Molecular backbone modification, alkyl-chain engineering, and end-group functionalization are promising strategies for developing efficient high-performance non-fullerene acceptors (NFAs). Herein, two new NFAs, named TPQ-eC7-4F and TPQ-eC7-4Cl, are designed and synthesized. Both molecules have linear octyl chains on fused quinoxaline-containing heterocyclics as the central backbone and difluorinated (2F)/dichlorinated (2Cl) 1,1-dicyanomethylene-3-indanone (IC) as the end-group units. The influences of alkyl-chains on fused quinoxaline backbone and different halogenated end-groups on optical, electrochemical, and photovoltaic performances of organic solar cells (OSCs) are studied. In comparison with TPQ-eC7-4Cl, TPQ-eC7-4F exhibits blue-shifted absorptions with higher molar extinction coefficients in the film state as well as in the donor/acceptor (D/A) blend film state and up-shifting lowest unoccupied molecular orbital (LUMO) energy level. As a result, the OSC devices based on the PBDB-T:TPQ-eC7-4F display an outstanding power conversion efficiency (PCE) of 15.83% with a simultaneously increased open-circuit voltage (V_oc) of 0.85 V, a short-circuit current-density (J_sc) of 25.89 mA cm^–2, and a fill factor (FF) of 72.20%, whereas the PBDB-T:TPQ-eC7-4Cl-based OSC device shows a decent PCE of 14.48% with a V_oc of 0.84 V, a J_sc of 24.56 mA/cm², and an FF of 69.77%. To the best of our knowledge, this is the highest photovoltaic performance of PBDB-T-based single-junction binary-OSCs. In comparison, ascribed to the high crystallinity and low solubility of BTP-eC7-4Cl, the corresponding PBDB-T:BTP-eC7-4Cl-based OSC device shows poor photovoltaic performance (PCE of 11.87%). The experimental results demonstrate that fine-tuning the fused quinoxaline backbone with alkyl-chain and end-group functionalization are promising strategies to construct high-performance NFAs for PBDB-T-based single-junction binary-OSCs.

中文翻译：

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基于 PBDB-T 的二元 OSC 通过端基官能化和含喹喔啉的非富勒烯受体的烷基链工程实现超过 15.83% 的效率

分子骨架修饰、烷基链工程和端基功能化是开发高效高性能非富勒烯受体 (NFA) 的有前景的策略。在此，设计和合成了两种新的 NFA，分别命名为 TPQ-eC7-4F 和 TPQ-eC7-4Cl。两种分子都在含稠合喹喔啉的杂环上具有线性辛基链作为中心主链，二氟化 (2F)/二氯化 (2Cl) 1,1-二氰亚甲基-3-茚满酮 (IC) 作为端基单元。研究了烷基链对稠合喹喔啉骨架和不同卤化端基对有机太阳能电池 (OSC) 的光学、电化学和光伏性能的影响。与 TPQ-eC7-4Cl 相比，TPQ-eC7-4F 在薄膜状态以及供体/受体 (D/A) 混合薄膜状态下表现出蓝移吸收，具有较高的摩尔消光系数，并上移最低未占分子轨道 (LUMO) 能级。结果，基于 PBDB-T:TPQ-eC7-4F 的 OSC 器件显示出 15.83% 的出色功率转换效率 (PCE)，同时开路电压增加（V _oc ) 为 0.85 V，短路电流密度 ( J _sc ) 为 25.89 mA cm ^–2，填充因子 (FF) 为 72.20%，而基于 PBDB-T:TPQ-eC7-4Cl 的 OSC器件的 PCE 为 14.48%，V _oc为 0.84 V，J _sc为 24.56 mA/cm ²，FF 为 69.77%。据我们所知，这是基于 PBDB-T 的单结二元 OSC 的最高光伏性能。相比之下，由于 BTP-eC7-4Cl 的高结晶度和低溶解度，相应的 PBDB-T:BTP-eC7-4Cl 基 OSC 器件的光伏性能较差（PCE 为 11.87%）。实验结果表明，用烷基链和端基官能化微调融合的喹喔啉骨架是构建基于 PBDB-T 的单结二元 OSC 的高性能 NFA 的有前景的策略。