Finely controlling the morphology of bulk heterojunction (BHJ) films by additives provides a critical and versatile tool to boost performance of solution processed polymer solar cells (PSCs). In great need are efficient additives that can optimize the arrangement of energetically paired donor and acceptor materials to propel individual photoelectric conversion steps close to unity either in conventional or inverted PSCs. Alternative to the paradigm additives such as 1-chloronaphthlene (CN) etc. for highly efficient conventional PSCs with Y6-type acceptors, herein, bis(5-chlorothiophen-2-yl)alkanes (BCTA-m) with 3 ∼ 6 methylene units (m = 3, 4, 5 and 6) were incorporated as solvent additives to fabricate inverted PM6:Y6 PSCs. The lateral phase separation and vertical composition distribution between PM6 and Y6 were discovered tunable by varying the length (m) of alkanes. The BCTA-4 device offers the maximum power conversion efficiency (PCE) of 15.59%, which is superior to the ones processed from the other BCTA-m (m = 3, 5 and 6) additives and comparable to that of the CN reference (15.62%). The outperformed exciton generation and dissociation, charge transport and suppressed charge recombination are evidently observed within the BCTA-4 device. Furthermore, the lateral phase-separated domain sizes between the pure Y6 (2) and the PM6:Y6 mixture () get an optimum ratio. The overwhelmingly vertical distribution of PM6 near the anode is also confirmed in the BCTA-4 device over the ones processed from the other three analogues. This work demonstrates the potential of BCTA-4 additive to realize high-performance inverted PSCs based on Y6-type acceptors.

中文翻译：

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通过双(5-氯噻吩-2-基)烷添加剂调节横向相分离和垂直成分分布的高效倒置 PM6:Y6 太阳能电池

通过添加剂精细控制本体异质结 (BHJ) 薄膜的形态，为提高溶液加工聚合物太阳能电池 (PSC) 的性能提供了关键且多功能的工具。非常需要有效的添加剂，它可以优化能量配对的供体和受体材料的排列，以推动传统或倒置 PSC 中的各个光电转换步骤接近统一。具有 Y6 型受体的高效传统 PSC 的范例添加剂如 1-氯萘 (CN) 等的替代品，本文中使用具有 3 ∼ 6 个亚甲基单元的双(5-氯噻吩-2-基)烷烃 (BCTA-m) （m = 3、4、5 和 6）作为溶剂添加剂用于制造倒置 PM6:Y6 PSC。发现 PM6 和 Y6 之间的横向相分离和垂直组成分布可以通过改变烷烃的长度 (m) 来调节。 BCTA-4 器件的最大功率转换效率 (PCE) 为 15.59%，优于其他 BCTA-m（m = 3、5 和 6）添加剂加工的器件，与 CN 参考器件相当（ 15.62%）。在 BCTA-4 器件中明显观察到优异的激子生成和解离、电荷传输和抑制的电荷复合。此外，纯Y6 (2) 和PM6:Y6 混合物() 之间的横向相分离域尺寸达到最佳比例。与其他三种类似物处理的设备相比，BCTA-4 设备中也证实了阳极附近 PM6 的绝大多数垂直分布。这项工作展示了 BCTA-4 添加剂在实现基于 Y6 型受体的高性能反向 PSC 方面的潜力。