Disentangling ion migration from artifacts in high-fidelity ToF-SIMS depth profiling of perovskite solar cells

Perovskites are poised to transform photovoltaics, yet their buried interfaces in complex organic-inorganic multilayer device stacks remain analytically elusive. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is widely applied to probe these interfaces; however, we show that device depth profiles diverge from thin films due to measurement-induced interactions unique to multilayer architectures. Through a systematic comparison, we demonstrate that previously unrecognized spurious ion gradients arise exclusively in multilayer architectures and originate from overlayer interactions that mimic genuine ion migration, which we isolated using a controlled peeling protocol. Building on this insight, we introduce fluence-matched acquisition and a statistically grounded, replicate-based analysis framework for artifact-aware, high-fidelity ToF-SIMS depth profiling. Applying this validated framework provides direct chemical evidence for redistribution of buried self-assembled monolayers during ambient aging, which reveals a degradation mechanism at hidden interfaces previously inferred only indirectly. Together, this work establishes a reproducible reference standard for nanoscale chemical analysis of complex multilayer semiconductor devices.