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The cathode interface layers (CILs) play a crucial role in enhancing the performance of organic solar cells (OSCs). However, challenges arise due to the high work function of CIL and inadequate contact with the active layer, leading to high interface trap recombination and poor charge extraction. In this study, a novel approach is proposed to improve charge injection and extraction in CILs by incorporating polyphenols, trihydroxybenzoic acid (TBA). Focusing on the CIL PDINN, its work function is successfully reduced from 4.14 eV to 3.80 eV and obtained charge collection efficiency of 91.23% through TBA regulation. These enhancements can be ascribed to improved contact between the active layer and the CILs, and enhanced the formation of a fine fiber phase width and inhibited interface recombination. As a result, the power conversion efficiency (PCE) of the binary OSCs comprising PM6: BTP‐ec9 exhibits an increase from 18.2% to 19.3%, placing it among the one of the highest PCE values. Moreover, this approach demonstrated notable applicability for another CILs, as well as various OSCs systems. Overall, this research underscores the importance of regulating and modifying CILs to fully exploit their potential in OSCs devices, while laying the groundwork for optimizing their efficiency and stability. [ABSTRACT FROM AUTHOR]

Although encouraging progress in spin‐coated small‐area organic solar cells (OSCs), reducing efficiency loss caused by differences in film uniformity and morphology when up‐scaled to large‐area modules through meniscus‐guided coating is an important but unsolved issue. In this work, in‐depth research is conducted on the influence of both liquid and solid additives on the film uniformity and morphology of active layer in blade‐coated PM6:L8‐BO binary system. The study reveals that high boiling point liquid additives like 1,8‐diiodooctane (DIO) used in blade‐coating not only delay the volatilization of the solvent but also trigger the Marangoni flow in the same direction as capillary flow, causing excessive aggregation of acceptors, therefore destroying device performance. On the contrary, the solid additive 2‐Iododiphenyl ether (IDPE), which is first reported in this work, can preserve the mechanism for improving device performance while effectively suppressing the excessive aggregation of acceptors during the film‐forming process in blade‐coating from halogen‐free solvent of toluene, resulting in highly homogeneous large‐area active layer films. Consequently, organic solar modules with an impressive efficiency of 15.34% with a total module area of 18.90 cm2 via blade‐coating based on PM6:L8‐BO are achieved. This study not only provides a deep understanding on the effect of liquid and solid additives during blade‐coating from the perspective of fluid mechanisms but also gives a pathway for the development of green solvent printed high‐efficiency OSCs. [ABSTRACT FROM AUTHOR]