Batteries are used in every facet of human lives. Desirable battery architectures demand high capacity, rechargeability, rapid charging speed, and cycling stability, all within an environmentally friendly platform. Many applications are limited by opaque batteries; thus, new functionalities can be unlocked by introducing transparent battery architectures. This can be achieved by incorporating electrochromic and energy storage functions. Transparent electrochromic batteries enable new applications, including variable optical attenuators, optical switches, addressable displays, touch screen devices, and most importantly smart windows for energy‐efficient buildings. However, this technology is in the incipient state due to limited electrochromic materials having satisfactory optical contrast and capacity. As such, triggering electrochromism via Zn2+ intercalation is advantageous: Zn is abundant, safe, easily processed in aqueous electrolytes and provides two electrons during redox reactions. Here, enhanced Zn2+ intercalation is demonstrated in Ti‐substituted tungsten molybdenum oxide, yielding improved capacity and electrochromic performance. This technique is employed to engineer cathodes exhibiting an areal capacity of 260 mAh m−2 and high optical contrast (76%), utilized in the fabrication of aqueous Zn‐ion electrochromic batteries. Remarkably, these batteries can be charged by external voltages and self‐recharged by spontaneously extracting Zn2+, providing a new technology for practical electrochromic devices.

No abstract

Electrochromic devices (ECDs) have received increased attention for applications including optoelectronics, smart windows, and low-emission displays. However, it has been recognized that the ECDs with transition-metal oxide (TMO) electrodes possess a high charge transport barrier because of their poor electrical conductivity, which limits their electrochromic performance. In this work, we addressed this limitation by utilizing a conjugated polymer to fabricate an organic-inorganic nanocomposite film that decreases the charge transport barrier of typical TMO electrodes. Using a conventional spray-layer-by-layer (spray-LbL) deposition technique, we demonstrate an electrochromic film composed of porous layers of tungsten molybdenum oxide (WMoO) nanorods permeated with an interconnected conductive layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The introduction of PEDOT:PSS is shown to significantly reduce the charge transport barrier, allowing the nanocomposite WMoO/PEDOT:PSS electrode to exhibit significantly improved electrochromic switching kinetics compared with the deposited WMoO films. Furthermore, the optical contrast of the nanocomposite electrode was observed to be superior to both pure PEDOT:PSS and WMoO electrodes, with a performance that exceeded the linearly predicted contrast of combining the pure films by 23%. The enhanced performance of the PEDOT:PSS-intercalated porous WMoO nanocomposite electrodes and the facile synthesis through a spray-LbL method demonstrate a viable strategy for preparing fast assembling high-performance nanocomposite electrodes for a wide variety of electrochemical devices.

Chalcogenide phase change semiconductors have played a crucial role in the evolution of photonic technologies. From their decades-long utilization at the core of optical disks to their emergence as a highly promising reconfigurable component for a variety of nanophotonic modulation, switching and sensing platforms, the field of optics has continuously recognized their potential and sought to engineer their properties through a variety of material, device and fabrication level schemes. Most recently, the integration of phase change semiconductors within various photonic metamaterials, metadevices and metasystems has ignited research interest worldwide. This has facilitated the development of a wealth of highly promising application-driven nanophotonic device platforms that address growing societal demands requiring higher data storage capacity, faster and more efficient telecommunication, as well as adaptive sensing and imaging with reduced size, weight and power requirements. Here, we present a comprehensive review on the evolution of reconfigurable phase change chalcogenide metamaterials that focuses not just on a device level perspective but also examines the underlying material and fabrication considerations that are critical to obtaining optimal performance in these groundbreaking devices.

Chalcogenide glasses have been widely adopted as a material platform for achieving reconfigurable metamaterials and metasurfaces, primarily through exploiting nonvolatile phase transitions inherent to these semiconductors. In such devices, the atomic lattice of the nanostructured medium reversibly changes between amorphous and crystalline phases, invoked through an energy‐intensive melt/quench process that can reduce device endurance due to chemical and geometrical drift. Metal‐doped amorphous chalcogenide semiconductors (MdACs) exhibit a directional photoinduced movement of their constituent metal‐ions when exposed to light with a photon energy equivalent or higher than the bandgap of the host chalcogenide glass. This “photoionic” movement results in nonvolatile changes of refractive index and conductivity at the nanoscale enabling a nonvolatile, nonbinary dynamic modulation of light removing the need for a phase transition. It is shown here that this photoionic movement in silver‐doped amorphous germanium selenide metasurfaces enables reversible optical switching. Understanding and integrating the photoionic mechanism within various optoelectronic device platforms presents significant potential for realizing a range of nonvolatile optically reconfigurable nanophotonic devices for emerging display, data storage, and signal processing applications.

The wrinkle period and morphology of a metal thin film on an elastic substrate is typically controlled by modifying the substrate before carrying out additional metal deposition steps. Herein, we show that a simultaneously selective and reactive sputtering plasma that modifies the surface of a polydimethylsiloxane (PDMS) substrate while not reacting with the metal during the deposition process decreases the wrinkle wavelength and induces additional wrinkling components and features such as ripples or folds. The selective reaction of the nitrogen plasma with PDMS functionalizes the siloxane surface into silicon oxynitride. This hardens the immediate surface of PDMS, with a quadratic increase in the Young’s modulus as a function of the sputtering flow ratio. The increase in the critical strain mismatch and the corresponding presence of folds in the nitrogen-modified wrinkled silver film form a suitable plasmonic platform for surface-enhanced Raman spectroscopy (SERS), yielding an enhancement factor of 4.8 × 105 for detecting lipids. This enhancement is linked to the emergence of electromagnetic hotspots from surface plasmon polariton coupling between the folds/wrinkles, which in turn enables the detection of low concentrations of organics using SERS. Furthermore, when strained, the nitrogen-modified wrinkles enhance electrical conductivity by a factor of 12 compared with unmodified films. Finally, the optical properties of the substrate can be tuned by altering the N2 content. The simple addition of nonreactive nitrogen to silver sputtering enables simultaneous PDMS hardening and growth of the silver film and together provide a new avenue for tuning wrinkling parameters and enhancing the electrical conductivity of pliable surfaces.

We report the first metasurfaces nanostructured from metal doped chalcogenide semiconductors that can be reversibly reconfigured through non-volatile photo-induced long range movement of their metal ions (photo-ionic behavior), without the need for a phase transition.

No abstract