Sorting-free utilization of semiconducting carbon nanotubes for large thermoelectric responses
Sorting-free utilization of semiconducting carbon nanotubes for large thermoelectric responses
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DOI：
10.1016/j.nanoen.2019.104282
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发表时间：
2020-01-01
期刊：
影响因子：
17.6
通讯作者：
Yu, Choongho
中科院分区：
文献类型：
--
作者：
Hsu, Jui-Hung;Yu, Choongho
半导体碳纳米管（s-CNTs）是一种很有前途的有机热电材料，主要是由于其大的热电势（或塞贝克系数），但在大量生产的CNTs中，从不同手性管的混合物中只挑选s-CNTs是不切实际的。在这里，我们报告了一种无分选的方法，通过抑制金属CNT（m-CNT）的电子输运来获得大的热电势。本研究采用了有机电化学晶体管（OECT）的配置，其中聚（3，4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT：PSS）通道设置在两个单独的CNT膜之间。基于实验构建的能带图和理论估计，PEDOT：PSS通道可以产生能量势垒，用于减少m-CNT对热电的贡献以及向CNT膜注入空穴。当栅极偏置电压升高到20 V时，热功率显著增加，从而导致最大功率因数。对于没有外部提供的偏置电压的实际应用，纳米级PEDOT：PSS沉积在CNT膜的一端的顶部用于面外空穴传输，然后PEDOT：PSS被化学去掺杂以调节费米能级，如OECT实验。在六个CNT-PEDOT连接的情况下，热电势被提高到接近150 μ V/K，并且在室温下获得了非常高的PF，接近1.3 × 10（3）μ W/m-K-2，这与原始CNT相比提高了460%，并且与无机对应物相当。该研究不仅为有机热电材料的热电行为提供了更好的理解，而且为抑制m-CNT的电子输运提供了一种实用的方法，这将广泛适用于其他有机热电材料及其他材料。
Semiconducting carbon nanotubes (s-CNTs) are promising organic thermoelectric materials mainly due to their large thermopower (or Seebeck coefficient), but it is impractical to pick only s-CNTs out of a mixture of different chirality tubes in mass-produced CNTs. Here we report a sorting-free method for getting the large thermopower by suppressing electronic transport from metallic CNT (m-CNT). This study employed an organic electrochemical transistor (OECT) configuration where poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) channel was disposed between two separated CNT films. Based on the experimentally constructed band diagrams and theoretical estimation, the PEDOT:PSS channel could create energy barriers for abating the contribution of m-CNT to thermopower as well as injecting holes to CNT films. As the gate bias voltage was raised up to 20 V, thermopower was noticeably increased, resulting in the maximum power factor. For practical applications without an externally supplied bias voltage, nanoscale PEDOT:PSS were deposited on top of one end of CNT films for the out-of-plane hole transport, and then PEDOT:PSS was chemically de-doped to adjust the Fermi level like the OECT experiment. With six CNT-PEDOT connections, the thermopower was raised up to similar to 150 mu V/K and a remarkably high PF was obtained up to similar to 1.3 x 10(3) mu W/m-K-2 at room temperature, which is similar to 460% improvement compared with that of pristine CNT and is comparable to those of inorganic counterparts. This study provides not only better understanding of thermoelectric behaviors for organic thermoelectric materials, but also a practical method for suppressing the electronic transport from m-CNT, which would be widely applicable to other organic materials for thermoelectrics and beyond.