Organic field-effect transistors based on single-crystalline active layer and top-gate insulator consistently fabricated by electrostatic spray deposition

• We report single-crystal OFETs with top-gate insulator fabricated by ESD.
• Large crystalline domains of TIPS pentacene were prepared by ESD.
• PMMA top-gate insulators were patterned via a shadow mask in the ESD process.
• A mobility of 0.29 cm2/V s was obtained in a device with a channel length of 5 μm.

An electrostatic spray deposition (ESD) method was applied to prepare both crystalline domains of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and insulating films of poly(methyl methacrylate) (PMMA) for fabricating top-gate single-crystal organic field-effect transistors (OFETs). The electrical characteristics of the top-gate device were compared to those of the bottom-gate one (SiO2 bottom-gate insulator) with the same active layer, and the lower charge-trap density at the interface between the top-gate insulator and single-crystalline active layer was demonstrated. The drain current compression in the output characteristics of the top-gate device, however, occurred due to the large parasitic resistance between the source/drain electrodes and accumulation channel. Reducing the thickness of the single-crystalline active layer resulted in a high charge-carrier mobility of 0.29 cm2/V s (channel length of 5 μm).

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