Correlated oxygen states and Schottky barrier heights in oxides: A DFT+U study

Beyond conventional electronics, the Schottky barrier height—the charge transfer barrier at metal-insulator interfaces—is a universal parameter for interfacial charge transfer that controls device performance, efficiency, and stability across diverse technologies. Semilocal density functional theory (DFT) exchange-correlation functionals suffer from a self-interaction error (SIE), which often results in misaligned band offsets in metal-insulator interfaces. In many transition-metal oxides (TMOs), the valence band maximum (VBM) is dominated by localized O-2p states with flat dispersion, making them particularly sensitive to SIE and leading to misaligned band offset at metal-oxide interfaces. Using a screening workflow from the Materials Project datasets, we identify TMOs with localized O-2p states, select systems with reported experimental SBHs, and perform explicit relaxed interface calculations using a supercell method. We employ Hubbard-corrected DFT (DFT+U) on O-2p states to reduce delocalization error from SIE and bring calculated SBHs into closer agreement with experiment for TMOs whose VBM is O-2p dominated, while leaving SBHs essentially unchanged in systems lacking correlated O-2p character. Our results suggest that applying DFT+U on O-2p states is a cost-effective approach for reliable SBHs prediction.