Incorporating solvent additives in donor and acceptor solutions is an effective strategy for achieving efficient organic solar cells. As the state-of-the-art photovoltaic materials have thiophene sequences along their conjugated backbones, in this contribution, thiophene analogues 2,5-dibromothiophene (HBrT) and 2,5-dibromo-3,4-difluoro-thiophene (FBrT) have been developed as solvent additives. Results show that FBrT has a high boiling point and the ability to dissolve donors and acceptors readily due to the “like dissolve like” principle, providing an effective tool in prolonging the crystallization and phase separation kinetic process of photovoltaic materials. Due to the concurrent formation of increased crystallinity, favorable phase separation, and P–i–N-like heterojunction, the FBrT-treated solar cells demonstrated improved exciton dissociation, charge transportation, extraction, and suppressed carrier recombination. Therefore, the PM6:Y6-based solar cells with FBrT additive reached an efficiency of 17.9% and fill factor of 78.6%, which are one of the highest values reached for the PM6:Y6-based binary solar cells. More strikingly, the FBrT solvent additive possesses general applicability in L8-BO, Y6-BO, and BTP-eC9-based solar cells and achieves significantly enhanced efficiencies of 18.6∼18.7% in devices. These findings make it clear that the thiophene derivatives are effective solvent additives for the further optimization of organic solar cells.

中文翻译：

---

卤代噻吩在调节形态和实现高效有机太阳能电池中用作溶剂添加剂

在供体和受体溶液中加入溶剂添加剂是实现高效有机太阳能电池的有效策略。由于最先进的光伏材料沿其共轭骨架具有噻吩序列，因此在此贡献中，噻吩类似物 2,5-二溴噻吩 (HBrT) 和 2,5-二溴-3,4-二氟噻吩 (FBrT)已开发为溶剂添加剂。结果表明，FBrT具有较高的沸点，并且由于“同类溶解”原理而具有容易溶解供体和受体的能力，为延长光伏材料的结晶和相分离动力学过程提供了有效的工具。由于同时形成增加的结晶度、有利的相分离和 P-i-N 类异质结，FBrT 处理的太阳能电池表现出改善的激子离解、电荷传输、提取和抑制载流子复合。因此，具有 FBrT 添加剂的 PM6:Y6 基太阳能电池的效率为 17.9%，填充因子为 78.6%，这是 PM6:Y6 基二元太阳能电池的最高值之​​一。更引人注目的是，FBrT 溶剂添加剂在 L8-BO、Y6-BO 和 BTP-eC9 基太阳能电池中具有普遍适用性，并且在器件中实现了 18.6~18.7% 的显着提高效率。这些发现清楚地表明，噻吩衍生物是进一步优化有机太阳能电池的有效溶剂添加剂。9% 和 78.6% 的填充因子，这是基于 PM6:Y6 的二元太阳能电池达到的最高值之​​一。更引人注目的是，FBrT 溶剂添加剂在 L8-BO、Y6-BO 和 BTP-eC9 基太阳能电池中具有普遍适用性，并且在器件中实现了 18.6~18.7% 的显着提高效率。这些发现清楚地表明，噻吩衍生物是进一步优化有机太阳能电池的有效溶剂添加剂。9% 和 78.6% 的填充因子，这是基于 PM6:Y6 的二元太阳能电池达到的最高值之​​一。更引人注目的是，FBrT 溶剂添加剂在 L8-BO、Y6-BO 和 BTP-eC9 基太阳能电池中具有普遍适用性，并且在器件中实现了 18.6~18.7% 的显着提高效率。这些发现清楚地表明，噻吩衍生物是进一步优化有机太阳能电池的有效溶剂添加剂。