Multifunctional smart window based on transparent embedded Ni-mesh electrodes

Flexible electrochromic devices (ECDs) are a future technology with huge impact on wearable displays, energy saving, and adaptive camouflage. In this work, we used embedded nickel (Ni) mesh transparent electrodes combined with a thin polymer film of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) to build a multifunctional flexible electrochemical device that integrates the functions of electrochromic and supercapacitor devices. The multi-layer architecture improves the device performance in terms of optical contrast and mechanical strength. Ni-mesh electrodes have a high optical transparency (84.8%), good mechanical flexibility, and low resistance (0.5 Ω/sq), which is conducive to efficient electron injection, benefiting to the response time of the constructed device. The thin polymer film of PEDOT:PSS is an electrochromic (EC) material that also uniformly distributes electrons for a uniform coloration. The fabricated device shows fast response to coloring and bleaching (1.2 and 0.8 s, respectively), an absolute transmittance contrast ratio of 40%, and area capacitance of up to 2.48 mF/cm 2 . Furthermore, the device exhibits excellent flexibility, and the electrochromic and electrochemical properties of the device are only partially diminished upon folding, which is beneficial for the construction of multifunctional flexible electrochromic devices. With its response time, working stability, and bending ability, our multifunctional device paves the way for the next generation of flexible electronics.