Electrochemistry and Electrogenerated Chemiluminescence from Silicon Nanocrystal Quantum Dots

Reversible electrochemical injection of discrete numbers of electrons into sterically stabilized silicon nanocrystals (NCs) (∼2 to 4 nanometers in diameter) was observed by differential pulse voltammetry (DPV) in N,N′-dimethylformamide and acetonitrile. The electrochemical gap between the onset of e...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2002-05, Vol.296 (5571), p.1293-1297
Main Authors: Ding, Zhifeng, Quinn, Bernadette M., Haram, Santosh K., Pell, Lindsay E., Korgel, Brian A., Bard, Allen J.
Format: Article
Language:English
Subjects:
Bards
Chemiluminescence
Chemistry
Crystals
Electrochemistry
Electrodes
Electron transfer
Electrons
Energy
Exact sciences and technology
General and physical chemistry
Light
Nanocrystals
Nanotechnology
Observations
Organic Chemistry
Photoelectrochemistry. Electrochemiluminescence
Quantum dots
Scientific Concepts
Semiconductors
Silicon
Voltammetry
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Summary:Reversible electrochemical injection of discrete numbers of electrons into sterically stabilized silicon nanocrystals (NCs) (∼2 to 4 nanometers in diameter) was observed by differential pulse voltammetry (DPV) in N,N′-dimethylformamide and acetonitrile. The electrochemical gap between the onset of electron injection and hole injection-related to the highest occupied and lowest unoccupied molecular orbitals-grew with decreasing nanocrystal size, and the DPV peak potentials above the onset for electron injection roughly correspond to expected Coulomb blockade or quantized double-layer charging energies. Electron transfer reactions between positively and negatively charged nanocrystals (or between charged nanocrystals and molecular redox-active coreactants) occurred that led to electron and hole annihilation, producing visible light. The electrogenerated chemiluminescence spectra exhibited a peak maximum at 640 nanometers, a significant red shift from the photoluminescence maximum (420 nanometers) of the same silicon NC solution. These results demonstrate that the chemical stability of silicon NCs could enable their use as redox-active macromolecular species with the combined optical and charging properties of semiconductor quantum dots.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1069336