Aligning Single-Walled Carbon Nanotubes By Means Of Langmuir-Blodgett Film Deposition: Optical, Morphological, and Photo-electrochemical Studies

An alkoxy-substituted poly(phenylene thiophene) is used in order to suspend single-walled carbon nanotubes in an organic solvent. The suspension is spread on the air water interface of a Langmuir trough and the floating film is characterized by means of Brewster angle microscopy and UV-visible reflection spectroscopy and the compression isotherm is recorded. The polymer/carbon-nanotube blend is transferred onto different substrates using the Langmuir-Blodgett technique. AFM measurements indicate the formation of globular structures for the samples transferred at low surface-pressure values and a tubular morphology for high-pressure-deposited samples. AFM analysis is repeated on a sample exposed to soft X-rays for about 5 h and a highly organized structure of bundles of carbon nanotubes rises up. Samples with different numbers of layers are transferred onto ITO substrates by means of the Langmuir-Blodgett method and are tested as photocathodes in a photo-electrochemical cell. A V-oc of 0.18 V, an I-sc of 85.8 mA, FF of 40.0%, and eta of (6.23 x 10(-3))% are obtained.