Surfactant-Mediated\nControl of Polyethylenimine Dopant\nfor Enhanced Thermoelectric Performance of Carbon Nanotube Buckypaper\nfor Varied Device Configurations

Carbon nanotubes (CNTs) are promising materials for flexible\np-type\napplications but require chemical doping to achieve n-type properties.\nUsing surfactants is essential to preventing agglomeration, which\ncan affect surface properties and dopant interaction. This research\ninvestigates the influence of surfactant on the thermoelectric properties\nof polyethylenimine (PEI)-doped CNT buckypaper. Two buckypaper variants\nwere prepared: one with chloroform as the solvent and the other with\na surfactant and deionized water. The study revealed that the use\nof a surfactant along with PEI dopants prevents environmental p-type\ndoping from oxygen molecules. The thermoelectric evaluations revealed\na notable improvement in the performance of surfactant-treated buckypapers\ncompared with their counterparts without surfactant. In essence, this\nresearch underscores the pivotal role of surfactants in shaping the\nthermoelectric properties of the CNT buckypapers. The module of a\nthermoelectric device having 60 pairs of p-n segments with dimensions\n2 cm × 0.5 cm showcased a substantial output of ∼31.61\nmV and ∼482.02 nW at a temperature gradient of 40 K. Furthermore,\npractical demonstrations conducted in this study highlight the utility\nof these thermoelectric devices in harnessing waste heat from everyday\nlow-temperature heat sources such as human body. This research underscores\nthe critical role of surfactants in shaping the thermoelectric properties\nof CNT buckypaper.