Electrochromic Metal Oxides: Recent Progress and Prospect

Abstract

The studied EC materials usually include viologens (as polymeric films), conjugated conducting polymers, transition metal oxides (e.g., WO 3 and NiO), metal coordination complexes (e.g., polymeric, evaporated, sublimed films). [7,11] Bene fitted by the diversity in composition/structure and the superior electrochromic performance, the electrochromism based on the thin-film transition metal oxides has become a hot topic. Recently, there have been some important breakthroughs in the transition metal oxide-based electrochromism, ranging from the development of new materials, [12] the introduction of new nanostructures, [13][14][15] element doping, [16,17] and composites [18][19][20][21] to novel designs and concepts of visible light and near-infrared radiation (NIR) dual-modulated smart windows [8,14,20] and the self-powered electrochromic batteries. [22,23] Therefore, the exploration of electrochromic devices with multifunctionalities and unique features by integrating both energy storage and electrochromism has been attracting great attention.There are several elaborate reviews serving as good references for this field, [1,3,4,6,[8][9][10] however, more comprehensive integration and up-to-date summaries embracing all relevant materials and applications are still lacking. Under such a background, as outlined in Figure 1, we attempt to provide a systematic and recapitulative review on the material developments and application status of electrochromism with a focus on transition metal oxides. Additionally, tailored synthesis and material design toward enhanced optical modulation and fast switching are also illustrated. Finally, an outlook on the future research trends in electrochromism is presented. This review will be very instructive and of special importance for directing other researchers in the future. Electrochromism: Fundamentals, Principles, and Device Structure Fundamentals and PrinciplesElectrochromism refers to the reversible change of colors and transparency under charge insertion/extraction or chemical reduction/oxidation induced by the application of an electrical current or a potential difference. [4][5][6] In the mid-1980s, the acceptance of electrochromism in fenestration technology as an approach to achieve energy efficiency in buildings captured the interest of researchers and the public. [3,24] This concept was coined as "smart window," which was capable of achieving Electrochromism has received increasing attention due to its unique electrochromic feature and the induced applications. This review provides an overview on the recent developments in the synthesis and application of the electrochromic metal oxides in smart windows, display devices, e-skins, and multifunctional energy storage devices. The main cathodic and anodic electrochromic metal oxides are surveyed here, with the discussion of representative examples in details. The current state-of-the-art research activities of the derived multifunctional electrochromic devices are highlighted, i.e., material systems, components, structures, m...

Electrochromic switching of tungsten oxide films grown by reactive ion-beam sputter deposition

“…The mostly studied EC materials include conjugated conducting polymers, transition metal oxides as well as metal coordination complexes [4][5][6][7][8][9]. Due to their diversity in composition and structure as well as their superior performance, electrochromism based on thin film transition metal oxides has become increasingly important in the last decade.…”

“…The EC properties of tungsten oxide layers depend on the composition, the crystal structure and the morphology [8,[30][31][32]. Compared to crystalline films, amorphous WO 3 exhibits more rapid coloration and improved efficiency but inferior stability [30,31].…”

Enhanced Supercapacitive Performance of Higher-Ordered 3D-Hierarchical Structures of Hydrothermally Obtained ZnCo2O4 for Energy Storage Devices

“…Over the past few decades, energy management, transportation and combination have become crucial for the rapidly growing market owing to the depletion of fossil fuel and the development of eco-friendly energy resources [ 1 , 2 , 3 , 4 ]. In this regard, clean, inexpensive, and consistent energy technologies such as batteries, and supercapacitors (SCs) have come into the limelight in our modern day-to-day life [ 5 , 6 , 7 ]. Recently, SCs are considered promising energy resources owing to excellent reliability, high power density, better setup safety, fast charge/discharge capability and large energy density [ 8 , 9 , 10 ].…”

Flexible Conductive Cellulose Network-Based Composite Hydrogel for Multifunctional Supercapacitors

“…As an energy storage device with an optical function, electrochromic supercapacitors (ESCs) have attracted much attention because of their advantages, such as rapid color change and efficient energy storage, while meeting specific application needs, such as smart windows, electronic paper, and auto-dimmer rearview mirrors [ 2 , 3 , 4 ]. Current electrochromic materials mainly include transition metal oxides (such as WO 3 and V 2 O 5 ) [ 5 , 6 , 7 ], Prussian blue, and conductive polymers (such as polyaniline (PANI) and polythiophene) [ 3 ]. Among these, tungsten trioxide (WO 3 ) serves as a cathodically coloring material, with PANI as an anodically coloring material, and there is a simultaneous complementary coloration for both of them in the electrochromic application.…”