Oligo(ethylene glycol) Side Chain Architecture Enables Alcohol-Processable Conjugated Polymers for Organic Solar Cells
Oligo(ethylene glycol) Side Chain Architecture Enables Alcohol-Processable Conjugated Polymers for Organic Solar Cells
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DOI：
10.1021/acs.macromol.2c02259
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发表时间：
2023-03
期刊：
影响因子：
5.5
通讯作者：
Justin Neu;Stephanie Samson;Kan Ding;J. Rech;H. Ade;W. You
中科院分区：
文献类型：
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作者：
Justin Neu;Stephanie Samson;Kan Ding;J. Rech;H. Ade;W. You
事实证明，实现共轭聚合物在真正的绿色溶剂(如醇)中的绿色溶剂溶解性是一个巨大的挑战。在这项工作中，我们报道了三种由poly[(thiophene)-alt-(6，7-difluoro-2-(2-hexyldecyloxy)quinoxaline)](PTQ10)衍生的共轭聚合物的合成和表征，目的是开发更环保的可溶剂加工的衍生物。传统的烷基侧链被各种不同结构的齐聚(乙二醇基)(OEG)侧链取代，包括一个直链和两个支链，它们都含有六个乙二醇基重复单元。确定了线性OEG侧链结构，即使足够长，也不会给出期望的绿色溶剂溶解度，表现为较小的溶解度(R0)。然而，支化的OEG侧链显著改善了溶解度，R0从PTQ10的4.7增加到PTQ-6bO/6bO2的11.9。尽管聚合物的溶液状态有很大的不同，但固态形态更相似，因为所有三种基于OEG的聚合物都保持了与PTQ10类似的主要面对面的分子取向。结果表明，在体相异质结太阳电池中，PTQ-6O器件的功率转换效率(PCE)与PTQ10最接近，而PTQ-6bO2和PTQ-6bO的性能较差。侧链上多了一个碳，PTQ-6bO2表现出比PTQ-6bO更高的PCE，这归因于PTQ-6bO2的聚集性质和固体形态的改善，突出了OEG侧链结构的重要性。这项工作为未来绿色溶剂加工的OPV的醇溶材料制定了重要的指导方针。
Achieving green-solvent solubility of conjugated polymers in truly green solvents such as alcohols has proven to be a significant challenge. In this work, we report the synthesis and characterization of three conjugated polymers derived from poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10) with the goal of developing derivates which are more green-solvent-processable. The traditional alkyl side chains are replaced by various oligo(ethylene glycol) (OEG) side chains of different architectures, including one linear and two branched, all of which contain six ethylene glycol repeating units. It is determined that the linear OEG side chain architecture, even when sufficiently long, will not give desired green-solvent solubility shown by a small solubility capacity (R0). However, branched OEG side chains significantly improve solubility asR0was increased from 4.7 of PTQ10 to 11.9 of PTQ-6bO/6bO2. Although the solution states of the polymers were vastly different, the solid-state morphologies were more similar as all three OEG-based polymers retained a predominately face-on molecular orientation similar to PTQ10. It was demonstrated that PTQ-6O devices showed the most comparable power conversion efficiencies (PCEs) to PTQ10 in bulk heterojunction solar cells, while PTQ-6bO2 and PTQ-6bO showed poorer performances. With one extra carbon in the side chain, PTQ-6bO2 showed higher PCE than PTQ-6bO, attributed to the improved aggregation properties and solid-state morphology of PTQ-6bO2, highlighting the importance of OEG side chain architecture. This work serves to develop important guidelines for future alcohol-soluble materials for green-solvent-processed OPVs.