Thermoelectric composites of poly(3-hexylthiophene) and carbon nanotubes with a large power factor

Composite films of poly(3-hexylthiophene) and single- as well as multi-walled carbon nanotubes are demonstrated to offer a competitive thermoelectric performance. The power factor significantly exceeds values obtained with either constituent alone provided that the conjugated polymer is sufficiently p-doped. The use of single-walled carbon nanotubes consistently results in a higher electrical conductivity with a maximum value above 10(3) S cm(-1) and thus gives rise to a power factor of 25 +/- 6 mu W m(-1) K-2 for a filler content of only 8 wt% and a maximum 95 +/- 12 mu W m(-1) K-2 for 42-81 wt%. Moreover, a carbon nanotube content of 8-10 wt% does not compromise the low bulk thermal conductivity of the polymer matrix, which promises a high figure of merit of at least ZT > 10(-2) at room-temperature. All samples are cast on plastic substrates, emphasising their suitability for large-area, flexible thermoelectric applications

ESR and LESR X-band study of morphology and charge carrier interaction in blended P3HT-SWCNT and P3HT-PCBM-SWCNT solid thin films

An electron spin resonance (ESR) X-band study of regio-regular poly(3-hexylthiophene) (RR-P3HT) and RR-P3HT/PCBM ([6,6]-phenyl-C 61-butyric acid methyl ester) composites blended with a low concentration (∼0.1-1%) of single wall carbon nanotubes (SWCNT) is presented. The substantial line-width broadening of polaron and PCBM anion radical ESR spectra was registered after SWCNT incorporation. The possibility of an electron spin exchange interaction between SWCNT conductive electrons and polymer polarons in the RR-P3HT:SWCNT blend without light illumination and between SWCNT conductive electrons and polymer polarons and PCBM anion radical electrons in the RR-P3HT:PCBM:SWCNT blend under light illumination is discussed. In addition, the unusually significant RR-P3HT film morphology (dominant crystalline phase orientation) is substantially altered, in particular a rotation of up to 90° of the P3HT crystalline phase relative to the film plane, due to SWCNT annexation in the polymer, is registered by the ESR spectra external magnetic field angular dependences. © 2011 Elsevier B.V. All rights reserved

ESR and LESR X-band study of morphology and charge carrier interaction in blended P3HT-SWCNT and P3HT-PCBM-SWCNT solid thin films

An electron spin resonance (ESR) X-band study of regio-regular poly(3-hexylthiophene) (RR-P3HT) and RR-P3HT/PCBM ([6,6]-phenyl-C 61-butyric acid methyl ester) composites blended with a low concentration (∼0.1-1%) of single wall carbon nanotubes (SWCNT) is presented. The substantial line-width broadening of polaron and PCBM anion radical ESR spectra was registered after SWCNT incorporation. The possibility of an electron spin exchange interaction between SWCNT conductive electrons and polymer polarons in the RR-P3HT:SWCNT blend without light illumination and between SWCNT conductive electrons and polymer polarons and PCBM anion radical electrons in the RR-P3HT:PCBM:SWCNT blend under light illumination is discussed. In addition, the unusually significant RR-P3HT film morphology (dominant crystalline phase orientation) is substantially altered, in particular a rotation of up to 90° of the P3HT crystalline phase relative to the film plane, due to SWCNT annexation in the polymer, is registered by the ESR spectra external magnetic field angular dependences. © 2011 Elsevier B.V. All rights reserved

ESR and LESR X-band study of morphology and charge carrier interaction in blended P3HT-SWCNT and P3HT-PCBM-SWCNT solid thin films

An electron spin resonance (ESR) X-band study of regio-regular poly(3-hexylthiophene) (RR-P3HT) and RR-P3HT/PCBM ([6,6]-phenyl-C 61-butyric acid methyl ester) composites blended with a low concentration (∼0.1-1%) of single wall carbon nanotubes (SWCNT) is presented. The substantial line-width broadening of polaron and PCBM anion radical ESR spectra was registered after SWCNT incorporation. The possibility of an electron spin exchange interaction between SWCNT conductive electrons and polymer polarons in the RR-P3HT:SWCNT blend without light illumination and between SWCNT conductive electrons and polymer polarons and PCBM anion radical electrons in the RR-P3HT:PCBM:SWCNT blend under light illumination is discussed. In addition, the unusually significant RR-P3HT film morphology (dominant crystalline phase orientation) is substantially altered, in particular a rotation of up to 90° of the P3HT crystalline phase relative to the film plane, due to SWCNT annexation in the polymer, is registered by the ESR spectra external magnetic field angular dependences. © 2011 Elsevier B.V. All rights reserved

Solid-state low-temperature extrusion of P3HT ribbons

Ribbons of poly(3-hexylthiophene) (P3HT) 0.15 and 0.30 mm thickness were extruded at the temperatures of 200 and 250 C, i.e., below and above the melting temperature of P3HT (~240 C), using a small homemade extrusion device. The ribbons produced by this method are continuous and freestanding. WAXS results show that all the extruded samples are more crystalline than the original powder, and the different processing conditions cause different variations in the crystal unit cell dimensions of P3HT. In terms of the degree of orientation, the ribbons extruded in the solid state (TTm), which is fully isotropic.This work was supported by FCT (Fundação para a Ciência e Tecnologia) through the program PEst-C/CTM/LA0025/2013 (Strategic Project—LA 25—2013–2014) and by the European Regional Development Fund (FEDER) through the program COMPETE (Project PTDC/CTM-POL/120843/2010). DN and DGB gratefully acknowledge partial support of this work from the U.S. Department of Energy, Division of Basic Energy Sciences under contract No. DE-FG02-10ER4779