Analogy for the maximum obtainable colouration between electrochromic, gasochromic, and electrocolouration in DC-sputtered thin WO3−y films

Optical absorption in lithiated tungsten oxide thin films: Experiment and theory

“…Hence, the coloration efficiency would increase with increasing substoichiometry, as observed by Lee et al 10 In addition, optical measurements at a single wavelength have been claimed to support this model. 11 However, the opposite result, namely, the coloration efficiency is highest for stoichiometric tungsten oxide films, has also been reported. 12 It has been found that substoichiometric films in the WO y range ͑ϳ2.75Ͻ y ഛ 3.0͒ are very transparent, 13 and a colored ͑blue͒ phase is seen only when the nonstoichiometry is substantial ͑y Ͻ ϳ 2.75͒.…”

Hydrogen incorporation and gasochromic coloration of tungsten oxide films

“…So far, hydrogen transport was measured mainly by electrochemical techniques and by infrared absorption measurements [6,7]. Besides, the gasochromic characteristics depended on the preparation methods of the WO 3 films, such as a sputtering evaporation and sol-gel coatings [8,9]. In this work, the hydrogen retention/release behavior in tungsten oxide films with different composition and structure prepared by RF magnetron sputtering was examined using ion beam analysis techniques.…”

Ion irradiation effects on the optical properties of tungsten oxide films

“…Although a variety of models have been proposed to explain the electrochromic and gasochromic phenomena in WO 3 film, a general model that explains the coloration mechanism has not been determined. Many experimental results have been reported supporting the various models, based on preparation methods, stoichiometry, the microstructure, film crystallinity, and coloration measurement techniques [3][4][5].…”