Research On Fabrication Technology Of Ink-jet Printed Flexible Transistor

Traditional silicon-based transistors manufacturing processes usually include processes like photoresist,exposure,development,and etching.This manufacturing process is not only complicated but also expensive and wastes consumables.In recent years,taking the advantages of high-speed,large-area,low-cost,fewer-consumable and environmental-protected,flexible printing electronic technology has a wide application prospect in the field of industrial manufacturing of thin-film transistor devices.Semiconducting carbon nanotubes(sc-SWCNTs)show high carrier mobility,excellent thermal conductivity,physical and chemical properties and easy compatibility with the flexible printing process.Thus they become are ideal semiconductor channel materials for flexible transistors fabrication.A method of fully printed flexible carbon nanotube field-effect transistors is proposed in this paper.The thesis work starts from the separation and dispersion experiment of the single-walled carbon nanotubes to prepare the SWCNT ink suitable for ink-jet printing equipment.The printing adaptability on the different flexible gate dielectric layers is studied,and synthetic paper coated with polypropylene film is selected as the flexible substrate.Using a hybrid printing method of ink-jet printing and roll-to-roll printing to print the catalytic layer on the substrate.After UV curing,the source/drain/gate copper electrode arrays are grown in situ by electroless deposition.Ink-jet printing the channel layer of semiconducting carbon nanotubes connecting the source/drain electrodes to complete the preparation of the flexible field-effect transistor.In this paper,the characterizations like ultraviolet-visible spectrometer,scanning electron microscope,conductivity tester and other tests were adopted to measure the SWCNT ink and electroless deposited copper layer electrodes.The electrical performance and bending resistance of the flexible transistor were tested,too.The semiconducting carbon nanotubes were separated from pristine SWCNTs through the selective coating of the conjugated polymer PFO-BT.The stable SWCNK ink was then formed under the dispersion of surfactants.Under the optimization of the electroless copper plating process,the copper layer electrodes obtained high conductivity with dense,smooth surface topography and high line accuracy.The prepared transistor exhibited an excellent I_on/I_offratio(I_on/I_off?2806)and was sensitive to gate voltage modulation,the electrical performance of the transistor is stable,consistent.The bottom-gate bottom-contact field-effect transistor prepared by the hybrid printing system of inkjet printing combined with roll-to-roll printing technology has stable and consistent electrical performance and bending resistance.This printing system simplifies the preparation process and is expected to greatly reduce the manufacturing cost of electronic devices.