Elevated Temperature Anodized Nb2O5: A Photoanode Material with Exceptionally Large Photoconversion Efficiencies

Here, we demonstrate that niobium pentoxide (Nb2O5) is an ideal candidate for increasing the efficiencies of dye-sensitized solar cells (DSSCs). The key lies in developing a Nb2O5 crisscross nanoporous network, using our unique elevated temperature anodization process. For the same thicknesses of ∼4 μm, the DSSC based on the Nb2O5 layer has a significantly higher efficiency (∼4.1%) when compared to that which incorporates a titanium dioxide nanotubular layer (∼2.7%). This is the highest efficiency among all of the reported photoanodes for such a thickness when utilizing back-side illumination. We ascribe this to a combination of reduced electron scattering, greater surface area, wider band gap, and higher conduction band edge, as well as longer effective electron lifetimes.