An international research team led by Dr. Fagui He and Prof. Christian Klinke from the University of Rostock has achieved a significant advance in materials science: the development of a controlled, scalable, and cost-effective method for producing high-quality, ultra-thin bismuth nanocrystals. The results, published in the journal Small, demonstrate that these materials, which hold great promise for future quantum, spintronics, and energy technologies, can now be produced and characterized more efficiently. The researchers have succeeded in directly mapping the electronic properties of individual nanostructures.
Bismuth's unique electronic properties, such as strong spin-orbit coupling and high thermoelectric efficiency, make it an ideal candidate for exploring novel quantum phenomena. However, previous synthesis methods were often expensive, not very scalable, and did not yield consistent quality in the two-dimensional (2D) nanolayers. The new approach is based on an optimized colloidal synthesis, in which the lateral size of the nanolayers can be precisely controlled by adjusting the process parameters. In particular, the larger nanolayers exhibit exceptionally high intrinsic oxidation resistance and long-term stability under ambient conditions. This robustness is attributed to their atomically smooth surface, which minimizes reactive edges.
A crucial aspect of this work is the ability to directly investigate these colloidally produced nanolayers as individual crystals using sophisticated techniques such as angle-resolved photoemission spectroscopy (μ-ARPES) at the ELETTRA synchrotron in Trieste. ARPES is a method that allows for the detailed visualization of the electronic band structure of materials. Measurements of individual nanolayers showed excellent agreement with theoretical calculations and confirmed the high crystal quality and structural uniformity of the material.
These research findings underline the potential of solution-based synthesis as a scalable platform for the production and characterization of high-quality 2D materials, which are now ready for integration into advanced technologies of the future.
The work also benefited from the expertise developed within the Collaborative Research Centre LiMatI (CRC 1477 “Light–Matter Interactions”) contributed by several of the scientists involved.
Publication:
Fagui He, Yan Yan Grisan Qiu, Simone Mearini, Vitaliy Feyer, Kevin Oldenburg, Rostyslav Lesyuk, Christian Klinke: Tunable Colloidal Synthesis Enabling μ-ARPES on Individual Two-dimensional Bismuth Nanocrystals, Small (2026) e12032
Contact:
Prof. Dr. Christian Klinke
Institute of Physics
University of Rostock
E-Mail: christian.klinke@uni-rostock.de