1. Colloidal ZnSe, ZnSe/ZnS, and ZnSe/ZnSeS Quantum Dots Synthesized from ZnO
- Author
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Gwo-Yang Chang, Hsueh-Shih Chen, Chien-Ming Chen, Shian-Jy Jassy Wang, Shih-Jung Tasi, Jen-Yu Hwang, and Bertrand Lo
- Subjects
Materials science ,Photoluminescence ,Passivation ,Chemistry ,business.industry ,Inorganic chemistry ,Quantum yield ,General Medicine ,Surfaces, Coatings and Films ,Colloid ,Chalcogen ,Transmission electron microscopy ,Quantum dot ,Monolayer ,Materials Chemistry ,Optoelectronics ,Physical and Theoretical Chemistry ,business ,Wurtzite crystal structure - Abstract
Colloidal ZnSe quantum dots were successfully synthesized from ZnO in a lauric acid/hexadecylamine mixture. X-ray diffraction patterns indicated that the ZnSe quantum dots possess a wurtzite structure. Transmission electron microscope images of the quantum dots showed that the average diameter are in the range of 25∼60 A. The size-dependent photoluminescence was controlled from 400 to 440 nm with the quantum yields of 6∼10% at room temperature. After passivation with 1.8 monolayer of ZnS overcoat by a traditional two-step method, the quantum yields of ZnSe/ZnS QDs are increased ∼4.5-fold (quantum yield ∼32%). An in-situ method of overcoating was done by directly injecting TOPS into the flask containing ZnSe, ZnO/lauric acid/hexadecylamine, and TOPSe. The photoluminescence quantum yields were improved ∼3.8-fold after introduction of 1.6 monolayer ZnSeS overcoat to the ZnSe QDs.
- Published
- 2005
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