Elucidating the Origin of Perovskites Degradation through Nanoimaging*

The primary barrier for perovskite solar cells towards commercialization is related to the fact that they degrade when exposed/submitted to ambient conditions. Thus, elucidating the driving forces for materials’ instabilities is imperative. Because the perovskite absorbing layer is often composed by mesoscale constructs, we resolve their performance with nanoscale spatial resolution, as a function of humidity, illumination, and temperature. For that, we realize and implement a scanning microscopy platform to quantify and spatially resolve the perovskites local electrical response. We find local Voc variations >300 mV, and a dynamic behavior upon illumination due to ion migration. Further, we identify a fully reversible voltage response within grains for Cs-triple cations perovskites. We anticipate the measurements of perovskites under controlled environment to advance the knowledge of the transient physical behaviors observed for certain compositions, including lead-free options and alternatives for dual junction designs.