Development of Functional Inks Based on Quasi-2D and Quasi-1D Materials for Application in Printed Electronics
Printed electronics technology, in which printing techniques are used with novel functional materials to manufacture electronic devices, has recently attracted a lot of attention. This is because utilization of printing process facilitates fabrication of higher volume of devices with lower cost and processing requirements compared to the conventional fabrication methods. Different functional materials have been used in the inks employed by various printing techniques. Recently, attention has been shifted towards a group of van der Waals materials with quasi-1D and quasi-2D structures such as transition metal chalcogenides. In this dissertation research, I report on the fabrication and characterization of electronic devices printed with inks of quasi-1D and quasi-2D van der Waals materials. In the first part of the dissertation research, the ink was prepared by the liquid-phase exfoliation of crystals of TiS3 semiconductor into quasi-1D nanoribbons dispersed in a mixture of ethanol and ethylene glycol. The ink was used to print electronic conducting channels. The temperature-dependent electrical measurements indicated that electron transport in the printed devices is dominated by the electron hopping mechanisms. The low-frequency electronic noise in the printed devices was of 1/f^γ-type with γ~1 near room temperature (f is the frequency). The abrupt changes in the temperature dependence of the noise spectral density and parameter can be indicative of the phase transition in individual TiS3 nanoribbons as well as modifications in the hopping transport regime. In the second part of the dissertation research, I used quasi-2D 1T-TaS2, which is a charge-density-wave material, for ink preparation. The two-terminal devices with 1T-TaS2 channels were printed on Si/SiO2 substrates. It has been demonstrated that the electrical conduction properties are preserved despite the use of solvents. The temperature-dependent electrical and low-frequency noise measurements indicated that the charge-density-wave phase transitions can be successfully induced in the printed devices. The results of this dissertation research are important for the development of printed electronics with innovative inks of quasi-1D and quasi-2D van der Waals materials.