Transparent Zinc‐Mesh Electrodes for Solar‐Charging Electrochromic Windows

Abstract

smart windows commercialization must overcome the challenges posed by slow switching speed, nonuniform switching processes, optical contrast, and energy consumption as the device is scaled up. Consequently, having an inexpensive new energy-efficient and high optical contrast electrochromic platform with a rapid and uniform switching process is a welcomed opportunity that will accelerate the development and commercialization of large-scale electrochromic smart windows. Simultaneously, the development of such an large-scale electrochromic platform would further advance the abovementioned applications using electrochromic technologies. In a conventional electrochromic smart window, the requirement of an external energy source brings about a few drawbacks, including complicated installation, increased cost, and offsetting energy savings. [9,10] To overcome these issues, several efforts have been devoted to the implantation of photovoltaic (PV)-electrochromic window systems. [11] As schematically shown in Figure 1a, the PV device provides the needed electrical energy, via the photoelectron conversion of light photons, to operate the electrochromic smart window. [12] Although this configuration eliminates the need for an external power source, the electrical wiring is quite elaborate as it requires control circuitry to manage the current and voltage that power the electrochromic window. [10] The solar-generated power consumed by the electrochromic window renders this system far from being an energy-efficient platform. Furthermore, in a normal operation requiring active sunlight regulation, the electrochromic window needs to be colored during the day and bleached at night or during sunlight intermittency. However, unless the electrical energy is stored in an external energy storage unit (e.g., battery), the lack of solar electrical power source to bleach the electrochromic window at night or during sunlight intermittency at daytime introduces another significant challenge to this PV-electrochromic window platform. [9] Recently, we reported on a new and fundamentally different class of ECDs which facilitates the ability to efficiently retrieve the consumed energy while preserving the natural electrochromic characteristics. [2,13,14] In these devices (defined as zincanode-based electrochromic device, ZECD), an aqueous electrolyte compatible zinc anode is used as the counter electrode. Most importantly, due to the redox potential difference between Newly born zinc-anode-based electrochromic devices (ZECDs), incorporating electrochromic and energy storage functions in a single transparent platform, represent the most promising technology for next-generation transparent electronics. As the existing ZECDs are limited by opaque zinc anodes, the key focus should be on the development of transparent zinc anodes. Here, the first demonstration of a flexible transparent zincmesh electrode is reported for a ZECD window that yields a remarkable electrochromic performance in an 80 cm 2 device, including rapid switching times (3.6 and ...

Reversible Zn2+ Insertion in Tungsten Ion-Activated Titanium Dioxide Nanocrystals for Electrochromic Windows

“…This, as a result, will lead to a decrease in the amount of inserted cations and is expected to enhance the electrochromic performance, including rapid switching times and good cycling stability [24,25]. In addition, some of the multivalent ions are compatible with aqueous electrolytes, which shows great advantages in operational safety and low production cost [17,20,24,26]. Therefore, multivalent metal ions are gradually considered as superior alternatives to construct high-performance electrochromic devices.…”

Fiber‐Shaped Electronic Devices

“…Given the high mechanical strength and the high electrical conductivity, stainless steel fibers were initially utilized as the core substrate for the fabrication of wearable electronics. [ 17 ] However, stainless steel fibers show poor softness and flexibility, [ 18 ] which significantly limit their weavability into textiles and stretchability for practical applications. Woven stainless steel filter meshes were found to be stretchable when being tailored along a direction of 45° to its weft or the warp.…”

“…Electrochromic materials, which are the most representative chromatic materials, could reversibly change colors or optical properties through redox reactions under an applied electric field. [ 322–324 ] These electrochromic materials demonstrated a great promise in many applications, including smart windows, [ 18,33,323,325,326 ] and displays. [ 307,327 ] With the demand for wearable electronics, new applications and functionalities were enabled via electrochromic materials.…”

Dynamic Windows Using Reversible Zinc Electrodeposition in Neutral Electrolytes with High Opacity and Excellent Resting Stability

“…[4,5] In addition to buildings, dynamic windows could also be used in automobiles, [6,7] sunglasses, [8,9] mirrors, [10,11] displays, [12,13] and transparent batteries. [14,15] Over the last three decades, researchers have explored various types of electrochromic materials for dynamic window applications. [16,17] The most common electrochromic materials are transition metal oxides, which switch color upon changing oxidation state.…”

“…[34] However, neutral pH electrolytes and Zn metal's sluggish ability to evolve H 2 can kinetically impede this unwanted side reaction. [14,35,36] Furthermore, ZnO, which also can form during electrodeposition, prevents H 2 production. [37] The Zn aqueous battery literature shows that organic acids or surfactants in the electrolyte can adsorb on electrodes and further increase the overpotential for H 2 generation.…”