Interfacial Modulation for High‐Efficiency Large‐Area Organic Photovoltaics and Perovskite‐Organic Tandem Solar Modules

ABSTRACT Self‐assembled monolayers (SAMs) have emerged as promising hole‐transporting layers (HTLs) for organic photovoltaics (OPVs). However, their practical application is often hindered by inherent aggregation issues and the difficulty of forming uniform thin films over large areas. To overcome these limitations, we developed a novel interfacial modification process using nicotinic hydrazide (NH) designed to eliminate residual SAM aggregates. We demonstrate that NH effectively eliminates the aggregated 2PACz by forming an energetically favorable complex with the phosphonic acid groups, yielding an uniform and aggregate‐free SAM layer. Comprehensive characterization confirms that this treatment enhances film quality and surface wettability, thereby improving the HTL/active layer interfacial contact. Integrating this optimized SAM into OPV devices leads to significantly improved efficiency of 15.38% using a blade‐coated 1 cm 2 active area, primarily due to improved charge extraction and reduced trap‐assisted recombination, which enhance both open‐circuit voltage and fill factor. Furthermore, the superior uniformity and reproducibility of NH‐treated HTL facilitates successful large‐area fabrication. As a result, the power conversion efficiency (PCE) of OPV modules are enhanced from 14.07% to 15.02%, and the resulting perovskite‐organic tandem module achieves a PCE of 19.89% at 16.41 cm 2 active area, demonstrating a robust pathway for high‐performance scalable photovoltaics.