Thermoelectric Performance Of Poly Research Articles

Enhancing Electrical Conductivity and Power Factor in Poly‐Glycol‐Bithienylthienothiophene with Oligoethylene Glycol Side Chains Through Tris (pentafluorophenyl) Borane Doping

AbstractDoping of organic semiconductors has served as an effective method to achieve high electrical conductivity and large thermoelectric power factor. This is of importance to the development of flexible/wearable electronics and green energy‐harvesting technologies. The doping impact of the Lewis acid tris (pentafluorophenyl) borane (BCF) on the thermoelectric performance of poly(2‐(4,4′‐bis(2‐methoxyethoxy)‐5′‐methyl‐[2,2′‐bithiophen]‐5‐yl)‐5‐methylthieno[3,2‐b]thiophene (pgBTTT), a thiophene‐based polymer featuring oligoethylene glycol side chains is investigated. Tetrafluorotetracyanoquinodimethane (F4TCNQ), a well‐established dopant, is utilized as a comparison; however, its inability to co‐dissolve with pgBTTT in less polar solvents hinders the attainment of higher doping levels. Consequently, a comparative study is performed on the thermoelectric behavior of pgBTTT doped with BCF and F4TCNQ at a very low doping level. Subsequent investigation is carried out with BCF at higher doping levels. Remarkably, at 50 wt% BCF doping level, the highest power factor of 223 ± 4 µW m−1 K2 is achieved with an electrical conductivity of 2180 ± 360 S cm−1 and a Seebeck coefficient of 32 ± 1.3 µV K−1. This findings not only contribute valuable insights to the dopant interactions with oxygenated side chain polymers but also open up new avenues for high conductivity thermoelectric polymers in flexible electronic applications.

Morphological modulation to improve thermoelectric performances of PEDOT:PSS films by DMSO vapor post-treatment

The thermoelectric performance of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films are optimized by dimethyl sulfoxide (DMSO) vapor post-treatment on the basis of DMSO addition in PEDOT:PSS solution. Compared with pristine films, the electrical conductivity of PEDOT:PSS with 5% DMSO films is increased by two orders of magnitude. When the PEDOT:PSS with 5% DMSO films are subjected to DMSO vapor post-treatment, the electrical conductivity and Seebeck coefficient are further enhanced. As a result, the power factor of 60 min treated PEDOT:PSS with 5% DMSO films is twice larger than the one without DMSO vapor treatment. Microscopical investigations reveal the morphological evolution of the DMSO vapor treated films. After certain of treating time, quite even and uniformed film morphology is developed, which indicates that film micro-structural order is improved. Through the study of carrier concentration by optical absorption spectra and XPS, it is confirmed that the improvements of thermoelectric performances are attributed to the enhancement of carrier mobility.

Improved thermoelectric performance of P3HT/SWCNTs composite films by HClO4 post-treatment

Abstract In this work, the thermoelectric performance of poly(3-hexylthiophene)/single walled carbon nanotubes (P3HT/SWCNTs) composite films has been effectively improved by HClO 4 post-treatment. The P3HT/SWCNTs composite films with 20 wt% of fillers achieved an optimal power factor of 27.99 μW m−1 K−2 after HClO4 post-treatment for 2 h. The increased thermoelectric performance of P3HT/SWCNTs composite films can be attributed to the HClO4 treatment that can promote the transitions of the P3HT spacers between the adjacent SWCNTs from their neutral state to the bipolaron state, which significantly increased the electrical conductivity of the composite films. P3HT/SWCNTs composite films filled with low-content SWCNTs possessed excellent flexibility. This excellent performance of P3HT/SWCNTs composite films should be attributed to the combination of advantages of organic/inorganic hybridization and acid post-treatment. This is an important strategy to improve the performance of thermoelectric materials in recent years.

Thermoelectric performance of poly(3-hexylthiophene) films doped by iodine vapor with promising high seebeck coefficient

Poly(3-hexylthiophene) (P3HT) films doped with iodine vapor have been prepared by casting a P3HT solution on glass substrates and their thermoelectric (TE) performances has been investigated. The maximum Seebeck coefficient and electrical conductivity of iodine-doped P3HT films were 386 µV·K−1 (at room temperature) and 4.7 × 10−1 S·cm−1, which is about five orders of magnitude higher than that of pristine P3HT films. The power factor of these iodine-doped P3HT films was estimated to be 7.0 µW·m−1·K−2 at room temperature, which is a relative high value for organic TE materials. The UV-vis spectra of iodine-doped P3HT films showed a slight red shift of the iodine-doped P3HT compared to those of pristine P3HT films. Atomic force microscopy images indicated the conformational changes in P3HT chains after treatment with iodine vapor. During this treatment, the P3HT chains self-organized into a more ordered structure, this organization improved the charge carrier transport capability and the TE performance of P3HT the films.

Novel solution-processable, dedoped semiconductors for application in thermoelectric devices

The thermoelectric performance of poly(3,4-ethylenedioxythiophene) complexed with a poly(4-styrenesulfonic acid) (PEDOT:PSS) film was enhanced by a three-step process.

Thermoelectric Performance of Poly(3,4-Ethylenedioxy-thiophene)/Poly(Styrenesulfonate) Pellets and Films

The thermoelectric performance of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) pellets and free-standing PEDOT/PSS films, prepared from PEDOT/PSS solution containing the additives dimethyl sulfoxide or ethylene glycol, have been systematically investigated. It has been found that the electrical conductivity of free-standing PEDOT/PSS films is invariably much higher than that of PEDOT/PSS pellets, while there is no distinct change in the Seebeck coefficient. The highest electrical conductivity of a free-standing PEDOT/PSS film can be up to 300 S cm−1, five to six times higher than that of PEDOT/PSS pellets (55 S cm−1). The thermal conductivity was measured over a wide temperature range, indicating that PEDOT/PSS has extremely low thermal conductivity. The figure of merit (ZT) of free-standing PEDOT/PSS films with good environmental stability can be up to 10−2, an order of magnitude higher than that of pressed PEDOT/PSS pellets (10−3).