Highly Conductive Hydrogel Polymer Fibers toward Promising Wearable Thermoelectric Energy Harvesting

Abstract

The requirement of a portable electron is functioning as a driving force for a wearable energy instrument. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), as one of the most promising organic electron materials, has been widely studied in energy conversion devices. However, the efforts for PEDOT:PSS fibers are insufficient to boost the development of wearable thermoelectric energy harvesting. Here, a highly conductive p-type PEDOT:PSS fiber was produced by gelation process, which was 3 orders of magnitude higher than that of previous hydrogel fibers. Surprisingly, a posttreatment with organic solvents such as ethylene glycol and dimethyl sulfoxide tripled their electrical conductivity with an only 5% decreased Seebeck coefficient, consequently leading to an optimized thermoelectric power factor. Furthermore, we assembled a p−n-type thermoelectric device connecting five pairs of p-type PEDOT:PSS fibers and n-type carbon nanotube fibers. This fiber-based device displayed an acceptable output voltage of 20.7 mV and a power density of 481.2 μW•cm −2 with a temperature difference of ∼60 K, which might pave the way for the development of organic thermoelectric fibers for wearable energy harvesting.

Robust PEDOT:PSS Wet‐Spun Fibers for Thermoelectric Textiles

“…Despite the potential of PEDOT:PSS fibers toward thermoelectric applications, most previous research on PEDOT:PSS‐based thermoelectric textiles with noticeable performance has been conducted by using composite fibers made of PEDOT:PSS and nanocarbon/inorganic materials or by coating mechanically robust fibers/yarns/fabrics with PEDOT:PSS. Recently, Liu et al investigated the thermoelectric properties of fibers that had been prepared from a PEDOT:PSS hydrogel; a α ≈ 15 μV K −1 and σ ≈ 173 S cm −1 gave rise to a power factor α 2 σ of ≈4 μW m −1 K −2 30. In conjunction with excellent electrical and thermoelectrical performance, fibers must display a high degree of fatigue resistance in order to withstand the considerable mechanical stresses encountered during textile manufacturing and daily use.…”

Solvent treatment inducing ultralong cycle stability poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) fibers as binding‐free electrodes for supercapacitors

“…Moreover, in order to obtain free‐standing PEDOT: PSS fiber, freeze‐drying was used to remove water, making the fiber structure loose and porous, while greatly reducing the strength and electrical conductivity of the fiber. Liu et al modified the method via releasing the cross‐linked PEDOT:PSS fibers into the low boiling point ethanol . High conductivity and dense structure of PEDOT:PSS fibers were obtained through solvent exchange, which provided an important reference for the development of PEDOT:PSS fiber‐based flexible electronics.…”

Assembly Strategy and Performance Evaluation of Flexible Thermoelectric Devices

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requirements for versatile applications in complex environments to harvest waste heat and generate electricity. Indeed, no general and regular standard has been effectively set up so far.To date, several design strategies have been developed to achieve flexible TE devices by assembling flexible films, [14][15][16] yarns, [17][18][19][20] and printing techniques. In cases of low thermal conductivities for the neat polymers and their composite materials, their TE performance is always evaluated by power factor (PF = S 2 σ).

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“…To date, several design strategies have been developed to achieve flexible TE devices by assembling flexible films, [14][15][16] yarns, [17][18][19][20] and printing techniques. [21][22][23][24] Here, we focus on the film assembly configuration, since this is the most extensively studied one till now.…”