Xiao Jingyang, Jia Xiao'e, Duan Chunhui, Huang Fei, Yip Hin-Lap, Cao Yong
State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China.
Institute of Preventive Medicine, School of Public Health, Dali University, Dali, 671000, P. R. China.
Adv Mater. 2021 Jun;33(25):e2008158. doi: 10.1002/adma.202008158. Epub 2021 May 10.
Benefiting from low cost and simple synthesis, polythiophene (PT) derivatives are one of the most popular donor materials for organic solar cells (OSCs). However, polythiophene-based OSCs still suffer from inferior power conversion efficiency (PCE) than those based on donor-acceptor (D-A)-type conjugated polymers. Herein, a fluorinated polythiophene derivative, namely P4T2F-HD, is introduced to modulate the miscibility and morphology of the bulk heterojunction (BHJ)-active layer, leading to a significant improvement of the OSC performance. The Flory-Huggins interaction parameters calculated from the surface energy and differential scanning calorimetry results suggest that P4T2F-HD shows moderate miscibility with the popular nonfullerene acceptor Y6-BO (2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2',3':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile), while poly(3-hexylthiophene) (P3HT) is very miscible with Y6-BO. As a result, the P4T2F-HD case forms desired nanoscale phase separation in the BHJ film while the P3HT case forms a completely mixed BHJ film, as revealed by transmission electron microscopy (TEM) and grazing-incidence wide-angle X-ray scattering (GIWAXS). By optimizing the cathode interface and the morphology of the P4T2F-HD:Y6-BO films processed from nonhalogenated solvents, a new record PCE of 13.65% for polythiophene-based OSCs is demonstrated. This work highlights the importance of controlling D/A interactions for achieving desired morphology and also demonstrates a promising OSC system for potential cost-effective organic photovoltaics.
得益于低成本和简单的合成方法，聚噻吩（PT）衍生物是有机太阳能电池（OSC）中最受欢迎的供体材料之一。然而，基于聚噻吩的有机太阳能电池的功率转换效率（PCE）仍低于基于供体-受体（D-A）型共轭聚合物的电池。在此，引入了一种氟化聚噻吩衍生物，即P4T2F-HD，以调节本体异质结（BHJ）活性层的混溶性和形态，从而显著提高有机太阳能电池的性能。根据表面能和差示扫描量热法结果计算得到的弗洛里-哈金斯相互作用参数表明，P4T2F-HD与常用的非富勒烯受体Y6-BO（2,2'-((2Z,2'Z)-((12,13-双(2-丁基辛基)-3,9-二十一烷基-12,13-二氢-[1,2,5]噻二唑并[3,4-e]噻吩并[2',3':4',5']噻吩并[2',3':4,5]吡咯并[3,2-g]噻吩并[2',3':4,5]噻吩并[3,2-b]吲哚-2,10-二基)双(亚甲基))双(5,6-二氟-3-氧代-2,3-二氢-1H-茚-2,1-二亚基))二丙二腈）具有适度的混溶性，而聚（3-己基噻吩）（P3HT）与Y6-BO非常混溶。结果，如透射电子显微镜（TEM）和掠入射广角X射线散射（GIWAXS）所示，P4T2F-HD的情况在BHJ薄膜中形成了所需的纳米级相分离，而P3HT的情况形成了完全混合的BHJ薄膜。通过优化由非卤代溶剂加工的P4T2F-HD:Y6-BO薄膜中的阴极界面和形态，基于聚噻吩的有机太阳能电池实现了13.65%的新纪录PCE。这项工作突出了控制供体/受体相互作用以实现所需形态的重要性，同时也展示了一个有前景的有机太阳能电池系统，有望用于具有成本效益的有机光伏领域。
