doi:10.1038/nindia.2012.92 Published online 25 June 2012
Hybrid nanostructures made from graphene and zinc oxide quantum dots could be used to design a novel class of optoelectronic devices.
In recent years, hybrid graphene–nanomaterial heterostructures have emerged as excellent candidates for fabricating novel optoelectronic devices. Such nanoscale architectures play an important role in improving the device performance of lithium-ion batteries, ultracapacitors, solar cells, gas sensors, fuel cells and optoelectronic devices.
To explore the potential of hybrid nanostructures made from graphene and ZnO quantum dots, the researchers synthesized ZnO–graphene quasi-core–shell quantum dots by mixing zinc acetate dihydrate and graphite oxide in dimethyl formamide. In the resulting hybrid nanostructure, the ZnO quantum dots became partially wrapped with a monolayer of graphene, forming nanocomposites with diameters of around 15.8 nm.
When the researchers irradiated the structure with light while applying voltages of up to 17 V, they found that photoexcited electrons shuttle between the ZnO quantum dots and the graphene, thereby causing photoluminescence. Varying the voltage resulted in uniform luminescence and made the structure appear bluish-white to the naked eye, owing to combined blue and yellow emission.
The researchers achieved white emission by combining these quantum dots with other emissive materials in a multilayer light-emitting diode. They say that blue emission was observed from the ZnO–graphene quantum dots, which has not been seen in pure-ZnO quantum dots.
The authors of this work are from: Interface Control Research Center, Future Convergence Research Division, Korea Institute of Science and Technology, Green Ceramics Division, Korea Institute of Ceramic Engineering and Technology, Department of Physics, Yonsei University, and Advanced Photonics Research Institute, Gwangju Institute of Science and Technology Seoul, Korea, and Department of Physics, Bangalore University,Bangalore, India.
- Son, D. I. et al. Emissive ZnO–graphene quantum dots for white-light-emitting diodes. Nature Nanotechnol. doi: 10.1038/nnano.2012.71 (2012)