Improved electrochromic performances of WO3-based thin films via addition of CNTs

Abstract Construction of a composite WO 3 film has been considered to be an important way to improving the electrochemical performances and electrochromic properties. Herein, we fabricated a composite film containing WO 3 nanoparticles, chitosan (CS), and carbon nanotubes (CNTs) by a layer-by-layer technique (LbL). The composite film displays light black to dark blue over the potential range from 0 to −1.5 V. Compared with the WO 3 /CS film, the WO 3 /CS-CNTs film displays increased current densities, which supported a greater number of sites for Li + ions intercalation and extraction. Furthermore, the electrochromic performance of the composite film is enhanced by incorporation of CNTs into the WO 3 film, resulting in coloration efficiency of 79.2 cm 2  C −1 and optical contrast of 13.5 % at 800 nm under a square wave potential from −1.5 to +1.5 V. Therefore, the improved electrochromic properties could be achieved using WO 3 and CNTs composite film. Graphical Abstract