First-principles Studies of Band Gap Engineering in Ferroelectric Oxides

In the last decade there has been a resurgence of activity in the field of photoferroelectrics with a focus on the studies of oxides. Ferroelectric (FE) materials have a spontaneous switchable polarization that can lead to interesting light-matter interactions such as the bulk photovoltaic effect. While a wide range of compositions has been explored for ferroelectrics, until recently, FE oxides were considered to be capable of absorbing UV light only. Playing a key role in the advance of the field, first-principles calculations have guided the experimental materials discovery efforts that have identified a wide variety of visible-light-absorbing oxides. First-principles research efforts have also achieved considerable progress in revealing the interplay between the composition, structure and light absorption properties in these materials, and it is now understood that even small changes in the local environment can lead to large changes in band gap character and magnitude. Here, we survey the first-principles efforts following different band-gap engineering strategies and the advances in the computational methods that have been driven by these studies.