A Transparent to Opaque Electrochromic Device Using Reversible Ag Deposition on PProDOT‐Me₂ with Robust Stability

Abstract A hybrid device integrating both electrochromic (EC) and metal electrodepositing effects is developed. The device consists of a working electrode made with poly(3,4‐(2,2‐dimethyl‐propylenedioxy)thiophene) (PProDOT‐Me₂), a counter electrode of bare indium tin oxide, and an electrolyte containing AgNO₃, LiBr, and Br₂. The electrolyte is specially designed to provide essential elements for both EC and electrodepositing reactions. By applying varying voltages, the device demonstrates three color states: transparent, blue, and opaque. Detailed measurements reveal that the device displays near‐zero transmittance in the opaque state and can work over 10 000 cycles, with 75.7% as the maximum optical modulation and about 5 s as its response time for both coloring and bleaching processes. This study may provide a way to break the limitation of conventional electrochromic devices (ECDs).