Bulk-heterojunction organic solar cells (OSCs) often suffer from morphological instability due to thermo- or photoinduced molecular diffusion. To circumvent such instability, OSCs incorporating a single-component block copolymer with covalently bonded blocks can restrain molecular diffusion. However, the device efficiencies of such block copolymers are lagging behind those based on a blended active layer due to a nonideal morphological problem. Herein, we successfully alleviate this problem by introducing a small-molecule additive, Y6, having a structure similar to that of the acceptor block. The addition of Y6 improves the packing of acceptor blocks in the block copolymer, PM6-b-PYIT. This helps improve electron transport and enhances the device efficiency to 15.55%, representing the highest value reported for block-copolymer-based OSCs. Moreover, the device stability is significantly improved due to the padding of Y6 into the nanovoids of the copolymer matrix to restrict the molecular motion. This work presents an effective strategy to address the efficiency–stability tradeoff in OSCs.

中文翻译：

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用于高效稳定有机太阳能电池的非富勒烯受体掺杂嵌段共聚物

体异质结有机太阳能电池 (OSC) 由于热或光诱导的分子扩散而经常遭受形态不稳定性。为了避免这种不稳定性，结合了单组分嵌段共聚物和共价键合嵌段的 OSC 可以抑制分子扩散。然而，由于非理想形态问题，这种嵌段共聚物的器件效率落后于基于混合活性层的器件效率。在这里，我们通过引入具有与受体块相似结构的小分子添加剂 Y6 成功地缓解了这个问题。Y6 的添加改善了嵌段共聚物 PM6- b中受体嵌段的堆积-PYIT。这有助于改善电子传输并将器件效率提高到 15.55%，代表基于嵌段共聚物的 OSC 报告的最高值。此外，由于将Y6填充到共聚物基体的纳米空隙中以限制分子运动，器件稳定性显着提高。这项工作提出了一种有效的策略来解决 OSC 中的效率-稳定性权衡。