Charge-Transfer-Driven Phase Transition of Two-Dimensional MoTe 2 in Donor-Acceptor Heterostructures.

In this work, based on first-principles calculations, we propose that electrene can be considered as an electron-donating substrate to drive the phase transition of MoTe 2 from the H to T' phase, which is a topic of long-standing interest and importance. In particular, new electrenes Ca 2 XN 2 (X = Zr, Hf) are predicted with the existence of a nearly free two-dimensional (2D) electron gas and ultralow work functions. In MoTe 2 /Ca 2 XN 2 donor-acceptor heterostructures, we find significantly large charge transfer (∼0.4 e per MoTe 2 unit cell) from Ca 2 XN 2 to MoTe 2 , which stabilizes the T' phase and decreases the phase transition barrier (from ∼0.9 to ∼0.5 eV per unit cell). In addition, the phase transition of MoTe 2 on Ca 2 XN 2 remains effective as the interlayer distance varies. It therefore can be confirmed conclusively that our results open a new avenue for phase transition study and provide new insights for the large-scale synthesis of metastable high-quality T'-phase MoTe 2 .