Department of Materials Science and Engineering and The Shenzhen Key Laboratory for Printed Organic Electronics, Southern University of Science and Technology (SUSTech), No. 1088, Xueyuan Road, Shenzhen, Guangdong, 518055, China.
Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, Guangdong, 510640, China.
Adv Mater. 2019 Apr;31(15):e1807220. doi: 10.1002/adma.201807220. Epub 2019 Feb 15.
A novel imide-functionalized arene, di(fluorothienyl)thienothiophene diimide (f-FBTI2), featuring a fused backbone functionalized with electron-withdrawing F atoms, is designed, and the synthetic challenges associated with highly electron-deficient fluorinated imide are overcome. The incorporation of f-FBTI2 into polymer affords a high-performance n-type semiconductor f-FBTI2-T, which shows a reduced bandgap and lower-lying lowest unoccupied molecular orbital (LUMO) energy level than the polymer analog without F or with F-functionalization on the donor moiety. These optoelectronic properties reflect the distinctive advantages of fluorination of electron-deficient acceptors, yielding "stronger acceptors," which are desirable for n-type polymers. When used as a polymer acceptor in all-polymer solar cells, an excellent power conversion efficiency of 8.1% is achieved without any solvent additive or thermal treatment, which is the highest value reported for all-polymer solar cells except well-studied naphthalene diimide and perylene diimide-based n-type polymers. In addition, the solar cells show an energy loss of 0.53 eV, the smallest value reported to date for all-polymer solar cells with efficiency > 8%. These results demonstrate that fluorination of imide-functionalized arenes offers an effective approach for developing new electron-deficient building blocks with improved optoelectronic properties, and the emergence of f-FBTI2 will change the scenario in terms of developing n-type polymers for high-performance all-polymer solar cells.
一种新型的酰亚胺官能化芳基化合物，双（氟噻吩基）噻吩二酰亚胺（f-FBTI2），具有富电子的 F 原子官能化的稠合骨架，被设计出来，并克服了与高度缺电子氟代酰亚胺相关的合成挑战。将 f-FBTI2 掺入聚合物中得到了高性能的 n 型半导体 f-FBTI2-T，其带隙减小，最低未占据分子轨道（LUMO）能级降低，与没有 F 或在给体部分具有 F 官能化的聚合物类似物相比。这些光电性能反映了富电子受体氟化的独特优势，产生了“更强的受体”，这是 n 型聚合物所需要的。当用作全聚合物太阳能电池中的聚合物受体时，在没有任何溶剂添加剂或热处理的情况下，实现了 8.1%的优异功率转换效率，这是除了经过充分研究的萘二酰亚胺和苝二酰亚胺基 n 型聚合物之外，所有聚合物太阳能电池中报道的最高值。此外，太阳能电池的能量损耗为 0.53eV，这是迄今为止报道的效率>8%的所有聚合物太阳能电池中最小的值。这些结果表明，酰亚胺官能化芳基的氟化提供了一种有效的方法来开发具有改善光电性能的新型缺电子构建块，并且 f-FBTI2 的出现将改变开发高性能全聚合物太阳能电池用 n 型聚合物的情况。
