Research Paper: Quantification of mobile ions in perovskite solar cells with thermally activated ion current measurements

Scientific Summary & Why it Matters

This study introduces a novel, non-invasive thermally activated ion current (TAIC) technique to accurately quantify mobile ion density, diffusion coefficient, and activation energy in perovskite solar cells (PSCs) within a single temperature sweep. This is critical for understanding and mitigating device degradation, a major challenge for PSC stability. Applied to MAPbI3 and triple-cation PSCs, TAIC revealed that triple-cation devices have higher activation energies (0.35 eV vs. 0.28 eV) and significantly lower diffusion coefficients (~10⁻¹⁴ cm²/s vs. ~5×10⁻¹³ cm²/s at 300K), indicating suppressed ion migration. Stressing devices at open-circuit voltage (Voc) increased ion density by an order of magnitude. The TAIC method also distinguishes different ionic processes, identifying slower halide vacancy migration through grains and, at elevated temperatures, a higher activation energy process (0.94 eV) likely associated with cation migration in triple-cation devices. These insights provide a powerful, intuitive tool for rationally designing more stable and efficient PSCs.

Publication Details

Schmidt, M.C., Alvarez, A.O., Pallotta, R., Seid, B.A., de Boer, J.J., Thiesbrummel, J., Lang, F., Grancini, G. and Ehrler, B. (Preprint), Quantification of mobile ions in perovskite solar cells with thermally activated ion current measurements. arXiv:2508.19403v1.

Fluxim Tools Used & Benefits

The commercial software Setfos (Fluxim) was crucial for drift-diffusion simulations to verify the analytical model underlying the TAIC method. Setfos simulated current behavior under varying ion densities and activation energies, distinguishing between ion-limited and field-limited cases. This strengthened the validity and interpretation of the novel TAIC technique, demonstrating its reliability in accurately extracting ionic parameters.