Constructing fibril morphology has been believed to be an effective method of achieving efficient exciton dissociation and charge transport in organic solar cells (OSCs). Despite emerging endeavors on the fibrillization of organic semiconductors via chemical structural design or physical manipulation, tuning of the fibril geometry, i.e., width and length, for tailored optoelectronic properties remains to be studied in depth. In this work, a series of alkoxythiophene additives featuring varied alkyl side chains connected to thiophene are designed to modulate the growth of fibril aggregates in cutting-edge polymer donors PM6 and D18. Molecular dynamics simulations and morphological characterizations reveal that these additives preferentially locate near and entangle with the side chains of polymer donors, which enhance the conjugated backbone stacking of polymer donors to form nanofibrils with the width expanding from 12.6 to 21.8 nm and the length increasing from 98.3 to 232.7 nm. This nanofibril structure is feasible to acquire efficient exciton dissociation and charge transport simultaneously. By integrating the fibril PM6 and L8-BO as the donor and acceptor layers in pseudo-bulk heterojunction (p-BHJ) OSCs via layer-by-layer deposition, an improvement of power conversion efficiency (PCE) from 18.7% to 19.8% is observed, contributed by enhanced light absorption, charge transport, and reduced charge recombination. The versatility of these additives is also verified in D18:L8-BO OSCs, with enhanced PCE from 19.3% to 20.1%, which is among the highest values reported for OSCs.

中文翻译：

---

通过侧链相互作用调整聚合物纳米原纤维的几何形状，以实现有机太阳能电池的 20.1% 效率


构建原纤维形态被认为是在有机太阳能电池 （OSC） 中实现高效激子解离和电荷传输的有效方法。尽管通过化学结构设计或物理操作在有机半导体的原纤化方面取得了新的努力，但调整原纤维几何形状（即宽度和长度）以实现定制的光电特性仍有待深入研究。在这项工作中，设计了一系列具有与噻吩连接的不同烷基侧链的烷氧基噻吩添加剂，以调节尖端聚合物供体 PM6 和 D18 中原纤维聚集体的生长。分子动力学模拟和形态学表征表明，这些添加剂优先位于聚合物供体的侧链附近并与之纠缠，这增强了聚合物供体的共轭骨架堆叠，形成纳米原纤维，宽度从 12.6 nm 扩大到 21.8 nm，长度从 98.3 增加到 232.7 nm。这种纳米原纤维结构可以同时获得有效的激子解离和电荷传输。通过逐层沉积将原纤维 PM6 和 L8-BO 作为供体层和受体层整合到伪体异质结 （p-BHJ） OSC 中，观察到功率转换效率 （PCE） 从 18.7% 提高到 19.8%，这得益于增强的光吸收、电荷传输和减少电荷复合。这些添加剂的多功能性也在 D18：L8-BO OSC 中得到验证，PCE 从 19.3% 提高到 20.1%，这是 OSC 报告的最高值之一。