Research Paper: Barrier layer design reduces top electrode ion migration in perovskite solar cells
Scientific Summary
This study quantitatively investigates mobile ion concentration (N0) and its correlation with the thermal stability of perovskite solar cells (PSCs), focusing on the efficacy of barrier layers against top electrode ion migration. The main goal was to establish N0 as a consistent, quantitative metric for ion migration-related degradation. Key findings demonstrate that tin oxide (SnO2) and ozone-nucleated SnO2 (O3–SnO2) barrier layers significantly reduce initial N0 by over 10 times for reactive silver (Ag) electrodes, effectively blocking Ag ion diffusion into the perovskite layer. This reduction in N0 directly correlates with enhanced thermal stability, extending the operational temperature range by at least 80 °C (from ~100 °C to ~180 °C). An empirical upper threshold of N0 (~3.0 × 10^16 cm⁻³) for device operation was identified. Furthermore, these barrier layers preserve bulk perovskite microstructure, preventing thermal degradation and exhibiting higher activation energies (0.503 eV for O3–SnO2 vs. 0.346 eV for control), indicating suppressed mobile ion activation.
Why it Matters
Ion migration is a primary cause of degradation in PSCs, hindering their commercialization and limiting field lifetimes. This research provides a critical, quantitative metric (N0) and an effective strategy (barrier layers) to mitigate ion migration and enhance thermal stability. By demonstrating that well-designed barrier layers significantly reduce mobile ion diffusion and improve device robustness, this work offers a clear pathway for accelerating the development of reliable, long-lifetime PSCs, essential for their market entry and widespread adoption in renewable energy applications.
Fluxim Tools Used
The PAIOS (Fluxim AG) all-in-one characterisation equipment was instrumental for all ionic and electronic measurements. PAIOS was used to perform transient dark current measurements to quantify the mobile ion concentration (N0). Furthermore, PAIOS was integrated with a Linkam temperature control stage to conduct in situ N0-temperature measurements from 300 K to 450 K and to determine the activation energy (EA) of mobile ions.
Publication Details
Penukula, S., Khanal, M.N., Sharma, M., Parashar, M., Kerner, R.A., Chen, M., Davis, M.A., Saha, R.A., Solano, E., Roeffaers, M.B.J., Berry, J.J., Luther, J.M., Steele, J.A., Palmstrom, A., Whiteside, V.R., Rout, B., Sellers, I.R. and Rolston, N. (2025), Barrier layer design reduces top electrode ion migration in perovskite solar cells. EES Sol., 1, 345. https://doi.org/10.1039/d5el00051c.