High switching speed and coloration efficiency of titanium-doped vanadium oxide thin film electrochromic devices

• Main Authors: Lu, Yingxi, Liu, Liang, Mandler, Daniel, Lee, Pooi See
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
• Online Access: https://hdl.handle.net/10356/105895; http://hdl.handle.net/10220/20955
• Institution: Nanyang Technological University

Titanium (Ti)-doped vanadium oxide thin films were fabricated by electrochemical deposition on linear polyethylenimine (LPEI)-modified indium tin oxide-coated glass from mixed vanadium oxide and titanium oxide solutions with different Ti concentrations. The as-prepared films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The electrochemical behaviour of the films was studied using cyclic voltammetry (CV) in 1.0 M LiClO4/propylene carbonate solution. Electrochromism of the oxide films upon Li-ion intercalation/deintercalation was investigated by transmittance measurements during the CV process. The charge transfer resistance of the Ti-doped vanadium oxide film was systematically analyzed with electrochemical impedance spectroscopy (EIS). The amorphous Ti-doped vanadium oxide film containing 4 mol% Ti exhibited the highest transmittance contrast (Δ%T = Tmax − Tmin) of ca. 51.1%T, and coloration efficiency of 95.7 cm2 C−1 at 415 nm. By increasing the Ti content to 10 mol%, the Ti-doped vanadium oxide film exhibited high switching speed and good cycling reversibility reaching 80% of colouring and bleaching time of 5 and 6 s, respectively. Furthermore, the transmittance contrast drops by only 10% after 600 cycles in a two-electrode system.