Effect of water adsorption on conductivity in epitaxial Sm0.1Ce0.9O2-δ thin film for micro solid oxide fuel cells applications

Water adsorption, splitting, and proton liberation were investigated on Sm0.1Ce0.9O2-δ thin films by scanning probe microscopy. An irreversible volume expansion was observed by applying a positive bias with increased temperature. The volume expansion is also linearly dependent on the relative humidity. A reversible water adsorption process and its effect on the conductivity were also investigated by electrochemical strain microscopy and first order reversal curve under a number of experiment conditions. The presence of a Ce3+ along with OH groups, detected by hard x-ray photoemission spectroscopy established a clear correlation between the water incorporation and the valence state of C

Strain Effects on the Work Function of an Organic Semiconductor

Establishing fundamental relationships between strain and work function (WF) in organic semiconductors is important not only for understanding electrical properties of organic thin films, which are subject to both intrinsic and extrinsic strains, but also for developing flexible electronic devices. Here we investigate tensile and compressive strain effects on the WF of rubrene single crystals. Mechanical strain induced by thermal expansion mismatch between the substrate and rubrene is quantified by X-ray diffraction. The corresponding WF change is measured by scanning Kelvin probe microscopy. The WF of rubrene increases (decreases) significantly with in-plane tensile (compressive) strain, which agrees qualitatively with density functional theory calculations. An elastic-to-plastic transition, characterized by a steep rise of the WF, occurs at ∼0.05% tensile strain along the rubrene π-stacking direction. The results provide the first concrete link between mechanical strain and WF of an organic semiconductor and have important implications for understanding the connection between structural and electronic disorder in soft organic electronic materials

Microstructure and compositional defects affects proton conductivity and reactions in Y-doped BaZrO3 thin films

In this paper, we report on BaZr0.8Y0.2O3-x (BZY) thin films grown on highly mismatched NdGaO3 (110) substrates by RHEED assisted pulsed laser deposition. The conduction and electrochemical performances are studied by Electrochemical Impedance Spectroscopy and Electrochemical Strain Microscopy respectively. Conductivity, as well as electrochemical response improves while decreasing the thickness, indicating that the proton movement is prompt at the defective interface region. Structural defects at the interface between film and substrate are clearly displayed by x-ray diffraction, RHEED patterns and transmission electron microscopy. The role of chemical defects on BZY film properties is elucidated by Hard X-ray Photoelectron Spectroscopy. Our results demonstrate that both structural dislocations and chemical defects influence the proton conduction and reaction process in BZY thin films. ©The Electrochemical Society