Controlled preparation of vanadium pentoxide films and their multicolor electrochromic properties

Vanadium pentoxide (V 2 O 5 ) films were fabricated on indium tin oxide substrates via a simple electrophoretic deposition method, with precise control over applied voltage and deposition duration. Both the electrophoretic deposition time and applied voltage are identified as key parameters in the electrophoretic deposition process. Systematic investigation was conducted to determine the optimal voltage and time for deposition of V 2 O 5 films. The uniform V 2 O 5 films with excellent multicolor electrochromic properties, such as yellow, yellow-green, green and orange-red, could be obtained when the electrophoretic deposition time was 5 min and the voltage was -2 V. An electrochromic device based on the as prepared V 2 O 5 film was assembled and its switching performance was evaluated. At 730 nm, the coloration efficiency (CE) value of the V 2 O 5 device was 22.6 cm 2 C -1 (from green to orange-red), and the coloring and fading times of the V 2 O 5 device were 6 s and 4 s, respectively. The V 2 O 5 films maintained 81.79% charge transfer after 200 cyclic voltammetry (CV) measurements in the voltage range of -1 V to 2 V. This work presents a facile and green strategy for the controllable preparation of V 2 O 5 films and their devices with multicolor electrochromic behaviors.