An extensible and tunable full-opaque cascade smart electrochromic device

Electrochromic devices (ECDs) are attracting attention for their simple controllable optical modulation and potential energy saving abilities. When integrated with solar cells self-powering and smart energy management systems may be realized. However, their performance, especially the opaque colored state for privacy protection and energy saving, is still a problem for most devices. Here we demonstrate a vertically integrated approach for preparing cascade electrochromic devices (CECDs) with marked performance compared with ECDs. The cascade strategy allows for devices that simultaneously achieve highly opaque colored states with shorter optical response times, stores comparably higher energy density, whilst protecting the device from electrical cycling degradation associated with high current densities. Furthermore, the adaptive electrochromic energy saving units are integrated, which could be an innovative green energy manage technology and enabling wide applications for smart home and daily or special use.