Facile Fabrication of Trimodal Switchable Mirror Device with Zero Transmittance in the Black State

The electrochromic mirror device (ECD) demonstrating transparent, mirror, and black states with zero transmittance in the black state is fabricated using facile dry deposition method. The device is capable of achieving both a highly reflective mirror and a complete black state. ECD is fabricated using a WO3 film deposited by nanoparticle deposition system (NPDS) and optical characteristics of its transparent, mirror, and black states are evaluated. Notably, the device demonstrates the mirror state with high reflectance over 80% and a black state that completely blocks the entire visible light, resulting in nearly zero transmittance. Device durability is evaluated over 100 cycles; the transmittance of the black and transparent states is measured to be 9.61%, 79.6% at its wavelength of 680 nm, respectively. Moreover, the reflectance of the mirror state at the same wavelength is measured to be 73.1% and 72.7% for the first and 100th cycles, respectively. Microstructural observations suggest that the visible light‐blocking effect is a consequence of the rough surface obtained using NPDS, which leads to uneven electrodeposition of Ag ions to produce localized surface plasmon resonance. Dry deposition method of the electrochromic layer is an excellent method for fabricating high‐contrast three‐mode electrochromic mirrors. Dry deposition method of the electrochromic layer is an excellent method for fabricating high‐contrast three‐mode electrochromic mirrors. The device demonstrates the mirror state with high reflectance over 80% and a black state that completely blocks the entire visible light, resulting in nearly zero transmittance due to uneven electrodeposition of Ag ions to produce localized surface plasmon resonance.