Impact of varying side chain structure on organic electrochemical transistor performance: a series of oligoethylene glycol-substituted polythiophenes
Impact of varying side chain structure on organic electrochemical transistor performance: a series of oligoethylene glycol-substituted polythiophenes
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不同侧链结构对有机电化学晶体管性能的影响：一系列低聚乙二醇取代的聚噻吩
DOI：
10.1039/d2ta00683a
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发表时间：
2022
影响因子：
11.9
通讯作者：
Ginger, David S.
中科院分区：
文献类型：
--
作者：
Chen, Shinya E.;Flagg, Lucas Q.;Onorato, Jonathan W.;Richter, Lee J.;Guo, Jiajie;Luscombe, Christine K.;Ginger, David S.
研究了一系列侧链含有乙二醇单元的聚噻吩均聚物在离液阴离子和离液阴离子溶液中的电化学掺杂/脱掺杂动力学和有机电化学晶体管（OECT）性能。我们将它们的性能与参考聚合物，具有二甘醇侧链的聚噻吩衍生物，聚（3-{[2-（2-甲氧基乙氧基）乙氧基]甲基}噻吩-2，5-二基）（P3 MEEMT）进行比较。我们发现较大的OECT材料品质因数μC*，其中μ是载流子迁移率，C* 是体积电容，并且如果氧原子远离聚噻吩主链，则侧链上的氧原子越多，掺杂动力学越快。用烷基单元取代靠近聚噻吩主链的氧原子增加了膜π-堆叠结晶度（未掺杂膜中的较高电子电导率），但牺牲了可用的掺杂位点（OECT中的较低体积电容C*）。我们表明，这种变化在C* 是改变μC* 产品为这个家庭的聚合物的主导因素。侧链上氧原子越多，或氧原子离聚合物主链越远，我们观察到更被动的溶胀和更高的C*。此外，我们表明，相比的掺杂速度，脱掺杂的速度，通过光谱电化学测量，一般都更快，更少依赖于离子种类或侧链氧含量。最后，通过OECT，电化学阻抗谱（EIS）和光谱电化学测量，我们表明，离液阴离子PF 6 −促进更高的掺杂水平，更快的掺杂动力学，和更低的掺杂阈值相比，kosmotropic阴离子Cl−，虽然确切的差异取决于聚合物侧链。我们的研究结果强调了在设计OECT活性层的分子结构时平衡μ和C* 的重要性。
The electrochemical doping/dedoping kinetics, and the organic electrochemical transistor (OECT) performance of a series of polythiophene homopolymers with ethylene glycol units in their side chains using both kosmotropic and chaotropic anion solutions were studied. We compare their performance to a reference polymer, the polythiophene derivative with diethylene glycol side chains, poly(3-{[2-(2-methoxyethoxy)ethoxy]methyl}thiophene-2,5-diyl) (P3MEEMT). We find larger OECT material figure of merit, μC*, where μ is the carrier mobility and C* is the volumetric capacitance, and faster doping kinetics with more oxygen atoms on the side chains, and if the oxygen atom is farther from the polythiophene backbone. Replacing the oxygen atom close to the polythiophene backbone with an alkyl unit increases the film π-stacking crystallinity (higher electronic conductivity in the undoped film) but sacrifices the available doping sites (lower volumetric capacitance C* in OECT). We show that this variation in C* is the dominant factor in changing the μC* product for this family of polymers. With more oxygen atoms on the side chain, or with the oxygen atom farther from the polymer backbone, we observe both more passive swelling and higher C*. In addition, we show that, compared to the doping speed, the dedoping speed, as measured via spectroelectrochemistry, is both generally faster and less dependent on ion species or side chain oxygen content. Last, through OECT, electrochemical impedance spectroscopy (EIS) and spectroelectrochemistry measurements, we show that the chaotropic anion PF6− facilitates higher doping levels, faster doping kinetics, and lower doping thresholds compared to the kosmotropic anion Cl−, although the exact differences depend on the polymer side chains. Our results highlight the importance of balancing μ and C* when designing molecular structures for OECT active layers.