Liang Ziqi, Gao Mengyuan, Zhang Bo, Wu Junjiang, Peng Zhongxiang, Li Miaomiao, Ye Long, Geng Yanhou
School of Materials Science and Engineering, Tianjin University, Tianjin, China.
Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin, China.
Front Chem. 2021 May 10;9:687996. doi: 10.3389/fchem.2021.687996. eCollection 2021.
Owing to the advantages of low synthetic cost and high scalability of synthesis, polythiophene and its derivatives (PTs) have been of interest in the community of organic photovoltaics (OPVs). Nevertheless, the typical efficiency of PT based photovoltaic devices reported so far is much lower than those of the prevailing push-pull type conjugated polymer donors. Recent studies have underscored that the excessively low miscibility between PT and nonfullerene acceptor is the major reason accounting for the unfavorable active layer morphology and the inferior performance of OPVs based on a well-known PT, namely PDCBT-Cl and a non-halogenated nonfullerene acceptor IDIC. How to manipulate the miscibility between PT and acceptor molecule is important for further improving the device efficiency of this class of potentially low-cost blend systems. In this study, we introduced different numbers of F atoms to the end groups of IDIC to tune the intermolecular interaction of the hypo-miscible blend system (PDCBT-Cl:IDIC). Based on calorimetric, microscopic, and scattering characterizations, a clear relationship between the number of F atoms, miscibility, and device performance was established. With the increased number of F atoms in IDIC, the resulting acceptors exhibited enhanced miscibility with PDCBT-Cl, and the domain sizes of the blend films were reduced substantially. As a result, distinctively different photovoltaic performances were achieved for these blend systems. This study demonstrates that varying the number of F atoms in the acceptors is a feasible way to manipulate the molecular interaction and the film morphology toward high-performance polythiophene:nonfullerene based OPVs.
由于聚噻吩及其衍生物（PTs）具有合成成本低和合成可扩展性高的优点，它们在有机光伏（OPV）领域受到了关注。然而，迄今为止报道的基于PT的光伏器件的典型效率远低于主流的推挽型共轭聚合物供体。最近的研究强调，PT与非富勒烯受体之间极低的混溶性是导致基于一种著名的PT（即PDCBT-Cl）和一种非卤化非富勒烯受体IDIC的OPV活性层形态不佳和性能较差的主要原因。如何控制PT与受体分子之间的混溶性对于进一步提高这类潜在低成本混合体系的器件效率至关重要。在本研究中，我们在IDIC的端基引入不同数量的F原子，以调节低混溶性混合体系（PDCBT-Cl:IDIC）的分子间相互作用。基于量热、显微镜和散射表征，建立了F原子数量、混溶性和器件性能之间的明确关系。随着IDIC中F原子数量的增加，所得受体与PDCBT-Cl的混溶性增强，混合膜的畴尺寸大幅减小。结果，这些混合体系实现了显著不同的光伏性能。本研究表明，改变受体中F原子的数量是一种可行的方法，可用于控制分子间相互作用和薄膜形态，以实现基于聚噻吩：非富勒烯的高性能OPV。
