Langmuir–Blodgett self organized nanocrystalline tungsten oxide thin films for electrochromic performance

Abstract

We explore a novel method to synthesize pebble-like nanocrystalline WO₃ thin films for the first time by thermal decomposition of a multilayer Langmuir–Blodgett film of an octadecylamine–tungsten complex. The resulting film was thoroughly characterized by various characterization techniques. The electrochromic performance was evaluated in Li⁺ as a charge-balancing ion. The WO₃ thin film displays a state-of-the-art performance with respect to optical modulation of 25.94% at λ₆₃₀ nm with a very rapid coloration and bleaching time of 3.57 s and 3.14 s, respectively and a high coloration efficiency of 71.26 cm² C⁻¹. The excellent electrochromic performance can be attributed to the high size uniformity of WO₃ nanoparticles, whose crystalline nature offer more active sites for Li⁺ diffusion and control the diffusion path length. Thus, the Langmuir–Blodgett WO₃ film contributes to high energy conversion devices.