Challenges and opportunities for the mechanical reliability of metal halide perovskites and photovoltaics

The unproven reliability of perovskite photovoltaics (PVs) is likely to pose an important technical hurdle in the path towards the widespread deployment of the technology. The overall reliability of perovskite PVs is directly affected by the mechanical reliability of the metal halide perovskite material, cells and modules, but this issue has been largely overlooked. Here we stress the importance of addressing the mechanical reliability issue comprehensively. We highlight the important challenges and opportunities, together with best practices, pertaining to the three key interrelated elements that determine the mechanical reliability of perovskite PVs: driving stresses, mechanical properties and mechanical failure. We discuss how to measure the driving stresses and mechanical properties accurately, together with their evolution over time, and the need to understand the relevant failure mechanisms and coupled effects. This effort will inform scientific approaches to making perovskite PVs more reliable and durable and help them reach their full potential. The mechanical reliability of perovskite solar cells is a key hurdle that needs to be addressed to commercialize the technology. Dai and Padture discuss the driving stress, mechanical properties and mechanical failures relevant to these devices and how they should be characterized.