Supertwisted WS2 spirals synthesized on step-edge non-Euclidean surfaces: Twist angle modulation and optical properties
image: Supertwisted WS2 spirals can be synthesized at the edges of nanoribbons, where larger step heights or contact areas of the nanoribbons lead to larger twist angles. The photoluminescence properties of the supertwisted structures reveal interlayer interaction decoupling and recoupling, while Raman spectroscopic analysis demonstrates lattice hardening dominated by interlayer van der Waals interactions.
Credit: Nano Research, Tsinghua University Press
Transition metal dichalcogenides (TMDCs) is a two-dimensional (2D) layered material composed of transition metal elements and chalcogenide elements. Among them, supertwisted WS2 spiral structure have attracted significant attention. As a twisted 2D layered material, supertwisted spirals exhibit multiple layers of continuous twisted structures, which give rise to their unique optoelectronic properties. Thus, the research of supertwisted spirals is very important.
A team of led by Xiaopeng Fan from Taiyuan University of Technology in Shanxi, China recently researched the supertwisted WS2 spirals synthesized at the edge of nanoribbons with nanoparticles. Due to interlayer twist angles introduce a new degree of freedom, which enables precise tuning of specific optoelectronic properties, therefore the study of twisted materials with controlled twist angles can pave the way for their potential applications in various fields. Current research is aimed at analyse the factors that affect the variation of twist angle in the supertwisted WS2 spirals, provide new insights into the regulation of twist angles and reveal the unique optical properties of the twisted spirals.
The team published their research in Nano Research on May 28, 2025.
“Here, we experimentally synthesized supertwisted WS2 spirals on substrates featuring both step-like nanoribbons and conical non-Euclidean surfaces. Furthermore, we systematically investigated the effect of nanoribbons on the variation of twist angles in these supertwisted WS2 spirals. In addition, in combination with the photoluminescence (PL) and Raman spectra, the effects of the twist angle and thickness of the WS₂ spiral structure on its optical properties were discussed. Overall, these findings may contribute to further studies on how to manipulate the interlayer twist of twisted TMDCs, as well as to a deeper understanding of the optical properties of twisted TMDCs materials.” said Xiaopeng Fan, senior author of the research article, associate professor in the School of College of Physics and Optoelectronic Engineering at Taiyuan University of Technology.
The research team demonstrated the effect of the contact surface between spiral structures and substrates on the twist angle. “The height of the contact region significantly impacts the twist angle. The phenomenon can be explained by the geometrical mismatch between the supertwist WS2 spirals and the nanoribbon. As the height of the nanoribbon step increases, the curvature of the underlying non-Euclidean surface becomes more pronounced, which enhances lattice distortion during the growth of WS₂ spirals. Consequently, the SDD mechanism transfers larger angular mismatches between successive layers, resulting in greater twist angles for spirals growing on thicker contact regions.” “a larger contact area between the base of the spiral and the nanoribbon results in greater curvature of the WS₂ grown via the SDD mechanism, thereby facilitating the formation of a supertwisted WS₂ spiral with a larger twist angle.” Xiaopeng Fan said.
The PL and Raman spectra tests for supertwist spiral structures will be particularly useful. Because it is essential to research the phenomena of moiré excitons and phonon-electron coupling in twisted structures from the point of view of twisted electronics, which are studied by means of PL and Raman tests, respectively.
The research team expects the research to spur synthesis of material with controllable interlayer twist angles and facilitate more photodetectors, memristors, energy storage devices and so on. “understanding the effects of interlayer twists not only deepens insight into the intrinsic physical mechanisms of these materials but also opens new avenues for designing advanced multifunctional optoelectronic devices based on twisted 2D materials.” said Xiaopeng Fan.
Other contributors include Peng Liu, Xinchao Wang, Junyuan Chen, Yang Bai, Yuying Hao, Hongli Yang from the School of College of Physics and Optoelectronic Engineering, College of Mining Engineering at Taiyuan University of Technology in Shanxi, China; Xiumeng Bao, Xiaoyong Fan from the PetroChina Tarim Oilfield Company in Korla, China; and Weihua Yang from the department of Physics, Xiamen University in Xiamen, China.
This work was supported by National Natural Science Foundation of China (Grant No. 52273252) and technical support from the Instrumental Analysis Center of Taiyuan University of Technology.
About the Authors
Dr. Xiaopeng Fan is a full-time professor in the College of Physics and Optoelectronic Engineering, Taiyuan University of Technology, China. His research interests focus on Synthesis and Optoelectronic Properties of Nanomaterials, encompassing but not limited to: Synthesis of novel two-dimensional twisted spiral moiré superlattices; Investigations into photoluminescence carrier dynamics; Nonlinear optical characterization studies; vortex-based optoelectronic detection devices. For more information, please pay attention to his research homepage https://www.x-mol.com/groups/fan_xiaopeng.
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.