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Wang. Soft Sci 2024;4:25 https://dx.doi.org/10.20517/ss.2024.14 Page 7 of 9

Figure 3. Simulated Peltier cooling capacity as a function of current for different cases of heat transfer coefficient (h) with varying
[8]
thermoelectric material parameters. The smaller the h denotes a more thermally resistive environment. Reproduced with permission .
Copyright 2019, Nature Publishing Group.
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[36]
contact resistance has been estimated to be < 1 × 10 m ·K·W according to computational simulations .
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The external thermal contact resistance is more complex and generally depends on the adhesion of the
Peltier cooling device on the heat source and their thermal conductivity mismatch. Under a thermally
resistive environment such as the human body, the thermoelectric ZT factor is not the only decisive factor
for the cooling capacity attainable where a low thermal conductivity can result in a significantly higher
cooling capacity in comparison to the same ZT factor achieved by either electrical conductivity or Seebeck
coefficient [Figure 3] making organic Peltier cooling devices attractive for wearable cooling applications [8,22] .

Reliability and stability are other important device considerations apart from the Peltier cooling
performance. For organic thermoelectrics, the air stability for n-type doped organic semiconductors is a
challenge, and hence, the design of proper encapsulation is necessary . However, in the context of flexible
[37]
Peltier cooling devices, novel encapsulation methods would need to be applied to allow flexibility and
minimal thermal insulation. One possibility would be using the multilayer laminate for flexible organic
light-emitting diode applications .
[38]