Thermoelectric energy from flexible P3HT films doped with a ferric salt of triflimide anions

Abstract

Due to their low thermal conductivity, non-toxicity and low cost, conductive polymer materials are potential candidates for thermoelectric applications. Here, a detailed investigation into the thermoelectric properties of P3HT films is reported. A thermoelectric power factor over 20 mW m À1 K À2 at room temperature was obtained by employing a ferric salt of triflimide (TFSI À ) anions as a dopant. Flexible films of P3HT-TFSI were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), along with temperature-variant electrical measurements. Given the promising results obtained from ordinary P3HT films by a simple doping treatment, this work suggests the significance of the appropriate choice of dopants and/or counterions, as well as the polymers themselves.

Micron-thick highly conductive PEDOT films synthesized via self-inhibited polymerization: roles of anions

“…The first peak appears at 6.3°, corresponding to the lamellar packing of PEDOT chains (d = 13.93 Å). Broader peaks with lower intensity were observed in PEDOT:CSA and PEDOT: BNSA, indicating increased structural disorder caused by large and rigid segments connected to SO 3 − that obstruct the crystal growth. The high crystallinity of PEDOT:DBSA is likely attributed to its smaller Roles of anions W Shi et al benzene segment and soft alkyl chains, which are able to fit in the free space without disturbing the crystal arrangements.…”

“…To obtain high quality films, the use of inhibitors reduced the film thickness by at least 30% due to the concentrating effect. 33 In contrast, the inhibitorfree viscous coating solutions (466 wt%) made by FeCSA 3 , FeBNSA 3 and FeDBSA 3 enable the formation of high quality films with significantly increased thicknesses, 4700 nm. PEDOT polymerized without PEPG demonstrated greater homogeneity.…”

“…Optimization of S 2 σ In TE applications, S 2 σ can be optimized by dedoping PEDOT films with reductants such as TDAE, 29 hydrazine, 46 NaBH 4 , 28 Na 2 SO 3 47 and even strong alkalis such as NaOH. 44 In the present experiment, we used 0.1 M phenylhydrazine (PHZ), a mild and alcohol-soluble reducer, diluted with ethanol and acidified with different ratios of dodecylbenzenesulfonic acid to adjust the reducing ability of the reductant solution.…”

“…Conducting polymer TE materials possess the advantages of low κ, good flexibility and low cost in comparison with inorganic materials. [1][2][3][4] Among them, commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS) has received the most attention due to its excellent water processability and high σ ( refs 5-11 ) and is also widely used as an electrode or conductive adhesive material in applications including solar cells, 12,13 organic light-emitting diodes (OLEDs), 14,15 supercapacitors, 16,17 sensors 18,19 and so on. The PSS polyanion enables the formation of aqueous PEDOT:PSS solutions, which benefits both film printing and the synthesis of hybrid materials.…”

“…S-PEDOTs are prepared by in situ polymerization techniques, including solution casting polymerization (CP) and vapor phase polymerization (VPP), using oxidants such as FeOTs 3 and FeOTf 3 . These conventional oxidants are highly acidic and reactive, which makes the polymerization uncontrollable and results in structural defects in the deposited film.…”