Phase transition represents an intriguing physical phenomenon that exists in a number of single-layer transition-metal dichalcogenides. This phenomenon often occurs below a critical temperature and breaks the long-range crystalline order leading to a reconstructed superstructure called the charge-density wave (CDW) structure, which can therefore be recovered by external stimuli such as temperature. Alternatively, we show here that another external stimulation, electric field can also result in the phase transition between the regular and CDW structures of a single-layer transition-metal dichalcogenide. We used single-layer TiSe₂ as an example to elucidate the mechanism of the CDW followed by calculations of the electronic structure using a hybrid density functional. We found that applying electric field can tune the phase transition between the 1T and CDW phases of single-layer TiSe₂. Our work opens up a route of tuning the phase transition of single-layer materials via electric field.

相变代表了一种有趣的物理现象，它存在于许多单层过渡金属二卤化物中。此现象通常在临界温度以下发生，并破坏了长程晶体顺序，从而导致了称为电荷密度波（CDW）结构的重建超结构，因此可以通过诸如温度之类的外部刺激来恢复。或者，我们在这里显示另一种外部刺激电场也可以导致单层过渡金属二卤化硅的规则结构与CDW结构之间的相变。我们使用了单层TiSe ₂以阐明CDW的机理为例，然后使用混合密度函数计算电子结构。我们发现，施加电场可以调节单层TiSe ₂的1 T和CDW相之间的相变。我们的工作为通过电场调整单层材料的相变开辟了一条途径。