Investigating the Effects of Chemical Gradients on Performance and Reliability within Perovskite Solar Cells with TOF‐SIMS

Time‐of‐flight secondary‐ion mass spectrometry (TOF‐SIMS), a powerful analytical technique sensitive to all components of perovskite solar cell (PSC) materials, can differentiate between the various organic species within a PSC absorber or a complete device stack. The ability to probe chemical gradients through the depth of a device (both organic and inorganic), with down to 100 nm lateral resolution, can lead to unique insights into the relationships between chemistry in the absorber bulk, at grain boundaries, and at interfaces as well as how they relate to changes in performance and/or stability. In this review, the technique is described; then, from the literature, several examples of how TOF‐SIMS have been used to provide unique insight into PSC absorbers and devices are covered. Finally, the common artifacts that can be introduced if the data are improperly collected, as well as methods to mitigate these artifacts are discussed.