Chinese scientists have found a new method for preparing two-dimensional double-layer twisted-angle transition metal chalcogenide materials

On January 21, the reporter learned from Northwestern Polytechnical University that the research group of Professor Wang Xuewen, a professor and doctoral supervisor at the Institute of Flexible Electronics of the university and the team of Academician Huang Wei of the Chinese Academy of Sciences, proposed a new method for preparing double-layer twisted transition metal dichalcogenides (TB-TMDCs) materials through a reconstructed nucleation strategy, achieving the preparation of interlayer twist angles from 0° to 120°. The relevant results were published in the international journal Nature Communications.

Double-layer twisted transition metal dichalcogenides (TB-TMDCs) have attracted much attention for their flat band structure and unique electronic properties related to moiré superlattices, and are considered to be another ideal platform for studying condensed matter physics after double-layer twisted graphene (TBG). In order to fully explore the novel physical properties caused by the twisted structure and promote the further development of torsional electronics, it is urgent to achieve the controllable preparation of two-dimensional double-layer twisted materials. However, thermodynamically, TB-TMDCs with twisted configurations can neither be directly obtained from bulk crystals nor prepared by traditional methods. Therefore, a preparation method that can achieve large-area, high-quality, and full-twist-angle range TB-TMDCs is urgently needed.

The research team of Northwestern Polytechnical University introduced confined space and NaCl into the traditional CVD system, changed the growth conditions of MoS2 in the reaction system, and achieved the CVD growth of TB-MoS2 with a thermodynamically unfavorable twist angle configuration. The twist angle-dependent Raman and PL spectra confirmed the strong correlation between the twist angle and the interlayer coupling strength of TB-MoS2. The research team discovered the key factors that determine the preparation of TB-MoS2, and achieved the regulation of the yield and density of TB-MoS2 by adjusting the gas flow rate, the ratio of molybdenum source and salt.

Professor Wang Xuewen introduced that, combining the experimental and simulation results, the research team proposed the growth mechanism of TB-MoS2 reconstructing nucleation strategy, which opened up a new path for the preparation of other new TB-TMDCs materials and laid the foundation for the basic research of TB-TMDCs material system and its application in torsional electronics.