Facile Doping Strategy with <i>m</i> -Aminobenzoic Acid Enables 19.61% Efficiency in Organic Solar Cells via PEDOT:PSS Optimization

In organic solar cells (OSCs), the hole transport layer (HTL) plays a pivotal role in enabling efficient charge extraction and transport. However, the conventional HTL material PEDOT:PSS suffers from low conductivity and insufficient electron-blocking capability, thereby limiting device performance. Herein, we present a facile yet effective modification strategy by incorporating <i>m</i>-aminobenzoic acid (MABA) and glycine (Gly) into PEDOT:PSS, which can markedly improve its film properties even at low concentrations (1 mg mL^-1). Comparative investigations reveal that, relative to Gly, MABA incorporation more effectively reduces the PSS/PEDOT ratio, induces a higher degree of conformational transition in PEDOT chains, and forms a denser conductive network, thereby enhancing film conductivity, hole mobility, and interfacial contact with the active layer. Device characterization further demonstrates that MABA doping significantly suppresses dark current and interfacial recombination in OSCs, leading to improved charge transport and collection efficiency. As a result, OSCs employing PEDOT:PSS + MABA as the HTL deliver champion power conversion efficiencies of 17.17% (PM6:Y6), 19.14% (PM6:L8-BO) and 19.61% (D18:L8-BO). This work offers a straightforward strategy for PEDOT:PSS modification and provides valuable insights into the design of high-performance OSCs.