Electronic and Photochemical Passivation by a Classic Sunscreen Material Leading to Reduced <i>V</i>_oc Losses and Enhanced Stability in Organic Solar Cells

Organic solar cells (OSCs) have been a popular topic of research for a long time. As a well-known electron transport layer (ETL) material for inverted device architecture, sol-gel-derived zinc oxide (ZnO) displays certain defective surfaces that cause excessive charge recombination and lower device performance. While ultraviolet (UV)-light soaking is sometimes necessary for the ZnO layer to function properly, the latter can also cause the photodegradation of conjugated organic semiconductors. The photostability of OSCs has always been a hot research topic, as the radiation of UV light may cause changes in the material's properties, and that, in turn, may cause rapid attenuation of the devices. Herein, ZnO is modified by inserting the commonly used sunscreen ingredient benzophenone-3 (BP-3) between the photoactive layer, consisting of a PM6:Y6 blend, and ZnO to reduce the impact of UV radiation on the photosensitive layer. The addition of BP-3 successfully enhances the photovoltaic parameters, and a remarkable open-circuit voltage (<i>V</i>_oc) value of 0.887 V is obtained for PM6:Y6-based inverted solar cells, corresponding to a <i>V</i>_oc loss as small as 0.547 V. Finally, the application of this strategy increases the device's power conversion efficiency from 12.44 to 13.71% and provides improved UV stability.