Novel approach for fabricating transparent and conducting SWCNTs/ITO thin films for optoelectronic applications
American Chemical Society
School of Engineering
Single-walled carbon nanotubes (SWCNTs) incorporated in indium tin oxide (ITO) were developed to fabricate transparent conductive thin films via a sol–gel spin coating technique. The fabricated thin films were annealed at 350 °C. The effects of incorporating SWCNTs and varying film thickness on crystal structure were systematically investigated by X-ray diffraction (XRD), Raman shift, surface elemental compositions, surface topography and roughness, optoelectronic characteristics, and mechanical properties. XRD results confirmed the body-centered cubic structure of indium oxide polycrystalline phase, indicating that the structural properties of the ITO films were not significantly altered by incorporating CNTs. The presence of CNTs in the ITO matrix was confirmed by analyses of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). FESEM images revealed the formation of SWCNTs/ITO nanoparticles, and the average crystallite size increased along with increasing film thickness. Electrical characteristics also improved as the film thickness increased. The lowest electrical resistivity (4.6 × 10–4 Ω cm), as well as the highest carrier concentration (3.3 × 1020 cm–3) and carrier mobility (41 cm2/V s) were achieved from the 320 nm thick film. However, the optical transparency decreased from 91 to 87.5% as the film thickness increased from 150 to 320 nm. The hardness and Young’s modulus of the prepared samples improved, with the increase of SWCNTs doping level, and achieved the maximum values of 28 and 306 GPa, respectively.