Sun Huiliang, Yu Han, Shi Yongqiang, Yu Jianwei, Peng Zhongxiang, Zhang Xianhe, Liu Bin, Wang Junwei, Singh Ranbir, Lee Jaewon, Li Yongchun, Wei Zixiang, Liao Qiaogan, Kan Zhipeng, Ye Long, Yan He, Gao Feng, Guo Xugang
Department of Materials Science and Engineering, Southern University of Science and Technology (SUSTech), No. 1088, Xueyuan Road, Shenzhen, Guangdong, 518055, P. R. China.
Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong, P. R. China.
Adv Mater. 2020 Oct;32(43):e2004183. doi: 10.1002/adma.202004183. Epub 2020 Sep 21.
Narrow-bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow-bandgap polymer acceptor L14, featuring an acceptor-acceptor (A-A) type backbone, is synthesized by copolymerizing a dibrominated fused-ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A-A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low-lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open-circuit voltage (V ), which is attributed to a small nonradiative recombination loss (E ) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor and V , an excellent efficiency of 14.3% is achieved, which is among the highest values for all-polymer solar cells (all-PSCs). The results demonstrate the superiority of narrow-bandgap A-A type polymers for improving all-PSC performance and pave a way toward developing high-performance polymer acceptors for all-PSCs.
窄带隙聚合物半导体对于推动有机太阳能电池的发展至关重要。在此，通过使二溴化稠环电子受体（FREA）与二锡化联噻吩酰亚胺共聚，合成了一种具有受体-受体（A-A）型主链的新型窄带隙聚合物受体L14。结合了FREA和A-A聚合物两者的优点，L14不仅显示出窄带隙和高吸收系数，而且具有较低的前沿分子轨道（FMO）能级。这种FMO能级产生了改善的电子转移特性，但出乎意料的是，并未牺牲开路电压（V），这归因于0.22 eV的小非辐射复合损失（E）。受益于改善的光电流以及高填充因子和V，实现了14.3%的优异效率，这在全聚合物太阳能电池（all-PSC）中处于最高值之列。结果证明了窄带隙A-A型聚合物在改善全PSC性能方面的优越性，并为开发用于全PSC的高性能聚合物受体铺平了道路。
