Emergence of high piezoelectricity along with robust electron mobility in Janus structures in semiconducting Group IVB dichalcogenide monolayers

Pristine, semiconducting 1T-MX 2 (M = Zr, Hf; X = S, Se, Te) monolayers are intrinsically centrosymmetric and non-piezoelectric. This inversion symmetry is broken in their Janus monolayer (non-centrosymmetric) structures, leading to a high degree of piezoelectricity.