremendous potential applications in a number of fields including the automotive and aerospace industries and for designing innovative smart materials such as artificial muscles but their applications remain limited primarily due to inadequate understanding of their unique mechanical properties. Here, using the Berkovich technique to probe the surface mechanical properties at different scales the nanoindentation response of a series of composites made by homogeneously dispersed CB nanoparticles inside a semicrystalline copolymer matrix has been explored. While the measured loading part of the force–displacement curves is well described by Meyer's empirical power relation, the inverted methodology (IM) approach to deal with the unloading part has been considered and its outcome has been compared with that obtained from the standard Oliver–Pharr's method. The results were consistent with the observed increase of hardness when the applied displacement decreases for all composite samples over a large range of CB volume fraction. Zhang and Xu's model is demonstrated to produce experimentally consistent explanation of this indentation size effect. X‐ray photoelectron spectroscopy (XPS) spectra also show composition gradients with depth up to 100 nm. Furthermore, the effect of CB content, surface features, and length scale‐dependent deformation on the hardness–displacement behavior have been considered. These findings highlight the possibility of attaining a diverse set of mechanical properties by a better understanding of the nanoindentation response of CB filled elastomers which can be useful for material selection and design improvements in a number of practical applications. [ABSTRACT FROM AUTHOR]

We have investigated the core levels and the valence band of (Ge2Sb2Te5)1-x(In3Sb1Te2)x quaternary phase system (IGST) by means of x-ray photoelectron spectroscopy. A systematic shift of Sb 3d and Ge 2p core-level peaks toward lower binding energies side was observed with increasing indium amount, whereas the In 3d and Te 3d core peaks showed less change. The Sb 3d and Ge 2p core-level shift is attributed to an increase in the electronic charge of p-electrons dependent of indium amount. The valence band spectra show a distinct change in the sp configuration with indium concentration change. The change in the local bonding as the indium amount increase has a profound impact on both local atomic arrangement and amorphous-to-crystalline transformation temperature. The difference in the photoemission spectra have been discussed according to a simple structural model suggesting that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

We present versatile ZnOxNy applicable to a wide range of imaging/display devices. A well-optimized ZnOxNy material exhibits high mobility exceeding 100 cm2/Vs, bandgap of 1.3 eV and nanocrystalline microstructure with multiphase. Accordingly, the performance of ZnOxNy-based device can be adjustable to meet the requisite of future electronic/photonic device elements. [ABSTRACT FROM AUTHOR]

We introduce single-phase In–Ge–Sb–Te (IGST) quaternary thin film (fcc structure when crystallized) deposited by cosputtering from Ge2Sb2Te5(GST) and In3Sb1Te2 targets. This film, compared with the GST ternary system, provides a significant increase of amorphous-to-crystalline transformation temperature. High-resolution x-ray photoelectron spectroscopy (HRXPS) revealed that, with increasing In amounts, the Sb 4d and Ge 3d core peaks shift toward lower binding energies (BEs), with negligible changes in spectral linewidths, whereas the In 4d and Te 4d core peaks show insignificant changes in BEs. HRXPS interpretation suggests that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

• The air stability of polymer layers p-doped with molybdenum dithiolene complexes is investigated. • Unstable doping signatures are observed under ambient air, related to a dedoping process. • Oxidation and degradation of the dopant molecule are evidenced by XPS analysis. Doping efficiency and stability are crucial requirements for the integration of doped organic semiconductors in optoelectronic devices. This work presents a detailed experimental study on the air stability of p-doped systems based on a low-bandgap polymer, poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl) (PBDTTT-c) doped with a strong molecular p-dopant, i.e. molybdenum tris[1-(trifluoroethanoyl)-2-(trifluoromethyl) ethane-1,2-dithiolene] (Mo(tfd-COCF 3) 3). The electrical conductivity and the optical absorption are measured for different dopant concentrations in argon atmosphere, and their variations monitored as a function of the air exposure time. The results indicate a clear instability under ambient air related to a dedoping process, which is particularly pronounced in ultra-thin (< 50 nm) doped layers. By evaluating the stability of the p-doped polymer layers under different atmospheres (ambient air, anhydrous air and argon), the detrimental impact of moisture and/or O 2 (H 2 0) n complexes is highlighted. X-ray Photoelectron Spectroscopy (XPS) revealed that the p-doping instability in ambient air can be assigned to changes in the oxidation state of the metallic center as well as to an intrinsic degradation of the dopant molecule. This study unravels an important degradation mechanism with this class of dopants that should be taken under consideration and solved for future integration of ultrathin p-doped layers in printed electronic devices. [ABSTRACT FROM AUTHOR]