Flexible-Blade Coating of Small Molecule Organic Semiconductor for Low Voltage Organic Field Effect Transistor

A flexible-blade coating (FBC) approach, using a simple thin and flexible steel sheet as the meniscus guide, is developed to deposit the blended small molecule organic semiconductor (OSC) solution on substrate surface with pre-fabricated electrode patterns. During coating, the bottom edge of the used flexible steel film touches the substrate surface, but can bend up adapting to the surface morphology variation without causing any damages to the bottom electrodes. With this approach, little amount of very dilute ink solution can be used to coat the channel film, resulting in the greatest material saving among all reported methods. It is shown that, by using the FBC at a moving speed of 12 mm/s to deposit the OSC layer, all solution processed low-voltage organic field effect transistor composed of another polymer gate dielectric layer and inkjet printed metal electrodes were achieved over relatively large area with high performance and good uniformity.