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Huh S.,Pohang University of Science and Technology | Park J.,Pohang University of Science and Technology | Kim K.S.,Pohang University of Science and Technology | Hong B.H.,Advanced Institute of Nanotechnology SAINT | And 2 more authors.
ACS Nano | Year: 2011

Selective n-type doping of graphene is developed by utilizing patternable gold nanoparticles functionalized with photoreactive cinnamate moieties. The gold nanoparticles can be regularly patterned on the graphene by UV-induced cross-linking of cinnamate, which provides a convenient method to control the optical and electrical properties of graphene site-specifically. The strong n-type doping of graphene covered with the patterned gold nanoparticles was confirmed by Raman, X-ray photoelectron spectroscopy, and electron transport measurements. We believe that our method would find numerous applications in the area of graphene-based optoelectronics including light-emitting devices, solar cells, and optical sensors. © 2011 American Chemical Society. Source


Lee K.Y.,Sungkyunkwan University | Kim D.,Advanced Institute of Nanotechnology SAINT | Lee J.-H.,Advanced Institute of Nanotechnology SAINT | Kim T.Y.,Advanced Institute of Nanotechnology SAINT | And 3 more authors.
Advanced Functional Materials | Year: 2014

The extremely stable high-power generation from hybrid piezoelectric nanogenerator (HP-NG) based on a composite of single-crystalline piezoelectric perovskite zinc stannate (ZnSnO3) nanocubes and polydimethylsiloxane without any electrical poling treatment is reported. The HP-NG generates large power output under only vertical compression, while there is negligible power generation with other configurations of applied strain, such as bending and folding. This unique high unidirectionality of power generation behavior of the HP-NG provides desirable features for large-area piezoelectric power generation based on vertical mechanical compression such as moving vehicles, railway transport, and human walking. The HP-NGs of ZnSnO3 nanocubes exhibit high mechanical durability, excellent robustness, and high power-generation performance. A large recordable output voltage of about 20 V and an output current density value of about 1 μA cm-2 are successfully achived, using a single cell of HP-NG obtained under rolling of a vehicle tire. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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