CeO<sub><i>x</i></sub>‑Mesoporous\nSilica Nanoparticle Antioxidants to Enhance the Stability of Organic\nPhotovoltaic Devices

Mitigating ultraviolet exposure-induced photodegradation\nremains\na critical challenge to the long-term stability of organic photovoltaics\n(OPVs). Here, we improved the stability of the OPV device by introducing\nan antioxidant interlayer composed of nanocrystalline ceria supported\non mesoporous silica nanoparticles (CeO<sub><i>x</i></sub>-MSN). The CeO<sub><i>x</i></sub> nanocrystals within the\nCeO<sub><i>x</i></sub>-MSN exhibited a high density of oxygen\nvacancies and a large ratio of Ce(III) chemical states known to scavenge\nreactive oxygen species. Optimizing the particle size of the CeO<sub><i>x</i></sub> nanocrystals further enhanced the ratio\nof Ce(III) states, enabling superior radical scavenging efficacy in\nmethyl violet degradation tests compared with commercial CeO<sub><i>x</i></sub> nanostructures. The OPV performance test confirmed\nthat the optimized CeO<sub><i>x</i></sub>-MSN (CeO<sub><i>x</i></sub>-MSN_S) can scavenge radicals without a degradation\nin initial performance under one-sun illumination. More importantly,\nthe photostability test revealed that the OPV device with CeO<sub><i>x</i></sub>-MSN_S retained 73% of initial performance\nwhile the conventional device retained only 54%, corroborating the\nexcellent radical scavenging efficacy of CeO<sub><i>x</i></sub>-MSN_S.