Irreversible Silver Migration in Single CsPbBr3 Perovskite Nanowire Devices

Abstract Silver (Ag) has gained interest as an electrode material for metal halide perovskites due to its high electrical conductivity, low cost, and simple deposition. The electromigration and interface redox-process of Ag has been exploited for electronic applications such as memristors. Studying the complex silver−perovskite interactions is challenging in a traditional thin film geometry due to the buried interfaces and heterogeneous crystal structure. In contrast, devices based on single crystal nanowires offer an open device geometry that is ideal for microscopy. Here, we investigate the interaction between Ag contacts and single CsPbBr3 nanowire devices by combining scanning electron microscopy, energy-dispersive spectroscopy, electrical measurements, and operando synchrotron-based scanning photoelectron microscopy. Ag is found to interact with the nanowire already upon contact formation, producing surface roughening and Ag-rich features that extend hundreds of nm from the surface. In symmetric Ag−Ag devices, a negative bias applied to one Ag electrode causes Ag accumulation near the negatively biased electrode while the perovskite framework remains partly preserved. After reversing the electric field, much stronger Ag enrichment and Br− redistribution are observed, together with a conductivity increase of about 7 orders of magnitude and a clear degradation of the nanowire region. In contrast, asymmetric Ag−(Ti/Au) devices show weaker structural and electrical evolution and reversing the field through the Ti/Au contact produces almost no additional change. Synchrotron-based nanofocused operando photoelectron microscopy further shows that under the lower electric field, Ag redistribution is gradual, spatially confined, and preferentially occurs at pre-existing defective or reactive regions. These results show that Ag actively drives interfacial evolution in perovskite nanowire devices and that contact configuration strongly affects migration and degradation.