第一作者：海杰峰*，李玲，宋远霞

通讯作者：海杰峰*，俞江升*，胡华伟*，陈尚尚*

单位：桂林理工大学，南京理工大学，东华大学，南京大学

尽管基于非富勒烯受体（non-fullerene acceptor, NFA）的有机太阳能电池（organic solar cells, OSCs）已经取得了长足的进步，光电转化效率（power conversion efficiency, PCE）超过了19%。但是在实现其商业化的道路上，克服传统工艺使用有害的卤代溶剂，采用绿色溶剂制备工艺（green solvent processed, GSP）制备器件获得高效的OSCs仍然极具挑战。因此，探索开发适用于高效GSP-OSCs的新型NFA材料变得尤为必要。

基于此，桂林理工大学海杰峰副教授联合南京理工大学俞江升副研究员、东华大学胡华伟研究员和南京大学陈尚尚教授，在知名期刊Chemical Engineering Journal上发表题为“Ending group modulation of asymmetric non-fullerene acceptors enables efficient green solvent processed organic solar cells”的研究论文。

该研究工作合成了系列具有不同端基的不对称NFA分子（BTP-SO-BrF, BTP-SO-1F, BTP-SO-2F），它们拥有相同的烷氧基/烷硫基支化侧链。不对称的烷氧基/烷硫基支化侧链修饰极大提升了此类NFA分子在绿色溶剂中和聚合物给体材料PM6的相溶性。

端基调控作用显示，与另外两类材料（BTP-SO-BrF, BTP-SO-1F）相比，基于PM6:BTP-SO-2F的共混膜展现出更紧密的分子间堆积距离、更合适的纤维状相分离形貌以及更均衡的载流子迁移率。最终，基于PM6:BTP-SO-2F的优化器件，其PCE达到17.6%，明显高于基于PM6:BTP-SO-BrF和PM6:BTP-SO-1F的器件效率（15.5%和16.2%），这也是目前文献报道绿色溶剂制备基于不对称NFA的OSCs的最高效率。这项工作展示了端基工程实现对NFA的形貌调控从而获得绿色高效OSCs的先进策略。

Figure 1. Table of content

Figure 1. (a) Chemical structures of BTP-SO-BrF, BTP-SO-1F, and BTP-SO-2F. Normalized absorption spectra of three NFAs in (b) dilute solutions and (c) thin films. (d) Energy level alignment of PM6 and three NFAs.

Figure 2. The computed (a) LUMO frontier molecular orbits, (b) HOMO frontier molecular orbits, and (c) ESP distributions of BTP-SO-BrF, BTP-SO-1F, and BTP-SO-2F

要点二：端基工程优化此类电池器件的光伏性能

Figure 3. (a) Schematic diagram of GSP-OSC devices. (b) The J-V curves of three groups of optimal GSP-OSCs. (c) EQE curves of GSP-OSCs. (d) The plot of PCE versus VOC for representative green non-halogen solvent processed binary OSCs based on symmetric/asymmetric NFA. (e) Photoluminescence quenching spectra of the neat PM6 and three blend films. (f) Jph vs. Veff curves, (g) JSC vs. Plight curves, (h) VOC vs. Plight curves. (i) Histogram of the hole and electron mobilities of PM6:NFA-based devices.

要点三：不同端基修饰NFA的分子结构和其共混膜形貌的关联

Figure 4. AFM (a) height and (b) phase images (2 μm × 2 μm) of the blend films based on PM6:BTP-SO-BrF, PM6:BTP-SO-1F, and PM6:BTP-SO-2F. 2D GIWAXS patterns of (c) three neat NFA films and (d) three blend films. The corresponding 1D GIWAXS line-cut profiles of the (e) in-plane (in dashed) and (f) out-of-plane (in solid) directions of three blend films. (g) π-π stacking distance and CCL out-of-plane π-π peak of three blend films. (h) Lorentz-corrected RSoXS profiles of three blend films.

Ending group modulation of asymmetric non-fullerene acceptors enables efficient green solvent processed organic solar cells

海杰峰副教授简介：桂林理工大学化学与生物工程学院副教授，主要从事有机光电材料（的结构设计及其光伏性能的研究。迄今在Advanced Functional Materials, Advanced Energy Materials, Science China Chemistry, Chemical Engineering Journal, Journal of Materials Chemistry A, Journal of Energy Chemistry, Journal of Colloid and Interface Science, Materials Chemistry Frontiers, Polymer Chemistry, Polymer, Dyes and pigments等国际期刊发表论文20余篇。