Electrolyte Effects in Reversible Metal Electrodeposition for Optically Switching Thin Films

Abstract

Thin films that electronically switch between optical states are of interest for a number of applications including dynamic windows, switchable sunglasses, and optical gating devices. We report thin films based on the reversible electrodeposition of Cu and Au on tin-doped indium oxide (ITO) electrodes modified with Pt nanoparticles that switch between transparent and opaque states. By systematically studying the voltammetry of electrolytes with various compositions, we determine that Cu and Au synergistically facilitate optically reversible metal electrodeposition and that comparable electrolytes with either metal alone do not give rise to reversible systems. Furthermore, we demonstrate that halides in the electrolyte promote optically reversible metal electrodeposition by accelerating both the metal electrodeposition and dissolution processes.

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

“…An RMED with two nonferrous metals (Cu and Au) was also reported, with a 59% transmittance change (600 nm) in 60 s of deposition, but the minimum transmittance only reached 32%. [31] RMEDs utilize reversible metal electrodeposition on a transparent electrode to modulate their optical properties. A high transmittance change could be obtained in a short time, making it a promising candidate for smart window applications.…”

“…An RMED with two nonferrous metals (Cu and Au) was also reported, with a 59% transmittance change (600 nm) in 60 s of deposition, but the minimum transmittance only reached 32%. [ 31 ]…”

“…[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.…”

“…[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.…”

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

“…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.…”