An n-type polymer (A701) is designed and synthesized with an alternative A′–DAD–A′-D′ backbone, where 1,1-dicyanomethylene-3-indanone (IC), dithienothiophen[3,2-b]-pyrrolobenzothiadiazole (TPBT), and benzodithiophene (BDT) are used as A′, DAD, and D′ units, respectively. A701 shows enhanced light absorption with a narrow bandgap of 1.42 eV and a high absorption coefficient of 6.85 × 10⁴ cm^–1 at 780 nm. It displays an uplifted LUMO (the lowest unoccupied molecular orbital) level of −3.80 eV. By introducing a high point solvent additive of 1,8-diiodooctane (DIO), all-polymer solar cells (all-PSCs) based on the PBDB-T:A701 blend exhibit efficient exciton dissociation, enhanced charge transport, and decreased bimolecular recombination. Thus, a high open-circuit voltage (V_OC) of 0.92 V, a short-circuit current (J_SC) of 18.27 mA cm^–2, and a fill factor (FF) of 0.64 are attained, affording an impressive power conversion efficiency (PCE) of 10.70%. The low voltage loss of 0.50 V and high efficiency of 10.7% are among the top values for all-PSCs. Our results indicate that the fused DAD-type heptacyclic ring can be utilized to construct not only nonfullerene small molecular acceptors but also promising polymer acceptors.

中文翻译：

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用于全聚合物太阳能电池应用的基于稠合 DAD 型七环的低带隙 n 型聚合物，功率转换效率为 10.7%

设计并合成了具有替代 A'-DAD-A'-D' 主链的 n 型聚合物 ( A701 )，其中 1,1-二氰亚甲基-3-茚满酮 (IC)、二噻吩并噻吩[3,2- b ]-吡咯并苯并噻二唑 (TPBT) 和苯并二噻吩 (BDT) 分别用作 A'、DAD 和 D' 单元。A701显示出增强的光吸收，在 780 nm 处具有 1.42 eV 的窄带隙和 6.85 × 10 ⁴ cm ^–1的高吸收系数。它显示了-3.80 eV 的升高的 LUMO（最低未占分子轨道）能级。通过引入 1,8-二碘辛烷 (DIO) 的高点溶剂添加剂，基于 PBDB-T: A701的全聚合物太阳能电池 (all-PSC)共混物表现出有效的激子解离、增强的电荷传输和减少的双分子重组。因此，实现了 0.92 V 的高开路电压 ( V _OC ) 、18.27 mA cm ^–2的短路电流 ( J _SC )和 0.64 的填充因子 (FF)，提供了令人印象深刻的功率转换效率(PCE) 为 10.70%。0.50 V 的低电压损耗和 10.7% 的高效率是全 PSC 的最高值。我们的研究结果表明，稠合的 DAD 型七环不仅可用于构建非富勒烯小分子受体，还可用于构建有前景的聚合物受体。