Tunable electronic structure in twisted WTe2/WSe2 heterojunction bilayer

Electronic structures of non-twisted and twisted WTe2/WSe2 heterojunction bilayers were investigated using first-principles calculations. Our results show that, for the twisted WTe2/WSe2 heterojunction bilayer, the bandgaps are all direct bandgaps, and the bandgap (K–K) increases significantly when the twist angle is from 0° to 10°. However, when the twist angle is from 11° to 14.2°, the bandgaps are all indirect bandgaps and the bandgap (G–K) significantly reduces. The band structure of the twisted WTe2/WSe2 heterojunction bilayer differs significantly from that of the non-twisted. Twisted WTe2/WSe2 heterojunction bilayers can be seen as a direct bandgap to an indirect bandgap conversion when turned to a certain angle. Interestingly, the bandgap of the WTe2/WSe2 heterojunction bilayer is very sensitive to the change in the twist angle. For example, when the twist angle is 10.5°, a maximum bandgap will appear. However, the minimum bandgap is 0.041 eV at 14.2°. Our findings have important guidance for device tuning of two-dimensional heterojunction materials.