Science

2D self-assembling semiconductor could beat out graphene

2D self-assembling semiconduct...
Scientists have found an alternative to graphene, that has the added bonus of self-assembly and a necessary bandgap (Image: Courtesy of researchers)
Scientists have found an alternative to graphene, that has the added bonus of self-assembly and a necessary bandgap (Image: Courtesy of researchers)
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The new compound Ni3(HITP)2 under a scanning electron microscope shows that the layers are collections of two-dimensional flakes (Image: Courtesy of the researchers)
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The new compound Ni3(HITP)2 under a scanning electron microscope shows that the layers are collections of two-dimensional flakes (Image: Courtesy of the researchers)
Scientists have found an alternative to graphene, that has the added bonus of self-assembly and a necessary bandgap (Image: Courtesy of researchers)
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Scientists have found an alternative to graphene, that has the added bonus of self-assembly and a necessary bandgap (Image: Courtesy of researchers)

Graphene may be talked about as the future wonder material (and for that matter, the present one), but it has one critical deficiency. It lacks a natural bandgap, the physical trait that puts the “semi” in “semiconductor," so it has to be doped to become effective. Enter Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 ... well, you can refer to it as a metal-organic graphene analogue for now. In addition to having a natural band gap, it’s able to self-assemble and represents a whole family of compounds that’s exciting to researchers for its novel properties.

Nickel (the metal) and HITP (the organic compound) are represented in the diagram at the top of the page, with nickel colored in green, amino groups in purple, and carbon rings in grey. The amino groups in the carbon rings are attracted to the nickel, and because of the symmetry and geometry in HITP, the overall organometallic complex almost has a fractal nature that allows this new semiconductor to self-organize perfectly. A band gap is created in the “hole” where electrons aren’t, a space that's just about 2 nm across.

The bandgap is important: graphene must be doped with other compounds to give it the properties of a semiconductor rather than a metal, but this process also negatively affects the otherwise desirable properties of graphene.

So with that chemistry and physics geek-out completed, researchers at MIT under Mircea Dincă initially studied the “bulk” form of this compound, rather than flat 2D sheets, and found even that data impressive. Pellets of Ni3(HITP)2 had a conductivity of 2 S/cm, a record for a metal-organic compound. After creating 2D sheets, the conductance was measured at 40 S/cm, also a record and among the best for any polymer.

To add to the interest even more, Ni3(HITP)2 represents an entire class of similar compounds. Dincă describes the potential as “an entire arsenal of organic synthesis and inorganic synthesis,” harnessable “with atom-like precision and virtually infinite tunability.” In other words, there could be an excellent self-assembling polymer of this type for varying applications, such as creating a solar panel tuned to multiple wavelengths of light.

The research was originally published in the Journal of the American Chemical Society.

Source: MIT

3 comments
The Skud
Good to see that people are still thinking of ways to improve our way of life. I hope these compounds can do better than graphene in enough ways that graphene can disappear into a footnote, now that it is being exposed as having similar long-term risks to asbestos fibres, also once hailed as a 'wonder material' for universal uses
S Michael
Skud... dont worry about it.. They can't produce enough to make anything worthwhile. It is so costly it will never get off the ground for the masses, or for that matter for the elites also. As for this stuff.. Humm I think if you inhaled it, might be a health problem. But don't hold your breath (no pun intended). It's still theoretical and only on paper.
Douglas Bennett Rogers
Most of the asbestos problem was from chrysotile, or blue asbestos. The problem is due to the .2-2 micron fiber diameter. Smaller diameter means greater surface. A minimum surface is required for a given binder shear strength and flaw frequency in the fiber. For this reason the fiberglass industry settled on 10 microns in the 50's. Two microns would have made a considerably stronger composite but would present asbestos-like health problems.