Cerium Oxide Incorporation for Radiation Tolerance and Stability in Perovskite Solar Cells

Halide perovskite solar cells (HPSCs) hold strong potential for next-generation photovoltaics owing to their high efficiency and defect-tolerant structure. Yet, achieving long-term stability under operational stressors such as heat, prolonged illumination, and ionizing radiation remains a key challenge, particularly for applications in space and other harsh environments. Here, we report a dual-passivation approach that incorporates cerium oxide (CeO x ) nanoparticles into the perovskite absorber layer using an n -octylammonium iodide (OAI)-assisted post-treatment. CeO x, a redox-active oxide widely used in radiation shielding, improves crystallinity, reduces defect density, and enhances interfacial energy alignment. The resulting devices exhibit a power conversion efficiency (PCE) of 24.9%, the highest reported for n-i-p HPSCs employing poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) as the hole transport layer. Under 0.05 MeV proton irradiation at fluences up to 2 × 10 14 protons cm –2, the treated devices retained 91% of their open-circuit voltage and 81% of their initial PCE. Spectroscopic and electrical analyses revealed suppressed nonradiative recombination, preserved grain boundary potential, and improved photothermal stability. These results demonstrate that CeO x incorporation offers an effective strategy for enhancing the durability of perovskite solar cells under simultaneous environmental and radiation exposure, paving the way toward reliable deployment in both terrestrial and aerospace energy technologies.