Calculating Band Alignment between Materials with Different Structures: The Case of Anatase and Rutile Titanium Dioxide

A method to calculate the band alignment between materials with different structures using passivated quantum dots is proposed. By using this method, the rutile/anatase titanium dioxide band offset is determined. The valence band maxima of anatase and rutile are close to each other, whereas the conduction band minimum of anatase is found to be about 0.2 eV higher than that of rutile, which is in agreement with the experimental fact that anatase has higher photocatalytic activity. The reliability of this method is further tested on several semiconductors, and reasonable results are obtained for most cases.