Large gap two-dimensional topological insulators with the coexistence of a significant Rashba effect and piezoelectricity in functionalized PbGe monolayers.

In recent years, two-dimensional (2D) multifunctional materials have become a research hotpot for their wide application range. In this work, PbGe(CN) and PbGe(CH) are predicted to realize the piezoelectricity, quantum spin Hall (QSH) insulator, and Rashba effects simultaneously. The topological bandgaps of PbGe(CN) and PbGe(CH) are 0.