Structural, Optical, and Electrochromic Properties of Pure and Mo-Doped WO₃ Films by RF Magnetron Sputtering

Abstract

Pure and Mo-doped WO3films were formed on ITO-coated glass substrate held at 473 K by RF magnetron sputtering technique. The structural, morphological, and optical properties of pure and Mo-doped WO3thin films have been systematically studied. The structural properties revealed that the pure WO3films exhibited a (020) reflection related to the orthorhombic phase of WO3, whereas Mo-doped films showed (200) reflection. The surface morphology revealed that pure WO3films showed the dense surface and Mo-doped films contained agglomerated grains which were uniformly distributed on the surface of the substrate. The optical transmittance decreased from 85% to 75% for pure and Mo-doped WO3films, respectively. The electrochromic properties of the films were measured by cyclic voltametry in 1 M Li2SO4electrolyte solution. The optical modulation of pure WO3films at near IR was 50%, and the calculated color efficiency was 33.8 cm2/C, while in Mo-doped WO3the efficiency improved to 42.5 cm2/C.

Compositional Optimization of Sputtered WO3/MoO3 Films for High Coloration Efficiency

“…Evaluation of the previous data of electrochromic properties measured at different but always discrete compositions [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ] led to the general conclusion that energy of the maximum of the absorption band of the mixed oxide films shifts towards higher energy as compared to pure WO 3 . Our experiences gained throughout the CE measurements cycles are in agreement with the results of Ref.…”

“…Madhavi and coworkers [ 11 ] prepared pure and Mo-doped WO 3 films on an ITO-coated glass substrate at 200 °C using RF magnetron sputtering. According to their observations, pure WO 3 films demonstrated a dense surface morphology while Mo-doped layers contained grain-like agglomerates uniformly distributed on the surface of the sample.…”

“…Despite the fact that tungsten and molybdenum oxides are both among the most extensively studied materials for electrochromic devices, relatively little effort has been made to understand the properties of mixed oxides [8][9][10][11][12][13][14][15][16][17]. Most of these works investigated only one composition, even only in the composition range of doping effect, i.e., low % of molybdenum oxide in WO 3 .…”