2D material holds promise for next gen optoelectronics

1 min read

Researchers at MIT have used a 2D material called tungsten selenide to create devices that can harness or emit light – paving the way towards ultra thin, lightweight and flexible photovoltaic cells, LEDs and other optoelectronic devices.

Tungsten diselenide, or WSe2, is part of a class of single molecule thick materials under investigation for possible use in next generation optoelectronics. In their experiments, the MIT researchers were able to use the material to produce diodes, the basic building block of modern electronics. Typically, diodes are made by doping, which is a process of injecting other atoms into the crystal structure of a host material. By using different materials for this irreversible process, it is possible to make either of the two basic kinds of semiconducting materials, p-type or n-type. With WSe2, however, both p-type and n-type functions can be obtained just by bringing the thin film into close proximity with an adjacent metal electrode, and tuning the voltage in this electrode from positive to negative. This means the material can easily and instantly be switched from one type to the other. In their experiments, the MIT team produced a device with a sheet of WSe2 that was electrically doped half n-type and half p-type, creating a working diode that was demonstrated in photodetectors, photovoltaic cells and LEDs. While the proof of concept devices are not designed for scaling up, the researchers believe they could have a range of potential uses. They are now exploring how to use the method to create p-type and n-type transistors, as well as other electronic components.