From Measurement to Modeling: Advancing ToF-SIMS Methodologies for Functional Insights in Organic-Based Electronic Materials

Abstract

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is increasingly used in perovskite (PVK) solar cell research for its high chemical specificity and ability to probe buried interfaces without invasive sample preparation. However, we show that acquisition and interpretation of ToF-SIMS data from multilayered PVK solar cells should not be conflated with that of its thin films. Here, we present a rigorously substantiated ToF-SIMS methodology that separates true ion migration from artifact-induced signals, revealing widely underappreciated measurement artifacts. Through systematic comparison of thin films and full devices of archetypal MAPbI3 (1.6 eV) and compositionally complex (FA75Cs25)(Pb60Sn40)I3 (1.25 eV), we show that spurious ion gradients arise exclusively in multilayer stacks, driven by top-layer interactions. We confirm their measurement-induced origin using a controlled peeling protocol designed to isolate these effects. We further introduce a novel fluence-matched acquisition protocol and the first statistically grounded workflow for replicate-based analysis—demonstrating that single-profile measurements can lead to contradictory interpretations, particularly in studies targeting subtle interfacial phenomena by trace passivation. Applying this framework, we enable reliable detection and aging analysis of buried self-assembled monolayers (SAMs), whose ultrathin (∼1 nm), localized nature presents unique analytical challenges and growing importance in the design of molecular transport layers for high-efficiency, stable devices. Together, these findings establish a reproducible, artifact-aware framework for high-fidelity ToF-SIMS depth profiling in PVK solar cells and provide a reference standard for reliable chemical analysis of hybrid multilayer semiconductors. This work advances best practices in nanoscale characterization, supporting precision interface engineering across next-generation energy technologies and beyond.