One-atom thick materials in combination promise highly efficient solar cells
03 May 2013
Researchers say combining graphene with other one-atom thick materials could create the next generation of solar cells and optoelectronic devices.
University of Manchester and National University of Singapore researchers have shown how building multi-layered heterostructures in a three-dimensional stack can produce an exciting physical phenomenon exploring new electronic devices.
The breakthrough, published in the journal, Science, could lead to electric energy that runs entire buildings generated by sunlight absorbed by its exposed walls; the energy can be used at will to change the transparency and reflectivity of fixtures and windows depending on environmental conditions, such as temperature and brightness.
The combinations of 2D crystals allow researchers to achieve functionality not available from any of the individual materials. Collectively, these 2D crystals demonstrate a huge variety of properties: from conductive to insulating, from opaque to transparent. Every new layer in these stacks adds new functions, so the heterostructures are ideal for creating novel, multifunctional devices.
The Manchester and Singapore researchers expanded the functionality of these heterostructures to optoelectronics and photonics. By combining graphene with monolayers of transition metal dichalcogenides (TMDC), the researchers were able to create extremely sensitive and efficient photovoltaic devices. Such devices could potentially be used as ultrasensitive photodetectors or very efficient solar cells.
In these devices, layers of TMDC were sandwiched between two layers of graphene, combining the exciting properties of both 2D crystals. TMDC layers act as very efficient light absorbers and graphene as a transparent conductive layer. This allows for further integration of such photovoltaic devices into more complex, more multifunctional heterostructures.
University of Manchester researcher and lead author Dr Liam Britnell added: “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 added: “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.”