First Principles Density Functional Theory Study of Polarons in Transition Metal Oxides*

Understanding of charge transport in complex materials is crucial for fundamental and technological relevance. In strongly correlated materials, such as transition metal oxides (TMO), charge carriers (electron and hole) interact strongly with phonons (quanta of lattice vibrations) and as a consequence, the resulting lattice distortions trap the carriers and form quasiparticles known as polarons. In such polaron forming materials, polarons play a decisive role towards determining the transport behavior of these materials. We have benchmarked the applied computational techniques by calculating polaron in binary TMO’s such as TiO₂ and Fe₂O₃. In the present work, we have studied the polaron formation in BiVO₄, one of the best metal-oxide photoanode materials for PEC H₂O splitting. In this study, we have theoretically characterized the polaron formation as well as calculated the site-to-site polaron hopping barrier and mobility along a specific hopping pathway within the framework of density functional theory (DFT). Finally, we have calculated the supercell size dependency towards the polaron formation in BiVO₄.