Fully Drawn All-Organic Flexible Transistors Prepared by Capillary Pen Printing on Flexible Planar and Curvilinear Substrates

Printing technologies are instrumental to the fabrication of low-cost lightweight flexible electronic devices and circuits, which are necessary to produce wearable electronic applications. However, attaining fully printed devices on flexible films over large areas has typically been a challenge. Here, the fabrication of fully drawn all-organic field-effect transistor (FET) arrays on mechanically flexible substrates using a capillary-pen printing method is demonstrated. A highly crystalline organic semiconductor (active layer), a smooth insulating polymer (dielectric layer), and a conducting polymer (source, drain, and gate electrodes) are deposited from solution sequentially. The bottom-gate bottom-contact FETs drawn onto flexible substrates exhibit superior field-effect mobilities of up to 0.54 cm² V⁻¹ s⁻¹, good reproducibility, operational stability, and mechanical bendability. Furthermore, to emphasize the methodological advantages of the capillary-pen printing, an organic FET (OFET) array on a curvilinear substrate of a plastic straw and the repairing concept for a broken electrical circuit are demonstrated. These results indicate that capillary pen printing shows promise as a manufacturing technique for a wide range of large-area electronic applications.