The researchers found that Molybdenum selenide was not as strong as they thought!
The Rice team, led by material scientist Jun Lou, tested the tensile strength of two-dimensional semiconductor molybdenum selenide and found that a defect with a small missing atom can cause catastrophic cracks under strain. "not all two-dimensional crystals have proved equal," said Rice, a professor of material science and nanoengineering. Graphene is more powerful than some of the other graphene we are dealing with now, just like this molybdenum selenide. We think it has something to do with the inherent defects of these materials.
The diselenide is a disulfide, a two-dimensional semiconductor material, a hexagonal array, which looks like a graphene, but is in fact a metal atom interlayer between two layers of chalcogen atoms, in which case selenium is present. The use of diselenide as a transistor and a next-generation solar cell, a photo-detector, and a catalyst, as well as electronic and optical devices, is being considered. Some of the projects led by the Rice postdoctoral researcher, Yinghao Yang, require that the diselenide be moved from the growth chamber in the chemical vapor deposition furnace to the microscope without introducing more defects. Yang uses a dry transfer process instead of standard pickling to solve the problem, which will damage the sample. Lou said the team was trying to measure the fracture toughness of the material, a measure of the possibility of crack growth, as they did in the early graphene research. But they have found that the pre-cut fracture is a two-selenide, which causes it to break before the stress is applied, he said.
