Selective Electrochromic Regulation for Near-Infrared and Visible Light via Porous Tungsten Oxide Films with Core/Shell Architecture

Abstract

Dual-band electrochromic smart windows have become a research hotspot owing to their unique ability to selectively control near-infrared (NIR) and visible (VIS) light. However, the design and exploitation of dual-band electrochromic films are still an extreme challenge due to the scarcity of relevant high-performance materials. To solve this issue, we here proposed a type of porous WO 3 film with nanowires/nanoparticles core/ shell architecture as a promising candidate, endowing smart windows with a dual-band electrochromic feature. Moreover, the mechanism of the dual-band electrochromism is illustrated by the response of the transmittance spectra in Li + -based or TBA + -based electrolytes to distinguish the electrochemical behavior and the cyclic voltammetry to determine the degree of diffusion-limited kinetics. Our results indicate that the dual-band electrochromic performance is credited to the progressive electrochemical reduction procedure, in which the capacitive charging process gives rise to NIR regulation and the following ion intercalation contributes to VIS light modulation. Furthermore, we develop a dual-band electrochromic energy storage prototype device utilizing the porous WO 3 film. This work describes a judicious strategy for designing dual-band electrochromic films, promoting the evolution of dual-band electrochromic technology.

Amorphous and Crystalline Ti-Doped WO3·2H2O for Dual-Band Electrochromic Smart Windows

“…With the increase of the applied voltage, the Li ions are apt to be diffused in the lattice, resulting in new absorption transitions in the VIS light. 23,24 At −0.5 V, the transmittance is only 2.6% at 633 nm and 0.05% at 1050 nm, respectively. In the dark mode, neither VIS nor NIR light can pass through the film, keeping the room dark and cool.…”

“…At −0.01 V, Li ions are mainly adsorbed on the nanosheet surface to form LSPR, which is difficult to insert into the lattice. , In the cool mode, the transmittance of 3% TiWH45 is 2.6% at 1050 nm and 49.7% at 633 nm, the NIR region was shielded by the 3% TiWH45 film, while VIS light can pass through the film, maintaining a bright and cool indoor environment. With the increase of the applied voltage, the Li ions are apt to be diffused in the lattice, resulting in new absorption transitions in the VIS light. , At −0.5 V, the transmittance is only 2.6% at 633 nm and 0.05% at 1050 nm, respectively. In the dark mode, neither VIS nor NIR light can pass through the film, keeping the room dark and cool.…”

“…9,18,23 Liu et al synthesized a WO 3 nanowire/nanoparticle film with an energy storage of 4.9 μAh cm −2 at 0.08 mA cm −2 and excellent dual-band electrochromism (633 nm: 87.1%, 1200 nm: 75.5%). 24 Increasing capacitance can enhance LSPR to achieve excellent dual-band electrochromism. 25,26 The introduction of structural water transforms battery-like behavior of WO 3 into the ideal pseudocapacitance of hydrated WO 3 .…”

Advanced inorganic nanomaterials for high-performance electrochromic applications

“…As shown in Fig. 8a–e, Cai et al 70 recently prepared a type of porous WO 3 film with nanowires/nanoparticles core/shell architecture as a promising candidate for smart windows with a dual-band electrochromic feature. The results indicated that the dual-band electrochromic performance was credited to the progressive electrochemical reduction procedure, in which the capacitive charging process gave rise to NIR regulation and the following ion intercalation contributed to VIS light modulation.…”

In situ efficient growth of Rubik nanocube WO3·0.33H2O array films for high-performance electrochromic energy storage devices

“…To date, a range of wet methods has been used for the attempted fabrication of WO 3 films, including chemical bath deposition, 25 electrodeposition, 26 hydrothermal, 27 solvothermal and sol-gel methods. 28,29 Among them, the hydrothermal technique offers attractive opportunities for fabricating WO 3 films with various crystal structures and morphologies.…”