Strained Organic Thin‐Film Single Crystals for High‐Mobility and High‐Frequency Transistors

Abstract Transistors fabricated from thin‐film single crystals of organic semiconductors (OSCs) have exhibited high mobility exceeding 10 cm 2 V −1 s −1 and show compatibility with low‐cost solution processing. However, their carrier mobility is limited by the molecular vibrations in their soft lattices. This study establishes a practical method for applying compressive strain to single‐crystal OSCs to enhance mobility and transistor performance. In this method, a polymer film substrate is bent to mechanically stretch its surface. Organic single‐crystal transistors are then laminated onto the stretched surface of substrate. Releazing the stretch by recovering the flat surface of the substrate allowed the transistors to be compressed by up to 3%. This resulted in a 52% increase in mobility, reaching 26.4 cm 2 V −1 s −1 . X‐ray diffraction measurements confirmed lattice strain in the OSC single crystals. Moreover, carrier mobility and cutoff frequency increased in MHz‐operating short‐channel transistors, demonstrating applicability for high‐frequency devices. The mobility increase is maintained even three years after introducing the 1% compressive strain, possibly owing to the flexible, molecularly thin characteristics of OSC single crystals. The proposed strain management methods may provide new avenues to enhance the performance of high‐mobility and high‐frequency electronic devices based on OSC thin‐film single crystals.