Can a material be too good at conducting electricity? Scientists developing a new one-atom-thick material to rival graphene, the carbon-based darling of the 2D world, think so.
This new 2D material is known as black phosphorous, and a new report in the journal Science shows that it can solve a problem that has plagued graphene: band gap. It's important for a conductor to have a band gap because this property allows the flow of electrical current to be turned on and off – an ability that is critical for most electronic devices.
As all of the buzz over graphene's electrical properties suggests, having no band gap is great for conductivity. A no-band-gap material can be thought of like a river with plenty of stepping stones the whole way across. In a similar fashion to a person hopscotching their way across a river, electricity-carrying particles have a much easier time moving along when the gaps are small.
In graphene's case, the stones are packed together so tightly that scientists can't even pull some of them up to manage the flow of electricity. Black phosphorous, on the other hand, is more malleable. The researchers were able to play around with the arrangement of stones such that black phosphorous' conductivity is comparable to that of graphene, while still maintaining the ability to switch the current on and off.
"[Graphene is] more efficient in its natural state than black phosphorus but it's difficult to open its band gap," senior study author Keun Su Kim of Pohang University of Science and Technology said in a statement. "Therefore we tuned black phosphorous's band gap to resemble the natural state of graphene, a unique state of matter that is different from conventional semiconductors."
Black phosphorous also avoids one of the other obstacles that has prevented graphene from gaining traction – it's cheaper and easier to mass-produce.
As far as materials go, both graphene and black phosphorous are still brand new. While this study suggests that black phosphorous could steal the spotlight from graphene, it's too soon to say whether either of them will actually end up in the electronics of the future. However, it does seem likely that a 2D material of some sort will lead the next revolution in electronics.
