PEDOT:PSS Films With Very High Thermoelectric Properties Through Water‐Swollen Assisted Reduction With a Tetrakis(dimethylamino)ethylene Solution

Abstract Thermoelectric (TE) materials have attracted significant attention because they can be used to directly harvest waste heat into electricity. Organic TE materials like poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have advantages including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. However, their TE properties are notably inferior to their inorganic counterparts. Here, PEDOT:PSS films with very high thermoelectric properties through the sequential treatments with H₂SO₄, water, and ethanol solution of tetrakis(dimethylamino)ethylene (TDAE) are reported for the first time. The PEDOT:PSS films can exhibit a Seebeck coefficient of 58.2 µV K⁻¹ and electrical conductivity of 1552 S cm⁻¹, and the corresponding power factor is 526 µW m⁻¹ K⁻². The water treatment prior to the TDAE solution treatment is crucial for the high TE properties of PEDOT:PSS films. Without the water treatment, the control PEDOT:PSS films exhibit a Seebeck coefficient of only 32.4 µV K⁻¹ and electrical conductivity of 1124 S cm⁻¹, and the corresponding power factor is only 118 µW m⁻¹ K⁻². The effect of the water treatment on the Seebeck coefficient is attributed to the swelling of PEDOT:PSS films, which facilitates the penetration of TDAE from solution into the polymer films and thus the reduction of PEDOT:PSS.