Engineering Proton Injection and Phase Separation in Phosphate Glass For Low-Barrier Transport in All-Solid-State Electrochromic Devices

Abstract

When compared to electrochromic devices (ECDs) that use other forms of ion transport, those that use small-sized protons as transport Ions have faster response rates. However, integrating high-concentration protons into robust all-inorganic solid-state ECDs is difficult. This work employed solid-state electrochemical techniques to replace sodium ions in phosphate glass with hydrogen ions, obtaining a proton conductor with a high proton concentration. Furthermore, under controlled heating conditions, a conductive reinforcing phase with low proton activation energy was induced to precipitate within the material, achieving room-temperature proton conduction. Based on this proton conductor as an electrolyte, a device with an “ITO/WO3/Proton conductor/NiO/ITO” structure was constructed by pulsed laser deposition, realizing the effective integration of protons in all-inorganic solid-state ECDs. The application restrictions of all-solid-state devices, which usually have slow response times, are overcome by this proton-transporting solid-state device's fast electrochromic effect (switching time close to 1s). This study presents a new strategy integrating fast switching for inorganic solid ECDs.