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shuihuo2012

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专业: 化学动力学

[交流] Colloidal Graphene Quantum Dots with Well-Defined Structures 已有5人参与

when the size of a semiconductor crystal is reduced to the nanometer scale, the crystal boundary significantly modifies electron distribution, making properties such as bandgap and energy relaxation dynamics size dependent. This phe- nomenon, known as quantum confinement, has been demonstrated in many semiconductor materials, leading to practical applications in areas such as bioimaging,photovoltaics, and light-emitting diodes.Graphene, a unique type of semiconductor, is a two-dimensional crystal with a zero bandgap and a zero effective mass of charge carriers. Consequently, we expect new phenomena from nanometersizedgraphene, orgraphenequantumdots(QDs),becausetheenergyofchargecarriersingraphenefollowssize-scalinglawsthatdifferfromthoseinothersemiconductors.Froma chemistry point of view, graphene is made of carbon, an element for which researchers have developed a whole branch of chemistry. Thus, it is possible to synthesize graphene QDs through stepwise, well-controlled organic chemistry, achieving structures with an atomic precision that has not been possible for any other semiconductor materials.
Recently, we developed a new solubilizing strategy that led to synthesis of stable colloidal graphene QDs with more than 100 conjugated carbon atoms, allowing us to study their properties in a new size regime. In this Account, we review our recent
progress working with the colloidal graphene QDs, including their synthesis and stabilization, tuning of their properties, and new phenomena in energy relaxation dynamics. In particular, we have observed extraordinarily slow “electron cooling”;the relaxation of electrons from high excited states to lower ones. With further investigation, these high-energy electrons could potentially be harvested in solar energy applications, for example, creating more efficient photovoltaic cells.
Wediscussadditionalemerging opportunities withthesenewmaterials andcurrent challenges,hopingtodrawtheinterest of researchers in various fields to overcome these obstacles.

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附件 1 : ColloidalGrapheneQuantumDotswithWell-DefinedStructures.pdf

2012-11-29 18:12:44, 1.08 M