Niobium Tungsten Oxides for Electrochromic Devices with Long-Term Stability

Abstract

There is a keen interest in the use of electrochromic materials because they can regulate light and heat, thereby reducing the cooling and heating energy. However, the long response time, short cycle life, and high power consumption of an electrochromic film hinder its development. Here, we report an electrochromic material of complex niobium tungsten oxides. The Nb18W16O93 thin films in the voltage range of 0 to −1.5 V show good redox kinetics with the coloration time of 4.7 s and bleaching time of 4.0 s, respectively. The electrochromic device based on the Nb18W16O93 thin film has an optical modulation of 53.1% at a wavelength of 633 nm, with the coloration efficiency of ∼46.57 cm2 C–1. An excellent electrochemical stability of 78.1% retention after 8000 cycles is also achieved. These good performances are due to the fast and stable Li-ion intercalation/extraction in the open framework of Nb18W16O93 with multiple ion positions. Our work provides a strategy for electrochromic materials with fast response time and good cycle stability.

Tunable Interaction between Zn2+ and Superstructured Nb18W16O93 Bimetallic Oxide for Multistep Tinted Electrochromic Device

“…The W 4f 7/2 , W 4f 5/2, and W 5p 3/2 peaks are located at 35.7, 37.9, and 41.6 eV in the W 4f spectrum, respectively, indicating the highest oxidation state of W in this bimetallic oxide (W 6+ , Figure d). In addition, the obtained Nb 18 W 16 O 93 material presents a nanorod-like microstructure with an aspect ratio about 4:1 (Figure e), which is in line with the XRD patterns of material growth along the (001) direction . Moreover, the high-resolution transmission electron microscopy (HRTEM) image shows a clear lattice fringe with a wide spacing of 0.38 nm, corresponding to the (001) orthogonal crystal plane of Nb 18 W 16 O 93 .…”

Fast-Switching WO3-Based Electrochromic Devices: Design, Fabrication, and Applications

“…(A) Schematic diagram of the Nb 18 W 16 O 93 molecular structure. Panel reproduced with permission from ref . Copyright 2022 American Chemical Society.…”

A forest geotexture-inspired ZnO@Ni/Co layered double hydroxide-based device with superior electrochromic and energy storage performance

“…The switching time is defined as the time required to reach 90% change between the bleached state and the colored state. The coloration efficiency is defined as: 30,31 where ΔOD is the optical density, Δ Q is the inserted charge, and T b and T c denote the transmittance of the film in the bleached and colored states at the specified wavelength, respectively. Areal capacity and gravimetric capacity of the films were calculated from the GCD curves using: 32,33 where C a (mC cm −2 ) is the areal capacity, C m (C g −1 ) is the gravimetric capacity, I (A) is the discharge current, Δ V (V) is the discharge voltage range exclusive of the IR drop, a (cm 2 ) is the area of the electrode and m (g) is the mass of the active material (the mass of the FTO-coated glass substrate is not included).…”

“…The switching time is dened as the time required to reach 90% change between the bleached state and the colored state. The coloration efficiency is dened as: 30,31 CEðlÞ…”