Ternary polymer solar cells (PSCs) with three active layer components (two donors with one acceptor, or two acceptors with one donor) have been demonstrated as an emerging strategy to improve the power conversion efficiencies (PCEs). So far, most of the third components utilized in the ternary PSCs are relatively complex molecules or polymers which are expensive due to complicated multi-step syntheses. Here, a simple small molecule of 4,7-bis(5-bromothiophen-2-yl)-5,6-difluorobenzo[c][1,2,5]thiadiazole (BTF), is first used as a second acceptor material to fabricate efficient ternary PSCs. The incorporation of BTF into a binary active layer based on a wide-bandgap polymer of J71 and a low-bandgap acceptor of ITIC, results in ternary PSCs with the best PCE of 12.35%, which is higher than the control J71:ITIC-based binary device with the best PCE of 10.79%. This significantly enhanced PCE results from the simultaneously improved short-circuit current density, open-circuit voltage, and fill factor in the ternary PSCs, and they are in part attributed to the increased light-harvesting with the BTF incorporation and in part attributed to the more balanced charge transportation induced by the improved polymer crystallinity. To determine the generality of BTF as a second acceptor in ternary PSCs, another benchmark binary active layer of PM6:Y6 has been incorporated with 10 wt% BTF, leading to a best-performance device with an outstanding PCE of 16.53% which is the highest among all ternary PSCs, to the best of our knowledge. Our work provides a simple strategy to efficiently boost the performance of ternary PSCs by using an easily available, low-cost acceptor of BTF.

中文翻译：

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最小的基于苯并[ c ] [1,2,5]噻二唑的电子受体作为三元聚合物太阳能电池的第三种组成材料，效率超过16.0％†

具有三个有源层组件（两个施主带有一个受主或两个受主带有一个施主）的三元聚合物太阳能电池（PSC）已被证明是一种新兴的提高功率转换效率（PCE）的策略。迄今为止，在三元PSC中使用的大多数第三组分是相对复杂的分子或聚合物，由于复杂的多步合成，它们是昂贵的。在这里，是一个简单的小分子4,7-双（5-溴噻吩-2-基）-5,6-二氟苯并[ c] [1,2,5]噻二唑（BTF）首先用作制造高效三元PSC的第二受体材料。将BTF掺入基于J71的宽带隙聚合物和ITIC的低带隙受体的二元活性层中，产生的三元PSC的最佳PCE为12.35％，高于基于对照的基于J71：ITIC的最佳PCE为10.79％的二进制设备。三元PSC中短路电流密度，开路电压和填充系数的同时提高导致PCE的显着提高，它们的部分归因于BTF的引入增加了光的收集，而部分归因于BTF的引入。改善的聚合物结晶度导致更平衡的电荷传输。为了确定BTF在三元PSC中作为第二受体的普遍性，据我们所知，PM6：Y6的另一个基准二进制有源层已包含10 wt％的BTF，从而导致了性能最佳的PCE达到16.53％，这是所有三元PSC中最高的。我们的工作提供了一种简单的策略，即通过使用易于使用的低成本BTF受体来有效提高三元PSC的性能。