Multi-walled carbon nanotubes (MWCNTs) have shown low n-type Seebeck coefficients (−10 μV K−1), which are not good enough to prepare high performance low-cost MWCNT based mechanically flexible thermoelectric devices.
Due to the excellent thermoelectric
performance, bismuth telluride
(Bi2Te3) compounds are highly promising for
the thermoelectric conversion in the room temperature range. However,
the inferior thermoelectric performance of the n-type leg severely
restricts the applications of Bi2Te3-based thermoelectric
couples. Herein, n-type Bi2Te2.7Se0.3 (BTS)-based thermoelectric materials incorporated with nanosized
Y2O3 (0.5–3 wt %) are prepared and their
thermoelectric properties are systematically studied. The dramatically
improved thermoelectric performance is ascribed to the realization
of a multiscale feature of Y2O3 nanoparticle
(NP)-induced interfacial decorations distributed along grain boundaries,
which creates massive BTS/Y2O3 interfaces for
the manipulation of carrier and phonon transport properties. The geometric
phase analysis is employed to further confirm the condition of local
strain in the BTS composite incorporated with Y2O3 NPs. Due to the presence of heterointerfaces and high density of
dislocations in BTS matrices, the minimum lattice thermal conductivity
(κl) of the nanocomposites (NCs) is dramatically
suppressed from 0.76 to 0.37 W m–1 K–1. With the incorporation of 3 wt % Y2O3 NPs,
the Vickers hardness of the BTS/Y2O3 NC is increased
by about 32%. Overall, the BTS + 1.5 wt % Y2O3 NC maintains excellent thermoelectric properties (ZTave = 1.1) in the whole operative temperature range (300–500
K). The present strategy of implementing high-density heterogeneous
interfaces by Y2O3 NP addition offers an applicable
pathway for fabricating high-performance thermoelectric materials
with both optimized thermoelectric properties and mechanical properties.
Finding a stable n-type flexible thermoelectric (TE) material with high power factor and mass production is a challenge for wearable TE devices. In this paper, we reported that metallic multiwalled...
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