Synergistic Structural-Compositional Modification of V2O5/C Films for Enhanced Multicolor Electrochromic Devices.

The color variations of electrochromic materials originate from the redox reaction triggered by the coinjection of electrons and ions under an applied electric field. Hence, the performance of electrochromic materials is highly dependent on the ion-electron transport process. However, the simultaneous realization of efficient ion and electron transport remains challenging. Herein, a porous V2O5/C electrochromic film with improved ion/electron transport rates was constructed through a dual structure-composition synergistic strategy. The porous structure of the film was optimized by a facile and economic plasma treatment technology due to the easily etched organic components introduced in the precursor. An optimized small-size pore structure results in outstanding electrolyte affinity and shorter ion transport paths. Furthermore, the residual carbon during the annealing process enhances the conductivity of the material, promoting electron transport. Benefiting from the optimized structure and composition, the plasma-treated V2O5/C film realizes superior ion and electron transport during electrochromic redox reactions. Therefore, the electrochromic performance of the film is significantly improved (18.4% faster switching and 51.9% greater optical modulation than unplasma-treated films), showing promising applications in smart windows and information displays. Such a simple and economical strategy for simultaneously enhancing ion/electron transport kinetics would offer a distinctive pathway for other metal oxide-based electrochemical materials.