  We study the electromechanical response of Janus transition metal
dichalcogenide (TMD) nanotubes from first principles. In particular,
considering both armchair and zigzag variants of twenty-seven select Janus TMD
nanotubes, we determine the change in bandgap and charge carriers' effective
mass upon axial and torsional deformations using density functional theory
(DFT). We observe that metallic nanotubes remain unaffected, whereas the
bandgap in semiconducting nanotubes decreases linearly and quadratically with
axial and shear strains, respectively, leading to semiconductor--metal
transitions. In addition, we find that there is a continuous decrease and
increase in the effective mass of holes and electrons with strains,
respectively, leading to n-type--p-type semiconductor transitions. We show that
this behavior is a consequence of the rehybridization of orbitals, rather than
charge transfer between the atoms. Overall, mechanical deformations form a
powerful tool for tailoring the electronic response of semiconducting Janus TMD
nanotubes.
