Room-Temperature Fabrication of NiO Films for Electrochromic Application by Electrophoretic Deposition (EPD): From Single Layers to Devices

Abstract

Nickel oxide (NiO) films for electrochromic prepared by chemical methods still have the problem of requiring high temperature treatment that limits its further application. In this study, electrophoretic deposition (EPD) was used to deposit NiO nanocrystallines onto transparent conducting oxide (TCO) substrates for electrochromic application. NiO nanocrystallines with a grain size of around 10.36 nm were synthesized by organic solvent method, and NiO suspension of 10 mg/mL was used in the EPD procedure under constant voltage of 4.5 V, 60 s at room temperature. The NiO films prepared by this method exhibit large optical modulation amplitude (54.1%) at 550nm, fast switching speed (coloring time is 7.3 s, bleaching time is 3.9 s), high coloration efficiency (25.7 cm2/C), and moderate cyclic durability. This study provides a simple and energy-saving way to deposit NiO films at room temperature, and all-solid-state complementary flexible electrochromic device (ECD) using electrochemically deposited WO3 film and electrophoretic deposited NiO film was successfully assembled, which is conductive to expand electrochromic applications and its future commercialization.