Graphene vs Borophene
For the past few years, many researchers and engineers alike have been looking into materials such as graphene for their strength, flexibility, and conductivity. Graphene has been showing up in the news many times recently for their growing popularity in research including graphene electronic applications, printed graphene in paper electronics, and applications in car batteries.
Graphene's regular structure. Image courtesy of AlexanderAlUS (own work) [CC BY-SA 3.0]
While graphene performs better on flexible devices than other materials such as indium-tin oxide, it may be too flat and difficult to stretch. This is due to the rigid hexagonal structure that graphene forms. But there exists a structure of boron known as “borophene” that may help to overcome the issues graphene has in flexible applications.
Boron Bucky Balls
Back in 2014, a research team led by theoretical physicist Boris Yakobson at Rice University showed that a boron structure (B36) would be highly stable. Photoelectron spectroscopy of B36 showed that the structure was symmetrical, which is crucial for a repeating sheet-like structure.
At the same time, researchers also announced the creation of a 40-atom buckyball that consisted entirely of boron. It is these structural properties that make boron real contender in the future of electronics.
Structure showing the 40 boron buckyball. Image courtesy of Materialscientist (own work) [CC BY-SA 3.0]
Borophene, Silver, and Its Applications
A team of researchers led by Boris at Rice University found that, when borophene is grown on a featureless surface (i.e. atomically flat), it forms a hexagonal structure that resembles graphene. However, if borophene is grown on a silver surface, it forms corrugations (like those found in an accordion) that suggests the borophene is much more flexible in this configuration.
But the relationship between borophene and silver is even more surprising because, when the borophene forms the corrugations, the silver reconstructs itself to match the waving pattern.
Borophene structure showing the triangluar lattice and the central vacancy. Image courtesy of Materialscientist (own work) [CC BY-SA 3.0]
Once the borophene is formed, it can easily be removed as the bond between the silver and borophene is weak. This may allow atom-thick slices of borophene to be transferred to any substrate once it has been formed with the corrugations. Once transferred, the borophene should exhibit the same properties as when it was grown on the silver surface (flexibility, electrical characteristics, etc.)
The borophene structure (red) on top of silver (grey / blue). Image courtesy of Zhuhua Zhang/Rice University
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But borophene properties go beyond its flexibility. Borophene in its typical state is metallic with strong electron-phonon coupling. This gives the possibility of superconductivity support which could see borophene be implemented in applications involving superconductors.
The borophene structure, a triangular lattice with periodic arrays of hexagonal vacancies, also contains Dirac cones which are important for applications involving the Hall Effect.
Borophene could be the key to the future of wearable devices, boasting flexible properties while exhibiting electrical properties. Materials that not only flex but can stretch would enable electronics to be mounted onto any surface with a much lower chance of breaking.
Borophene may also find its way into the future of superconductors and, if coupled with room temperature superconductors, may change the world forever.