Investigation of the electromagnetic properties of single walled carbon nanotube thin films

Küçükyıldız, Şeyda
The work presented in this thesis can be divided in two parts. First part discusses the dispersion and deposition routes of single walled carbon nanotube (SWNT) thin films. Two different types of SWNTs and several dispersing agents were examined to achieve a homogeneous SWNT solution. A tip-sonicator and an ultrasonic bath was compared and it has been found that tip-sonicator increases the efficiency of SWNT dispersions. Vacuum filtration and spray coating techniques were utilized for the deposition of SWNT thin films. Optoelectronic properties of the films were examined for different SWNT densities. Moreover, SWNT thin film functionalization with acid treatment was investigated in order to improve the electrical conductivities of the thin films. Centrifugation of SWNT solutions provided higher optical transmittance at a given wavelength of 550 nm and lower sheet resistance values. It has also been found that, 150 Ω/□ sheet resistance can be achieved at an optical transmittance of 90 % for SWNT thin films on glass substrates that were deposited via vacuum filtration method. The second part investigated the electromagnetic interference shielding properties of the SWNT films. For this purpose, glass fiber woven fabrics were coated with SWNT thin films by spray coating method. Different densities of SWNT films were investigated and the electromagnetic wave reflection and transmission values were analyzed through the utilization of free-space method within a frequency range of 18 – 40 GHz. Our results indicated that the electromagnetic wave reflection properties of the samples were not satisfactory despite their conductivities within the investigated frequency range.