(20a) Superelastic and Shape Memory Single Crystal Electronics

Like silicon, single crystals of organic semiconductors are pursued to attain intrinsic charge transport properties. However, they are intolerant to mechanical deformation, impeding their applicability in flexible electronic devices. Such contradictory properties, namely exceptional molecular ordering and mechanical flexibility are unified in this work. We discover certain types of organic semiconductor single crystals can undergo mechanically induced structural transitions to exhibit superelasticity, ferroelasticity and shape memory effect. We show that such properties arise from cooperative and correlated molecular displacements and rotation in response to mechanical stress. By utilizing a bending-induced ferroelastic transition, flexible single-crystal electronic devices are demonstrated that can tolerate strains over 10%, while maintaining the charge carrier mobility of unstrained crystals. We further demonstrate large and reversible modulation of electronic properties via shape memory effect. Our work will pave the way for high performance ultraflexible and dynamic single-crystal organic electronics for sensors, memories, and robotic applications.