Polymer Crystallinity Controls Water Uptake in Glycol Side-Chain Polymer Organic Electrochemical Transistors
Polymer Crystallinity Controls Water Uptake in Glycol Side-Chain Polymer Organic Electrochemical Transistors
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DOI：
10.1021/jacs.8b12640
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发表时间：
2019-03-13
影响因子：
15
通讯作者：
Ginger, David S.
中科院分区：
文献类型：
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作者：
Flagg, Lucas Q.;Bischak, Connor G.;Ginger, David S.
我们研究了聚（34-[2-（2-甲氧基乙氧基）乙氧基]甲基}噻吩-2，5-二基）（P3 MEEMT），一种新的聚噻吩衍生物与乙二醇为基础的侧链，作为一个有前途的半导体聚合物的积累模式的有机电化学晶体管（OECTs）的优点与国家的最先进的材料。通过表征P3 MEEMT晶体管的OECT性能作为阴离子的函数，我们发现，大的疏水性阴离子降低阈值电压。我们发现，与聚（3-己基噻吩-2，5-二基）（P3 HT）相比，P3 MEEMT具有更快的阴离子注入速率，这归因于P3 MEEMT晶格的水合作用。我们研究了基于P3 MEEMT的OECT和有机场效应晶体管（OFET）性能与薄膜结晶度的关系，并表明通过热退火改变聚合物的结晶度会增加OFET的迁移率，但会降低OECT的迁移率。我们将这种差异归因于这样一个事实，即与OFFEST不同，OECTs在水性环境中运行。为了探索水合作用如何影响OECTs的操作，我们使用电化学石英微天平（EQCM）重量分析法研究了水在电化学掺杂中的作用。我们发现，稳态水合和水合动力学电化学偏压下显着不同的结晶和非晶P3 MEEMT膜。这些结果表明，水的存在降低了P3 MEEMT的结晶区域之间的电子连接性，从而降低了在溶液中的迁移率。总的来说，我们的研究强调了聚合物水合作用和纳米级形态在阐明OECT操作设计原则中的重要性。
We study poly(34[2-(2-methoxyethoxy)ethoxy]methyl}thiophene-2,5-diyl) (P3MEEMT), a new polythiophene derivative with ethylene glycol-based side chains, as a promising semiconducting polymer for accumulation-mode organic electrochemical transistors (OECTs) with figures of merit comparable to those of state-of-the-art materials. By characterizing the OECT performance of P3MEEMT transistors as a function of the anion, we find that large hydrophobic anions lower the threshold voltage. We find that, compared to poly(3-hexylthiophene-2,5-diyl) (P3HT), P3MEEMT has faster anion injection rates, which we attribute to the hydration of the P3MEEMT crystal lattice. We study P3MEEMT-based OECT and organic field-effect transistor (OFET) performance as a function of film crystallinity and show that changing the crystallinity of the polymer by thermal annealing increases the OFET mobility yet decreases the OECT mobility. We attribute this difference to the fact that, unlike OFETs, OECTs operate in aqueous environments. To probe how hydration affects the operation of OECTs, we investigate the role of water in electrochemical doping using electrochemical quartz microbalance (EQCM) gravimetry. We find that steady-state hydration and hydration dynamics under electrochemical bias differ dramatically between the crystalline and amorphous P3MEEMT films. These results suggest that the presence of water reduces the electronic connectivity between the crystalline regions of P3MEEMT, thus lowering the mobility in solution. Overall, our study highlights the importance of the role of polymer hydration and nanoscale morphology in elucidating design principles for OECT operation.