Unveiling the Fatigue Behavior of 2D Hybrid Organic-Inorganic Perovskites: Insights for Long-Term Durability

2D hybrid organic-inorganic perovskites (HOIPs) are commonly found under subcritical cyclic stress states and suffer from fatigue issues during device operation, significantly limiting their service lifetime. However, the fatigue properties of these materials remain unknown, which is crucial for mitigating fatigue failure and predicting the lifetime for scheduled maintenance. Here, we systematically investigate the fatigue behavior of (C₄H₉-NH₃)₂(CH₃NH₃)₂Pb₃I₁₀, the archetype 2D HOIP, by atomic force microscopy (AFM) dynamic stretching suspended 2D membranes. We find that 2D HOIPs are much more fatigue resilient than polymers and can survive over 1 billion cycles. The failure morphology indicates that the 2D HOIPs tend to exhibit brittle failure at high mean stress levels but behave as ductile materials at low mean stress levels. Our results suggest the presence of a plastic deformation mechanism in these ionic hybrid organic-inorganic materials at low mean stress levels, which may contribute to the long fatigue lifetime but is inhibited at higher mean stresses. The stiffness and strength of 2D HOIPs are gradually weakened under subcritical loading, potentially as a result of stress-induced defects accumulating and nucleating. The cyclic loading component can further accelerate this process. The fatigue lifetime of 2D HOIPs can be extended by reducing the mean stress, stress amplitude, or increasing the thickness. Our results can provide indispensable insights into designing and engineering 2D HOIPs and other hybrid organic-inorganic materials for long-term mechanical durability.