Conjugated Polymer Chain and Crystallite Orientation Induced by Vertically Aligned Carbon Nanotube Arrays.

ACS applied materials & interfaces

PubMedID: 23947724

Kang SJ, Kim YS, Kim WB, Kim DY, Noh YY. Conjugated Polymer Chain and Crystallite Orientation Induced by Vertically Aligned Carbon Nanotube Arrays. ACS Appl Mater Interfaces. 2013;.
We report a method for controlling the orientations of conjugated polymers in the active layer of organic thin-film transistors (OTFTs) by annealing the film at the melting temperature in a vertically aligned multiwalled carbon nanotube (VA-CNT) template under various load pressures. Poly(3-hexylthiophene) [P3HT] molecules are effectively aligned in the melting state annealing at 240 °C for 30 min, as a result of intermolecular p-p and CH3-p interactions between the polymer and the VA-CNTs, which are separated from the conjugated polymer film after cooling to room temperature. In-plane and out-of-plane X-ray diffraction results show that the melt-annealed P3HT film with VA-CNTs has better crystallite ordering than a pristine 80 °C baked film and a melt-annealed film without VA-CNTs, and a larger number of crystallites in the treated P3HT film are oriented in the [100] direction, which is normal to the substrate. When we used the melt-aligned P3HT film with VA-CNTs as the active layer in OTFTs, the P3HT OTFT exhibits a better field-effect mobility value of 0.12 cm(2)/(V s) than a simply melt-annealed device without VA-CNTs [0.06 cm(2)/(V s)].