Abstract
Hybrid nanostructures combining inorganic materials and graphene are being developed for applications such as fuel cells, batteries, photovoltaics and sensors. However, the absence of a bandgap in graphene has restricted the electrical and optical characteristics of these hybrids, particularly their emissive properties. Here, we use a simple solution method to prepare emissive hybrid quantum dots consisting of a ZnO core wrapped in a shell of single-layer graphene. We then use these quantum dots to make a white-light-emitting diode with a brightness of 798 cd m−2. The strain introduced by curvature opens an electronic bandgap of 250 meV in the graphene, and two additional blue emission peaks are observed in the luminescent spectrum of the quantum dot. Density functional theory calculations reveal that these additional peaks result from a splitting of the lowest unoccupied orbitals of the graphene into three orbitals with distinct energy levels. White emission is achieved by combining the quantum dots with other emissive materials in a multilayer light-emitting diode.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).
Zhang, Y. B., Tan, Y. M., Stormer, H. L. & Kim, P. Experimental observation of the quantum Hall effect and Berry's phase in graphene. Nature 438, 201–204 (2005).
Alexander, A. Low-energy theory of disordered graphene. Phys. Rev. Lett. 97, 236802 (2006).
Jannik, C. M. et al. The structure of suspended graphene sheets. Nature 446, 60–63 (2007).
Schedin, F. et al. Detection of individual gas molecules adsorbed on graphene. Nature Mater. 6, 652–655 (2007).
Son, D. I. et al. Flexible organic bistable devices based on graphene embedded in an insulating poly(methyl methacrylate) polymer layer. Nano Lett. 10, 2441–2447 (2010).
Sun, X. W., Huang, J. Z., Wang, J. X. & Xu, Z. Inorganic/organic hetero-structure light-emitting diode emitting at 342 nm. Nano Lett. 8, 1219–1223 (2008).
Cole, J. J., Wang, X., Knuesel, R. J. & Jacobs, H. O. Integration of ZnO microcrystals with tailored dimensions forming light emitting diodes and UV photovoltaic cells. Nano Lett. 8, 1477–1481 (2008).
Caruge, J. M., Halpert, J. E., Wood, V., Bulović, V. & Bawendi, M. G. Colloidal quantum-dot light-emitting diodes with metal-oxide charge transport layers. Nature Photon. 2, 247–250 (2008).
Anikeeva, P. O., Halpert, J. E., Bawendi, M. G. & Bulovic, V. Electroluminescence from a mixed red–green–blue colloidal quantum dot monolayer. Nano Lett. 7, 2196–2200 (2007).
Son, D. I. et al. Bistable organic memory device with gold nanoparticles embedded in a conducting poly(n-vinylcarbazole) colloids hybrid. J. Phys. Chem. C 115, 2341–2348 (2011).
McAlpine, M. C., Ahmad, H., Wang, D. & Heath, J. R. Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors. Nature Mater. 6, 379–384 (2007).
Sun, Y. & Rogers, J. A. Inorganic semiconductors for flexible electronics. Adv. Mater. 19, 1897–1916 (2007).
Terrones, M. et al. Graphene and graphite nanoribbons: morphology, properties, synthesis, defects and applications. Nano Today 5, 351–372 (2010).
Son, D. I. et al. Polymer–ultrathin graphite sheet–polymer composite structured flexible nonvolatile bistable organic memory devices. Nanotechnology 22, 295203 (2011).
Zhang, Y., Tang, Z-R., Fu, X. & Xu, Y-J. TiO2–graphene nanocomposites for gas-phase photocatalytic degradation of volatile aromatic pollutant: is TiO2–graphene truly different from other TiO2–carbon composite materials? ACS Nano 4, 7303–7314 (2010).
Zhang, M. et al. Fast synthesis of SnO2/graphene composites by reducing graphene oxide with stannous ions. J. Mater. Chem. 21, 1673–1676 (2011).
Niyogi, S. et al. Solution properties of graphite and graphene. J. Am. Chem. Soc. 128, 7720–7721 (2006).
