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Page 18 of 26 Wang et al. Soft Sci 2023;3:34 https://dx.doi.org/10.20517/ss.2023.25

Table 4. Room-temperature TE properties of other inorganic TE materials
S σ PF
Materials Preparation method 2 ZT Ref.
(μV/K) (S/cm) (μW/mK )
Cu Te NWs/PVDF Mechanical Press, drop-coating 9.6 2,490 23 ~ [105]
1.75
Cu Se NW/PVDF Drop casting, cold pressing 14.16 5,578.2 111.84 ~0.04 [106]
2-x
CuI/Nylon Wet-chemical process, hot pressing 600 0.09 3.03 ~ [107]
Ag Te NWs Hydrothermal -99.48 153.35 151.76 ~ [108]
2
Room-temperature welding -154.96 149.82 359.76 ~
Ag Te NWs Hydrothermal, -50.4 192.5 48.9 ~ [109]
x
in situ chemical transformation,
CNF/Bi Sb Te 3 Vacuum filtration 154 493 1,169.2 ~ [110]
1.5
0.5
CNF/Bi Se Te 2.7 -130 532 899.08 ~
0.3
2
Bi Te and Sb Te modified paper Vacuum filtration 142 ~ ~ ~ [111]
2 3 2 3
Se/Ag S Wet-chemical process, hot pressing -81.4 743 492.6 > 0.26 [112]
2
CNF: Cellulose nanofiber; NWs: nanowires; TE: thermoelectric; ZT: thermoelectric figure of merit; PF: PEDOT:PSS-functionalized; PVP:
poly(vinylpyrrolidone); PVDF: polyvinylidene fluoride.

Figure 13. Schematic diagram of the preparation process for the flexible Cu Te NW/PVDF TE fabric, including (A) vacuum filtration;
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(B) mechanical pressing; (C) annealing; (D) drop-coating PVDF solution upon the film; and (E) peeling off the NW/PVDF film; (F) The
[105] ©
roll-up photograph of the fabricated Cu Te NW/PVDF film. Reproduced with permission from Ref . Copyright 2015. American
1.75
Chemical Society. NW: Nanowire; PVDF: polyvinylidene fluoride; TE: thermoelectric.
TWO-DIMENSIONAL TE MATERIALS
Two-dimensional materials have unique state densities with confined electrons and holes, making them
promising TE materials. Due to its high in-plane carrier mobility (200-500 cm /Vs) and low thermal
2
conductivity (0.1-1 W/mK), MoS has attracted wide attention. In 2016, Wang et al. prepared exfoliated
2
bulk MoS by lithium intercalation and obtained the restacked MoS thin film using a filtration
2
2
technique . The maximum Seebeck coefficient reached 93.5 μV/K; the highest ZT = 0.01 was calculated.
[113]
Also, this method could be imitated on other transitional metal dichalcogenides. Piao et al. synthesized 1T
phase WS nanosheets through hydrothermal methods and fabricated flexible WS thin films by vacuum
2
2
[114]
filtration with an electrical conductivity of 45 S/cm and a Seebeck coefficient of 30 μV/K . After thermal
annealing, the electrical conductivity was enhanced to 120 S/cm while not lowering the Seebeck coefficient,
2
resulting in an optimized power factor of 9.40 μW/mK . Then, they reported a bottom-up hydrothermal
route to prepare 1T-WS /SWCNT hybrid composites with 3D architecture in which 1D SWCNT nanotubes
2
and 2D WS nanosheets interweaving . Enhanced electrical conductivity and Seebeck coefficients were
[115]
2
obtained by introducing SWCNTs into 1T-WS . Flexible thin films with an impressive power factor of
2