Single-walled carbon nanotubes (SWCNTs) are important candidates for flexible and non-toxic thermoelectric (TE) energy-harvesting devices because they have large Seebeck coefficients, good flexibility, and inkjet printability onto plastic substrates. Here we describe the successful n-type conversion of intrinsic p-type SWCNTs by polymer–dopant charge transfer. The negative Seebeck coefficients of the polymer-doped SWCNTs were strongly related to the highest occupied molecular orbital levels of the polymer, demonstrating that the polymers were electron donors for the nanotubes and that the doping level could be controlled by modifying the functional groups. The n-type SWCNTs obtained using oxygen-abundant polymers, such as poly(vinyl alcohol) and poly(vinyl acetate), exhibited the largest negative Seebeck coefficients and high stability under ambient conditions lasting for at least 3 weeks. Printed and folded p- and n-type SWCNTs on flexible substrates showed efficient TE voltage improvements. Our findings enable the easy, low-cost preparation of air-stable n-type SWCNTs, permitting the exploitation of SWCNTs as flexible and eco-friendly TE materials.

中文翻译：

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通过使用富氧简单聚合物将电子掺杂到喷墨印刷的碳纳米管中而制造的高度稳定的n型热电材料

单壁碳纳米管（SWCNT）是柔性且无毒的热电（TE）能量收集设备的重要候选产品，因为它们具有很大的塞贝克系数，良好的柔韧性和在塑料基板上的喷墨可印刷性。在这里，我们描述了通过聚合物-掺杂剂电荷转移成功完成内在p型SWCNT的n型转化。聚合物掺杂的SWCNT的负塞贝克系数与聚合物的最高占据分子轨道水平密切相关，表明该聚合物是纳米管的电子给体，并且可以通过修饰官能团来控制掺杂水平。使用富含氧的聚合物（例如聚乙烯醇和聚乙酸乙烯酯）获得的n型SWCNT，表现出最大的负塞贝克系数，并且在持续至少3周的环境条件下具有很高的稳定性。在柔性基板上印刷和折叠的p型和n型SWCNT显示出有效的TE电压提高。我们的发现使得能够以简单，低成本的方式制备稳定的n型单壁碳纳米管，从而允许将单壁碳纳米管开发为柔性且环保的TE材料。