Sol-gel derived nanostructured niobium pentoxide thin films for electrochromic applications

Nb2O5 thin films have been prepared using diethanolamine stabilized precursor sol and annealed at 500 degrees C. The optical, electrochemical, structural and morphological properties of Nb2O5 thin film are described. The X-ray diffraction study shows the formation of hexagonal crystal structure in the film. The presence of Nb-O linkage has been confirmed from the FT-IR. data. The coexistence of nanorod-like structures and round shaped polycrystalline grains has contributed to an enhanced electrochemical activity in the film. The Li ion storage capacity of the film is similar to 9.0 mC cm(-2) at a sweep rate of 20 mV s(-1) a single layer coating. The optical modulation, coloration efficiency, and coloration/bleaching time of the film are 30.6% (at 550 nm), 25 cm(2) C-1 (at 550 nm) and 171 s/6 s, respectively. The appreciably high coloration efficiency and fast switching kinetics shows the potential utility of these films in electrochromic windows.