Herman Artur P, Zelewski Szymon J, Misztal Kamil, Kudrawiec Robert
Department of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław, 50-370, Poland.
Nanophotonics. 2022 Feb 24;11(7):1335-1344. doi: 10.1515/nanoph-2021-0741. eCollection 2022 Mar.
Understanding the dissociation of excitons into long-lived free charge carriers is a crucial issue when considering the applications of transition metal dichalcogenides (excitonic semiconductors) oriented toward the use of solar energy (such as photovoltaics or photocatalysis). In our work, long-lived carriers have been observed by time-resolved microwave photoconductivity (TRMC) for the first time in both atomically thin and bulk MoS, MoSe, WS, and WSe crystals. The lifetime of majority carriers is close to microseconds and can even reach several microseconds due to different contribution of surface and defect states, as well as surface band bending (bulk). The three components depend on the material and vary from sample to sample, therefore determining the dynamics of the TRMC signal. The rise time of TRMC signal was found to be in the range of 0.1-0.2 μs and as it depends on the studied material it can be speculated that it is related to the dissociation time of excitons captured by traps.
在考虑将过渡金属二硫属化物（激子半导体）应用于太阳能利用（如光伏或光催化）时，理解激子解离成长寿命自由电荷载流子是一个关键问题。在我们的工作中，首次通过时间分辨微波光电导（TRMC）在原子级薄和块状的MoS、MoSe、WS和WSe晶体中观察到了长寿命载流子。由于表面和缺陷态以及表面能带弯曲（体相）的不同贡献，多数载流子的寿命接近微秒，甚至可达几微秒。这三个因素取决于材料，且因样品而异，因此决定了TRMC信号的动力学。发现TRMC信号的上升时间在0.1 - 0.2微秒范围内，由于它取决于所研究的材料，可以推测它与陷阱捕获的激子的解离时间有关。
