Peering into interfaces in perovskite solar cells: a first-principles perspective

Over the past decade, perovskite solar cells (PSCs) have experienced a rapid development. The remarkable increase in the photoelectric conversion efficiency demonstrates great promise of halide perovskites in the field of photovoltaics. Despite the excellent photovoltaic performance, further efforts are needed to enhance efficiency and stability. Interfacial engineering plays a crucial role in enhancing the efficiency and stability of PSCs, enabling champion cells to sustain a power conversion efficiency above 26% for over 1000 h. As a powerful theoretical tool for characterizing interfaces in PSCs, first-principles calculations have contributed to understanding interfacial properties and guiding the materials design. In this Perspective, we highlight the recent progress in theoretically profiling the interfaces between halide perovskites and other materials, focusing on the effects of energy band alignment and electronic structure on the carrier transport at the interfaces. These first-principles calculations help to reveal the atomic and electronic properties of the interfaces, and to provide important theoretical guidance for experimental research and device optimization. We also analyze potential strategies to enhance carrier separation and transport in PSCs, and discuss the challenges in accurate modeling interfaces in PSCs, which will help to understand the fundamental physics of interfaces in PSCs and to guide their further optimization.