Lee Juhyung, Bang Junhyeok, Kang Joongoo
Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea.
Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea.
J Phys Chem Lett. 2022 Jun 30;13(25):5711-5718. doi: 10.1021/acs.jpclett.2c01352. Epub 2022 Jun 17.
Ultrafast charge transfer in van der Waals (vdW) heterostructures enables efficient control of two-dimensional material properties through strong optical absorption and subsequent carrier transfer. Here, using real-time time-dependent density functional theory coupled to molecular dynamics, we investigated the nonequilibrium dynamics of charge-density-wave (CDW) melting in 1-TaS triggered by ultrafast charge transfer in 1-TaS/MoSe or WSe heterostructures. Despite the fast and sufficient charge transfer from the MoSe (or WSe) "electrode" to the 1-TaS layer, the electronic excitation of the vdW heterostructure does not lead to the nonthermal CDW transition of 1-TaS. Instead, the TaS lattice is heated by carrier-lattice scattering, leading to thermal CDW melting at high ionic temperatures. The lack of nonthermal melting follows from the fact that the time scale of carrier recombination in 1-TaS is similar to or faster than that of charge transfer. These findings provide physical insights into understanding the CDW melting dynamics in vdW heterostructures under nonequilibrium conditions.
范德华（vdW）异质结构中的超快电荷转移能够通过强光学吸收和随后的载流子转移有效地控制二维材料的性质。在此，我们使用与分子动力学相结合的实时含时密度泛函理论，研究了1-TaS/MoSe或WSe异质结构中超快电荷转移引发的1-TaS中电荷密度波（CDW）熔化的非平衡动力学。尽管电荷从MoSe（或WSe）“电极”快速且充分地转移到1-TaS层，但vdW异质结构的电子激发并未导致1-TaS的非热CDW转变。相反，TaS晶格通过载流子-晶格散射被加热，导致在高离子温度下发生热CDW熔化。缺乏非热熔化是由于1-TaS中载流子复合的时间尺度与电荷转移的时间尺度相似或更快。这些发现为理解非平衡条件下vdW异质结构中的CDW熔化动力学提供了物理见解。
