Researchers around the world have been working to harness the unusual properties of graphene, a two-dimensional sheet of carbon atoms. But graphene lacks one important characteristic that would make it even more useful: a property called a bandgap, which is essential for making devices such as computer chips and solar cells.
Now, researchers at MIT and Harvard University have discovered a two-dimensional material whose properties are very similar to graphene, but with some distinct advantages — including the fact that this material naturally has a usable bandgap.
The new material, a combination of nickel and an organic compound called HITP, also has the advantage of self-assembly - a 'bottom-up' approach that could lend itself to easier manufacturing and tuning of desired properties by adjusting relative amounts of the ingredients.
The new compound, Ni3(HITP)2, shares graphene’s perfectly hexagonal honeycomb structure. What’s more, multiple layers of the material naturally form perfectly aligned stacks, with the openings at the centres of the hexagons all of precisely the same size - about two nanometres across.
In these initial experiments, the researchers studied the material in bulk form, rather than as flat sheets, and achieved excellent electrical conductivity. This is encouraging, since these properties should be better yet in a 2D version of the material.
This is the first of what could be a diverse family of similar materials built from different metals or organic compounds. According to MIT assistant professor of chemistry Mircea Dinca, who carried out the research, there is now an entire arsenal of organic synthesis and inorganic synthesis that could be harnessed to “tune the properties, with atom-like precision and virtually infinite tunability.”
Such materials, Dinca says, might ultimately lend themselves to solar cells whose ability to capture different wavelengths of light could be matched to the solar spectrum, or to the construction of improved supercapacitors.