Abstract
In an effort to create a paintable/printable thermoelectric materials, comprised exclusively of organic components, polyaniline (PANi), graphene, and double-walled carbon nanotubes (DWNT) were alternately deposited from aqueous solutions using the layer-by-layer assembly technique. Graphene and DWNT are stabilized with an intrinsically conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A 1 µm thick film, composed of 80 PANi/graphene-PEDOT:PSS/PANi/DWNT-PEDOT:PSS quadlayers (QL) exhibits electrical conductivity (σ) of 1.88 X 105 S/m and a Seebeck coefficient (S) of 120 µV/K, producing a thermoelectric power factor (S 2∙σ) of 2710 µW/(m∙K2). This is the highest value ever reported for a completely organic material measured at room temperature. Furthermore, this performance matches or exceeds that of commercial bismuth telluride. Air-stable n-type organic thermoelectric nanocomposites were achieved by depositing layers of double-walled carbon nanotubes (DWNT), stabilized with polyethylenimine (PEI), and graphene oxide (GO) in a layer-by-layer fashion from aqueous solutions. A 30 bilayer film (~ 610 nm thick), comprised of this DWNT-PEI/GO sequence, exhibits electrical conductivity of 27.3 S/cm and Seebeck coefficient of -30 µV/K, producing a power factor of 2.5 µW/(m∙K2). Low temperature thermal reduction (150 °C for 30 min) of this composite thin film significantly improves its thermoelectric performance. An electrical conductivity of 460 S/cm and Seebeck coefficient of -93 µV/K are achieved. A 30 BL DWNT-PEI/reduced graphene oxide (rGO) film (~480 nm thick) exhibits a power factor as large as 400 µW/(m∙K2), which is one of the highest values reported for an organic n-type material. The combination of water-based processing, air stability and high power factor is a major step toward producing efficient thermoelectric devices on flexible substrates (e.g. textiles for clothing). For the first time, there is a real opportunity to harness waste heat from unconventional sources, such as body heat to power devices in an environmentally-benign way. Figure 1
Published Version
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