Abstract
Flexible, lightweight, textile-based thermoelectric (TE) generators are needed for powering electronic devices[1–4] and for harvesting electrical energy from the thermal energy of combustion engines and plant waste streams. Commercial TE devices are rigid, consisting of n- and p-type TEs connected electrically in-series and in-parallel through metallic interconnects. The rigidity of these conventional devices[5,6] limits applications. Flexible TE sheets and nonwoven fabrics based on poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene),[7–9] doped carbon nanotube sheets,[10,11] and graphite composites[12] have been demonstrated in recent pioneering work. However, these sheet-based devices harvest thermal energy in the in-plane direction, rather than in more desirable sheet-thickness direction. TE textiles based on metal wires or metal wire sheaths have been used to harvest thermal energy in the textile thickness directions, but the extremely low figure of merit (ZT) of the metals limited their performance.[13,14] In other work, which resulted in a high ZT for thickness-direction thermal-energy harvesting, Kim et al.[15] screen printed Sb2Te3 and Bi2Te3 pellets on a bendable glass textile and incorporated this structure into flexible rubber sheets. Though a textile was not fabricated, Liang et al.[16] have used a mat of PbTe-coated glass fibers for a single-leg energy harvester that was wrapped on a hot pipe to harvest thermal energy. Additionally, concepts for novel TE textiles that harvest thermal energy in the through-thickness textile direction have been proposed in patents, but neither fabrication methods nor performance results on fabricated textiles were provided.[17,18]