Ion Coordination and Chelation in a Glycolated Polymer Semiconductor: Molecular Dynamics and X-ray Fluorescence Study
Ion Coordination and Chelation in a Glycolated Polymer Semiconductor: Molecular Dynamics and X-ray Fluorescence Study
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DOI：
10.1021/acs.chemmater.0c01984
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发表时间：
2020-09-08
影响因子：
8.6
通讯作者：
Rivnay, Jonathan
中科院分区：
文献类型：
--
作者：
Matta, Micaela;Wu, Ruiheng;Rivnay, Jonathan
含有乙醇化侧链的聚噻吩类化合物因其具有高空穴迁移率和高电荷密度的体积离子渗透性而迅速成为有机电化学晶体管(OECTS)中性能最好的材料。其中，p(g2T-tt)具有最高的优值系数。我们的工作提供了一个原子图像的p(g2T-tt)-电解液界面在“关闭”状态的OECT，预计是由阳离子-聚合物相互作用主导的。结合分子动力学模拟和X射线荧光，我们展示了不同的阴离子如何有效地调节p(g2T-TT)对阳离子的配位和络合作用。同时，较软的疏水阴离子如TFSI-和ClO4-优先与p(g2T-TT)相相互作用，进一步加强了聚合物与阳离子的络合作用。我们强调了TFSI-更强的疏水性如何导致它在聚合物界面上优先积累，进一步增强了阴离子激活的阳离子-聚合物螯合作用。除了为全面研究操作器件中的电解质掺杂机制铺平道路外，我们的结果还表明，为不同的应用和材料量身定做电解液可能是调整混合导电器件性能的可行策略。
Polythiophenes bearing glycolated side chains have rapidly surged as the highest performing materials for organic electrochemical transistors (OECTs) because of their ability to conjugate volumetric ion penetration with high hole mobility and charge density. Among them, p(g2T-TT) has one of the highest figures of merit. Our work provides an atomistic picture of the p(g2T-TT)-electrolyte interface in the "off" state of an OECT, expected to be dominated by cation-polymer interactions. Using a combination of molecular dynamics simulations and X-ray fluorescence, we show how different anions effectively tune the coordination and chelation of cations by p(g2T-TT). At the same time, softer and hydrophobic anions such as TFSI- and ClO4- are found to preferentially interact with the p(g2T-TT) phase, further enhancing the polymer-cation chelation. We highlight how the stronger hydrophobic nature of TFSI- causes its preferential accumulation at the polymer interface, further enhancing the anion-enabled cation-polymer chelation. Besides opening the way for a full study of electrolyte doping mechanisms in operating devices, our results suggest that tailoring the electrolyte for different applications and materials might be a viable strategy to tune the performance of mixed conducting devices.