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Hong et al. Soft Sci 2023;3:29 https://dx.doi.org/10.20517/ss.2023.20 Page 3 of 16

Table 1. Typical flexible thermoelectric materials synthesized by printing methods
Treatment -1 -1 2 -1 -2
Materials Method Additive S (mV·K ) (S·cm ) S (mW·m ·K ) Ref.
T (°C)
Sb Te Screen printing - 500 °C 98 1,500 1,441 [54]
2 3
Bi Te /PEDOT Screen printing dimethyl sulfoxide 450 °C -138 73 138.6 [55]
2
3
Sb Bi Te /Te Screen printing α-Terpineol + Disperbyk-110 450 °C 204 720 3,000 [56]
1.6 0.4 3
Bi Te Se 0.2 Screen printing α-Terpineol + Disperbyk-110 430 °C -126 310 490 [57]
2.8
2
+ glass frits
Bi Te /epoxy Extrusion printing epoxy resin + anhydride 250 °C -157 61 150 [58]
2 3
-based hardener
Bi Te /Se/epoxy Extrusion printing epoxy resin 350 °C -170 96 277 [59]
2 3
Sb Te /epoxy Extrusion printing 2-butoxy ethanol + 250 °C 160 63 160 [60]
2
3
dibutyl phthalate
Bi Sb Te 3 Extrusion printing glycerol, 450 °C 165 554 1,508 [61]
0.5
1.5
TiS (HA)x Inkjet printing N-Methylformamide 110 °C -70 430 211 [62]
2
Sb Te /Te Aerosol jet printing ethylene glycol, + glycerol, 400 °C 198 560 2,200 [63]
2
3
+ ethanol
SnSe/PEDOT Drop casting - 328 °C 110 320 390 [64]
CNT/P3HT Spray printing - - 97 345 325 [65]
and spray printing . These printing techniques have been extensively explored in recent years, and
[65]
significant progress has been made in optimizing the printing parameters, ink formulations, and post-
[66]
processing methods to enhance the thermoelectric performance of printed materials and devices .
Furthermore, printed thermoelectric materials and devices have found applications in energy harvesting,
waste heat recovery, wearable electronics, and flexible electronics [67-70] .
Given the significant advances and potential applications of printing methods for thermoelectric materials
and devices, it is timely to review the recent progress in this field. This review aims to provide a
comprehensive overview of the recent advances in printing methods for thermoelectric materials and
devices, covering the key principles, challenges, and opportunities associated with various printing
techniques. The review highlights the progress made in optimizing the printing parameters, ink
formulations, and post-processing methods to improve the thermoelectric performance of printed materials
and devices. Furthermore, their applications in energy harvesting, waste heat recovery, wearable electronics,
and flexible electronics, are discussed, providing insights into the current state-of-the-art and future
directions of this promising field.

SCREEN PRINTING
Screen printing is a versatile printing technique used for a wide range of applications, including textiles,
graphics, electronics, and more recently, thermoelectric materials and devices [71-74] . The process involves
[75]
several steps, as depicted in Figure 1A . First, pastes or inks are added to a screen, which is a mesh-like
stencil made of fabric or other materials. The paste is then smeared across the screen surface using a blade,
spreading it evenly over the openings in the screen. Next, a squeegee is pressed against the screen with
pressure, driving the paste through the holes in the screen. As the squeegee passes across the screen, it leaves
a thin layer of paste on the substrate in the desired pattern. Ultimately, the deposited pattern is formed on
the substrate after removing the screen.

Figure 1B depicts flexible thermoelectric generators (TEGs) that has been screen printed onto polyimide
substrates . The thermoelectric legs were n-type Bi Te Se and p-type Bi Sb Te , which were mixed with
[76]
0.5
3
1.5
2.7
2
0.3
epoxy resin and then screen printed onto the substrates. The formed radial structured TEGs with five