Cao Zhixiong, Chen Jiale, Liu Shengjian, Jiao Xuechen, Ma Shanshan, Zhao Jiaji, Li Qingduan, Cai Yue-Peng, Huang Fei
School of Chemistry, Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, Guangdong Provincial Engineering Technology Research Center for Materials for Energy Conversion and Storage , South China Normal University (SCNU) , Guangzhou 510006 , People's Republic of China.
Department of Materials Science and Engineering , Monash University , Victoria 3800 , Australia.
ACS Appl Mater Interfaces. 2020 Feb 26;12(8):9545-9554. doi: 10.1021/acsami.9b22987. Epub 2020 Feb 17.
State-of-the-art non-fullerene bulk-heterojunction (BHJ) polymer solar cells outperform the more extensively studied polymer-fullerene BHJ solar cells in terms of efficiency, thermal-, and photostability. Considering the strong light absorption in the near-infrared region (600-1000 nm) for most of the efficient acceptors, the exploration of high-performing large band gap (LBG) polymer donors with complementary optical absorption ranging from 400 to 700 nm remains critical. In this work, the strategy of concurrently incorporating fluorine (-F) and unsaturated nitrogen (-N) substituents along the polymer backbones is used to develop the LBG polymer donor PB[N][F]. Results show that the F- and N-substituted polymer donor PB[N][F] realizes up to 14.4% efficiency in BHJ photovoltaic devices when paired with a benchmark molecule acceptor Y6, which largely outperforms the analogues PB with an efficiency of only 3.6% and PB[N] with an efficiency of 11.8%. Systematic examinations show that synergistic effects of polymer backbone fluorination and nitrogenation can significantly increase ionization potential values, improve charge transport, and reduce bimolecular recombination and trap-assisted recombination in the PB[N][F]:Y6 BHJ system. Importantly, our study shows that the F- and N-substituted conjugated polymers are promising electron-donor materials for solution-processed non-fullerene BHJ solar cells.
目前最先进的非富勒烯体异质结（BHJ）聚合物太阳能电池在效率、热稳定性和光稳定性方面优于研究更为广泛的聚合物-富勒烯BHJ太阳能电池。考虑到大多数高效受体在近红外区域（600-1000 nm）有强烈的光吸收，探索具有400至700 nm互补光吸收的高性能大带隙（LBG）聚合物供体仍然至关重要。在这项工作中，沿着聚合物主链同时引入氟（-F）和不饱和氮（-N）取代基的策略被用于开发LBG聚合物供体PB[N][F]。结果表明，当与基准分子受体Y6配对时，F和N取代的聚合物供体PB[N][F]在BHJ光伏器件中实现了高达14.4%的效率，这大大超过了类似物PB（效率仅为3.6%）和PB[N]（效率为11.8%）。系统研究表明，聚合物主链氟化和氮化的协同效应可以显著提高电离势值，改善电荷传输，并减少PB[N][F]:Y6 BHJ系统中的双分子复合和陷阱辅助复合。重要的是，我们的研究表明，F和N取代的共轭聚合物是用于溶液加工非富勒烯BHJ太阳能电池的有前途的电子供体材料。
