01415nas a2200193   4500008004100000022001400041245006000055210006000115260012500175300001100300490000800311520069900319100001801018700002001036700002401056700003001080700002001110856009101130       2013                        eng d  a0003-695100aHysteresis and charge trapping in graphene quantum dots0 aHysteresis and charge trapping in graphene quantum dots  aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScAPR  a1431040 v1023 a<p>We report current hysteresis in response to applied voltage in graphene quantum dots of average diameter 4.5 +/- 0.55 nm, synthesized electrochemically using multiwalled carbon nanotubes. In response to step voltages, transient current decay, characteristic of deep and shallow level charge traps with time constants 186 ms and 6 s, is observed. Discharging current transients indicate charge storage of the order of 100 mu C. Trap states are believed to arise due to the fast physisorption of external adsorbates, which are found to have a significant effect on charge transport and changes the resistance of the prepared device by an order of 3. (C) 2013 American Institute of Physics.</p>1 aKalita, Hemen1 aHarikrishnan, V1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K.1 aAslam, Mohammed  uhttp://library.ncl.res.in/content/hysteresis-and-charge-trapping-graphene-quantum-dots02225nas a2200205   4500008004100000022001400041245010300055210006900158260011000227300001600337490000600353520140600359100002401765700002201789700001801811700002001829700001901849700002601868856012501894       2014                        eng d  a2046-206900aPhotophysical and photoconductivity properties of thiol-functionalized graphene-CdSe QD composites0 aPhotophysical and photoconductivity properties of thiolfunctiona  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJAN  a13788-137950 v43 a<p>Graphene-semiconductor QD hybrid nanostructure materials have recently emerged as a new class of functional materials because of their potential applications in solar energy conversion, optoelectronic devices, sensing etc. Here, oleic acid-capped CdSe QDs are attached to -PhSH functionalized graphene by ligand exchange via bonding with the -SH group. The shifting of the G-band and D-band due to structural changes for the attachment of QD with graphene has been evaluated by using Raman spectroscopy. Steady state photoluminescence (PL) and time resolved fluorescence measurements have been employed to understand the electronic interactions between graphene and CdSe QDs. A time resolved fluorescence spectroscopic study has been used to understand the fluorescence dynamics of the photoexcitated CdSe QDs in the presence of graphene. It is evident that the electron transfer occurs from photoexcited QDs to graphene and the electron transfer rate is found to be 12.8 x 10(8) s(-1) for 3.8 nm CdSe QDs. Photoconductivity properties of the graphene-QD device under illumination have been examined and it is to be noted that 2-3 fold increase in the photocurrent is found in this composite device in presence of 1.5 AM solar simulated light. The enhancement of the photocurrent in this hybrid device is found to be suitable for potential applications in optoelectronic and solar cell systems.</p>1 aDebgupta, Joyashish1 aMandal, Sadananda1 aKalita, Hemen1 aAslam, Mohammed1 aPatra, Amitava1 aPillai, Vijayamohanan  uhttp://library.ncl.res.in/content/photophysical-and-photoconductivity-properties-thiol-functionalized-graphene-cdse-qd-0