Energy Conversion in Single‐Crystal‐to‐Single‐Crystal Phase Transition Materials

Abstract Single‐crystal‐to‐single‐crystal (SCSC) phase transitions are direct structural evolutions of crystalline materials in the solid state without the damage of ordering in the crystal lattice. These multidimensional SCSC phase transition materials are responsive to multiple external stimuli (heat, light, mechanical force, electricity, etc.), and have therefore demonstrated promising applications in many fields such as sensors, actuators, artificial muscles, soft robotics, and energy harvesting. The directionality and cooperativity of intermolecular interactions in crystal structures together with a sustained and long‐range dynamics, and the fact that they can operate at high frequency, enable fast and efficient energy conversion processes in SCSC phase transition materials. In this review, the SCSC phase transition materials are analyzed by dividing them into different types of energy transformation, from the point of view of different stimuli that initiate and drive the phase transition, including the thermo‐, photo‐, electric‐, and mechanic‐induced energy transformation, and the dimensionality dependent characteristics in these processes are presented. Moreover, the state‐of‐the‐art design and fabrication of the SCSC phase transition materials as well as the mechanisms of their energy conversion processes are discussed. Finally, the challenges and future potentials are also discussed.