Fabrication of Printed Organic Thin-Film Transistors Using Roll Printing

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 x 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-1 s(-1), an on/off current ratio between 104 and 105, 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 pm 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. (C) 2009 The Japan Society of Applied Physics