Interface engineering: a step towards device integration of chalcogenide perovskites

Chalcogenide semiconductors have played a crucial role in a wide range of applications, including optoelectronics, photovoltaics, sensing, and more. Chalcogenide perovskites have recently emerged as a new and promising addition to this family, offering enhanced stability along with promising properties. The improved stability is achieved at the expense of rigorous synthesis conditions, often requiring high temperatures and sulfur-rich environments. Such aggressive conditions are highly detrimental to most conductive back contacts, thereby severely limiting device integration. In this work, we address this challenge by introducing an ultrathin Al₂O₃ layer as a protective barrier. Al₂O₃ film of a few nanometers was deposited via atomic layer deposition onto a molybdenum substrate, forming a robust interfacial layer that prevents substrate degradation. This interfacial engineering has enabled, for the first time, the deposition of phase-pure BaZrS₃ thin films on conductive substrates without degradation. These results represent a critical step towards the realization of functional chalcogenide perovskite devices.