Complementary multicolor electrochromic devices with excellent stability based on porous tin oxide nanosheet scaffold

Electrochromic devices (ECDs) have been extensively investigated as promising candidates in broad cutting-edge applications, such as smart windows, electronic labels, adaptive camouflage, etc. However, they have suffered from either inadequate color variations or poor cycling stability for a long time. Herein, we developed a general strategy to boost the cyclic stability and enrich the color variations of ECDs by scrupulous design of the composition and nanostructure of electrodes, in which porous tin oxide (SnO₂) nanosheets serve as the scaffold and typical metal oxides or conducting polymers as the active electrochromic materials. Various electrochromic composite materials, including polyaniline (PANI)@SnO₂, V₂O₅@SnO₂, and WO₃@SnO₂ heterostructured nanoarrays were prepared by the facile wet-chemical method. These composite electrodes exhibit remarkable electrochromic performances, e.g., superior cycling stability (more than 2000 cycles), rich color variations (more than 5 colors for PANI@SnO₂), and enlarged optical modulation. These excellent performances account for the heterogenous porous nanoarrays, which not only facilitate the intercalation/extraction of ions but also relieve the stress generated during the electrochemical process. In addition, diverse prototypes of complementary multicolor ECD with excellent cycling stability (over thousands of cycles) and rich color variations (8 colors) were realized for the first time. We believe that our work put forward a general strategy for developing high-quality multicolor complementary electrochromic devices.