Inkjet printing of fluorinated materials and their application to patterning organic semiconductors

With the rise of functional printing there is a need to understand the inkjet printability of a greater range of materials. Fluorinated materials and solvents have some unusual properties but this study finds them to be reliably inkjet printable. The fluorinated ink used has Reynolds and Weber numbers of 9.2 ± 1.8 and 20.3 ± 3.0, respectively. Printed line widths on silicon can be varied from 45 μm to 90 μm by adjusting printing parameters. A key advantage of printing from fluorinated solvents is that they can be printed on other organic layers without damaging or dissolving the underlayer. Test patterns are demonstrated on PMMA, P3HT, pentacene and F8BT. This naturally suggests their application to patterning organic semiconductors by selectively protecting some areas. The utility of this technique is demonstrated in the fabrication of an array of P3HT transistors with 2 μm channel lengths in which the active area is patterned using an inkjet printed single-drop fluoropolymer etch mask.