Piezotronics and Tribotronics of 2D Materials

Two-dimensional (2D) materials, featuring superior electronic/thermal/mechanical properties, offer a paradigm shift in material science for boosting the rapid development of various sophisticated electronics. Combining with 2D materials, emerging piezotronics and tribotronics can further utilize external mechanical stimuli to modulate their transport properties in an active and direct fashion, delivering more diverse and versatile possibilities in the post-Moore era. Starting with the origin and development of piezotronics and tribotronics with 2D materials, this review provides a comprehensive investigation of their working mechanism, piezotronics in 2D materials, and research progress on piezoelectric nanogenerator (PENG)/triboelectric nanogenerator (TENG) modulated 2D field-effect transistors (FETs) and their broad applications. First, this review focuses on non-centrosymmetric piezoelectric materials and interface engineering to endow 2D materials with piezoelectric properties, and discusses diverse structural designs and applications in environmental/mechanical sensing. Second, the applications of PENG/TENG modulated 2D FETs are discussed regarding mechanical sensing, band structure engineering, artificial synapses, and so on. Finally, the advantages of piezotronics and tribotronics of 2D materials from material to device level are summarized in terms of structural design and functionality. Challenges related to the preparation and processing, reliability and stability of the devices are also pointed out. Synergistic integration of 2D materials with piezo/tribotronics is expected to be a significant complement to current information technology to go beyond Moore's Law, presenting great promise in self-powered smart devices/systems, adaptive human-robot interaction, edge-intelligent artificial prosthesis, etc.