Piezoelectric networks and ferroelectric moir\'e superlattice domains in twistronic WS2/MoS2 and WSe2/MoSe2 bilayers
Abstract
Twistronic van der Waals heterostrutures offer exciting opportunities for engineering optoelectronic properties of nanomaterials. Here, we use multiscale modeling to study trapping of charge carriers and excitons by ferroelectric polarisation and piezoelectric charges by domain structures in twistronic WX2/MoX2 bilayers (X=S,Se). For almost aligned 2H-type bilayers, we find that holes and electrons are trapped in the opposite -- WMo and XX (tungsten over molybdenum versus overlaying chalcogens) -- corners of the honeycomb domain wall network, swapping their position at a twist angle 0.2, with XX corners providing 30\,meV deep traps for the interlayer excitons for all angles. In 3R-type bilayers, both electrons and holes are trapped in triangular "3R stacking" domains, where WX2 chalcogens set over MoX2 molybdenums, which act as 130\,meV deep quantum boxes for interlayer excitons for twist angles 1, for larger angles shifting towards domain wall network XX stacking sites.