Hydration of a Side-Chain-Free n-Type Semiconducting Ladder Polymer Driven by Electrochemical Doping
Hydration of a Side-Chain-Free n-Type Semiconducting Ladder Polymer Driven by Electrochemical Doping
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DOI：
10.1021/jacs.2c11468
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发表时间：
2023-01-11
影响因子：
15
通讯作者：
Ginger, David S.
中科院分区：
文献类型：
--
作者：
Guo, Jiajie;Flagg, Lucas Q.;Ginger, David S.
我们研究了梯形聚合物聚苯并咪唑苯并菲咯啉 (BBL) 的有机电化学晶体管 (OECT) 性能，试图更好地了解表面疏水的无侧链聚合物如何能够在水性环境中作为具有良好氧化还原动力学的 OECT 运行。我们检查了来自不同来源的两种不同分子质量的 BBL。无论分子量如何，两种 BBL 在初始还原步骤中都表现出显着的膜膨胀。通过结合电化学石英晶体微天平重量分析、操作内原子力显微镜以及异位和操作内掠入射广角X射线散射（GIWAXS），我们提供了在没有任何亲水侧链的情况下BBL中电化学电荷注入过程的详细结构图。与异位测量相比，操作中 GIWAXS 显示电化学掺杂时的膨胀程度比之前认识到的更大，并且去掺杂时的收缩程度较小。数据显示，BBL 薄膜经历了由初始电化学掺杂循环驱动的不可逆水合，并在随后的氧化/还原循环中持续存在显着的保水性和层状膨胀。这种溶胀创造了一个亲水环境，在许多其他聚合物系统中不存在亲水侧链的情况下，有利于随后的快速水合离子传输。由于其刚性的阶梯主链和不存在亲水性侧链，初级BBL吸水不会显着降低晶序，干燥后可恢复原来的脱水、未溶胀状态。掺杂诱导的亲水性和稳定的晶体有序性相结合，可实现高效的离子传输和良好的稳定性。
We study the organic electrochemical transistor (OECT) performance of the ladder polymer poly-(benzimidazobenzophenanthroline) (BBL) in an attempt to better understand how an apparently hydrophobic side-chain-free polymer is able to operate as an OECT with favorable redox kinetics in an aqueous environment. We examine two BBLs of different molecular masses from different sources. Regardless of molecular mass, both BBLs show significant film swelling during the initial reduction step. By combining electrochemical quartz crystal microbalance gravimetry, in-operando atomic force micros-copy, and both ex-situ and in-operando grazing incidence wide-angle X-ray scattering (GIWAXS), we provide a detailed structural picture of the electrochemical charge injection process in BBL in the absence of any hydrophilic side-chains. Compared with ex-situ measurements, in-operando GIWAXS shows both more swelling upon electrochemical doping than has previously been recognized and less contraction upon dedoping. The data show that BBL films undergo an irreversible hydration driven by the initial electrochemical doping cycle with significant water retention and lamellar expansion that persists across subsequent oxidation/ reduction cycles. This swelling creates a hydrophilic environment that facilitates the subsequent fast hydrated ion transport in the absence of the hydrophilic side-chains used in many other polymer systems. Due to its rigid ladder backbone and absence of hydrophilic side-chains, the primary BBL water uptake does not significantly degrade the crystalline order, and the original dehydrated, unswelled state can be recovered after drying. The combination of doping induced hydrophilicity and robust crystalline order leads to efficient ionic transport and good stability.