Three narrow bandgap non-fullerene acceptors (NFAs) named as IDTT2OT, IDTT2OT-2F, and IDTT2OT-4F were designed and synthesized using a 3,4-dimethoxythiophene as a π–spacer linking the indacenodithieno[3,2-b]thiophene (IDTT) core and 2-(3-oxo-2,2,3-dihydroinden-1-ylidene) (IC) end groups. The NFAs exhibited relatively narrow bandgaps (1.51, 1.45, and 1.42 eV) and up-shifted unoccupied molecular orbital (LUMO) energy levels (–3.69, –3.83, and −3.90 eV) owing to the 3,4-dimethoxythiophene effect compared with the similar structures. By finely tuning the energy levels modulation with a 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']dithiophene-4,8-dione)) (PBDB-T) donor, all the NFA-based devices showed the broad photo-responses, at 300–900 nm, with small energy losses of 0.56–0.58 eV, and thus enhanced the light-harvesting ability of organic solar cells (OSCs). Among the NFA-based blends, the PBDB-T:IDTT2OT-4F device exhibited the best power conversion efficiency (PCE, 10.40%) with a high short-circuit current density (J_SC) of 19.3 mA cm^–2 and an open-circuit voltage (V_OC) of 0.86 V. Our results demonstrate that introducing 3,4-dimethoxythiophene is an efficient strategy for improving the electron accepting ability of NFAs by tuning frontier energy levels.

使用3,4-二甲氧基噻吩作为连接茚二噻吩并[3,2- b ]噻吩的π-间隔基，设计并合成了三种窄带隙非富勒烯受体（NFAs），分别命名为IDTT2OT、IDTT2OT-2F和IDTT2OT-4F （ IDTT) 核心和 2-(3-oxo-2,2,3-dihydroinden-1-ylidene) (IC) 端基。由于 3,4-二甲氧基噻吩效应，NFA 表现出相对窄的带隙（1.51、1.45 和 1.42 eV）和上移的未占分子轨道（LUMO）能级（–3.69、–3.83 和 -3.90 eV）类似的结构。通过用聚[2,6-4,8-​​双(5-(2-乙基己基)噻吩-2-基)-苯并-1,2- b :4,5 - b ']微调能级调制dithiophene])-alt-(5,5-(1,3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'- c :4',5') ——c ']dithiophene-4,8-​​dione)) (PBDB-T) 供体，所有基于 NFA 的器件在 300-900 nm 处显示出广泛的光响应，具有 0.56-0.58 eV 的小能量损失，因此增强了有机太阳能电池（OSC）的光捕获能力。在基于 NFA 的混合物中，PBDB-T:IDTT2OT-4F 器件表现出最佳的功率转换效率 (PCE，10.40%)，具有19.3 mA cm ^–2的高短路电流密度 ( J _SC )和开路-电路电压 ( V _OC ) 为 0.86 V。我们的结果表明，引入 3,4-二甲氧基噻吩是通过调整前沿能级来提高 NFA 电子接受能力的有效策略。