Blade-coated organic photovoltaics with a dichlorophthalic acid self-assembled monolayer

Abstract

To meet the demands of future industrialization, organic photovoltaics (OPVs) necessitate improved power conversion efficiency (PCE) and optimized manufacturing processes. The anode interfacial layer (AIL) is a critical component within the OPV architecture. Yet, the prevalent PEDOT:PSS AIL exhibits hygroscopic and acidic nature, undermining device stability. Herein, we introduce 4,5-dichlorophthalic acid (2C2BA), a self-assembled monolayer (SAM) material, as an AIL. The 2C2BA AIL is formed by in situ self-assembly following the deposition of the donor:acceptor:2C2BA solution, obviating extra monolayer processing. Both active layers of small- and large-area devices are fabricated by blade coating. Devices with a PM6:BO-4Cl active layer and 2C2BA AIL achieve a high PCE of 17.8%, exceeding the PCE of PEDOT:PSS-based devices (17.4%). Devices with PM6:BTP-eC9 and 2C2BA achieve a high PCE of 18.1%, and a notable short-circuit current density (J_SC) of 28.2 mA cm⁻². Scaling to 2 cm², PM6:BTP-eC9-based OPVs with 2C2BA hit a PCE of 16.7%, outperforming OPV devices or modules with areas ≥ 2 cm² with a SAM from the literature. This work stands as an advancement in the application of SAMs for large-area OPVs, providing insights into scalable and high-throughput OPV manufacturing.