Abstract:

Electrochromic materials are energy-saving and environmentally friendly materials that can reduce energy use by adjusting sunlight and solar-heat. In particular, transition metal oxides with stable chemical properties have been widely studied as electrochromic materials. Recently, bimetallic oxides with two variable valence states of metal ions have received increasing attention due to their better electrochemical activity. In this study, Ti₂Nb₁₀O₂₉ films were successfully prepared on conductive glasses, and the effect of the atomic ratio of niobium to titanium in the precursor on the electrochromic properties of the thin films was investigated. The results show that the thin film prepared from precursors with an atomic ratio of niobium to titanium of 3 : 1 possesses the best electrochromic properties. It is worth noting that the thin film achieves a large optical modulation in the wavelength range of 300-1100 nm, and the transmittance in the bleached state is nearly 90%, appearing grayish blue under the action of −1.6 V, colorless state under the action of 0.4 V, and achieving a maximum optical modulation of 69.4% at the wavelength of 750 nm. After a square-wave potential of -1.6 V for 60 s and 0.4 V for 15 s, the film shows response time of 29.8 s for coloring and 5.9 s for bleaching. Coloration efficiency of the as-prepared film is 68.3 cm²·C^-1. The above results indicate that the successfully prepared Ti₂Nb₁₀O₂₉ thin film enriches variety of bimetallic oxide electrochromic materials and has widely application prospect.

Key words: electrochromic, bimetallic oxide, Ti₂Nb₁₀O₂₉, neutral color, optical modulation