18.9% Efficiency Binary Organic Solar Cells Enabled by Regulating the Intrinsic Properties of PEDOT:PSS

Abstract Anode interlayers play critical roles in organic solar cells, impacting the electrode's work function, energy level alignment, hole extraction, and electrode surfaces. However, the development of the commonly used anode interlayer PEDOT:PSS lags behind the rapid development of organic solar cells due to its low conductivity, acidity, and poor electron‐blocking capabilities. Herein, an innovative strategy is proposed to regulate the intrinsic properties of PEDOT:PSS by incorporating molybdenum‐containing semiconductors (MoO₃, MoS₂), which is validated using the state‐of‐the‐art active layer consisting of PM6:Y6 in conventional devices. The addition of molybdenum‐containing semiconductors alters the aggregation morphology of the PEDOT:PSS layer, increasing its conductivity and reducing its acidity. Furthermore, the hole extraction and electron‐blocking ability are improved by changing the work function of the anode with the influence of the deep energy level and by forming a trap energy level to capture electrons. Consequently, when the interlayer is employed, a champion power conversion efficiency of 17.1% in the PM6:Y6 devices and 18.9% in organic solar cells composed of PM6:L8‐BO is achieved. The results, which enhance the intrinsic properties of PEDOT:PSS with molybdenum‐containing semiconductors, offer valuable guidelines for engineering anode interlayers to fabricate highly efficient non‐fullerene organic solar cells.