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. Fully drawn all‐organic flexible transistor arrays are realized using capillary pen printing. This demonstrates that the method shows promise for the large‐area patterning and fabrication of high‐performance flexible electronic devices.