A p‐Type Liquid‐Crystal Semiconductor with Synergistic Morphological and Charge‐Dynamic Modulation Enables 20.3%‐Efficiency Binary Organic Solar Cells

Abstract Solid additives serve as an effective strategy for modulating the morphology of organic solar cell (OSC) active layers, which critically linked to devices performance. However, current solid additives primarily focus on morphological control, while their inherently weak electrical characteristics may limit improvements in carrier mobility and other electrical properties. This study innovatively introduces a p‐type rod‐like liquid crystalline (LC) organic‐semiconductor, 2‐decyl‐7‐phenylbenzo[b]benzo[4,5]thieno[2,3‐d]thiophene (Ph‐BTBT‐10), as a multifunctional additive in D18:L8‐BO‐based binary OSCs. Benefiting from its strong π‐π stacking and high intrinsic mobility, Ph‐BTBT‐10 enables precise morphological control while simultaneously improving electrical properties. This dual effect synergistically extends exciton diffusion length, enhances charge separation, suppresses recombination, and significantly boosts hole mobility in blend films. Consequently, the optimized binary devices attained a competitive power conversion efficiency (PCE) of 20.3%, alongside a short‐circuit current density of 27.28 mA cm −2 and fill factor of 80.5%. To the best of knowledge, this performance ranks among the highest reported for binary systems exceeding the 20% PCE threshold. This work demonstrates that p‐type LC semiconductors function as multifunctional additives capable of concurrently regulating morphology and boosting intrinsic electrical properties by establishing expanded charge‐transport networks, presenting a promising new paradigm for advancing OSC performance.