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 (5.4eV) 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. © 2005 The Japan Society of Applied Physics.