Enhanced Piezoelectric Properties Enabled by Engineered Low-Dimensional Nanomaterials

Today's electronic products are moving toward personal, portable, and flexible electronics with the integration of multifunctional sensors and self-powering technologies. Consequently, efficient and high-performance mechanical–electronic interfaces will be heavily considered in the development of future electronics. Piezotronic materials are active components for the conversion of mechanical stimuli to electrical signals and vice versa. In particular, low-dimensional (LD) materials offer greater efficiencies in piezoelectric materials than their bulk counterparts. Piezoelectric LD materials have attracted significant attention because of their successful integration in miniatured and flexible electronics. The origin of the piezoelectric responses of the LD materials is ascribed as a loss of centrosymmetry and inversion center. However, challenges exist in utilizing piezoelectric materials to their full potential, including effective charge separation upon external stimuli and imperfections in their crystal structures. Therefore, considerable efforts have been devoted to engineering the LD piezoelectric materials by rational structural design and chemical modification to further improve the piezoelectric performances. Herein, we comprehensively review the recent advances for engineering technologies of piezoelectric materials on the scale of zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D), which are mainly focused on creating defects, doping, and forming Janus structures and heterointerfaces with other materials. Meanwhile, the relationships between the morphological, physicochemical, and electronics of engineered LD piezoelectric materials and their piezoelectric performances are systematically discussed. Finally, we further present the prospect and challenge of the field and future research direction, aiming to inspire more research for achieving high-performance LD piezoelectric materials in sensors, actuators, and micro- and nanoelectromechanical systems.