Kudin, K. N. et al. Raman spectra of graphite oxide and functionalized graphene sheets. Nano Lett. 8, 36–41 (2008).
Mohiuddin, T. M. G. et al. Uniaxial strain in graphene by Raman spectroscopy: G peak splitting, Grüneisen parameters, and sample orientation. Phys. Rev. B 79, 205433 (2009).
Ni, Z. H. et al. Uniaxial strain on graphene: Raman spectroscopy study and band-gap opening. ACS Nano 2, 2301–2305 (2008).
Dato, A., Radmilovic, V., Lee, Z. H., Phillips, J. & Frenklach, M. Substrate-free gas-phase synthesis of graphene sheets. Nano Lett. 8, 2012–2016 (2008).
Son, D. I. et al. Carrier transport in flexible organic bistable devices of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) polymer layer. Nanotechnology 20, 195203 (2009).
Frisch, M. J. et al. Gaussian 03 (Gaussian, 2003).
Eda, G. et al. Blue photoluminescence from chemically derived graphene oxide. Adv. Mater. 22, 505–509 (2010).
Saxena, S. et al. Investigation of structural and electronic properties of graphene oxide. Appl. Phys. Lett. 99, 013104 (2011).
Huang, J., Xu, Z. & Yang, Y. Low-work-function surface formed by solution-processed and thermally deposited nanoscale layers of cesium carbonate. Adv. Funct. Mater. 17, 1966–1973 (2007).
Yang, H. Y., Son, D. I., Kim, T. W., Lee, J. M. & Park, W. I. Enhancement of the photocurrent in ultraviolet photodetectors fabricated utilizing hybrid polymer–ZnO quantum dot nanocomposites due to an embedded graphene layer. Org. Electron. 11, 1313–1317 (2010).
Wang, F. et al. Gate-variable optical transitions in graphene. Science 320, 206–209 (2008).
Kumar, B., Gong, H., Chow, S. Y., Tripathy, S. & Hua, Y. Photoluminescence and multiphonon resonant Raman scattering in low-temperature grown ZnO nanostructures. Appl. Phys. Lett. 89, 071922 (2006).
Acknowledgements
Won-Kook Choi acknowledges financial support from the KIST Future Resource Program (2E22721).
Author information
Authors and Affiliations
Contributions
D.I.S., B.W.K. and W.K.C. conceived and designed the experiments. D.I.S. and B.W.K. performed the experiment. D.I.S., B.W.K. and W.K.C. interpreted and analysed the data. D.I.S., B.W.K., D.H.P., W.S., B.A. and C-L.L. contributed materials/analysis tools. Y.Y. performed DFT calculations. D.I.S. and W.K.C. prepared the manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Supplementary information
Supplementary information
Supplementary information (PDF 7285 kb)
Rights and permissions
About this article
Cite this article
Son, D., Kwon, B., Park, D. et al. Emissive ZnO–graphene quantum dots for white-light-emitting diodes. Nature Nanotech 7, 465–471 (2012). https://doi.org/10.1038/nnano.2012.71
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nnano.2012.71
This article is cited by
-
Green synthesis of rGO nanosheets wrapped on Ni-doped ZnO nanocomposite using P. dodecandra L’Herit (P.d) leaves extract and their photocatalytic and antioxidant performance
Journal of Materials Science: Materials in Electronics (2024)
-
High-efficiency upconversion process in cobalt and neodymium doped graphene QDs for biomedical applications
Scientific Reports (2023)
-
Realization of Lasing Emission from the Different Perovskite Quantum Dot–Doped Materials
Plasmonics (2023)
-
Polarity, intramolecular charge transfer, and hydrogen bond co-mediated solvent effects on the optical properties of graphene quantum dots
Nano Research (2023)
-
Light Enhancement of Green Up-Conversion Emission from Er-Doped Silica Microspheres by Carbon Quantum Dot Coatings
Journal of Fluorescence (2023)