CeOx-Mesoporous Silica Nanoparticle Antioxidants to Enhance the Stability of Organic Photovoltaic Devices

Mitigating ultraviolet exposure-induced photodegradation remains a critical challenge to the long-term stability of organic photovoltaics (OPVs). Here, we improved the stability of the OPV device by introducing an antioxidant interlayer composed of nanocrystalline ceria supported on mesoporous silica nanoparticles (CeO_x-MSN). The CeO_x nanocrystals within the CeO_x-MSN exhibited a high density of oxygen vacancies and a large ratio of Ce(III) chemical states known to scavenge reactive oxygen species. Optimizing the particle size of the CeO_x nanocrystals further enhanced the ratio of Ce(III) states, enabling superior radical scavenging efficacy in methyl violet degradation tests compared with commercial CeO_x nanostructures. The OPV performance test confirmed that the optimized CeO_x-MSN (CeO_x-MSN_S) can scavenge radicals without a degradation in initial performance under one-sun illumination. More importantly, the photostability test revealed that the OPV device with CeO_x-MSN_S retained 73% of initial performance while the conventional device retained only 54%, corroborating the excellent radical scavenging efficacy of CeO_x-MSN_S.