Disentangling the Effects of Inter- and Intra-octahedral Distortions on the Electronic Structure in Binary Metal Trioxides

Recently, a subclass of binary perovskite-structured metal trioxides, such as WO₃ and MoO₃, have been propounded for many key optoelectronic applications due to their proper band edge positions and appropriate band gap sizes. Unlike their superclass perovskites, the structure-property relationship for these binary metal trioxides is less apparent, given that they suffer from much larger structural deformities within the octahedra. In this work, by using first-principles density-functional theory calculations and atomistic scale models, we examine the internal and external distortions of WO₃ and MoO₃ polymorphs. We then compare our results with conventional polyhedral distortion descriptors and finally use a refined data set of different perovskite-structured oxides to establish and demonstrate how these binary metal trioxides operate with a different structure-property relationship from the conventional oxide perovskites.