Tuning Morphology and Packing of TIPS-Pentacene with Enhanced Charge Transport Using Solution Shearing

Solution deposition of organic semiconductors (OSC) is a leading contender for producing large-area, inexpensive, and flexible organic electronics. We recently developed a solution deposition method for OSCs resulted in  better organic field effect transistor (OFET) performance compared to those fabricated from simple drop casting or spin casting methods. We found that this method has achieved a wide range of reproducible morphologies, which results in differing FET performance. Certain conditions have yielded remarkable FET performance, yielding large area films (> 4 cm²) on which FETs show an average charge carrier mobility around 2 cm² V^-1s^-1 with some transistors showing mobilities as high as 4 cm² V^-1s^-1, a current On/Off ratio of  > 10⁶, low hysteresis and a low threshold voltage. We discuss the characteristics of this method and its applicability to a wide range of OSCs. We quantitatively measure the molecular ordering resulting from different deposition conditions and show effective tuning of molecular packing that yields higher charge carrier performance without changing the molecular structure. We investigate the stability of this molecular packing structure and also measure the relationship between the morphological features and its impact on charge carrier transport. We also study the general applicability of this method onto various OSCs.