Nonfullerene acceptors (NFAs) have played an important role in the development of organic solar cells. However, the optical absorption of most NFAs is limited within 600–900 nm, prohibiting further improvement of short-circuit current density (J_sc). To alleviate this problem, a fused-ring π-core BzS was designed by combining weakly electron-withdrawing benzotriazole (Bz) and strongly electron-donating selenophene together. Besides, the length of N-alkyl chain on the Bz moiety was engineered to tune the morphology, affording two NFAs mBzS-4F and EHBzS-4F. Both NFAs possess an absorption edge approaching 1000 nm, as resulted from the enhanced intramolecular charge transfer in conjunction with efficient intra- and intermolecular interactions. Binary photovoltaic devices based on PM6:mBzS-4F showed a power conversion efficiency of 17.02% with a very high J_sc of 27.72 mA/cm² and a low energy loss of 0.446 eV. This work provides a strategy for future design of efficient NIR-responsive materials.

中文翻译：

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硒烯键合的非富勒烯受体可实现光响应达到1000 nm的效率超过17％的二元有机太阳能电池

非富勒烯受体（NFA）在有机太阳能电池的开发中发挥了重要作用。但是，大多数NFA的光吸收被限制在600-900 nm之内，从而阻止了短路电流密度（J _sc）的进一步提高。为了缓解这个问题，通过将弱吸电子的苯并三唑（Bz）和强供电子的硒基分子结合在一起，设计了稠环π核BzS。此外，工程改造了Bz部分上N-烷基链的长度以调整形态，从而提供了两个NFA mBzS-4F和EHBzS-4F。两种NFA都具有接近1000 nm的吸收边，这是由于分子内电荷转移增强以及有效的分子内和分子间相互作用共同导致的。基于PM6：mBzS-4F的二元光伏器件显示出17.02％的功率转换效率，具有非常高的J _sc（27.72 mA / cm ^2）和0.446 eV的低能量损耗。这项工作为未来设计有效的近红外响应材料提供了策略。