标题：Modulating the morphology and molecular arrangement via the well-compatible polymer donor in multiple working mechanisms interwined ternary organic solar cells
作者：Zhang, Kang-Ning; Yang, Xiao-Yu; Niu, Meng-Si; Wen, Zhen-Chuan; Chen, Zhi-Hao; Feng, Lin; Feng, Xian-Jin; Hao, Xiao-Tao
作者机构：[Zhang, Kang-Ning; Yang, Xiao-Yu; Niu, Meng-Si; Wen, Zhen-Chuan; Chen, Zhi-Hao; Feng, Lin; Hao, Xiao-Tao] Shandong Univ, Sch Phys, State Key Lab Cryst 更多
通讯作者：Hao, XT;Hao, XiaoTao
通讯作者地址：[Hao, XT]Shandong Univ, Sch Phys, State Key Lab Crystal Mat, Jinan 250100, Shandong, Peoples R China.
关键词：Organic solar cells; Morphological control; Energy transfer; Molecular; orientation; Multiple working mechanisms
摘要：In solution-processed small molecule organic solar cells (SM-OSCs), morphology of the active layer is a critically important factor in determining photovoltaic performance improvements, which needs to be optimized by more effective morphology modulation approaches. Herein, a medium bandgap conjugated polymer, namely poly [(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithio-phene-4,8-dione))] (PBDB-T), as a morphology regulator was incorporated into the dominating binary SM system comprising of (2,2'-((5Z,5'Z)-5,5'-((3,3''',3"",4'-tetraoctyl-[2,2':5',2 '':5 '',2''':5''',2""-quinquethio-phenel-5,5""-diyl)bis(methanyly-lidene))bis(3-ethyl-4-oxothiazoli-dine-5,2-diylidene))dimalononitrile) (DRCN5T) donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) acceptor to fabricate efficient ternary devices. The PBDB-T not only exhibits the better compatibility and miscibility with DRCN5T but also modulates the crystallinity and molecular arrangement of blend films, which is beneficial to enhance the charge carrier mobility to yield the higher fill factor. Photophysical investigations demonstrate that charge transfer and Forster resonance energy transfer processes coexist between PBDB-T and DRCN5T, which enables the higher short-circuit current density to bring about the efficiency improvements in ternary devices. In addition, the relationship between underlying operating mechanisms and nanoscale morphology evolution is systematically studied. Based on the interwined multi-working mechanisms involving energy transfer and two distinct charge transfer manners associated with microstructure, a 22.1% increase of the PCE was obtained for the ternary devices. These results indicate that selecting the compatible and miscible polymer donor as the third component for SM:fullerene based binary system should be an effective method for morphology optimization to further achieve high performance ternary OSCs.