Engineering noncentrosymmetry in 2D atomic crystals via chemical vapor deposition

Abstract

In contrast to extensively studied centrosymmetric 2D materials, noncentrosymmetric 2D atomic crystals (2DACs) exhibit unique properties—such as nonlinear optical responses, ferroelectricity, and piezoelectricity—making them promising for next-generation optoelectronics and quantum devices. Despite their potential, the controlled synthesis and scalable fabrication of these materials remain challenging, limiting further exploration of their physics and applications. This Feature Article highlights our group's recent advances in engineering noncentrosymmetry in 2DACs via chemical vapor deposition (CVD). We discuss three key strategies: (1) thinning of intrinsically noncentrosymmetric bulk crystals (e.g., nonlayered materials), (2) precise manipulation of van der Waals (vdW) stacking sequences to break inversion symmetry in 2DACs, and (3) alternative routes including self-intercalation, heterostructure assembly, and etching. By correlating synthesis protocols with emergent properties, we demonstrate how CVD enables tailored asymmetry at the atomic scale. Finally, we provide a forward-looking perspective on unresolved challenges, such as achieving phase purity and large-area homogeneity, and propose future research directions for integrating noncentrosymmetric 2DACs into functional devices. This review aims to serve as a roadmap for the controlled synthesis and property exploration of noncentrosymmetric 2DACs.