Investigation of the Thermoelectric Power Factor of KOH-Treated PEDOT:PSS Dispersions for Printing Applications

Abstract

This work studies the modification of commercially available dispersions of intrinsically conductive polymer PEDOT:PSS with a strong base, KOH. It is concluded that addition of base derives a dedoping of the PEDOT chain and increase Seebeck coefficient from 15 µV/K to 90 µV/K. Supportive UV-Vis-NIR spectroscopy was used for tracking the doping level of the polymer. A surface morphology study of the dedoped PEDOT:PSS films was monitored by SEM. It was shown that if KOH is used in excess with respect to the acid component of PEDOT:PSS dispersions, it segregates at the surface forming crystallites. They, however could be easily removed by methanol rinsing without destroying the sample integrity. After material modification, a dispenser-printed polymer unileg-TEG with 61 unicouples was fabricated by printing. The TEG in form of 253 mm-long stripe shows a flexible behavior. At 90 K temperature difference a resulting power output of ~ 100 nW could be measured. We suggest that the low power output is due to a high internal generator resistance.

Significantly Enhanced Thermoelectric Properties of PEDOT:PSS Films through Sequential Post‐Treatments with Common Acids and Bases

“…Combined with the high charge mobility arising from the acid treatment, the acid‐base treated films also have high electrical conductivity. Compared with the works in which the as‐prepared PEDOT:PSS films (or 5% DMSO‐added) are directly treated by bases, we achieved a several times higher electrical conductivity and Seebeck coefficient at the optimal condition. With a high electrical conductivity of 2170 S cm −1 and Seebeck coefficient of 39.2 µV K −1 , the highest PF we obtained is 334 µW (m −1 K −2 ), nearly one order greater than the previous works published on the base treatment of PEDOT films (as compared in Table S1, Supporting Information).…”

“…In a heavily doped PEDOT sample, the position of Fermi level shifts deep inside the valence band, the H 2 SO 4 ‐treated PEDOT:PSS thereby possesses a small Seebeck coefficient . When the H 2 SO 4 ‐treated PEDOT:PSS is subjected to a base treatment, the OH − can dedope PEDOT and localize the positive charges on PEDOT . In an acid environment, slight protonation of PEDOT could take place at the Cα‐ atom .…”

Mechanically enhanced electrically conductive films from polymerization of 3,4‐ethylenedioxythiophene with wood microfibers

“…This reduces the portion of PSS–H, which has a higher capability to generate charge carriers . In essence, the H 3 O + ions dissociated from the PSS–H are able to protonate PEDOT; reducing these H 3 O + ions would reduce the degree of protonation thus also charge carriers of PEDOT:PSS . Simply stated, alkaline soaking reduced the amount of PSS–H, and so decreased the charge carriers needed for conductivity.…”

Thermoelectric Generators on Satellites—An Approach for Waste Heat Recovery in Space

“…Consequently large area devices are feasible; therefore the heat does not to be concentrated. Furthermore functional surface coatings could be conceivable [7,24,25].…”