Enhanced coloration efficiency for electrochromic devices based on anodized Nb2O5/Electrodeposited MoO3 binary systems

There is a continuous quest for developing electrochromic (EC) transition metal oxides (TMOs) with increased coloration efficiency. As emerging TMOs, Nb2O5 films, even those of ordered anodized nanochannels, have failed to produce the required EC performance for practical applications. This is attributed to limitations presented by its relatively wide bandgap and low capacity for accommodating ions. To overcome such issues, MoO3 was electrodeposited onto Nb2O5 nanochannelled films as homogeneously conformal and stratified alpha-MoO3 coatings of different thickness. The EC performance of the resultant MoO3 coated Nb2O5 binary system was evaluated. The system exhibited a coloration efficiency of 149.0 cm(2) C-1 exceeding that of any previous reports on MoO3 and Nb2O5 individually or their compounds. The enhancement was ascribed to a combination of the reduced effective bandgap of the binary system, the increased intercalation probability from the layered alpha-MoO3 coating, and a high surface-to-volume ratio, while the Nb2O5 nanochannelled templates provided stability and low impurity pathways for charge transfer to occur.