Reversible Metal Electrodeposition Devices: An Emerging Approach to Effective Light Modulation and Thermal Management

Abstract

light-emitting devices. Chromogenic materials and devices are widely used in smart windows and paper-like displays, particularly electrochromic materials, which can be actively and reliably controlled because they only respond to electrical stimuli. [11][12][13][14][15] Reversible metal electrodeposition device (RMED) is a novel type of electrochromic devices that can switch from transparent to opaque state by the electrodeposition of a metal layer onto the transparent electrode, and switch back to transparent state by the dissolution of the metal layer. The appearance and disappearance of the metal layer cause the color change of RMEDs. They take advantage of the unique optical properties of thin metal films with different thicknesses and morphologies to allow for excellent light modulation, thermal management, and display effects. The switchability of electrochromic devices between not only transparent and tinted states (including black, red, yellow, blue, etc.) but also the mirror state is advantageous, because this allows them to choose the optimal working mode as desired, and thus to function more effectively for multiple tasks. Owing to its high extinction coefficient, a thin metal film with a thickness of a few tens of nanometers would be completely opaque and highly reflective like bulk metals. [16] Research has also shown that the reflectance of RMEDs in the visible and infrared (IR) regions can reach ≈100% [17] and 90%, [18] respectively. Because RMEDs utilize the reversible deposition of metals to change their color, without a fixed electrochromic layer, their structure would be much simpler than that of typical electrochromic devices. The wide reflectance modulation range and simple device structure of RMEDs render them distinct from other electrochromic devices. The best performance reported for RMEDs are listed in Table 1.In the last century and the first decade of the 21th century, sustained efforts have been invested to apply the reversible electrodeposition mechanism to display devices. [19][20][21][22][23][24] In recent years, research on RMEDs has been progressing owing to their potential applications in energy-saving fields, especially in light modulation [8,[25][26][27][28] and thermal management. [18,29,30] Ag, Bi, and Cu are the most widely studied metals for reversible electrodeposition because of their high reversibility and the use of hazard-free electrolytes. The reversible electrodeposition of Au, [31] Zn, [32] Pb [8] and other metals is rarely reported due to their poor reversibility or the need for hazardous electrolytes.The reversible metal electrodeposition device (RMED) is a novel electrochromic application that utilizes the appearance and disappearance of a metal layer to achieve spectrum control. A thin metal film with a thickness of a few tens of nanometers would be highly reflective in the visible and infrared region, making it an ideal material to achieve light and heat modulation. Because of their outstanding spectrum control ability, RMEDs can be applied to displays, smart ...

Bistable Silver Electrodeposition‐Based Electrochromic Device with Reversible Three‐State Optical Transformation By Using WO3 Nanoislands Modified ITO Electrode

“…It is apparent that the CV curves of the 2-electrode cells at each electrode are different from that of EC devices with ionic liquid-based electrolyte solutions, suggesting that the introduction of HBImBr will have certain influence on the electrochemical reaction. Nonetheless, all of the electrotransmittance changes are similar for the EC devices with and without HBImBr, which are the same three-state systems reported in the literature, [8,32,52,57,61] except for the electrochemical stability, as described below.…”

“…These optical changes are based on the mechanism of reversible electrodeposition and dissolution of Ag according to previous studies. [8,32,52,57,61] Since the formation of a rough Ag deposition layer will cause light absorption and/or multiple scattering, the surface modification of planar ITO with WO 3 nanoislands plays a great important role in achieving the black optical state. [33] Moreover, unlike the transient three-state EC device, the mirror and black state of the as-fabricated devices can remain stable for a long period without drawing power.…”

“…The second exploits reversible electrodeposition by depositing and dissolving metal (Ag, Bi, Cu, Ni, Pb, and others) onto a transparent conducting substrate to modulate its optical properties. [1,2,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] For the electrodeposition-based EC systems, the device structures mainly consist of two opposite transparent electrodes with an electrolyte in-between. The metal dissolved in the electrolyte will be deposited on the electrode surface when voltage is applied to the electrodes.…”

Dual-Band Electrochromism: Plasmonic and Polaronic Mechanisms

“…Reversible electrodeposition is instead the preferred strategy for creating EC devices from such materials, as discussed more elsewhere. [27][28] Instead, nanocrystals of doped metal oxides such as ITO, TiO2-x, Nb2O5-x, and WO3-x possessing low to intermediate carrier concentration (10 19 -10 21 cm -3 ) and LSPR absorption in the near-to mid-infrared region are regularly employed for capacitive plasmonic EC because of their ability to accommodate a wide range of electron concentrations, tuned both during synthesis and post-synthetically. [29][30] In fact, doped metal oxides can be utilized as both polaronic and plasmonic materials, and added electronic charge can be balanced by ions at the surface or interstitially, depending on the size of the crystal, the potential applied, and the size of the charge compensating ions compared to the interstitial channels.…”

Nanoscale Manipulating Silver Adatoms for Aqueous Plasmonic Electrochromic Devices

“…[14][15][16][17] This class of electrochromic devices not only can switch between multiple colors but also retains their colored states without the need for external electrical power. [18][19][20][21] While the electrochromic displays, based on organic molecules, [22][23] polymers, [24][25][26] or transition metal oxides, [27][28][29][30] have demonstrated multicolor characteristics, these devices exhibit inferior cycling stability compared to reversible metal deposition (RME). [31][32][33] Such a limitation hindered their practical applications and their potential commercialization.…”