Enhanced electrochromic switches and tunable green fluorescence based on terbium ion doped WO₃ films

Multifunctional WO₃-based materials have been increasingly attracting attention due to their unique physical and electrochemical nature. In this work, the luminescent species, terbium (Tb) ions, were first successfully doped into WO₃ films by a hydrothermal method to incorporate their electrochromic and photoluminescent functions. The amorphous state and porous net structure are introduced, which can be attributed to the inhibited orientation growth caused by the occupation of Tb ions in the WO₃ lattice. Here, the optimal 13% Tb-WO₃ film exhibits enhanced electrochromic properties: a high transmittance modulation of 66.71%; a fast response speed of less than 10 s; an improved CE value of 48.33 cm² C^-1 at 680 nm; and cycling stability over 600 cycles without obvious degradation, arising from its larger active surface area. Meanwhile, its green-colored emission could be realized under 260 nm UV light and is electro-switchable upon applying voltage.