Controlled sequential crystallization of donors and acceptors is a critical factor for achieving enhanced phase separation and efficient charge transfer performance in polymer solar cells (PSCs). In this study, a comprehensive investigation of a structurally simple solvent additive, 1-fluoro-2-iodobenzene (OFIB) is conducted, which efficiently controls the morphology of the active layer, resulting in fibrous assembly and significantly enhancing the power conversion efficiency from 16.34% to 18.38% based on the PM6:L8-BO system. Density functional theory, molecular dynamics simulations, and grazing incidence small- and wide-angle X-ray scattering techniques reveal that the addition of OFIB to the processed blend aligns the orientation of the acceptor molecules, thereby enhancing the overall π–π stacking in the active layer. OFIB establishes nearly equal-strength π–π interactions with the conjugated frameworks of both the donor and acceptor materials, benefiting from the multiple electron conjugation between its iodine atom and the conjugated framework in the active layer. Femtosecond-timescale photophysical studies demonstrate that the OFIB-optimized active layer shows reduced exciton losses at the donor–acceptor interface. This study offers a new perspective on the mechanism underlying the function of solvent additives and presents a comprehensive research methodology that will guide the development of next-generation non-fullerene acceptors for efficient PSCs.

中文翻译：

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1-氟-2-碘苯溶剂添加剂对聚合物太阳能电池中施主和受主结晶以及超快载流子动力学的影响

供体和受体的受控顺序结晶是聚合物太阳能电池（PSC）中实现增强相分离和高效电荷转移性能的关键因素。在这项研究中，对结构简单的溶剂添加剂1-氟-2-碘苯（OFIB）进行了全面研究，它有效地控制活性层的形态，产生纤维状组装，并显着提高功率转换效率从16.34 % 至 18.38%（基于 PM6:L8-BO 系统）。密度泛函理论、分子动力学模拟和掠入射小角和广角 X 射线散射技术表明，在加工后的混合物中添加 OFIB 可以对齐受体分子的方向，从而增强了体系中的整体 π-π 堆积。活性层。 OFIB 与给体和受体材料的共轭骨架建立了几乎等强度的 π-π 相互作用，这得益于其碘原子与活性层中的共轭骨架之间的多电子共轭。飞秒时间尺度的光物理研究表明，OFIB 优化的活性层显示出供体-受体界面处的激子损失减少。这项研究为溶剂添加剂功能背后的机制提供了新的视角，并提出了一种全面的研究方法，将指导开发高效 PSC 的下一代非富勒烯受体。