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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]

Research regarding electrochromic (EC) materials, such materials that change their color upon application of an electrochemical stimulus, has been conducted for centuries. However, most recently, increasing efforts have been put into developing novel solutions to utilize these on-off switching materials in advanced nanoplasmonic and nanophotonic devices. Due to the significant change in dielectric properties of oxides such as WO3, NiO, Mn2O3 and conducting polymers like PEDOT:PSS and PANI, EC materials have transcended beyond simple smart window applications and are now found in plasmonic devices for full-color displays and enhanced modulation transmission and photonic devices with ultra-high on-off ratios and sensing abilities. Advancements in nanophotonic ECDs have further decreased EC switching speed by several orders of magnitude, allowing integration in real-time measurement and lab-on-chip applications. The EC nature of such nanoscale devices promises low energy consumption with low operating voltages paired with bistability and long lifetimes. We summarize these novel approaches to EC device design, lay out the current short comings and draw a path forward for future utilization. [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]

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]