A team from MIT has discovered that a 2D material called molybdenum disulphde (MoS2) could usher in a completely new domain of electronic materials and devices, including clothing with embedded electronics and glasses with built-in display screens.
Molybdenum disulphide has been used in used in industry for many years as an industrial lubricant, but it hadn't been seen as a 2D platform for electronic devices until last year, when scientists at the Swiss university EPFL produced a transistor on the material. Now under close inspection at MIT, the researchers there believe it could pose as a rival to the wonder material known as graphene, a sheet of carbon just one atom thick with exceptional strength and electrical properties.
Yi-Hsien Lee, a postdoc at the university's department of electrical engineering and computer science, found a way to make large sheets of the Molybdenum disulfide using a chemical vapour deposition process. Graduate students Han Wang and Lili Yu then set about producing building blocks of electronic circuits on the sheets made by Lee, as well as on MoS2 flakes produced by a mechanical method.
Wang and colleagues were able to fabricate a variety of basic electronic devices on the material: an inverter, which switches an input voltage to its opposite; a NAND gate, a basic logic element that can be combined to carry out almost any kind of logic operation; a memory device, one of the key components of all computational devices; and a more complex circuit called a ring oscillator, made up of 12 interconnected transistors, which can produce a precisely tuned wave output.
Lee says the material is so thin that it's completely transparent, and it can be deposited on virtually any other material. For example, MoS2 could be applied to glass, producing displays built into a pair of eyeglasses or the window of a house or office, he says.
Another potential application is large screen displays such as television sets and computer monitors, where a separate transistor controls each pixel of the display. Because the material is just one molecule thick — unlike the highly purified silicon that is used for conventional transistors and must be millions of atoms thick — even a very large display would use only an infinitesimal quantity of the raw materials. This could potentially reduce cost and weight and improve energy efficiency.
In the future, Lee believes MoS2 could also enable entirely new kinds of devices. The material could be used, he says, in combination with other 2D materials, to make light-emitting devices. Instead of producing a point source of light from one bulb, an entire wall could be made to glow, producing softer, less glaring light. Similarly, the antenna and other circuitry of a mobile phone might be woven into fabric, providing a much more sensitive antenna that needs less power and could be incorporated into clothing.