Multifunctional Sulfonated Surfactant with Oriented Alignment and Surface Tension Modulation for High‐Efficiency Eco‐Friendly Perovskite Solar Cells

Abstract Perovskite solar cells (PSCs) have emerged as a promising next‐generation photovoltaic technology due to their low cost and high efficiency. However, their commercialization remains hindered by critical challenges, including the inherent instability and suboptimal quality of perovskite films, as well as environmental issues related to lead‐containing compositions. In this work, this study innovatively introduces a multifunctional polymer surfactant, ammonium polyacryloyldimethyl taurate (APT), to address these limitations. Leveraging its amphiphilic nature, APT self‐assembles in perovskite precursor solutions to regulate interfacial tension and template crystal growth, synergistically regulating film formation kinetics. This results in perovskite films with enhanced crystallinity, homogeneous grain distribution, and minimized grain boundary defects‌, with grain sizes enlarged to exceed 2 µm. Furthermore, APT effectively passivates undercoordinated Pb²⁺/I⁻ defects through strong chemical coordination, suppressing non‐radiative recombination and extending charge carrier lifetimes, thereby elevating the power conversion efficiency (PCE) from 23.37% to 25.17%. The hydrophobic alkyl chains of APT further self‐assemble into moisture‐resistant barriers, endowing the perovskite films with exceptional environmental stability. Crucially, APT mitigates lead leakage risks by forming stable coordination bonds with Pb²⁺ at perovskite interfaces. This study underscores the versatility of APT as a multifunctional additive for simultaneously optimizing film quality, device performance, and eco‐compatibility.