Unveiling Surface-Driven Degradation in Perovskite Solar Cells: A Novel Spatially Resolved Imaging Approach

Perovskite solar cells hold great promise for next-generation photovoltaics, but their long-term stability remains a critical challenge. In our work, we present a powerful new approach that allows us to directly visualize and track degradation processes in these devices using a combination of luminescence imaging, advanced modelling, and Bayesian inference. This novel methodology not only maps out key device parameters, such as carrier lifetime and surface recombination, but also reveals how they evolve during accelerated aging.

Our results are extremely informative: we observe that degradation occurs unevenly across the devices, with stable regions exhibiting bulk-driven decay while more problematic areas show rapid surface degradation at the electron transport layer (ETL) interface. Strikingly, we demonstrate that targeted passivation treatments can effectively halt this degradation at the ETL/perovskite interface, significantly improving both surface and bulk stability. This real-time visualisation of the degradation pathway, across full devices, gives fresh insights into the previously underappreciated role of surface recombination as the primary driver of failure, even in devices where the perovskite material seemed stable.

This work provides critical insights into how and where perovskite devices fail, and our technique offers a new way to pinpoint and address these issues at the macroscopic level. We hope this method will inspire further research to tackle stability challenges in perovskite and other emerging solar technologies.