Fabrication of Printed Organic Thin-Film Transistors Using Roll Printing

Abstract

The roll-printed electrodes of organic thin-film transistors (OTFTs) were fabricated by gravure or flexography printing using engraved plates with various channel lengths and nanoparticle silver (Ag) pastes on flexible 150 Â 134 mm 2 plastic substrates. The roll-printed OTFTs used poly(vinyl phenol) (PVP) polymeric dielectrics and bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) organic semiconductors. Depending on the choice of the type of roll-printing method, the printed OTFTs obtained had a field-effect mobility between 0.08 and 0.1 cm 2 V À1 s À1 , an on/off current ratio between 10 4 and 10 5 , and a subthreshold slope between 1.94 and 2.53 V/decade. The roll printing and soluble processes made it possible to fabricate a printed OTFT with a channel length between 16 to 62 mm on a plastic substrate; this was not previously possible using traditional printing techniques. The proposed fabrication process was 20 steps shorter than conventional fabrication techniques.

Patterned silver nanowires using the gravure printing process for flexible applications

“…3b, c, and d, which were printed at speeds of 4, 8, and 12 cm/s, respectively. These effects were observed during silver particle ink printing at high speeds because the bleed-out at the line edges was minimized at high shear force [13]. The higher speeds narrowed the lines, as shown in Figs.…”

“…In general, gravure patterning is a superior printing method and is used to produce continues electrical conductive ink lines for the use in printed electronics [1,8,13]. The gravure printing of continuous lines may be achieved using one of the methods: gravure line printing, in which a series of separate cells is etched close together to form lines, or intaglio trenches, in which a continuous trench is etched into a gravure cylinder.…”

“…4. The ink level remaining in the engraved pattern immediately after the doctoring process was not flush with the elevated areas of the pattern; rather, the remaining ink formed a concave meniscus due to the capillary pressure generated between the blade and the pattern, as well as the wettability of the doctor blade [10,13]. Thus, an appropriate pressure was required to ensure complete contact between the rolling substrate and the ink surface, thereby achieving efficient ink transfer.…”

“…Kang et al demonstrated that the uniformity of the printed lines might be improved by using small nanoparticles that reduce the formation of pinholes in the printed lines [12]. Although gravure printing process are useful for preparing printed electronics using a variety materials [13,14], few systematic studies have examined the use of gravure printing on transparent conductive materials, which are critical to the fabrication of optoelectronic and other transparent devices [15].…”

Paper Electronics

“…Insoluble semiconducting polymers can be made solution processable and printable, for example by adding alkyl-chains to the polymer backbone or by using a soluble precursor such as triisopropylsilyl (TIPS)-pentacene. [79][80][81] The highest reported values of the charge carrier mobility in solution-deposited semiconductors are above 1 cm 2 V − 1 s − 1 . [ 79 , 82 ] The charge transport and mobility of organic semiconductors in organic FETs (OFETs) depends on numerous factors including the semiconductor material, impurities, atmosphere, solvents, concentration, deposition technique, annealing conditions, geometry, semiconductor thickness, insulator, surface roughness, and electric fi eld.…”