Sustainable plasma polymer encapsulation materials for organic solar cells

The rapid degradation of organic photovoltaics (OPVs) under ambient conditions represents a major limitation to this promising technology. Device encapsulation is an effective approach to increase the lifetime of OPVs. Herein, we report the time and cost-effective synthesis of ultrathin encapsulation materials for OPVs by radio frequency (RF) plasma polymerization from plant extract. The encapsulated device retained 66% and 87% of its initial power conversion efficiency (PCE) and fill factor, respectively, after 90 days under ambient conditions while the reference device degraded within the first month. More interestingly, the open circuit voltage of the encapsulated device was found unchanged after >4.5 months with 70% of its original short circuit current density. The investigated thin films have shown strong absorption in the ultraviolet (UV) range with high transmission exceeding 98% to visible light and can be employed to prevent harmful UV photons from reaching the photoactive layer of the device. Additionally, the synthesized films have revealed a high chemical stability under artificial UV irradiation. Thus, this work presents a solvent-free and room temperature encapsulation method based on sustainable materials to increase the lifetime of OPVs without altering the device performance.