Stabilizing the Interfaces of Efficient Perovskite Solar Cells

Perovskite photovoltaics have achieved remarkable progress over the past decade, with the best lab-scale cells now reaching over 26% power conversion efficiency. This rapid advancement is largely due to a better understanding and control of the interfaces within perovskite solar cells. As we transition from single-junction to multi-junction solar cells, interface quality becomes even more critical, given the increasing number of heterojunctions. Each additional sub-cell introduces two new interfaces, which must be carefully managed. In this talk, I will discuss the instability of these interfaces, especially under combined stress of light and heat, and the pathways toward their stabilization. One example of instability is the interdiffusion of cations between the bulk 3D perovskite and popular passivating 2D perovskite layers in 2D/3D heterostructures. Another is halide migration through the interface into the carrier transport layer and even the electrode. I will also present strategies to stabilize the 2D/3D interface using non-2D passivation layers and methods to block halide migration under accelerated conditions by employing compact, uniform metal oxide barrier layers.