Study on Properties of Low-Temperature-Prepared Zinc Oxide-Based Inverted Organic Solar Cells and Improvement of their Photodurability

The power conversion efficiency (PCE) of organic solar cells (OSCs) has improved steadily thanks to aggressive research and development efforts. On the other hand, improvement of device durability of OSCs is also an important factor for the practical application of OSCs. In this work, we studied the photodurability of inverted OSCs (i-OSCs) with ZnO prepared at 100 and 250 °C (ZnO100 and ZnO250). The photodurability of the ZnO100-based i-OSCs is much poorer than that of ZnO250-based ones. This could have originated from the higher photocatalytic activity of ZnO100, which relates to the number of surface OH groups and adsorbed water species. To suppress the photocatalytic activity of ZnO100, we fabricated a self-assembled monolayer (SAM) on the surface of ZnO100 and found that the photodurability of the surface-treated ZnO100-based i-OSC was improved. This result indicated that the photodurability of i-OSC can be influenced by the surface conditions of ZnO and can be improved by SAM modification.