Modulating the molecular orientation of linear benzodifuran-based isomeric polymers by exchanging the positions of chlorine and fluorine atoms
Modulating the molecular orientation of linear benzodifuran-based isomeric polymers by exchanging the positions of chlorine and fluorine atoms
复制标题
通过交换氯和氟原子的位置来调节线性苯并二呋喃异构聚合物的分子取向
DOI：
10.1016/j.nanoen.2022.107413
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发表时间：
2022-08-01
期刊：
影响因子：
17.6
通讯作者：
Zhou, Erjun
中科院分区：
文献类型：
--
作者：
Dai, Tingting;Li, Xianda;Zhou, Erjun
光伏聚合物的分子取向和分子间相互作用在决定有机太阳能电池（BHJ-OSCs）中共混膜形态、改善激子解离和携带输运方面起着至关重要的作用。然而，目前仍缺乏简单有效的方法来调节分子取向，这极大地限制了新型光伏聚合物的发展。在这里，我们利用线性D-p-A型聚合物来研究这个课题，其中苯二呋喃（BDF）、噻吩（TT）和苯并三唑（BTA）分别作为D、p和A单元。通过交换氟原子和氯原子的取代位置，聚合物取向可以成功地从PE24 （D单元上的氯化）的边对转移到PE25 （A单元上的氯化）的面对。值得注意的是，当与具有不同带隙的三种经典受体Y6、ITIC和F-BTA5混合时，由THF制成的基于pe25的器件的性能总是比PE24有很大的提高。此外，能量损失分析表明，所有基于pe25的设备都具有更高的EQEEL，最终导致总能量损失小于基于pe24的设备，而voc则大于基于pe24的设备。令人兴奋的是，基于PE25: f - bta5的器件实现了1.14 V的最高VOC和11.3%的PCE，这是高压OSCs的最佳结果之一。我们的结果不仅提供了一种可行的方法来调整分子取向，而且还表明在某些聚合物中氯化a单元可能比经典的氟化a单元更值得尝试。
The molecular orientation and intermolecular interaction of photovoltaic polymers play a crucial role in determining the blend film morphology, improving the exciton dissociation and carries transport in bulk-heterojunction organic solar cells (BHJ-OSCs). However, there is still a lack of simple and effective methods to adjust the molecular orientation, which tremendously limit the development of new photovoltaic polymers. Here, we utilize the linear D-p-A type polymers to study this topic, where benzodifurans (BDF), thienothiophene (TT) and benzotriazole (BTA) are utilized as D, p and A units respectively. By exchanging the substitution position of the fluorine and chlorine atoms, the polymer orientation can be successfully transferred from edge-on for PE24 (chlorination on D unit) to face-on for PE25 (chlorination on A unit). Notably, when blended with three classic acceptors Y6, ITIC, and F-BTA5 with different bandgaps, PE25-based devices fabricated from THF always exhibit greatly enhanced performance over PE24. In addition, energy loss analysis manifests that higher EQEEL occured in all PE25-based devices, ultimately resulting in smaller total energy losses and larger VOCs than PE24-based devices. Excitingly, PE25: F-BTA5-based device realizes the highest VOC of 1.14 V with a PCE of 11.3%, which are among the best results for high-voltage OSCs. Our results not only provide a feasible method to tune the molecular orientation, but also suggest that chlorinated A unit may be more worth trying than classic fluorinated A unit in some polymers.