Mechanically Durable and Flexible Thermoelectric Films from PEDOT:PSS/PVA/Bi_0.5Sb_1.5Te₃ Nanocomposites

Abstract

approaches to significantly enhance ZT values. One is using low-dimensional TE materials [4] such as nanowire, [5,6] nanotube, [7] nanocrystal, [8] and superlattice film [9] owing to quantum size effects, and the other is based on new phonon glasselectron crystal TE materials [10] such as skutterudites, [11] clathrates, [12] and some composites [13] due to specific components and unique structures.A large amount of previous work has been devoted to the inorganic TE materials, and Bi 2 Te 3 -based alloys have already been used in commercial products because of their high TE performance at room temperature. [14][15][16][17] The reported ZT values of p-type Bi x Sb 2−x Te 3 nanocomposite [14] and Bi 2 Te 3 /Sb 2 Te 3 superlattice [9] are as high as 1.35 and 2.4 at room temperature, respectively. Still, several drawbacks of inorganic thermoelectrics limit their broad applications inclusive of expensive raw materials, heavy metal pollution, high processing cost, difficult fabrication on large-area, rigid, and heavy TE devices. Furthermore, with advances in flexible and wearable electronic devices, the demand for flexible energy generation has rapidly increased. [18][19][20] Thermoelectrics has the potential to harvest energy from the natural temperature difference between the human body and the environment, and then charge the wearable electronic devices. To address this increasing need, high performance flexible thermoelectrics base on organic conductive polymers have been studied [21][22][23] thanks to their intrinsically high electrical conductivity, low thermal conductivity, and high mechanical flexibility to cover hot source with arbitrary geometry. Recently, major breakthroughs have focused on the TE properties of the conducting polymers such as polyaniline, [24] polythiophene, [25] and especially for poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). [26][27][28][29] PEDOT:PSS is a conductive polymer for optoelectronics applications with high optical transparency and electrical conductivity up to 3400 S cm −1 by secondarily doping organic solvents such as dimethyl sulfoxide (DMSO), ethylene glycol (EG), and N-methyl-2-pyrrolidinone (NMP). [30] More specifically, a maximum ZT value of 0.28 was obtained for EG-mixed PEDOT:PSS thin film and a maximum value of 0.42 for DMSO-mixed PEDOT:PSS thin film at room temperature by tuning the doping/dedoping level. [28] Another effective way to enhance the TE performance of conducting polymers is to introduce inorganic nanomaterials with high TE property into conducting polymer matrix Advances in organic thermoelectric materials have focused on the enhancement of mechanical property to address the limitations and needs of forming flexible and free-standing films for the application of flexible/wearable thermoelectric devices. Herein, thermoelectric nanocomposite films are fabricated based on conductive polymer poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS), plastic reinforcer polyvinyl alcohol (PVA), and inorganic Bi 0.5 Sb 1.5 Te 3 th...

Exceptional thermoelectric properties of flexible organic−inorganic hybrids with monodispersed and periodic nanophase

“…All of these results indicated that the interfacial transport also played an important role in final thermoelectric properties of hybrids apart from the simple mixed effect. Energy filtering effect has been reported to improve the Seebeck coefficient in organic−inorganic hybrids in which interfaces form energy barriers that preferentially scattered low-energy carriers 7 , 16 , 33 . This can make the relaxation time strongly depend on energy and increase the asymmetry of carrier transport about the Fermi level, resulting in an enhanced Seebeck coefficient.…”

“…Highest ZT values of ~0.32 for P type and ~0.2 for N type (at room temperature) were achieved in poly(3,4-ethylenedioxythiophene) (PEDOT)/SnSe nanosheets composite films and organic molecules intercalated TiS 2 single crystals, respectively 5 , 9 , 14 . Furthermore, organic−inorganic hybrid thermoelectrics can be flexible and relatively light weight 1 , 8 , 15 , 16 . These features make them feasible to act as self-powered wearable devices by utilizing body’s heat or other heat source to generate electricity, wearable temperature sensors, and flexible solid-state coolers, which are very difficult to achieve for inorganic thermoelectric materials since they are intrinsically brittle and rigid.…”

“…Here we presented a versatile method for fabricating flexible hybrids with monodispersed and periodic nanophase patterned by nanosphere lithography, in which both the size and spacing of nanophase were fine tuned from tens to hundreds of nanometers. PEDOT/Bi 2 Te 3 hybrid was chosen as a model system for thermoelectric studies, not only due to the excellent properties of each component, but also because of the similar work functions of PEDOT and Bi 2 Te 3 which could make high-energy carriers readily pass through the interfaces 16 , 24 . The prepared PEDOT/Bi 2 Te 3 hybrid films displayed a large power factor by combining the high electrical conductivity of tosylate doped PEDOT and the high Seebeck coefficient of thermally evaporated Bi 2 Te 3 as well as carrier-filtering effect at the nanoscaled PEDOT-Bi 2 Te 3 interfaces.…”

Proton‐Irradiation Effects on the Thermoelectric Properties of Flexible Bi2Te3/PEDOT:PSS Composite Films

“…Moreover, there is plenty of room to manipulate the σ and S of the composite via tuning the inorganic/organic component ratio and optimize the TE power factor. In this context, Bi 2 Te 3 /PEDOT:PSS based inorganic–organic composites have been investigated for enhancing PF/ZT . However, in the reported studies, either the S is limited by the maximum S of PEDOT:PSS [Refs.…”

Electrospun nanostructures for solar energy harvesting and motion sensing

“…In the future work, we plan to continue on the following two projects: and n-type Bi2Se3 324 and organic thermoelectric materials like PEDOT:PSS polymer 325 , and we also tried to combine the organic and inorganic materials together to utilize the flexibility of polymer while using the inorganic thermoelectric materials to enhance the thermoelectric property 325 . In the future, we plan to use electrospinning technique to process the thermoelectric polymer materials and we can also introduce inorganic nanoparticles during the processing to improve the thermoelectric response.…”