EFFECT OF MECHANICAL BENDING ON MOLYBDENUM DISULFIDE/CARBON NANOTUBE COMPOSITE THIN FILMS ON FLEXIBLE POLYMER SUBSTRATES FOR ELECTRONIC APPLICATIONS

Abstract

The thesis focuses on preparing and characterizing MoS2/MWNT composite thin films on different polymer substrates and examining their electrical behavior upon external mechanical forces. The experimental process involved creating a composite by mixing MoS2 nanosheets with multi-walled carbon nanotubes (MWNT). The MoS2 nanosheets were produced through liquid phase exfoliation of bulk MoS2 powder. The substrates used included Polyethylene Terephthalate (PET), Polyethylene (PE), Polypropylene (PP), and Polyvinyl Chloride (PVC). Each type of substrate was prepared by cutting polymer sheets to the required dimensions. The deposition process involved applying the MoS2/MWNT dispersion onto the substrates by drop casting method, followed by a heating procedure to evaporate the solvent and form polycrystalline thin films. For substrates used in conductivity tests, multiple drop-casting cycles were performed to enhance the deposition area. The choice of N-Methyl-2-pyrrolidone (NMP) as the solvent was crucial due to its efficiency in producing 2D materials, with careful temperature control during heating to prevent substrate damage. Structural analysis was conducted using X-ray Diffraction (XRD) to examine the crystallographic characteristics of the thin films. Topography and morphology studies were carried out using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) to understand the physical properties and surface features of the films. Electrical analysis was performed using a four-point probe to study the current-voltage characteristics of the thin films. A unique aspect of the research involved bending studies of the thin films using a specialized bending device. The films were subjected to controlled bending cycles to assess electrical performance under stress. The results provided valuable insights into the electrical properties of the MoS2/MWNT composite thin films on different polymer substrates, offering potential applications and understanding their behavior under mechanical bending conditions. Stable MoS2-MWNT thin layers were successfully deposited on various flexible substrates, with analyses confirmed well-defined crystalline structures showing significant substrate-dependent variations in surface features. Electrical performance evaluations indicated that PET substrates performed best under bending, suggesting their suitability for flexible electronics applications.