Multi-walled carbon nanotubes (MWCNTs) have shown low n-type Seebeck coefficients (−10 μV K⁻¹), which are not good enough to prepare high performance low-cost MWCNT based mechanically flexible thermoelectric devices. Here, we present a double doping approach utilizing a small n-type doping molecule, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidazole (N-DMBI), in addition to encapsulated metal (iron) nanoparticles for achieving a high n-type thermoelectric performance with MWCNTs. With double doping, we have shown high n-type Seebeck coefficients up to −56 μV K⁻¹ along with a power factor up to 112 μW m⁻¹ K⁻² at room temperature, which, to the best of our knowledge, is at least an order of magnitude higher than the power factors of previously reported n-type MWCNT based organic materials. More importantly, the negative Seebeck coefficient was maintained even after 60 days' exposure to air. An outstanding output power of 1.9 W m⁻² at a temperature difference of 60 K was generated with a flexible thermoelectric device made of only MWCNT mats. The new findings could lead to the development of robust and flexible thermoelectric devices made of only low-cost MWCNTs.

中文翻译：

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双掺杂方法可从p型多壁碳纳米管垫上获得异常稳定且较大的n型热电电压

多壁碳纳米管（MWCNT）显示出低n型塞贝克系数（-10μVK ^-1），不足以制备高性能，低成本，基于MWCNT的机械柔性热电器件。在这里，我们提出了一种双重掺杂方法，除了封装的金属（铁）之外，还使用一种小的n型掺杂分子1,3-二甲基-2-苯基-2,3-二氢-1 H-苯并咪唑（N-DMBI） ）纳米颗粒，用于通过MWCNT实现高n型热电性能。通过双掺杂，我们显示出高达-56μVK ^-1的高n型塞贝克系数以及高达112μWm ^-1 K ^-2的功率因数据我们所知，室温下的温度至少比先前报道的基于n型MWCNT的有机材料的功率因数高一个数量级。更重要的是，即使暴露于空气中60天，塞贝克系数仍保持负值。用仅由MWCNT垫制成的柔性热电装置在60 K的温差下产生了1.9 W m ^-2的出色输出功率。新发现可能会导致仅由低成本MWCNT制成的坚固，灵活的热电器件的开发。