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 cm 2 /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 WO 3 film and electrophoretic deposited NiO film was successfully assembled, which is conductive to expand electrochromic applications and its future commercialization.

Extraordinarily Stable Aqueous Electrochromic Battery Based on Li4Ti5O12 and Hybrid Al3+/Zn2+ Electrolyte

“…The numerous diffusion channels allow fast ion incorporations and extractions from the entire LTO layer, which is extremely important to the fast switching of the electrochromic cell. 36,37 Although the LTO film has a porous microstructure populated with nanotunnels, the root-mean-square surface roughness (R q ) is only 3.25 nm, as confirmed by the AFM image in Figure 1c. Such high level of flatness reduces the scattering of light at the LTO surface, thus enhancing the transparency of the electrode in the bleach state.…”

“…It can be seen that the 580 nm-thick LTO film possesses a mesoporous structure composed of small grains that stack over one another throughout the entire structure, leading to the formation of a three-dimensional interconnected channel network for ion diffusion. The numerous diffusion channels allow fast ion incorporations and extractions from the entire LTO layer, which is extremely important to the fast switching of the electrochromic cell. , Although the LTO film has a porous microstructure populated with nanotunnels, the root-mean-square surface roughness ( R q ) is only 3.25 nm, as confirmed by the AFM image in Figure c. Such high level of flatness reduces the scattering of light at the LTO surface, thus enhancing the transparency of the electrode in the bleach state.…”

Electrochromic Smart Windows Based on Nanometer-Thick Films of WO3 Nanowire/Cu and TiO2/NiO as Composite Electrodes

“…Although the switching time of TiO 2 /NiO composite film is longer than that of NiO film, it still has a good response speed compared with other reports. 28,29 The relatively slow response speed of the TiO 2 /NiO composite film may be affected by an interface impedance between TiO 2 and NiO, which hinders the transport of electrons. 30 Figure 5f reveals the curves of ΔOD at the wavelength of 633 nm versus the charge density at a potential of +1.5 V, and the coloration efficiency (CE) of NiO and TiO 2 /NiO composite films was obtained and presented in Table 2.…”