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The complementary electrochromic device, where the optical transmittance changes upon the flow of cations back and forth between anodic and cathodic electrodes, operates in a rocking‐chair fashion if it can inherently self‐discharge. Herein, the first demonstration of a dual‐mode electrochromic platform having self‐coloring and self‐bleaching characteristics is reported, which is realized by sandwiching zinc metal within a newly‐designed Prussian blue (PB)‐WO3 rocking‐chair type electrochromic device. It is demonstrated that the redox potential differences between the zinc metal and the WO3/PB electrodes endow the self‐color‐switching of these electrodes. By employing a hybrid electrolyte of Zn2+/K+, it is further shown that the colored PB‐WO3 rocking‐chair device is capable of spontaneously bleaching when the anodic and cathodic electrodes are coupled. This dual‐mode light‐control strategy enables the electrochromic devices to exhibit four distinct optical states with the highest optical contrast of 72.6% and fast switching times (<5 s for the bleaching/coloration processes). Furthermore, the built‐in voltage of the dual‐mode electrochromic devices not only promotes energy efficiency, but also augments the bistability of the devices. It is envisioned that the broad implication of the present platform is in the development of self‐powered smart windows, colorful displays, optoelectronic switches, and optical sensors. [ABSTRACT FROM AUTHOR]

Electrochromic devices with a wide color gamut distribution have long been sought after for non‐emissive display technologies. The current state‐of‐the‐art multicolor electrochromic displays utilize a single electrochromic layer, which restricts their color tunability within a linear or curved segment scope in International Commission on Illumination (CIE) color space and thus leads to limited color hues. Herein, it is demonstrated vivid electrochromic displays with broadened color hues via fabricating Zn‐based multicolor electrochromic displays having 2D CIE color space tunability. In addition, it is revealed that a Fabry–Perot nanocavity structure can further tune the color hues via altering the coordinate of the 2D CIE color space. It is known that this is the first demonstration of 2D CIE color space tunability realization from a single transparent or reflective electrochromic device. These findings represent a novel strategy for fabricating multicolor electrochromic displays and are expected to advance the development of electrochromic displays. [ABSTRACT FROM AUTHOR]

Since the discovery of electrochemical coloration phenomenon, electrochromic devices capable of monitoring transmittance, reflectance, and absorption at designated wavelengths have embraced great achievements. The marriage of electrochemistry and optical modulation has infused fascinating properties in electrochromic devices, which find applications in thermal management, display, smart windows, and camouflage. Inspired by the multipronged advancements in electrochemical devices, the incorporation of multivalent metal ions having rich electrochemistry into electrochromic devices is bloomed in recent years. Zinc, distinguished by its high crustal abundance, suitable standard redox potential, and inherent safety, has facilitated the assembly of highly efficient electrochromic devices. Zinc anode-based electrochromic devices with dual-band (visible and near-infrared) tunability, energy retrieval functions, multi-color options, multiple working modes (transmittance mode and reflectance mode), and scalability have been prominently showcased. Here in this review, the birth of zinc anode-based electrochromic devices will be systematically narrated, starting from the discovery of electrochromic phenomenon, to the evolution of electrochromic devices, and to the latest achievements in zinc anode-based electrochromic devices. Additionally, this review delves into the future development trends and perspectives of zinc anode-based electrochromic devices. This review serves as a handbook, which summarizes the history of electrochromism, introduces the physics behind it, highlights the development in zinc anode-based electrochromic devices, and aims to inspire future endeavors into this field, particularly those focused on developing energy-efficient electrochromic devices. [ABSTRACT FROM AUTHOR]

Highlights: La3+/Na+ bimetallically doped vanadate, designed for the first time, is promising in many electrochemical applications (e.g., batteries, electrochromics). This is the first report of electrochromic displays employing bimetallically doped vanadate. It is demonstrated for the first time that zinc dendrites and vanadate dissolution are significantly inhibited by employing an aqueous hybrid Zn2+/Na+ electrolyte. Vanadates are a class of the most promising electrochromic materials for displays as their multicolor characteristics. However, the slow switching times and vanadate dissolution issues of recently reported vanadates significantly hinder their diverse practical applications. Herein, novel strategies are developed to design electrochemically stable vanadates having rapid switching times. We show that the interlayer spacing is greatly broadened by introducing sodium and lanthanum ions into V3O8 interlayers, which facilitates the transportation of cations and enhances the electrochemical kinetics. In addition, a hybrid Zn2+/Na+ electrolyte is designed to inhibit vanadate dissolution while significantly accelerating electrochemical kinetics. As a result, our electrochromic displays yield the most rapid switching times in comparison with any reported Zn-vanadate electrochromic displays. It is envisioned that stable vanadate-based electrochromic displays having video speed switching are appearing on the near horizon. [ABSTRACT FROM AUTHOR]

The Zn anode-based electrochromic energy storage devices (EESDs) provide a promising strategy to overcome the contradiction of electrochromism and energy storage for efficient devices. In this regard, the device configuration can endow the electrochromic devices with superior electrochromic performance and excellent energy recovery efficiencies. [Display omitted] With the emerging demand of multifunctional optoelectronic devices, the integration of electrochromism and energy storage functionalities within a single platform has become a research frontier in the electrochromic community. However, the conventional electrochromic function is inherently contradictory to the energy storage function in electrochromic devices. In this review, we firstly introduced the working principles and device configurations of the rudimentary electrochromic energy storage devices (EESDs), where the origin of the contradiction between electrochromic and energy storage functionalities is comprehensively introduced. We then reviewed the current status and applications of EESDs, where we hope to clearly reveal the developing trends of the EESDs. Finally, we proposed our perspectives on the design strategy of zinc anode-based electrochromic devices for overcoming the contradiction between electrochromism and energy storage of EESDs. [ABSTRACT FROM AUTHOR]

Electrochromic displays have attracted increased attention owing to their reversible switch of multicolors. However, the external voltage requirement for triggering the color switching makes them far from an optimum energy‐efficient technology. The newly developed electrochromic batteries eliminate the energy consumption for coloration while they can retrieve the consumed energy for bleaching. Such features make the electrochromic battery technology the most promising technology for energy‐efficient electrochromic displays. Here, a scalable method to synthesize colloidal V3O7 nanoparticles is presented, which is compatible with solution‐process techniques for aqueous Zn‐V3O7 electrochromic battery displays. The Zn‐V3O7 electrochromic battery display shows an optical transmittance contrast (21%), rapid self‐coloration time (6.6 s), and switching times (10.4/28.6 s for coloration/bleaching processes). Moreover, the electrochromic battery display shows a compelling energy retrieval function. For a proof of concept, a prototype display is constructed, which possesses an open‐circuit potential (OCP) of 1.38 V. The prototype display can reversibly switch between the multicolors (fully yellow, fully grayish‐blue, and half yellow‐half grayish‐blue images) and partially retrieve the consumed energy. This research presents a facile strategy to synthesize colloidal V3O7 nanoparticles, as well as a novel electrochromic battery display having energy retrieval functions, thus facilitating the development of energy‐efficient electrochromic displays. [ABSTRACT FROM AUTHOR]