Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan.
RIKEN Center for Emergent Matter Science (CEMS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Am Chem Soc. 2016 Aug 17;138(32):10265-75. doi: 10.1021/jacs.6b05418. Epub 2016 Aug 5.
The development of semiconducting polymers is imperative to improve the performance of polymer-based solar cells (PSCs). In this study, new semiconducting polymers based on naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole (NTz), PNTz4TF2 and PNTz4TF4, having 3,3'-difluoro-2,2'-bithiophene and 3,3',4,4'-tetrafluoro-2,2'-bithiophene, respectively, are designed and synthesized. These polymers possess a deeper HOMO energy level than their counterpart, PNTz4T, which results in higher open-circuit voltages in solar cells. This concequently reduces the photon energy loss that is one of the most important issues surrounding PSCs. The PNTz4TF4 cell exhibits up to 6.5% power conversion efficiency (PCE), whereas the PNTz4TF2 cell demonstrates outstanding device performance with as high as 10.5% PCE, which is quite high for PSCs. We further discuss the performances of the PSCs based on these polymers by correlating the charge generation and recombination dynamics with the polymer structure and ordering structure. We believe that the results provide new insights into the design of semiconducting polymers and that there is still much room for improvement of PSC efficiency.
半导体聚合物的发展对于提高基于聚合物的太阳能电池（PSC）的性能至关重要。在这项研究中，设计并合成了两种基于萘[1,2-c:5,6-c']双[1,2,5]噻二唑（NTz）的新型半导体聚合物，PNTz4TF2 和 PNTz4TF4，它们分别具有 3,3'-二氟-2,2'-联噻吩和 3,3',4,4'-四氟-2,2'-联噻吩。这些聚合物具有比其对应物 PNTz4T 更深的 HOMO 能级，这导致太阳能电池具有更高的开路电压。这相应地减少了光子能量损失，这是 PSCs 面临的最重要问题之一。PNTz4TF4 电池的功率转换效率（PCE）高达 6.5%，而 PNTz4TF2 电池的器件性能非常出色，PCE 高达 10.5%，这对于 PSCs 来说相当高。我们通过将电荷产生和复合动力学与聚合物结构和有序结构相关联，进一步讨论了基于这些聚合物的 PSCs 的性能。我们相信，这些结果为半导体聚合物的设计提供了新的见解，并且 PSC 效率仍有很大的提高空间。
