Potential‐Driven Semiconductor‐to‐Metal Transition in Monolayer Transition Metal Dichalcogenides

The potential‐driven semiconductor‐to‐metal transition is investigated in monolayer transition metal dichalcogenides by employing a new proposed method, i.e., the fixed‐potential method (FPM). Under the same voltage, the semiconducting and metallic phases will be charged differently due to their different electronic properties. The potential‐driven phase transition process is simulated by the injection of unequal electrons in the semiconducting and metallic phases. The unequal electron injection is more consistent with the actual experimental process, although equal electron injection also can theoretically induce a phase transition. MoTe2 is chosen as a prototypical example to examine the physical mechanism. When the fixed electrode potential is above the potential of zero‐charge, excess electrons are injected into the metallic 1T’ phase instead of the semiconducting 2H phase, stabilizing the 1T’ phase. In addition, the potential‐dependent kinetics, in which the charge transfer is fluctuating, suggests that increasing the electrode potential will decrease the kinetic barrier of the 2H→1T’ transition process. The calculated relative transition voltage of 2.5 V agrees well with the experimental results, demonstrating the validity of the FPM. This study provides new insight into potential‐driven semiconductor‐to‐metal phase transitions and suggests a new theoretical approach for studies under constant voltage conditions. During the potential‐driven semiconductor‐to‐metal phase transition, more electrons are injected into the metallic phase than the semiconducting phase under same electrode potential. MoTe2 is chosen as a prototypical example to study the phase transition by utilizing the fixed‐potential method, which verifies the mechanism and agrees well with the experimental results. The calculations can provide experimental groups with an explicit picture of the potential effects on the phase transition directly.