Structural Phase Engineering of Two-Dimensional Materials Toward Precision for Electronic Applications

The diverse polymorphic phases of 2D materials constitute a unique platform for property engineering, making precise phase control a pivotal enabler for next-generation electronics. This review provides a comprehensive survey of recent advances in the phase engineering of 2D materials, with a focus on metal chalcogenides that exhibit rich polymorphism and stoichiometry-dependent structural variations. We begin by outlining the expansive phase space and corresponding property spectrum, spanning semiconducting, metallic, insulating, and ferroelectric states. We then delve into the fundamental principles and experimental methodologies for precise phase manipulation, including pathways toward phase-pure synthesis and both irreversible and reversible phase transformations, while highlighting the governing roles of thermodynamics, kinetics, and stoichiometry. Furthermore, we showcase how these strategies enable revolutionary device concepts, such as high-performance 2D transistors, phase-change memories, and ferroelectric devices. Finally, we discuss the remaining challenges and future perspectives in achieving scalable integration and dynamic phase control, underscoring the transformative potential of phase engineering in advancing the field of 2D electronics.