Siloxane as Humidity-Resistant and Stabilizing Additive for Ambient-Processed Organic Solar Cells

Abstract

High-performing organic solar cells (OSCs) being processed in ambient conditions and possessing long-term stability are desired toward commercialization. Here, resultantly bifunctional additive is proposed for organic active layer, which can greatly enhance humidity endurance during the air-processing of the active layer and device stability in the meantime. Intriguingly, with 1% octamethyltrisiloxane (3Si) as the additive, casting PM6:L8-BO active layer even in 90% relative humidity (RH) air could show comparable efficiency to that in N₂ condition. Furthermore, the 3Si-processed active layers also display remarkably enhanced thermal and light stabilities in conventional OSCs. After thermal aging at 85 °C for 1000 h and simulated solar light aging with UV band at 100 mW cm⁻² and 55°C for 1000 h, the 3Si-processed PM6:L8-BO binary OSCs maintain 91.6% and 86.1% of the initial efficiency, leading to final averaged efficiencies of 16.17% and 15.42%, respectively. The results represent the most stable OSCs based on additive strategy. The universality of siloxane as a humidity-resistant and stabilizing agent is also confirmed with other active layer systems, paving a way for broader application of the bifunctional additive.