Marangoni Effect‐Controlled Growth of Oriented Film for High Performance C8‐BTBT Transistors

Abstract Highly oriented organic semiconductors have the advantages of relative low trap density and high carrier mobility. These features make organic transistors valuable in many commercial fields, such as electronic sensor arrays and flexible circuits. Here a simple and efficient “Marangoni effect‐controlled growth” method is introduced to fabricate highly oriented 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) films on AlO x substrates. The oriented film can cover nearly 60% of the substrate surface (5 cm × 1 cm). The grazing‐incidence X‐ray diffraction and transmission electron microscopy measurements show that the C8‐BTBT molecules in the film are highly oriented. Raman spectrum also affirms that the molecular is highly oriented with herringbone stacking structure. Top‐contact and bottom‐gate organic transistors are fabricated and exhibited threshold voltages lower than −3 V. After calibration by the reliable factor, the maximum mobility of the devices is found to be 23.5 cm 2 V −1 s −1 . With long channel length, the nongate voltage–dependent mobility can reach 25 cm 2 V −1 s −1 . These results demonstrate that the proposed method is promising for the fabrication of highly oriented films and high performance organic electronic transistors.