Quadrupole Moment‐Assisted Additive towards Enhanced Intermolecular Interaction and Optimized Hierarchical Morphology for Achieving Highly Efficient and Stable Organic Solar Cells

Comprehensive Summary Precise modulation of the active layer morphology to optimize exciton dissociation and charge collection efficiency is the research priority in organic solar cells (OSCs). In this work, two novel additives, TFFB as well as TCFB, are proposed and doped into acceptor using layer‐by‐layer deposition method to realize high‐performance bilayer OSCs based on D18‐Cl/Y6 system. The asymmetric additive TFFB was introduced to improve molecular polarity, facilitate molecular stacking and promote film crystallization. Compared to the control devices without additive‐treated, power conversion efficiency (PCE) of D18‐Cl/Y6(TFFB) OSCs was increased from 18.04% to 18.85%. Furthermore, TCFB with trichloromethyl instead of trifluoromethyl caused large quadrupole moment, which further enhanced the intermolecular interactions and induced the components distribution to form a better three‐dimensional morphology structure. Corresponding D18‐Cl/Y6(TCFB) devices achieved an excellent PCE of 19.15%, one of the highest PCE reported for binary OSCs to date. In addition, TCFB‐treated devices exhibited favorable storage stability, remaining over 95% of the original efficiency after 2500 hours of placement. This study presents a simple and valid method that utilizing the role of quadrupole moment to optimize the hierarchical morphology and improve the charge dynamics process, finally realizing highly efficient and stable OSCs.