Researchers from the University of Manchester and the University of Singapore have delved into the possibilities of one-atom thick graphene combined with other one atom thick materials providing electricity. Basically this means, the walls of a building could absorb sunlight very efficiently and this could be used to power the entire building!

Graphene is a material composed of pure carbon and looks like atoms shaped in a hexagonal pattern. Many layers stacked together create a form of graphite – thus it can be described as one atom thick layer of mineral graphite. It is often also described as a two dimensional crystal. The isolation of grapheme by Professor Andre Geim and Professor Kostya Novoselov in 2004 won them a Noble Prize and also lead to the discovery of many other one atom thick materials. Graphene is the world’s thinnest, strongest and most conductive material ever produced.

Researchers from the two universities have discovered that when graphene is combined with transition metal dichalcogenides (TMDC) – another two dimensional crystal – the materials become a very sensitive and extremely efficient photovoltaic cell. The TMDC is sandwiched between two layers of graphene – the TMDC acts as a light absorber while the graphene acts as a transparent conductive layer. The creation of such ‘heterostructures’ could lead to flexible solar cells or phototransistors.

Professor Novoselov said, “We are excited about the new physics and new opportunities which are brought to us by heterostructures based on 2D atomic crystals. The library of available 2D crystals is already quite rich, covering a large parameter space. Such photoactive heterostructures add yet new possibilities, and pave the road for new types of experiments. As we create more and more complex heterostructures, so the functionalities of the devices will become richer, entering the realm of multifunctional devices.”

University of Manchester researcher and lead author Dr Liam Britnell said, “It was impressive how quickly we passed from the idea of such photosensitive heterostructures to the working device. It worked practically from the very beginning and even the most unoptimised structures showed very respectable characteristics.”

Professor Antonio Castro Neto, Director of the Graphene Research Centre at the National University of Singapore said, “We were able to identify the ideal combination of materials: very photosensitive TMDC and optically transparent and conductive graphene, which collectively create a very efficient photovoltaic device. We are sure that as we research more into the area of 2D atomic crystals we will be able to identify more of such complimentary materials and create more complex heterostructures with multiple functionalities. This is really an open field and we will explore it.”

Dr Cinzia Casiraghi, from The University of Manchester, said, “Photosensitive heterostructures would open a way for other heterostructures with new functionalities. Also, in future we plan for cheaper and more efficient heterostructure for photovoltaic applications.”