Horizonatally Aligned MWCNT/PEDOT:SS Organic Thermoelectric Composite Films
Topic(s) : Multifunctional and smart composites
Co-authors :
Wonvin KIM (KOREA, REPUBLIC OF), Su Hyun LIM (KOREA, REPUBLIC OF), Hyunsoo HONG , Jingyao DAI (UNITED STATES), Luiz ACAUAN (UNITED STATES), Brian L. WARDLE , Seong Su KIM (KOREA, REPUBLIC OF)Abstract :
As fossil fuels continue diminishing and contributing to environmental pollution, various initiatives have been undertaken to replace them with eco-friendly energy harvesting systems. Thermoelectricity can harness energy from waste heat; however, its limited thermoelectric performance restricts its application to small devices. In addition, many high-performance thermoelectric materials correspond to rare metals. Therefore, there is a growing need to develop new thermoelectric composite materials that can offer high performance at a low cost.
The conjugated polymer poly (3,4 – ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is one of the most attractive organic thermoelectric materials and has various potentials such as transparency, flexibility, and high stability under harsh environments, but its low electrical conductivity should be complemented. Carbon nanotube (CNT) can be a great candidate as potential nano-scale reinforcements with high electrical conductivity. A multiwall carbon nanotube (MWCNT) with an aligned structure can enhance its electrical conductivity, yielding high thermoelectric performance.
This study developed the horizontally aligned MWCNT/poly (3,4 – ethylenedioxythiophene) polystyrene sulfonate (HA-MWCNT/PEDOT:PSS) thermoelectric composite film. Vertically aligned MWCNT was fabricated using a chemical vapor deposition (CVD) process [1] and subsequently, their horizontal alignment was achieved through a “knock-down” process [2]. The MWCNT surfaces were treated with O2 plasma for 45 minutes to enhance the impregnation of PEDOT:PSS via a drop-casting method. Film morphology was analyzed using filed-emission scanning electron microscopy (FE-SEM), confirming the successful impregnation of PEDOT:PSS colloids into HA-MWCNT. Quantification of sulfur composition through X-ray photoelectron spectroscopy (XPS) determined the degree of impregnation, while X-ray diffraction (XRD) quantified defects introduced by O2 plasma.
Finally, the HA-MWCNT/PEDOT:PSS thermoelectric composite films had high electrical conductivity with anisotropy due to their alignment and densification without any treatment. It exhibited remarkable power factors of 47.7 μW/m∙K^2 in aligned direction and 12.9 μW/m∙K^2 in the perpendicular direction, signifying their potential for energy harvesting.
The conjugated polymer poly (3,4 – ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is one of the most attractive organic thermoelectric materials and has various potentials such as transparency, flexibility, and high stability under harsh environments, but its low electrical conductivity should be complemented. Carbon nanotube (CNT) can be a great candidate as potential nano-scale reinforcements with high electrical conductivity. A multiwall carbon nanotube (MWCNT) with an aligned structure can enhance its electrical conductivity, yielding high thermoelectric performance.
This study developed the horizontally aligned MWCNT/poly (3,4 – ethylenedioxythiophene) polystyrene sulfonate (HA-MWCNT/PEDOT:PSS) thermoelectric composite film. Vertically aligned MWCNT was fabricated using a chemical vapor deposition (CVD) process [1] and subsequently, their horizontal alignment was achieved through a “knock-down” process [2]. The MWCNT surfaces were treated with O2 plasma for 45 minutes to enhance the impregnation of PEDOT:PSS via a drop-casting method. Film morphology was analyzed using filed-emission scanning electron microscopy (FE-SEM), confirming the successful impregnation of PEDOT:PSS colloids into HA-MWCNT. Quantification of sulfur composition through X-ray photoelectron spectroscopy (XPS) determined the degree of impregnation, while X-ray diffraction (XRD) quantified defects introduced by O2 plasma.
Finally, the HA-MWCNT/PEDOT:PSS thermoelectric composite films had high electrical conductivity with anisotropy due to their alignment and densification without any treatment. It exhibited remarkable power factors of 47.7 μW/m∙K^2 in aligned direction and 12.9 μW/m∙K^2 in the perpendicular direction, signifying their potential for energy harvesting.