Trapped charge driven degradation of perovskite solar cells

Perovskite solar cells have shown fast deterioration during actual operation even with encapsulation, but its mechanism has been elusive. We found the fundamental mechanism for irreversible degradation of perovskite materials in which trapped charges regardless of the polarity play a decisive role. A novel experimental setup utilizing different polarity ions revealed that the moisture induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. Our finding clearly explained the intriguing observations why light soaking induces irreversible degradation while in the dark, moisture only causes reversible hydration, and why degradation begins from different side of interface for different charge extraction layers. The deprotonation of organic cations by trapped charge induced local electric field is attributed to the initiation of irreversible decomposition.