Optimized ink-jet printing condition for stable and reproducible performance of organic thin film transistor

• For fabrication OTFT device to optimize ink-jet printing condition.
• Temperature and spacing size had influence on the morphology of shape of dot and electrode line.
• To print electrode line without defect on active layer coated surface treatment.
• A substrate temperature of 80 °C was found suitable to prevent coffee ring effect.
• The device showed good electrode morphology and electrical properties.

In this work, we fabricated an electrically stable and reproducible organic thin film transistor (OTFT) by optimizing the electrode printing conditions to avoid the coffee ring effect and the Marangoni effect. The electrodes were printed on substrates with different temperature and line spacing to compare the uniformity of electrode morphology and their electrical performance. The Ag gate electrode was printed on poly (methyl methacrylate) (PMMA) coated glass substrate. As a top contact device, source and drain electrodes were also printed on the pentacene layer. The optimized gate electrode was printed at substrate with a temperature of 30 °C and 30 μm spacing size while the source drain electrodes were printed with 80 μm spacing size at 80 °C. The final devices showed reproducible electrode morphology and electrical properties with a mobility of 0.025 cm2/V-s, threshold voltage Vth = −5.6 V and on/off ratio >104.

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