Light intensity modulated photoluminescence for rapid series resistance mapping of perovskite solar cells

The champion efficiency of small area perovskite solar cells is marginally behind their silicon counterpart. However, when up-scaled to large area modules, the performance of perovskite solar cells drops significantly due primarily to the inclusion of defects during fabrication. The future of perovskite solar cells depends greatly on the ability to fabricate high efficiency large area devices which requires methods for rapidly and reliably identifying the presence of damage or imperfections that limit their performance. In this work we employ, for the first time, intensity modulated photoluminescence to spatially map the series resistance of perovskite solar cells with high spatial resolution. The technique permits the rapid identification of a range of different macroscopic defects and quantifies the impact on the local series resistance. It is performed under steady-state conditions to avoid complications of transient behaviour occurring in the perovskite film. The robustness of the approach is demonstrated by characterising an entire batch of perovskite solar cells with the mean series resistance values validated using established electrical analysis methods. Our method can be readily applied by other research groups for device optimisation or scaled to large areas for automated process control and validation.