Light-weight, mechanically flexible, transparent thermoelectric modules are promising as portable and easy-to-integrate energy sources. Here, we demonstrate flexible, transparent thermoelectric modules by using a conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the p-type leg and indium tin oxide (ITO)-PEDOT:PSS as the n-type leg. Main observations include the following: (1) the bilayer combination of ITO-PEDOT:PSS (PEDOT:PSS coated on top of the ITO) displays a negative Seebeck coefficient ( S) and the value is similar to that of the ITO single layer; (2) the S value of the ITO-PEDOT:PSS is almost not dependent on the area ratio of the stacked PEDOT:PSS and ITO; and (3) the conducting polymer PEDOT:PSS deposition on top of ITO helps the ITO not to generate cracks during bending, which enhances the mechanical flexibility of the ITO. On the basis of these observations, thermoelectric modules with eight pairs of junctions are fabricated and the thermoelectric modules' Δ V/Δ T (modules' generated thermovoltage per temperature difference) is nearly the addition of S values of all legs. Thermoelectric modules show good mechanical flexibility and air stability. Applications of thermoelectric modules have also been demonstrated to produce thermovoltage via the temperature difference produced by a human hand or warm water.
Keywords: charge carrier mobility; conducting polymer; flexible and transparent thermoelectric device; hybrid thermoelectric module; thermoelectric.