This finding has paved the way for an inexpensive route to the mass production of OLEDs with a large-area and low-cost flexible plastic substrate, which can be rolled up like wallpaper and applied to a vast range of surfaces.
Due to their superb image quality, low power consumption and ultra-thin device structure, OLEDs have been the focus of interest for more than 20 years, and have recently found application in ultra-thin televisions and other display screens, such as those on digital cameras and mobile phones. OLEDs consist of an active organic luminescent structure sandwiched between two electrodes, one of which must be transparent. Traditionally indium tin oxide (ITO) is used in these type of devices, however indium is rare, expensive and difficult to recycle, so scientists have been actively searching for alternatives.
The next generation of optoelectronic devices requires transparent conductive electrodes to be lightweight, flexible, cheap, environmentally attractive, and compatible with large-scale manufacturing methods. Graphene is becoming a very promising candidate due to its unique electrical and optical properties. Recently researchers at Stanford University successfully demonstrated the application of graphene in OLEDs for the first time.
Junbo Wu, leading researcher of the development, said they achieved OLEDs on graphene with performance similar to a control device on conventional ITO transparent anodes, which is very exciting and promising for real-world application. Prof. Peter Peumans, of Electrical Engineering at Stanford, said; ‘‘Graphene has the potential to be a transparent electrode with higher performance, which results in greater transparency whilst at the same time, improved conductivity. It could also be a great deal cheaper than conventional transparent conductors, such as ITO’’. He added; ‘‘It (graphene) does have additional advantage that the electrode is very thin, only a couple of nanometers thick, which gives you potentially a lot more freedom how you design your devices’’.
This research sheds light on the enormous potential of graphene, and opens up an entirely new avenue towards the development of efficient and economical transparent conductors for flexible optoelectronic devices such as OLEDs and organic photovoltaic cells.