We report the synthesis of ethylenediamine-intercalated NbSe2 and Li-ethylenediamine-intercalated MoSe2 single crystals with increased interlayer distances and their electronic structures measured by means of angle-resolved photoemission spectroscopy (ARPES). X-ray diffraction patterns and transmission electron microscopy images confirm the successful intercalation and an increase in the interlayer distance. ARPES measurement reveals that intercalated NbSe2 shows an electronic structure almost identical to that of monolayer NbSe2. Intercalated MoSe2 also returns the characteristic feature of the monolayer electronic structure, a direct band gap, which generates sizable photoluminescence even in the bulk form. Our results demonstrate that the properties and phenomena of the monolayer transition metal dichalcogenides can be achieved with large-scale bulk samples by blocking the interlayer interaction through intercalation.
This work was supported by the National Research Foundation of Korea via Grants 2021R1A2C1013119, 2017R1A3B1023686, 2020R1A4A2002828, and 2022K1A3A1A25081713, funded by the Ministry of Science and ICT of the Republic of Korea. This work was also supported by National Measurement Standard Services and Technical Services for SME funded by Korea Research Institute of Standards and Science (KRISS-2023-GP2023-0015). The work at Ajou University was supported by the National Research Foundation of Korea, funded by the Ministry of Education (2021R1A6A1A10044950) and the Ministry of Science and ICT (RS-2023-00210828). Use of the Advanced Light Source, Lawrence Berkeley National Laboratory, is supported by the Office of Basic Energy Sciences of the U.S. Department of Energy under Contract DE-AC02-05CH11231. The authors acknowledge KAIST Analysis Center for Research Advancement (KARA) for XRD and PL measurement facilities.
