Annealing synthesis of coralline V₂O₅ nanorod architecture for multicolor energy-efficient electrochromic device

A coralline vanadium pentoxide nanorod architecture on an indium-doped tin oxide substrate for energy-efficient electrochromism has been prepared by a simple annealing treatment from an overfilled amorphous three-dimensionally ordered macroporous vanadia film. The coralline vanadium pentoxide nanorod architecture exhibited multicolor electrochromic performance (yellow, blue-green, and olive), high transmittance modulations (25% and 27% at the typical wavelengths of 460 nm and 1000 nm, respectively), and fast switching speeds (4.8 s for coloration and 7.2 s for bleaching at 890 nm). In addition, the coralline vanadium pentoxide nanorod architecture exhibited desirable cycle stability. After 100 cycles, negligible transmittance modulation decreased in the visible spectrum, and a decrease of only approximately 5.6% was found in the near-infrared spectrum. Cyclic voltammetry measurements indicated that the majority of the current response of the redox reactions of the coralline V₂O₅ nanorod architecture was surface controlled, which resulted in desirable cycling stability and fast switching speeds. A indium-doped tin oxide substrate/vanadia/liquid electrolyte/poly(3,4-ethylenedioxythiophene)/indium-doped tin oxide substrate electrochromic device was assembled, and the device showed multicolor changes with acceptable transmittance modulation and good cycling stability.