Liu Ye, Nitschke Mirko, Stepien Lukas, Khavrus Vyacheslav, Bezugly Viktor, Cuniberti Gianaurelio
Institute for Materials Science and Max Bergmann Center of Biomaterials , TU Dresden , 01069 Dresden , Germany.
Leibniz Institute of Polymer Research Dresden , Hohe Str. 6 , 01069 Dresden , Germany.
ACS Appl Mater Interfaces. 2019 Jun 19;11(24):21807-21814. doi: 10.1021/acsami.9b02918. Epub 2019 Jun 4.
We explore an n-type doping strategy of semiconducting single-walled carbon nanotubes (sc-SWCNTs) by a covalent functionalization in ammonia plasma and elucidate the effect of air exposure on thermoelectric properties of the sc-SWCNTs before and after doping. Without doping, the sc-SWCNT films have a Seebeck coefficient of 125 μV/K and a power factor (PF) of 95 μW/m K in ambient conditions. Heating of such films in air up to 100 °C and above is not changing their thermoelectric properties noticeably; however, the films can be converted to an n-type material simply by gas desorption at low pressure and room temperature, showing an outstanding negative Seebeck coefficient of -133 μV/K and a PF of 55 μW/m K. Doping of the sc-SWCNT films with ammonia plasma leads to the reduction of the Seebeck coefficient down to 40 μV/K in ambient conditions, which is the result of two competing effects: attachment of electron-donating functional groups during plasma treatment and adsorption of water molecules when exposing films to air. At temperatures slightly higher than the boiling point of water, the doped films of sc-SWCNTs show the lowest Seebeck coefficient of -80 μV/K in air. A similar value of the Seebeck coefficient is obtained for the same films at low pressures and room temperature. To our knowledge, this is one of the best values ever reported for n-type pure carbon nanotube films.
我们通过在氨等离子体中进行共价功能化来探索半导体单壁碳纳米管（sc-SWCNTs）的n型掺杂策略，并阐明空气暴露对掺杂前后sc-SWCNTs热电性能的影响。在未掺杂的情况下，sc-SWCNT薄膜在环境条件下的塞贝克系数为125 μV/K，功率因子（PF）为95 μW/m K。将此类薄膜在空气中加热至100°C及以上时，其热电性能并无明显变化；然而，通过在低压和室温下进行气体解吸，薄膜可简单地转变为n型材料，表现出-133 μV/K的出色负塞贝克系数和55 μW/m K的功率因子。用氨等离子体对sc-SWCNT薄膜进行掺杂会导致在环境条件下塞贝克系数降至40 μV/K，这是两种相互竞争效应的结果：等离子体处理过程中供电子官能团的附着以及薄膜暴露于空气中时水分子的吸附。在略高于水沸点的温度下，sc-SWCNTs的掺杂薄膜在空气中表现出-80 μV/K的最低塞贝克系数。在低压和室温下，相同薄膜也可获得类似的塞贝克系数值。据我们所知，这是n型纯碳纳米管薄膜所报道的最佳值之一。
