Carbon nanotube array electrodes for organic thin film

As the energy demand in the world increases, more and more extensive research is undertaken concerning renewable energy sources. Developing reliable and low-cost technologies to make use of renewable energy sources is the main objective of many research topics. Several researches are on-going to develop efficient photovoltaic devices which are used to convert solar energy directly to electricity. The aim of this work was to investigate how carbon nanotubes can be applied in the development of novel photovoltaic devices. This has been done by taking an existing system of single-walled carbon nanotubes on glass surfaces and adapting it to solar cell design. Organik photovoltaics require the use of a transparent electrode to allow photons to enter or exit the devices efficiently and to simultaneously allow the extraction or injection of charge carriers. Typically, indium tin oxide (ITO) is utilized as the electrode due to its excellent transparency throughout the visible spectrum, its relatively low sheet resistance, and its work function, which is compatible with the injection and collection of charge carriers in organik semiconductors. However, ITO may ultimately hinder the full market integration of organik electronics due to its increasing cost, lack of mechanical flexibility, chemical instability, and sustainability pertaining to the environment and material utilization. Therefore, alternatives for ITO in organik electronics are being pursued. Transparent electrodes comprised of single wall carbon nanotubes (SWNTs) are an appealing choice as a surrogate for ITO in organik electronics because of the extraordinary electrical and mechanical properties these structures possess, and the demonstrated potential of state of the art SWNT films. As such, the research presented in this dissertation has been conducted to advance the goal of manufacturing SWNT networks with transparent electrode properties that meet or exceed those of ITO. Optical transmittance observations, electrical sheet resistance measurements, and a theoretical understanding of carbon nanotube electronic density of states to clearly elucidate the effect of unintentional and chemically induced doping on SWNT films. There are many methods have been developed for KNT synthesis such as arc discharge, laser vaporization and chemical vapor deposition. Among them, chemical vapor deposition is widely used because of its advantages. CVD appears to be the most promising method because of its low-cost and high-yield production. KNT synthesis by CVD method involves hydrocarbon gas which passes through the tubular reactor in which a catalyst materials is present at high temperatures. At high temperature, hydrocarbon gas decomposes and KNTs grow on the catalyst in the reactor. In order to collect the KNTs, the system has to be cooled to room temperature. In this study, single-walled carbon nanotubes were synthesized by chemical vapor deposition method by using different support materials and catalysts at Material Production and Preparation Laboratory of Istanbul Technical University – Energy Institute. The relation between support materials and catalysts were investigated and the carbon efficiencies are determined for each product. Termogravimetric Analysis, Raman Spectroscopy and XRD were used for the characterization of the synthesized carbon nanotubes. Those KNTs were purified by nitric asid and then they coated on lam glass by spinning method and vakum filtration method. Scanning Electron Microscope (SEM), Optic Profilometer and U-V were used for KNTs characterization. Finally, TDKNTs were used as an electrodes in OPVs and the electrical features of OPVs were measured by solar simulator.