In this work, thermoelectrical properties of flexible
thermoelectric
films fabricated by the encapsulation of multiwalled carbon nanotube-antimony
telluride (Sb2Te3-MWCNT) hybrid networks with
different Sb2Te3:MWCNT mass ratios in polydimethylsiloxane
(PDMS) were studied for the first time. Sb2Te3-MWCNTs were synthesized by the direct physical vapor deposition
of Sb2Te3 nanostructures on the MWCNT network,
spray-coated on a flexible polyimide substrate, and encapsulated in
PDMS using a drop-casting technique. A study of electrical and thermoelectric
properties of Sb2Te3-MWCNT hybrid networks before
and after encapsulation revealed that encapsulation effectively preserves
the properties of the hybrid networks and improves their durability
under repetitive bending, showing deviations in resistance not exceeding
0.5% of the initial value during 100 repetitive bending cycles down
to a 3 mm radius. Encapsulated Sb2Te3-MWCNT
networks showed the thermoelectric power factor (PF) reaching 9.5
μW·m–1 K–2, which is
∼3 orders of magnitude higher than the values of PF showed
previously by the composites prepared by mechanical mixing of the
Sb2Te3-MWCNT hybrid networks with a nonconductive
polymer. PDMS-encapsulated Sb2Te3-MWCNT hybrid
networks in combination with previously reported PVA-encapsulated
Bi2Se3-MWCNT hybrid networks were used to assemble
4-leg-pair flexible thermoelectric generators, where leg pairs were
connected in series or parallel. Both types of generators showed stable
performance with different external resistances connected in the circuit
and reached an output power of ∼7–10 μW·cm–2 and an output current of ∼1–5 μA.
These parameters illustrate the significant potential of the presented
PDMS-encapsulated Sb2Te3-MWCNT hybrid networks
as building blocks for custom flexible devices for micro- and nanopower
applications.