Despite its long list of impressive properties, including remarkable electrical conductivity, flexibility and mechanical strength among others, graphene was until now quite poor at absorbing light. As part of a new research, scientists at UK-based University of Surrey have developed an incredibly innovative technique that greatly enhances the light-absorption abilities of this one-atom-thick wonder material. The breakthrough, the team claims, could pave the way for efficient solar harvesters.
For the research, the team relied on an advanced technique, called nanotexturing. Taking inspiration from nature, particularly moths’ eyes, the researchers grew nanometer-thin layers of graphene on a special textured metallic surface. Using this method of nano-patterning, they were able to improve graphene’s light-trapping capabilities by a staggering 90-percent. According to them, the tiny spaces present along the surface of the new material help localize incident light. Speaking about the project, recently published in the Science Advances journal, Ravi Silva, a professor at the university, said:
Nature has evolved simple yet powerful adaptations, from which we have taken inspiration in order to answer challenges of future technologies. Moths’ eyes have microscopic patterning that allows them to see in the dimmest conditions. These work by channeling light towards the middle of the eye, with the added benefit of eliminating reflections, which would otherwise alert predators of their location.
With the help of a somewhat similar technique, the scientists successfully produced a new type of textured graphene that exhibits impressive light-absorption properties. The breakthrough, the team believes, could help develop “smart wallpaper”, which when applied to windows and PV cells could harvest solar energy with remarkable efficiency. What is more, it could be made to generate usable electricity from waste heat or light, thus powering a variety of electronic gadgets and appliances. Silva added:
Solar cells coated with this material would be able to harvest very dim light… New types of sensors and energy harvesters connected through the Internet of Things would also benefit from this type of coating.
According to the researchers, graphene’s thinness is one of the major reasons behind its inability to trap large amounts of light. In general, the light-absorption capacity of this one-atom-thick substance ranges between 2 to 3-percent. When produced using the process of nanotexturing, however, graphene has been found to capture nearly 95-percent of the incident light, be it UV, visible or infrared light. This is because nanotexturing creates microscopic gaps along the material’s surface, which in turn enhances its ability to channel incoming light rays into these spaces. Silva said:
The next step is to incorporate this material in a variety of existing and emerging technologies. We are very excited about the potential to exploit this material in existing optical devices for performance enhancement, whilst looking towards new applications.
The research was conducted with help from BAE Systems.
Source: University of Surrey