Understanding the structural and electronic properties of disordered oxide interfaces in photoelectrodes for solar-to-fuel conversion

Understanding the structural and electronic properties of amorphous/crystalline interfaces in oxide materials is crucial for advancing the design of photoelectrodes for solar-to-fuel conversion. Hence, it is important to build realistic atomistic models of these interfaces, that are representative of experimental samples. In this study, we focus on the interface between crystalline BiVO₄, a promising photoanode for photoelectrochemical cells, with amorphous TiO₂, used as a protective layer to stabilize BiVO₄ in harsh pH conditions. Using forces and energies obtained in first-principles molecular dynamics simulations with the Qbox code, we generate a machine learning-force field with the Allegro code, and we derive a structural model of the interface. We present a study of the structural and electronic properties of the amorphous/crystalline interface, and we compare them with those of crystalline TiO₂/BiVO₄ interfaces. We also relate the atomic structure obtained in our simulations to those of interfaces present in experimental thin films, where varied deposition techniques are used. Our predictions of band alignments and charge localization at the interfaces shed light on how to design interfacial layers to optimize the performance of photoelectrodes.