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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]

Continued development in the areas of communication, security, medicine, and safety is calling for terahertz-wave technologies to evolve beyond laboratory research and into the realm of real-world applications. Due to the compatibility of waveguides with on-chip fabrication techniques and their ability to realize a small footprint, such structures provide a unique opportunity to achieve terahertz radiation generation in an on-chip arrangement, ideal for practical applications requiring terahertz electric fields. This review considers waveguiding arrangements that produce terahertz radiation using the nonlinear frequency-conversion techniques of optical rectification and difference frequency generation. The investigated terahertz radiation waveguiding sources are categorized into three different classes: those that confine and guide both the excitation electric fields and the generated terahertz radiation, those that confine and guide the excitation electric fields but not the generated terahertz radiation, and those that confine and guide the generated terahertz radiation but not the excitation electric fields. Various types of waveguides are surveyed from each category, including dielectric waveguides, metallic waveguides, photonic crystal waveguides, poled waveguides, and multiple waveguides embedded within one another. This review provides a detailed overview of state-of-the-art terahertz radiation waveguide sources, with the intent of aiding in the continuing development of such sources. [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]

Vanadium oxides are highly valued as electrochromic materials because of their multicolor capabilities. However, their practical applications have been limited due to challenges such as the dissolution of vanadate into aqueous electrolytes, leading to poor long‐term stability. Herein, a solution is proposed to the vanadate dissolution issue by utilizing a hybrid electrolyte consisting of tetraethylene glycol dimethyl ether (TEGDME) and water. This electrolyte has the unique ability to form a robust cathode electrolyte interface layer on vanadium oxide electrodes. As a proof of concept, zinc‐anode‐based multicolor transparent electrochromic displays are prepared using layered potassium vanadate (K2V6O16·1.5H2O, KVO) with a TEGDME–water hybrid electrolyte. By soaking the KVO electrode in the hybrid electrolyte, it is demonstrated that KVO has remarkable stability against dissolution. Furthermore, it is shown that KVO has superior electrochromic performance compared to sodium vanadate (NaV3O8·1.5H2O, SVO), due to the wide KVO interlayer spacing. Given the enhanced performance of this hybrid electrolyte and KVO cathode material, a zinc‐anode‐based electrochromic display prototype is shown to exhibit compelling performance. As such, this work is expected to be a significant catalyst for accelerating the development of vanadate‐based electrochromic displays. [ABSTRACT FROM AUTHOR]

The development of electrochromic materials has opened the door to the development of numerous devices including smart windows, color displays, optical filters, wearable camouflages, among others. Although the current electrochromic devices do not consume energy while maintaining their colored or colorless states, their bistable operation requires external electrical energy to be consumed during switching. To reduce the energy consumption of an electrochromic device, an emerging Zn anode‐based electrochromic device concept was recently introduced to partially retrieve the consumed electrical energy. In this Review, key technological developments and scientific challenges are presented for a broad range of Zn anode‐based electrochromic device configurations with emphasis on the inherent distinctions between the Zn anode‐based and conventional electrochromic devices. Specifically, a comprehensive comparison of the two classes of electrochromic devices in the high‐performance device design is provided. For the electrochromic layer, the methods for obtaining high‐quality electrochromic materials and thin films are reviewed. For the electrolytes, the effect of the dual ion system on the electrochromic performance is discussed. Also, some critical but unresolved issues in the device design and fabrication are discussed. The perspectives and outlook at the end of this Review provide recommendations to improve performance for future electrochromic studies. [ABSTRACT FROM AUTHOR]

Textile electronics embedded in clothing represent an exciting new frontier for modern healthcare and communication systems. Fundamental to the development of these textile electronics is the development of the fibers forming the cloths into electronic devices. An electronic fiber must undergo diverse scrutiny for its selection for a multifunctional textile, viz., from the material selection to the device architecture, from the wearability to mechanical stresses, and from the environmental compatibility to the end‐use management. Herein, the performance requirements of fiber‐shaped electronics are reviewed considering the characteristics of single electronic fibers and their assemblies in smart clothing. Broadly, this article includes i) processing strategies of electronic fibers with required properties from precursor to material, ii) the state‐of‐art of current fiber‐shaped electronics emphasizing light‐emitting devices, solar cells, sensors, nanogenerators, supercapacitors storage, and chromatic devices, iii) mechanisms involved in the operation of the above devices, iv) limitations of the current materials and device manufacturing techniques to achieve the target performance, and v) the knowledge gap that must be minimized prior to their deployment. Lessons learned from this review with regard to the challenges and prospects for developing fiber‐shaped electronic components are presented as directions for future research on wearable electronics. [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]