0000000000627377
AUTHOR
Laurent Broch
Morphological and chemical dynamics upon electrochemical cyclic sodiation of electrochromic tungsten oxide coatings extracted by in situ ellipsometry.
The sodiation–desodiation process of sputtered amorphous electrochromic tungsten oxide coatings in an aqueous-based medium was simultaneously monitored over 99 cycles by cyclic voltammetry and in situ spectroscopic ellipsometry. This allowed extracting the evolution of optical and geometrical parameters upon cycling. The resulting electrochemical coloring-bleaching process was dynamically fitted in the 1.8–2.8 eV optical range with a four-phase model including a constrained spline parametrization of the dielectric function. This allows real time access to thickness, surface roughness, and dielectric function of N a x W O 3 . The temporal evolution of the latter in the fully colored state wa…
Electrodéposition et caractérisations optiques de nanofils de Tellure monocristallins
International audience
Real-Time ellipsometric spectra without systematics errors
International audience; In real-time measurement, it is difficult to reduce systematic errors on spectra of ellipsometric angles Ψ and Δ by the mean of two measurementsat two analyzer positions with the incidence plane +45° and -45° [1-2]. Generally, the analyzer is mounted on a motorized rotation stage. Therotation of the optical component from -45° to +45° requires few seconds, and this is incompatible with dynamic measurements.
Design of a real-time spectroscopic rotating compensator ellipsometer without systematic errors
6th International Conference on Spectroscopic Ellipsometry (ICSE), Kyoto, JAPAN, MAY 26-31, 2013; International audience; We describe a spectroscopic ellipsometer in the visible domain (400-800 nm) based on a rotating compensator technology using two detectors. The classical analyzer is replaced by a fixed Rochon birefringent beamsplitter which splits the incidence light wave into two perpendicularly polarized waves, one oriented at +45 degrees and the other one at-45 degrees according to the plane of incidence. Both emergent optical signals are analyzed by two identical CCD detectors which are synchronized by an optical encoder fixed on the shaft of the step-by-step motor of the compensato…
Coloration mechanism of electrochromic Na x WO3 thin films
International audience; The coloration mechanism of tungsten trioxide (WO3) upon insertion of alkali ions is still under debate after several decades of research. This Letter provides new insights into the reversible insertion and coloration mechanisms of Na+ ions in WO3 thin films sputter-deposited on ITO/glass substrates. A unique model based on a constrained spline approach was developed and applied to draw out ε1+iε2 from spectroscopic ellipsometry data from 0.6 to 4.8 eV whatever the state of the electrochromic active layer, i.e. as-deposited, colored or bleached. It is shown that electrochemically intercalated sodium-tungsten trioxide, NaxWO3 (x=0.1, 0.2, 0.35), exhibits an absorption…