Electrical properties of single-walled carbon nanotube network films

Abstract

Random networks of single-walled carbon nanotubes(SWNTs) have been received significant attention for applications such as transparent electrodes for flat panel displays, various sensors, solar cells, field-effect transistors. In this study, we compare the electrical behavior of network films of as-prepared, purified, cut SWNTs and hybrid of SWNT networks and gold nanoparticles as a function of transmittance under mediation of defects. SWNT network films in the range of 40~99% transmittance were prepared on glass substrate by vacuum filtration methods. SWNTs were characterized by TGA, Raman spectroscopy, and properties of SWNT network films were measured by scanning electron microscopy, UV/VIS/NIR spectra photometer and sheet resistance. The change of electrical properties of SWNT network films is dependent on their structural modifications, but sheet resistance of SWNT net work films does not always depend on the degree of defects. Sheet resistance of cut SWNT network films was lower than purified SWNT network films about below 91% transmittance. We found that there are two critical points and exponents based on percolation theory in sheet resistance versus transmittance or extraction volume in DMF solution graphs. The $2^{nd}$ critical points were observed for all SWNT network films but their origins are not certain. The relationships between transmittance and extraction volume in DMF solution can be found through percolation theory. These results are expected to offer considerable scope for the development of carbon nanotube based electronic devices, especially for devices using transparent conducting films.