Synergistic construction of preferential growth of WO3 and ion channels induced by non-ionic polyethylene glycol to enhance electrochromic performance

This study focuses on the promising electrochromic material tungsten oxide. A WO 3 ·0.33H 2 O film with a controllable microstructure was successfully synthesized using a surfactant-assisted hydrothermal method. Compared with the WO 3 -SDS films regulated by the ionic surfactant sodium dodecyl sulfate (SDS) and the pure-phase WO 3 ·0.33H 2 O films (Marked as WO 3 films), this study used non-ionic polyethylene glycol (PEG) as a structure-directing agent to successfully fabricate high-crystallinity WO 3 -PEG films with preferred (220) crystal plane orientation. Scanning electron microscopy (SEM) analysis shows that the film exhibits uniform particle morphology, with tightly packed particles forming interparticle channels, creating layered ion diffusion paths. Electrochemical tests showed that the WO 3 -PEG film exhibited excellent electrochromic performance: the Li + diffusion coefficient (5.094 × 10 −13  cm 2 /s) was significantly improved, 1.71 times higher than that of pure WO 3 (2.971 × 10 −13  cm 2 /s). The response time was fast ((t c /t b  = 4.73 s/4.57 s), and the optical modulation amplitude was high (ΔT of 61.50% at 600 nm wavelength). By optimizing the synergistic effect of crystallinity and engineered ion channel structure, synchronous electron transfer and ion insertion are achieved, providing a new approach for the design of high-performance electrochromic materials.