Regulation of ion migration in perovskite nanocrystals via charge-carrier extraction on conductive substrates

Ion migration poses a critical impediment to perovskite commercialization by directly degrading device performance and stability, driving intense scientific scrutiny into suppression strategies. However, existing studies predominantly focus on crystal modifications while overlooking the role of substrates in contact with perovskite materials. Here, we select quartz, indium tin oxide (ITO), Ga:ZnO (GZO), ZnO, NiO x and Ag substrates to study light-induced ion migration kinetics in all-inorganic mixed-halide perovskite nanocrystals. ITO and GZO substrates can effectively suppress ion migration, indicating that these conductive substrates provide transfer channels for photogenerated charge carriers and thus weaken the local electric field caused by charge accumulation. Furthermore, electrons are inferred to be the dominant carriers in this process. While the ZnO nanoparticle substrate exhibits weak suppression, the NiO x nanoparticle substrate with hole conductivity shows a negligible effect, underscoring the critical role of electron transport. Surprisingly, the nanocrystals film on the Ag substrate exhibits an irreversible spectral shift, suggesting a possible photoinduced chemical reaction between Ag and iodide ions. Overall, substrates can regulate the ion migration behavior of perovskite nanocrystals, providing an alternative approach to improving perovskite device stability.