Electrochromic properties of vertically aligned Ni-doped WO₃ nanostructure films and their application in complementary electrochromic devices

Abstract

High-contrast electrochromic device of tunable color change from transparent to black were achieved with vertically aligned Ni-doped WO3 films.

Electronic Structure Control of Tungsten Oxide Activated by Ni for Ultrahigh‐Performance Supercapacitors

“…Fermi energy level ( E f ) is located at the range of conduction band, in agreement with the former reports that PWO belongs to conductor. [20b] In the primitive crystal model of W 18 O 49 , the sites of W atom are labeled in letters from “A” to “R” and Ni‐doped tungsten oxide with specified substitution are labeled as NWO‐X (X: “A” to “R,” Figures S1 and S4, Supporting Information). In the figure of density of state (DOS) (Figure b) of NWO‐L (Figures S5–S7, Supporting Information), the DOS at E f increases (Figure b and Table S1, Supporting Information) owing to the contribution of the d orbit for Ni (Figure S7, Supporting Information).…”

“…Among them, heteroatom doping has emerged as an effective strategy to generate active sites[17c,18c] and regulate electronic structure to modify the performance of tungsten oxide. [17b,20] For example, the introduction of Mo element can efficiently optimize the electronic structure and thus significantly improve the hydrogen evolution reaction (HER) performance. [17c] Further, nonmetal elements such as elemental C can play the similar role in the optimization of electron structures.…”

“…[17a] Even so, rare papers report heteroatom‐doped tungsten oxide as electrode materials for supercapacitors with high pseudocapacitance performance. Besides, one downside of heteroatom doping that large amounts of heteroatoms certainly distort the structure of original materials[3a,20a] and change pristine bond length to weaken the structural stability and then affect electronic transfer, is seldom discussed.…”

Research Impact on Emerging Quantum Materials for Electrochromic Applications

“…Said differently, the electrical and optical properties that vary by carrier concentration and mobility of the WO 3 layers mainly determine the kinetics of the EC reactions. Therefore, many studies on the doped nanostructures have used suitable metal ions with a lower oxidizing capability or a higher electronegativity compared to those of host ions, such as Ti, Ni, Fe, and P. [19][20][21][22] Interestingly, in addition to the modification of electrical and optical properties on the host EC materials, this approach can induce a variation of morphology or crystallinity, which is expected to benefit the EC performances of switching speed, CE, and cycling retention. As a major result, Cai et al reported the hierarchical structure Ti-doped WO 3 films prepared using the hydrothermal method (see Figure 3a).…”

Aqueous synthesis of tin- and indium-doped WO3 films via evaporation-driven deposition and their electrochromic properties

“…Doping with metal ions (such as Ni and Ti, among others) has been widely investigated as another strategy for making high-performance WO 3 electrochromic materials. [24][25][26][27] Bathe et al investigated the inuence of Ti doping on the electrochromic properties of WO 3 thin lms prepared by pulsed spray pyrolysis, and suggested that doping WO 3 with Ti induced a phase transformation from monoclinic to amorphous and a rough surface morphology, resulting in improvement in the cycle stability, charge storage capacity, and reversibility of the lms. 24 Cai et al prepared Ti-doped WO 3 lms with a hierarchical star-like structure by a hydrothermal method, where the star-like structure had a low charge-transfer resistance and ion diffusion resistance, leading to fast switching speed and high coloration efficiency.…”