Polymer Field‐Effect Transistors Fabricated by the Sequential Gravure Printing of Polythiophene, Two Insulator Layers, and a Metal Ink Gate

Abstract

The mass production technique of gravure contact printing is used to fabricate state‐of‐the art polymer field‐effect transistors (FETs). Using plastic substrates with prepatterned indium tin oxide source and drain contacts as required for display applications, four different layers are sequentially gravure‐printed: the semiconductor poly(3‐hexylthiophene‐2,5‐diyl) (P3HT), two insulator layers, and an Ag gate. A crosslinkable insulator and an Ag ink are developed which are both printable and highly robust. Printing in ambient and using this bottom‐contact/top‐gate geometry, an on/off ratio of >104 and a mobility of 0.04 cm2 V−1 s−1 are achieved. This rivals the best top‐gate polymer FETs fabricated with these materials. Printing using low concentration, low viscosity ink formulations, and different P3HT molecular weights is demonstrated. The printing speed of 40 m min−1 on a flexible polymer substrate demonstrates that very high‐volume, reel‐to‐reel production of organic electronic devices is possible.

Roll‐to‐Roll fabrication of large area functional organic materials

“…94 In recent years, efforts have been made to R2R manufacture devices including organic thin film transistors to enable integrated circuitry such as inverters 95 and ring oscillators. 96 Still, most of the devices containing polymer materials are fabricated by sheet-to-sheet methods using R2R-compatible processes such as inkjet, 63,97 gravure, 64,65 screen printing, 66 and spray coating. 98 Kang et al, for example, utilize an optimized microgravure process to print silver patterns and poly(4-vinyl phenol) (PVP) dielectric layers.…”

Large-area formation of self-aligned crystalline domains of organic semiconductors on transistor channels using CONNECT

“…To address the above challenges, various groups have developed methods to pattern OSCs (3,9,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24), such as templating OSCs (14,(19)(20)(21), inkjet printing (9,18), gravure printing, and other roll-to-roll coating methods (25)(26)(27). In addition, the use of solvent wetting/dewetting surface treatments has been widely used in conjunction with the patterning methods described above (10, 11, 13, 15-17, 22, 28, 29).…”

Organic Photovoltaics: Technologies and Manufacturing

“…The challenge is to find appropriate solvent systems for polymer-fullerene blends, which will provide appropriate spreading and wetting of the ink on the substrate and homogeneous drying with the required morphology of the active layer. Gravure printing, which is widely used for the printing of organic transistors (Kaihovirta et al, 2008;Voigt et al, 2010), has also been applied for the deposition of OPV layers (Ding et al, 2009;Kopola et al, 2011;Kopola et al, 2010;Voigt et al, 2011). The main difficulty in gravure printing is the required viscosity of the ink, which is for most of the OPV blend systems difficult to reach due to the limited solubility of the components.…”