Nd–Nb Co-doped SnO₂/α-WO₃ Electrochromic Materials: Enhanced Stability and Switching Properties

Abstract

The fabrication of Nd−Nb co-doped SnO 2 /α-WO 3 electrochromic (EC) materials for smart window applications is presented in the present paper. Nb is a good dopant candidate for ECs owing to its ability to introduce active sites on the surface of α-WO 3 without causing much lattice strain due to the similar ionic radius of Nb 5+ and W 6+ . These active sites introduce more channels for charge insertion or removal during redox reactions, improving the overall EC performance. However, Nb suffers from prolonged utilization due to the Li + ions trapped within the ECs. By coupling Nd with Nb, the co-dopants would transfer their excess electrons to SnO 2 , improving the electronic conductivity and easing the insertion and extraction of Li + cations from the ECs. The enhanced Nd−Nb co-doped SnO 2 /α-WO 3 exhibited excellent visible light transmission (90% transmittance), high near-infrared (NIR) contrast (60% NIR modulation), rapid switching time (∼1 s), and excellent stability (>65% of NIR modulation was retained after repeated electrochemical cycles). The mechanism of enhanced EC performance was also investigated. The novel combination of Nd−Nb co-doped SnO 2 /α-WO 3 presented in this work demonstrates an excellent candidate material for smart window applications to be used in green buildings.

Review on recent progress in WO3-based electrochromic films: preparation methods and performance enhancement strategies

“…Specific composite structures may endow the films with more functions and expand the application scenarios of the films. 21,23,37,38,104,[158][159][160][161] Yin et al 21 prepared Gd-WO 3 /Ag/ Gd-WO 3 (WGd-Ag-WGd, 52/12/42 nm) film with the functions of a transparent conductive layer and electrochromic layer by reactive sputtering, as shown in Fig. 10a and b.…”

Effect of metal dopants on the electrochromic performance of hydrothermally-prepared tungsten oxide materials

“…On the other hand, when the distortion of the WO x cage is too much, leading to amorphization, the movement of the Li + ions is obstructed, with the consequent drop of diffusion values. 37 The EC reversibility of the samples is estimated by using the ratio of charge de-insertion (Q out ) to charge insertion (Q in ) in the lms. All the doped samples present higher reversibility than the pristine WO x sample (10% increase in Nb-low), but higher metal ions amount result in a decrease of the performances.…”

High Optical Contrast of Quartet Dual-Band Electrochromic Device for Energy-Efficient Smart Window

“…6,7 For instance, tungsten oxide, which is a representative inorganic material, can change its color from transparent to blue only, thereby blocking the near-infrared (NIR) wavelength region. 8 Recent studies on the development of ECDs have primarily focused on fabricating multifunctional devices to overcome the challenges associated with improving the functional properties of a single material. Dual-band ECDs are among the recently developed ECDs, which can independently control the transmittance at specific wavelengths.…”

“…Electrochromic materials are divided into inorganic and organic materials . The inorganic materials are widely used owing to their excellent thermal and chemical stability, high durability, and high optical contrast; however, they are capable of achieving only single coloration, which limits their applicability. , For instance, tungsten oxide, which is a representative inorganic material, can change its color from transparent to blue only, thereby blocking the near-infrared (NIR) wavelength region …”