Fast‐Switching Speed and Ultralong Lifespan Au/Prussian Blue Electrochromic Film for Iris Devices Applications

Abstract

AbstractPrussian Blue (PB) is an excellent electrochromic (EC) material, possessing many praiseworthy advantages such as proper redox potential, large transmittance, environmental benignity, neutral colored state, and low cost. However, the co‐influence of weak interaction force and low electrical conductivity results in poor cyclic stability and slow switching speed. In this work, the novel Pt/Au and Au/PB films are prepared by electrodeposition to improve the EC properties of PB. The introduction of Au and Pt nanoparticles not only enhances the conductivity and inhibits polarization, but also increases the contact area and alleviates the stress and strain caused by volume expansion during ion insertion/extraction. Furthermore, the Pt/PB and Au/PB heterojunction with a strong inner electronic field promote the separation of electrons and holes and quicken charge transfer. In consideration of the better electrical conductivity, higher transmittance and strong local plasma resonance effect of Au nanoparticles, the Au/PB film shows ultrastable EC cyclic stability (96.4% after 2000), fast coloration/bleaching switching time (1.36/2.32 s), small charge transfer resistance (38.2 Ω), and high coloration efficiency (131.3 cm2 C−1). In addition, the EC iris devices are designed and assembled using Au/PB film as an EC layer to confirm the feasibility of the material in digital cameras and mobile phones.