Colorless/Black Switching Electrochromic Device Based on WO₃·<i>x</i>H₂O and Reversible Metal Electrodeposition

Electrochromic (EC) smart windows utilizing reversible metal electrodeposition device (RMED) offer a compelling alternative for dynamically regulating the transmissions of optical and thermal energy.An EC device (ECD) is constructed by utilizing RME of Bi/Cu on WO3xH2O film electrodeposited onto fluorine-doped tin oxide (FTO) transparent conductive glass.The electrolyte consists of CuCl2, BiCl3, KCl and HCl aqueous solution, supplying necessary components for both electrochemical and electrodeposition processes.The device shows the ability to rapidly transition between colorless and black states, which achieves a large optical modulation of 77.0% at 570 nm.In the black state, the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm.Furthermore, the device is able to maintain 96.6% of its initial optical modulation after coloration/bleaching cycling of 60,000 s, exhibiting a good cyclic stability.And this RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance.The results offer a solution to overcome the limitations of RMEDs that have poor cyclic stability and improve the optical modulation of ECDs.