Abstract:

Electrochromic Nb₂O₅ films were prepared successfully by RF sputtering process. These films are transparent in bleached state and brownish gray in
colored state. Cyclic voltammetry (CV) measurement results show that the film has good stability, high reversibility of Li^+ insertion/extraction. The
coloration efficiency is 16.68cm²/C at 550nm. The difference of transmittance between bleached and colered states is 20%-30% in visible range.
XPS results show that the electrochromic properties of the Nb₂O₅ film can be attributed to the reversible redox reaction between Nb^V and Nb^IV with
the double injection/extraction of Li⁺ and e^-, which can be described as:
mmNb^V₂O₅→ Li_xNb_x^IVNb_2-x^VO₅
←→ Li_x-yNb_x-y^IVNb_2-(x-y)^VO₅ (x≥y).

Key words: iobium oxide, RF sputtering, electrochromism