DFT Insights into Layer-Dependent Superhigh Piezoelectricity and Carrier Mobility in 2D Hexagonal SnNBr

The experimental synthesis and theoretical investigations of transition metal nitride halides have served as a catalyst for predicting and exploring the promising, nontoxic 2D SnNBr system in this current study. It reveals all-round stability, a direct bandgap nature, and impressive carrier mobility. On tiptoe, the 2D SnNBr system possesses high out-of-plane piezoelectricity and most necessarily durable mechanical stability. Furthermore, a meticulous atomic-scale investigation was conducted to elucidate both the negative in-plane and positive out-of-plane piezoelectricity and their respective signs. Positive clamped-ion contribution to piezoelectricity has been found in two-dimensional SnNBr like the MoSSe monolayer, which differs from the usual negativity expected in the clamped-ion piezoelectric response in bulk materials composed of multilayered van der Waals structures [Qi and Rappe, Phys. Rev. Lett. 2021, 126 (21), 217601]. Moreover, the tunability of these commendable physical properties with the number of layers, which is very highly anticipated in device applications, has been thoroughly emphasized. The remarkable versatility and extensive range of tunability achievable from a single 2D SnNBr structure emphasize the critical need for its experimental synthesis in cutting-edge applications such as futuristic nano piezotronics, electromechanical memories, smart robotics, and self-adaptive nanoelectronic devices.

Automated summary

This study predicts and explores the potential nontoxic 2D SnNBr system through experimental synthesis and theoretical investigations. The system exhibits stability, direct bandgap, and high carrier mobility. Furthermore, it possesses high out-of-plane piezoelectricity and shows positive clamped-ion contribution to piezoelectricity, which is different from the usual response in bulk materials. The tunability of these properties with the number of layers is also emphasized.