Zhang Lili, Zhu Xiangwei, Deng Dan, Wang Zhen, Zhang Ziqi, Li Yi, Zhang Jianqi, Lv Kun, Liu Lixuan, Zhang Xuning, Zhou Huiqiong, Ade Harald, Wei Zhixiang
CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.
Sino-Danish Center for Education and Research, Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, China.
Adv Mater. 2022 Feb;34(5):e2106316. doi: 10.1002/adma.202106316. Epub 2021 Dec 13.
In all-small-molecule organic solar cells (ASM-OSCs), a high short-circuit current (J ) usually needs a small phase separation, while a high fill factor (FF) is generally realized in a highly ordered packing system. However, small domain and ordered packing always conflicted each other in ASM-OSCs, leading to a mutually restricted J and FF. In this study, alleviation of the previous dilemma by the strategy of obtaining simultaneous good miscibility and ordered packing through modulating homo- and heteromolecular interactions is proposed. By moving the alkyl-thiolation side chains from the para- to the meta-position in the small-molecule donor, the surface tension and molecular planarity are synchronously enhanced, resulting in compatible properties of good miscibility with acceptor BTP-eC9 and strong self-assembly ability. As a result, an optimized morphology with multi-length-scale domains and highly ordered packing is realized. The device exhibits a long carrier lifetime (39.8 μs) and fast charge collection (15.5 ns). A record efficiency of 16.2% with a high FF of 75.6% and a J of 25.4 mA cm in the ASM-OSCs is obtained. These results demonstrate that the strategy of simultaneously obtaining good miscibility with high crystallinity could be an efficient photovoltaic material design principle for high-performance ASM-OSCs.
在所有小分子有机太阳能电池（ASM-OSCs）中，高短路电流（J）通常需要较小的相分离，而高填充因子（FF）一般在高度有序的堆积体系中实现。然而，在ASM-OSCs中，小尺寸域和有序堆积总是相互矛盾，导致J和FF相互制约。在本研究中，提出了一种通过调节同分子和异分子相互作用来同时获得良好混溶性和有序堆积的策略，以缓解之前的困境。通过将小分子给体中的烷基硫醇化侧链从对位移至间位，表面张力和分子平面性同步增强，从而产生与受体BTP-eC9具有良好混溶性和强大自组装能力的兼容性质。结果，实现了具有多长度尺度域和高度有序堆积的优化形貌。该器件表现出较长的载流子寿命（39.8 μs）和快速的电荷收集（15.5 ns）。在ASM-OSCs中获得了创纪录的16.2%的效率，FF高达75.6%，J为25.4 mA cm 。这些结果表明，同时获得良好混溶性和高结晶度的策略可能是高性能ASM-OSCs的一种有效的光伏材料设计原则。
