Semiconducting Eggs and Ladders: Understanding Exciton Landscape Formation in Aqueous π-Conjugated Inter-Polyelectrolyte Complexes
Semiconducting Eggs and Ladders: Understanding Exciton Landscape Formation in Aqueous π-Conjugated Inter-Polyelectrolyte Complexes
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DOI：
10.1021/acs.macromol.0c00029
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发表时间：
2020-04-14
期刊：
影响因子：
5.5
通讯作者：
Ayzner, Alexander L.
中科院分区：
文献类型：
--
作者：
Hollingsworth, William R.;Williams, Vanessa;Ayzner, Alexander L.
共轭聚合物显示出显着的光电性能，出现从离域π电子之间的强耦合，导致高度移动的激发态。从光捕获的角度来看，这是一个非常有用的属性。我们以前表明，一个有前途的和环境有吸引力的方法来形成一个超快的光捕获天线是使用带相反电荷的共轭聚电解质（CPE）的水溶液离子组装。然而，为了合理地设计激发态转移效率，必须阐明CPE组装的基本物理化学。我们证明，离域的π-电子和离子侧链相对于共轭平面的取向一起决定络合动力学和热力学，从而得到的结构。我们发现，络合的焓大大大于以前观察到的非共轭聚电解质。进一步证明了反应焓随温度的升高而变号。我们认为，水溶剂化壳层和可极化的芳香族主链之间的相互作用是理解活化能和反应焓的关键。
Conjugated polymers display remarkable optoelectronic properties that emerge from the strong coupling between delocalized pi-electrons, leading to highly mobile excited states. This is a very useful property from a light-harvesting perspective. We showed previously that a promising and environmentally attractive approach to formation of an ultrafast light-harvesting antenna is to use aqueous ionic assembly of oppositely charged conjugated polyelectrolytes (CPEs). However, to rationally design the excited-state transfer efficiency, the basic physical chemistry of inter CPE assembly must be elucidated. We demonstrate that the delocalization of pi-electrons and the orientation of ionic sidechains relative to the conjugation plane together dictate the complexation kinetics and thermodynamics, and thus the resulting structure. We find that the enthalpy of complexation is substantially larger than previously observed with nonconjugated polyelectrolytes. We further show that the reaction enthalpy changes sign with increasing temperature. We argue that the interaction between the water solvation shell and the polarizable aromatic backbone is key to understanding both the activation energy and the reaction enthalpy.