Self-Assembled Three-Dimensional Bi₂Te₃ Nanowire–PEDOT:PSS Hybrid Nanofilm Network for Ubiquitous Thermoelectrics

Abstract

Thermoelectric generation capable of delivering reliable performance in the low-temperature range (<150 °C) for large-scale deployment has been a challenge mainly due to limited properties of thermoelectric materials. However, realizing interdependence of topological insulators and thermoelectricity, a new research dimension on tailoring and using the topological-insulator boundary states for thermoelectric enhancement has emerged. Here, we demonstrate a promising hybrid nanowire of topological bismuth telluride (Bi2Te3) within the conductive poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) matrix using the in situ one-pot synthesis to be incorporated into a three-dimensional network of self-assembled hybrid thermoelectric nanofilms for the scalable thermoelectric application. Significantly, the nanowire-incorporated film network exhibits simultaneous increase in electrical conductivity and Seebeck coefficient as opposed to reduced thermal conductivity, improving thermoelectric performance. Based on comprehensive measurements for electronic transport of individual nanowires revealing an interfacial conduction path along the Bi2Te3 core inside the encapsulating layer and that the hybrid nanowire is n-type semiconducting, the enhanced thermoelectricity is ascribed to increased hole mobility due to electron transfer from Bi2Te3 to PEDOT:PSS and importantly charge transport via the Bi2Te3–PEDOT:PSS interface. Scaling up the nanostructured material to construct a thermoelectric generator having the generic pipeline-insulator geometry, the device exhibits a power factor and a figure of merit of 7.45 μW m–1 K–2 and 0.048, respectively, with an unprecedented output power of 130 μW and 15 day operational stability at ΔT = 60 °C. Our findings not only encourage a new approach to cost-effective thermoelectric generation, but they could also provide a route for the enhancement of other applications based on the topological nanowire.

Screen-printed bismuth telluride nanostructured composites for flexible thermoelectric applications

“…The annealed and screen-printed Bi 2 Te 3 /PVDF NW composite films displayed a maximum Seebeck coefficient of −192 µV K −1 with a PF of 36 µW m −1 K −2 at 225 K and a room temperature Seebeck coefficient and PF of −185 µV K −1 and 30 µW m −1 K −2 respectively. These values are in good agreement with those reported in studies on flexible and printed composite nanomaterials [24][25][26][27]. For example Ou et al recently reported a PF of 30 µW m −1 K −2 for aerosol jet printed nanocrystals of Bi 2 Te 3 /Sb 2 Te 3 embedded within a flexible poly(3,4-ethylenedioxythiophene)polystyrene sulfonate matrix [27].…”

High Thermoelectric and Flexible PEDOT/SWCNT/BC Nanoporous Films Derived from Aerogels

“…39−42 For example, Tan et al 43 fabricated graphene oxide (rGO)/ single-walled carbon nanotube (SWCNT) hybrid aerogels with an ultralow thermal conductivity of 0.021 W m −1 K −1 and ZT = 8.03 × 10 −3 at room temperature. Thongkham et al 44 prepared a self-assembled Bi 2 Te 3 nanowire-PEDOT:PSS hybrid foam with a thermal conductivity of 0.047 W m −1 K −1 and ZT of 0.048. However, a large number of micrometersized pores result in the poor electrical conductivity of aerogels.…”

“…Recently, the special aerogel structure capable of suppressing thermal conductivity has been introduced into TE materials, such as PANI-based aerogels, PEDOT-based aerogels, , and carbon nanotubes and graphene composite aerogels. − For example, Tan et al fabricated graphene oxide (rGO)/single-walled carbon nanotube (SWCNT) hybrid aerogels with an ultralow thermal conductivity of 0.021 W m –1 K –1 and ZT = 8.03 × 10 –3 at room temperature. Thongkham et al prepared a self-assembled Bi 2 Te 3 nanowire-PEDOT:PSS hybrid foam with a thermal conductivity of 0.047 W m –1 K –1 and ZT of 0.048. However, a large number of micrometer-sized pores result in the poor electrical conductivity of aerogels.…”

Polymer‐Based Low‐Temperature Thermoelectric Composites

“…Among inorganic‐based systems for the creation of hybrid composites, researchers are not infrequently using conventional semiconductor systems. The core (polymer) and shell (Bi 2 Te 3 nanowire) structure [ 57 ] was formed via in‐situ one‐pot synthesis, based on which a scalable 3D network of self‐assembled nanofilms incorporated with hybrid nanowires was created with elevated TE performance for highly porous material‐foam. The addition of sodium dodecyl sulfide and ethylene glycol allowed reaching high output power (up to 130 µW) at low temperature (less than 100 °C) with unprecedented 15 days stability.…”