Reduced Synthesis Temperatures of SrNbO2N Perovskite Films for Photoelectrochemical Fuel Production

Perovskite oxynitrides, such as SrNbO₂N, have been shown to be promising materials for photoanodes in tandem photoelectrochemical cells, due to their suitable bandgap and charge transport. However, thin film synthesis and characterization of oxynitride perovskites are challenging due to high processing temperatures that are incompatible with available substrates. In this work, we report on reduced synthesis temperatures of SrNbO₂N perovskite thin films on Si substrates across a range of chemical compositions. Polycrystalline thin films with perovskite crystal structure are obtained by sputtering at ambient temperature and annealing at 550–600 °C. The perovskite structure has a relatively broad range of cation composition between 50 and 60% Sr with varying O/N ratio according to Rutherford backscattering spectrometry. The maximum photocurrent density was obtained at 55 cation % of Sr, which is slightly Sr-rich compared to the nominal SrNbO₂N stoichiometry. This work shows the importance of considering cation and anion composition in studying oxynitride perovskites for solar fuel applications. Graphical abstract: [Figure not available: see fulltext.]