Spectroscopic Investigation of Oxygen Sensitivity in CdTe and CdTe/CdS Nanocrystals
| Autor: | P. Gregory Van Patten, Cheryl B. Vaughn, Lei Wang, Yueran Yan, Gang Chen |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Nanostructure
Quenching (fluorescence) Materials science Condensed Matter::Other business.industry Physics::Optics Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Cadmium telluride photovoltaics Surfaces Coatings and Films Electronic Optical and Magnetic Materials Condensed Matter::Materials Science General Energy Nanocrystal Picosecond Excited state Ultrafast laser spectroscopy Physics::Atomic and Molecular Clusters Optoelectronics Physical and Theoretical Chemistry business Spectroscopy |
| Zdroj: | The Journal of Physical Chemistry C. 115:24521-24527 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp2067638 |
| Popis: | Excited-state dynamics of CdTe nanocrystals and CdTe/CdS core/shell nanocrystals have been studied on the picosecond time scale using pump–probe transient absorption spectroscopy. The results show that exposure of CdTe nanocrystals to air can produce profound changes in the ultrafast excited-state dynamics. These changes occur even after a brief air exposure, but they are not observed in CdTe nanocrystals that are protected by a thin CdS shell. The quenching is caused by reaction of molecular oxygen with Te atoms on the nanocrystal surface, which produces traps for one or both excited carriers. The trapping event occurs on the single picosecond time scale and is sufficiently fast to compete with hot carrier cooling. This phenomenon has important implications for interpretation of excited-state dynamics in CdTe-containing nanoheterostructures as well as ultrafast charge separation in photoexcited nanostructures. |
| Databáze: | OpenAIRE |
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