The recent development in the field of wearable electronics has increased the demand for batteries as power sources which are subjected to periodic recharging and replacement. Therefore, the next challenge is to design new systems for sustainable energy to power portable electronic devices that can be easily integrated into textiles such as thermoelectric generators that can convert waste heat into electricity. Looking at this scenario, this work shows a methodology to prepare thermoelectric textiles by electrochemical polymerization of poly(3,4‐ethylenedioxythiophene) (PEDOT) on felt fabrics. The polymerization of PEDOT is carried out utilizing three different counterions, LiClO₄, 1‐butyl‐3‐methylimidazolium hexafluorophosphate (PF₆), and 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (BTFMSI) to provide a complete understanding of the role of the counterion in the thermoelectric properties. The electrical conductivity and Seebeck coefficient are dependent on the counterion, reaching the maximum ZT for PEDOT polymerized in presence of BTFMSI due to an improvement of carrier mobility. In addition, the manufactured textile thermoelectric device showed an outstanding power output (6.5 µW) compared to the previous devices reported to date.

Thermoelectric (TE) materials can have a strong benefit to harvest thermal energy if they can be applied to large areas without losing their performance over time. One way of achieving large-area films is through hybrid materials, where a blend of TE materials with polymers can be applied as coating. Here, we present the development of all solution-processed TE ink and hybrid films with varying contents of TE Sb₂Te₃ and Bi₂Te₃ nanomaterials, along with their characterization. Using (1-methoxy-2-propyl) acetate (MPA) as the solvent and poly (methyl methacrylate) as the durable polymer, large-area homogeneous hybrid TE films have been fabricated. The conductivity and TE power factor improve with nanoparticle volume fraction, peaking around 60-70% solid material fill factor. For larger fill factors, the conductivity drops, possibly because of an increase in the interface resistance through interface defects and reduced connectivity between the platelets in the medium. The use of dodecanethiol (DDT) as an additive in the ink formulation enabled an improvement in the electrical conductivity through modification of interfaces and the compactness of the resultant films, leading to a 4-5 times increase in the power factor for both p- and n-type hybrid TE films, respectively. The observed trends were captured by combining percolation theory with analytical resistive theory, with the above assumption of increasing interface resistance and connectivity with polymer volume reduction. The results obtained on these hybrid films open a new low-cost route to produce and implement TE coatings on a large scale, which can be ideal for driving flexible, large-area energy scavenging technologies such as personal medical devices and the IoT.

The development of wearable technology has promoted the research of new power supply sources to feed wearable devices without the need of batteries. Wearable thermoelectric generators (wTEGs) can generate energy using the thermal gradient between the human body and the ambient temperature. The most comfortable way to adapt wTEGs to the human body is by using textiles, which are flexible and breathable. In this work, we have developed a method to coat textiles with conductive polymers by electrodeposition on fabrics previously coated with multi-walled carbon nanotubes (MWCNT). The results show that the fabrics coated with polyaniline: sulfuric acid (PANI:H₂SO₄) present a very low thermal stability, and the variation of the electrical conductivity under wearable stress is not suitable for their use in smart textiles. However, the fabrics coated with poly (3,4-ethylenedioxythiophene: perchlorate) (PEDOT:ClO₄) and polypyrrole: perchlorate (PPy:ClO₄) show a good thermal stability, positive evolution of the electrical conductivity as a function of the twist angle, bending cycles, and bending radius, demostrating their potential use in practical wearable applications to coat fabrics by electrochemical deposition.