Enhanced black state induced by spatial silver nanoparticles in an electrochromic device

The use of three-dimensional (3D) hierarchical indium tin oxide (ITO) branches of electrochromic devices (ECDs) is an effective approach for increasing the optical properties via localized surface plasmon resonance compared with two-dimensional nanostructured electrodes. ECDs with 3D branches were designed to operate in transparent, mirror and black states. Finite-difference time-domain simulation was used to find the electrical field distributions in three types of ECD: glass/ITO with Ag film, glass/ITO branches and glass/ITO branches with Ag nanoparticles. The ECDs had an optical transmittance of 73.76% in the transparent state, a reflectance of 79.77% in the mirror state and a reflectance of 8.78% in the black state. We achieved an ECD with high stability that can show ∼10 000 switching cycles among the three states.