A new generation of electronics and optoelectronics may soon be possible by controlling twist angles in a particular type of bilayer 2D material used in these devices, strengthening the intrinsic electric charge that exists between the two layers, according to researchers from Penn State, Harvard University, Massachusetts Institute of Technology and Rutgers University.
The researchers worked with regular transition metal dichalcogenides (TMD) 2D materials and Janus TMDs, a class of 2D materials named after the Roman god of duality, Janus. These bilayer 2D materials have an interaction between layers known as a van der Waals interlayer coupling that leads to a charge transfer, a process important to the functionality of electronic devices. The charge transfer for both sides of conventional TMDs is the same due to each side having the same type of atoms. In the case of Janus TMD materials, the atoms on each side of the material are different types, leading to varied charge transfer when each side is in contact with other 2D materials.
"In our study, the two types of atoms on each side of the Janus TMD material were sulfur and selenium," said Shengxi Huang, assistant professor of electrical engineering and biomedical engineering at Penn State and co-author of the study recently published in ACS Nano. "Because they are different, there can be a charge separation or charge imbalance for the top and bottom side. It creates a vertically directed intrinsic electric field that is very different from conventional 2D materials."
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