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ABSTRACT: n-Type graphene: A new, easy, and cheap method to produce n-type reduced graphene oxide was developed by synthesizing a partially reduced intermediate containing nitrogen (PrGO-IL, see scheme) by treating graphene oxide (GO) with an ionic liquid (IL) at 160 °C followed by rapid thermal annealing (RTA) at temperatures ranging from 400 to 1000 °C. A high N-doping level of 6 % was achieved and the N-doped rGO exhibits n-type behavior with a Dirac point at -38 V at 400 °C.
Chemistry 08/2012; 18(39):12207-12. · 5.93 Impact Factor
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ABSTRACT: Recently, the number of studies concerning organic memory devices has grown rapidly due to increase in the demand for electronic devices. Among the organic memory devices, the development of organic nonvolatile memory materials and devices is becoming an important research topic due to their low power consumption.
Chemical Communications 03/2012; 48(35):4235-7. · 6.17 Impact Factor
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ABSTRACT: Play the field: A field-effect transistor using reduced graphene oxides was prepared through the reduction of graphene oxides connected between two electrodes. The use of pyrene with an electron-withdrawing group and an electron-donating group showed the p- and n-doping effects, respectively, while the pyrene backbone with no electron-withdrawing or -donating groups showed no doping effect.
Chemistry 03/2012; 18(17):5155-9. · 5.93 Impact Factor
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ABSTRACT: Nonvolatile memory devices using gold nanoparticles (AuNPs) and reduced graphene oxide (rGO) sheets were fabricated in both horizontal and vertical structures. The horizontal memory device, in which a singly and doubly overlayered semiconducting rGO channel was formed by simply using a spin-casting technique to connect two gold electrodes, was designed for understanding the origin of charging effects. AuNPs were chemically bound to the rGO channel through a π-conjugated molecular linker. The π-conjugated bifunctional molecular linker, 4-mercapto-benzenediazonium tetrafluoroborate (MBDT) salt, was newly synthesized and used as a molecular bridge to connect the AuNPs and rGOs. By using a self-assembly technique, the diazonium functional group of the MBDT molecular linker was spontaneously immobilized on the rGOs. Then, the monolayered AuNPs working as capacitors were covalently connected to the thiol groups of the MBDT molecules, which were attached to rGOs (AuNP-frGO). These covalent bonds were confirmed by XPS analyses. The current-voltage characteristics of both the horizontal and vertical AuNP-frGO memory devices showed noticeable nonlinear hysteresis, stable write-multiple read-erase-multiple read cycles over 1000 s, and a long retention time over 700 s. In addition, the vertical AuNP-frGO memory device showed a large current ON/OFF ratio and high stability.
ACS Nano 08/2011; 5(9):6826-33. · 10.77 Impact Factor
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Angewandte Chemie International Edition 05/2011; 50(19):4414-8. · 13.45 Impact Factor
