Non-fullerene small molecular acceptors (NFSMAs) exhibit promising photovoltaic performance which promoted the rapid progress of organic solar cells (OSCs). In this study, an attempt is done to explore indenothiophene-based high-performance small molecular electron acceptors for organic solar cells. We have designed five acceptor molecules (M1–M5) with strong donor moiety indenothiophene linked to five different end-capped group acceptor moieties: diflouro-2-methylene-3-oxo-2,3-dihydroindene-1-ylidene)malononitrile (A1), 1-(dicyanomethylene)-2-methylene-3-oxo-2,3-dihydro-1H-indene-5,6-dicarbonitrile (A2), methyl-6-cyano-3-(dicyanomethylene)-2-methylene-1-oxo-2,3-dihydro-1H-indene-5-carboylate (A3), 2-(6-cyano-5-fluoro-2-methylene-3-oxo-2,3 dihydro-1H-indene-1-ylidene)malononitrile (A4), and (Z)-methyl 3-(benzo [c][1,2,5]thiadiazol-4-yl)-2-cyanoacrylate (A5) respectively. The structure–property relationship was studied and effects of structural modification on the optoelectronic properties of these acceptors (M1–M5) were determined systematically by comparing it with reference molecule R, which is recently reported as excellent non-fullerene-based small acceptor molecule. Among all designed molecules, M5 is proven as a suitable candidate for organic solar cell applications due to better photovoltaic properties including narrow HOMO-LUMO energy gap (2.11 eV), smallest electron mobility (λ_e = 0.0038 eV), highest λ_max values (702.82 nm in gas) and (663.09 nm in chloroform solvent) and highest open-circuit voltage (V_oc = 1.49 V) with respect to HOMO_PTB7-Th–LUMO_acceptor. Our results indicate that introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFSMAs. This theoretical framework also proves that the conceptualized NFSMAs are superior and thus are recommended for the future construction of high-performance organic solar cell devices.

Graphical abstract

中文翻译：

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为无富勒烯有机太阳能电池设计具有高效光伏参数的基于茚并噻吩的受体材料。

非富勒烯小分子受体（NFSMA）展现出令人鼓舞的光伏性能，从而促进了有机太阳能电池（OSC）的快速发展。在这项研究中，试图探索用于有机太阳能电池的基于茚并噻吩的高性能小分子电子受体。我们设计了五个受体分子（M1–M5）具有强大的供体部分茚并噻吩与五个不同的封端基团受体部分相连：二氟-2-亚甲基-3-氧代-2,3-二氢茚基-1-亚烷基）丙二腈（A1），1-（二氰基亚甲基）-2-亚甲基-3-氧代-2,3-二氢-1H-茚-5,6-二腈（A2），甲基-6-氰基-3-（二氰基亚甲基）-2-亚甲基-1-氧代-2,3-二氢-1H-茚-5-甲酸酯（A3），2-（6-氰基-5-氟-2-亚甲基-3-氧代-2,3-二氢-1H-茚-1-亚烷基）丙二腈（A4）和（Z）-甲基3-（苯并[c] [1,2,5]噻二唑-4-基）-2-氰基丙烯酸酯（A5）。通过与参比分子R的比较，系统地确定了结构与性质之间的关系，并系统地确定了结构修饰对这些受体（M1-M5）的光电性能的影响。，最近被报道为基于非富勒烯的优秀小受体分子。在所有设计的分子，M5被证明作为合适的候选的有机太阳能电池应用由于更好的光电特性，包括窄HOMO-LUMO能隙（2.11电子伏特），最小的电子迁移率（λ _Ë  = 0.0038电子伏特），最高λ_最大值（ 相对于HOMO _PTB7-Th –LUMO_受体，在气体中为702.82 nm）（在氯仿溶剂中为663.09 nm）和最高开路电压（V _oc = 1.49 V）。我们的结果表明，引入更多的封端电子接受单元是设计有前途的NFSMA的一种简单有效的替代策略。该理论框架还证明，概念化的NFSMA具有优越性，因此被推荐用于高性能有机太阳能电池器件的未来构造。

图形概要