Molybdenum induced defective WO3 multifunctional nanostructure as an electrochromic energy storage device: Novel assembled photovoltaic-electrochromic Mo–WO3 film.

[Display omitted] • Mo-doped WO 3 as a multifunctional nanostructure. • Oxygen defect sites are successfully grown over WO 3 surface. • Doped nanostructure provides sufficient active sites for insertion and extraction of Li⁺ ions. • Novel assembly of QDSSC assisted electrochromic integrated device is developed. In this work, a self-powered electrochromic device incorporating molybdenum-doped tungsten oxide (WO 3) is developed for enhanced performances, offering a potential solution for energy efficient technologies. Defective nanostructure of WO 3 , enabled with molybdenum doping, is achieved through an electrochemical co-deposition method. A film of Mo–WO 3 is investigated for multifunctional purposes, acting as both an electrochromic (EC) and energy storage device (ESD). As an EC film, it exhibits an optimal optical contrast of 84.5 %, minimum coloration time of 0.4 s, high coloration efficiency of 90.4 cm²/C, and excellent optical stability. In ESD applications, Mo–WO 3 displays charge-transfer resistance of 7.6 Ω, a commendable capacitance of 39.1 mF/cm², and excellent capacitance retention of 80.4 %. The integration of Mo ions into the WO 3 nanostructure results in the formation of oxygen defect sites, which enhances the mobility of Li⁺ ions over the amorphous and deagglomerated morphology of Mo–WO 3. Furthermore, the EC activity of Mo–WO 3 film does not require an external power source as the film is powered by an integrated quantum dot-sensitized solar cell (QDSSCs). The open circuit voltage of 0.62 V, resulting from the QDSSCs power source, successfully facilitates the switching operation of the Mo–WO 3 EC film. [ABSTRACT FROM AUTHOR]