Although organic mixed ionic–electronic conductors are widely proposed for use in bioelectronics, energy generation/storage and neuromorphic computing, our fundamental understanding of the charge-compensating interactions between the ionic and electronic carriers and the dynamics of ions remains poor, particularly for hydrated devices and on electrochemical cycling. Here we show that operando ²³Na and ¹H nuclear magnetic resonance (NMR) spectroscopy can quantify cation and water movement during the doping/dedoping of films comprising the widely used mixed conductor poly(3,4-ethylene dioxythiophene) poly(styrene sulfonate) (PEDOT:PSS). A distinct ²³Na quadrupolar splitting is observed due to the partial ordering of the PSS chains within the PEDOT:PSS-rich domains, with respect to the substrate. Operando ²³Na NMR studies reveal a close-to-linear correlation between the quadrupolar splitting and the charge stored, which is quantitatively explained by a model in which the holes on the PEDOT backbone are bound to the PSS SO₃⁻ groups; an increase in hole concentration during doping inversely correlates with the number of Na⁺ ions bound to the PSS chains within the PEDOT-rich ordered domains, leading to a decrease in ions within the ordered regions and a decrease in quadrupolar splitting. The Na⁺-to-electron coupling efficiency, measured via ²³Na NMR intensity changes, is close to 100% when using a 1 M NaCl electrolyte. Operando ¹H NMR spectroscopy confirms that the Na⁺ ions injected into/extracted from the wet films are hydrated. These findings shed light on the working principles of organic mixed conductors and demonstrate the utility of operando NMR spectroscopy in revealing structure–property relationships in electroactive polymers.

尽管有机混合离子电子导体被广泛用于生物电子学、能量产生/储存和神经形态计算，但我们对离子和电子载体之间的电荷补偿相互作用以及离子动力学的基本理解仍然很差，特别是对于水合设备和电化学循环。在这里，我们表明原位²³ Na 和¹ H 核磁共振 (NMR) 光谱可以量化包含广泛使用的混合导体聚（3,4-乙烯二氧噻吩）聚（苯乙烯磺酸盐）的薄膜掺杂/去掺杂过程中的阳离子和水运动（PEDOT：PSS）。与众不同的²³由于 PEDOT:PSS 富集域内的 PSS 链相对于底物的部分排序，观察到 Na 四极分裂。Operando ²³ Na NMR 研究揭示了四极分裂与存储的电荷之间接近线性的相关性，这可以通过一个模型进行定量解释，在该模型中，PEDOT 骨架上的空穴与 PSS SO 3 - 基_团^结合；掺杂过程中空穴浓度的增加与富含 PEDOT 的有序域内 PSS 链上结合的Na ⁺离子数量呈负相关，导致有序区域内离子的减少和四极分裂的减少。Na ⁺ -电子耦合效率，通过^23测量使用 1 M NaCl 电解质时，Na NMR 强度变化接近 100%。Operando ¹ H NMR 光谱证实注入到湿膜中/从湿膜中提取的 Na ⁺离子是水合的。这些发现阐明了有机混合导体的工作原理，并证明了操作核磁共振光谱在揭示电活性聚合物的结构-性质关系方面的效用。