Inkjet Printing of Polymeric Field-Effect Transistors and Its Applications

Abstract

In this paper, the inkjet printing of polymeric field-effect transistors (FETs), inverters and active-matrix backplanes will be reviewed. Inkjet printing, which is characterized as an additive and noncontact patterning method, is an efficient method of fabricating organic devices. All-solution-processed FETs were prepared in ambient air by inkjet-printing the liquid sources of a conductor or a semiconductor, and exhibited a high on–off current ratio of more than 105. This stability is attributed to the high ionization potential (5.4 eV) of the fluorene–bithiophene copolymer used in our work. Channel lengths of less than 20 µm were also achieved by depositing an aqueous dispersion of a conducting polymer along a prepatterned strip that exhibited a hydrophobic surface, thus defining the transistor channel. Partially-solution-processed FETs were also obtained by combining conventional vacuum processes and the inkjet printing of solutions. This approach is considered to be efficient for producing actual devices, and flexible active-matrix backplanes were fabricated using this structure. A flexible electrophoretic display has been achieved by laminating an inkjet-printed active-matrix backplane with an electrophoretic device.