By: Arthur W.
The concept of two-dimensionality is a tricky one because it doesn’t seem quite right. Everything physical in our world is technically three-dimensional, because every physical object has an element of depth to it; a piece of paper has a length and a width, but it obviously also has a height, even though it is incredibly small. This is even true for the ink on a piece of paper, because it too has a certain thickness. However, some materials are classified as 2D, one of these materials being graphene. Graphene is a form of carbon that is one atom thick, or one million times thinner than a human hair, making it the thinnest material on Earth. It is a truly amazing material: ultra-thin but yet 200 times stronger than steel, the most conductive material yet, transparent and flexible, and applicable to every-day life in a vast variety of ways. Its potential is even larger, limited only by what we can think of. Why graphene is referred to as two-dimensional has an answer, but a complex one that goes deep into the science of the quantum world. This isn’t the point though. The point is that there are materials out there similar to graphene, materials that are just as thin and have just as much to offer, if not more. There is a whole world of 2D materials, a world we are only now beginning to discover and explore.
The discovery of graphene was cutting-edge. Scientists all over the world had known that the material existed for quite a while, particularly because graphite, the material found in pencils, is millions of layers of graphene stacked on top of one another. The problem was that no one knew how to isolate it until 2004, when two physicists at the University of Manchester had managed to do it. The discovery spread around the world like wildfire and received an incredible amount of praise. It was the first 2D material to be made by man, and as scientists began to realize that such creations were actually possible, research into the field of 2D materials rapidly grew. As a result, there are several promising ones in existence today.
One of the most remarkable of this new array of materials is silicene. The very recent new material is being investigated for its use in electronics and semiconductor technologies. Silicene is similar to graphene in many ways, but there is one crucial difference: band gap, a characteristic electrons need to effectively carry an electric current, and a ‘switch’ that turns conducting properties on and off. Silicene has this characteristic, so it should be more suitable for use in the electronics industry. However, silicene is much harder to work with as it reacts and degrades within minutes and needs to be man-made in a difficult process, making it commercially impractical for the time being.
Another interesting material is phosphorene, similar to graphene and silicene, but again, slightly different. Phosphene’s electrical properties and potential application in the semiconductor industry are even better than those of silicene because it too has a band gap, one that allows the semiconductor (which operates only in certain conditions due to this band gap) to function fast and effectively so that it can be used in for example computers. Phosphene also has favorable optical properties, which, in combination with the electrical properties makes it very appropriate for use in solar energy and other light-related technologies.
New 2D materials are surfacing every now and then, some better than others, but all unique. It doesn’t end with these individual materials though; they can be combined to give the most unpredictable properties, properties leading to new applications. It’s all very exciting and creative, especially when considering the number of possible combinations. I think it’s fair to say that we’ll be hearing and seeing quite a bit of these magnificent materials in the foreseeable future. This is merely the start of a material revolution.