Borophene acts as an efficient 2D plasmonic material

According to scientists from Rice Univesity, an atom-thick film of boron could be the first pure two-dimensional material able to emit visible and near-infrared light. The material does this by activating its plasmons. That would make the material known as borophene a candidate for plasmonic and photonic devices like biomolecule sensors, waveguides, nanoscale light harvesters and nanoantennas.

The material is naturally able to emit visible and near-infrared light by activating its plasmons. Plasmons are collective excitations of electrons that flow across the surface of metals when triggered by an input of energy, like laser light. Also, delivering light to a plasmonic material in one color can prompt the emission of light in another color. The lab’s simulations are detailed in the Journal of the American Chemical Society.

Boron is a semiconductor in three dimensions but a metal in 2-D form.The researchers used a computational modeling technique called density functional theory to test plasmonic behavior in three types of free-standing borophene. The material’s baseline crystal structure is a grid of triangles.

The lab studied models of plain borophene and two polymorphs. Polymorphs are solids that incorporate more than one crystalline structure that are formed when some of those middle atoms are removed. Their calculations showed triangular borophene had the widest emission frequencies, including visible light, while the other two reached near-infrared.

The researchers said their results present the interesting possibility of manipulating data at subdiffraction wavelengths. If there is an optical signal with a wavelength that’s larger than an electronic circuit of a few nanometers, there’s a mismatch. Now a signal can be used to excite plasmons in the material that pack the same information (carried by the light) into a much smaller space. This will help to squeeze the signal so that it can go into the electronic circuit.