Researchers at the Indian Institute of Science (IISc) in Bengaluru have created a novel hybrid of two remarkable materials called graphene and quantum dots in a breakthrough that may inspire highly efficient and controllable next-generation displays and LEDs.
Quantum dots are semiconductor nanocrystals with the potential to revolutionise diverse technologies, from photovoltaics and medical imaging to quantum computing. They can absorb ultraviolet (UV) light and produce sharp, bright colours, making them especially attractive for TVs, smartphones and LEDs. They are extremely tiny particles with properties vastly superior to conventional semiconductors. When activated by UV light, they can produce visible light in different colours depending on their size. Small dots produce blue light, for example, while large ones radiate red.
Quantum dots absorb light very well, but they are poor electrical conductors; quantum dot-based devices that convert light to electricity are, therefore, not very efficient.
Graphene, on the other hand, is almost transparent to light, but it is an excellent electrical conductor. When the two are combined, graphene could, in principle, quickly pull the absorbed energy away from quantum dots—cutting down energy loss—and convert it to an electrical signal, for example. This makes it possible to create devices such as photodetectors with extremely high efficiency. Adding graphene would also confer the ability to tinker with the output even after fabrication, or turn the device on and off at will.
Although the combination works well for photodetectors and sensors, it is practically useless for displays and LEDs because quantum dots lose their ability to emit light when fused with graphene. By modifying some experimental conditions, the IISc scientists have found a way to eliminate this effect and create a highly efficient and tunable hybrid material. The results of the study were published in ACS Photonics.
“You get the best of both,” says Jaydeep Kumar Basu, professor of physics at IISc and lead author of the study.
Compiled by T.V. Jayan