Solution‐Processed Centimeter‐Scale Highly Aligned Organic Crystalline Arrays for High‐Performance Organic Field‐Effect Transistors

Solution-printed organic single-crystalline films hold great potential for achieving low-cost manufacturing of large-area and flexible electronics. For practical applications, organic field-effect transistor arrays must exhibit high performance and small device-to-device variation. However, scalable fabrication of highly aligned organic crystalline arrays is rather difficult due to the lack of control over the crystallographic orientation, crystal uniformity, and thickness. Here, a facile solution-printing method to fabricate centimeter-sized highly aligned organic crystalline arrays with a thickness of a few molecular layers is reported. In this study, the solution shearing technique is used to produce large-area, organic highly crystalline thin films. Water-soluble ink is printed on the hydrophobic surface of organic crystalline films, to selectively protect it, followed by etching. It is shown that the addition of a surfactant dramatically changes the fluid drying dynamics and increases the contact line friction of the aqueous solution to the underlying nonwetting organic crystalline film. As a result, centimeter-scale highly aligned organic crystalline arrays are successfully prepared on different substrates. The devices based on organic crystalline arrays show good performance and uniformity. This study demonstrates that solution printing is close to industrial application and also expands its applicability to various printed flexible electronics.