Efficient and Stable Air‐Processed Organic Solar Cells Enabled by an Antioxidant Additive

Abstract Current high‐efficiency organic solar cells (OSCs) are generally fabricated in an inert atmosphere that limits their real‐world scalable manufacturing, while the efficiencies of air‐processed OSCs lag far behind. The impacts of ambient factors on solar cell fabrication remain unclear. In this work, the effects of ambient factors on cell fabrication are systematically investigated, and it is unveiled that the oxidation and doping of organic light absorbers are the dominant reasons causing cell degradation when fabricated in air. To address this issue, a new strategy for fabricating high‐performance air‐processed OSCs by introducing an antioxidant additive (4‐bromophenylhydrazine, BPH) into the precursor solutions, is developed. BPH can effectively inhibit oxygen infiltration from the ambient to the photoactive layer and suppress trap formation caused by oxidation. Compared with conventional air‐processed OSCs, this strategy remarkably increases the cell power conversion efficiency (PCE) from 16.7% to 19.3% (independently certified as 19.2%), representing the top value of air‐processed OSCs. Furthermore, BPH significantly improves the operational stability of the cells in air by two times with a T80 lifetime of over 500 h. This study highlights the potential of using antioxidant additives to fabricate high‐efficiency and stable OSCs in air, significantly promoting the industrialization of OSCs.