Molecular Design Features for Charge Transport in Nonconjugated Radical Polymers.
Molecular Design Features for Charge Transport in Nonconjugated Radical Polymers.
复制标题
非共轭自由基聚合物中电荷传输的分子设计特征。
DOI：
--
复制
发表时间：
2021
影响因子：
15
通讯作者：
B. Savoie
中科院分区：
文献类型：
--
作者：
Ying Tan;Nicholas C Casetti;B. Boudouris;B. Savoie
与传统的掺杂共轭聚合物相比，基于开壳自由基部分的导电聚合物表现出潜在的有利的加工、稳定性和光学属性。尽管它们的优势，报道的自由基导体几乎完全基于（2，2，6，6-四甲基哌啶-1-基）氧基（克里思），这引起了关于这些材料中电荷传输的极限的基本问题，以及当代材料所表现出的一些缺陷是否是由于自由基化学的选择。为了解决这些问题，我们对与自由基导体相关的广泛开壳层化学物质（包括p型、n型和双极开壳层化学物质）的电荷转移特征进行了密度泛函理论（DFT）研究。我们观察到，远离代表性，克里思表现出惊人的高重组能量，由于强大的电荷本地化。这反过来又限制了克里思中的电荷转移，与更离域的开壳层物种相比。通过全面映射自由基-自由基取向上的电荷转移的依赖性，我们还确定了分子间相互作用所青睐的构象和在所有研究的开壳层化学中最大化电荷转移的构象之间的大失配。这些结果表明，存在重大的机会，利用直接相互作用，以促进自由基聚合物中的电荷传输。
Conducting polymers based on open-shell radical moieties exhibit potentially advantageous processing, stability, and optical attributes compared with conventional doped conjugated polymers. Despite their ascendance, reported radical conductors have been based almost exclusively on (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), which raises fundamental questions regarding the ultimate limits of charge transport in these materials and whether some of the deficiencies exhibited by contemporary materials are due to the choice of radical chemistry. To address these questions, we have performed a density functional theory (DFT) study of the charge transfer characteristics of a broad range of open-shell chemistries relevant to radical conductors, including p-type, n-type, and ambipolar open-shell chemistries. We observe that far from being representative, TEMPO exhibits anomalously high reorganization energies due to strong charge localization. This, in turn, limits charge transfer in TEMPO compared with more delocalized open-shell species. By comprehensively mapping the dependence of charge transfer on radical-radical orientation, we have also identified a large mismatch between the conformations that are favored by intermolecular interactions and the conformations that maximize charge transfer in all of the open-shell chemistries investigated. These results suggest that significant opportunities exist to exploit directing interactions to promote charge transport in radical polymers.