Phase Separation Inside the CdTe−CdSe Type II Quantum Dots Revealed by Synchrotron X-ray Diffraction and Scattering
| Autor: | Meng-Ju Yang, U-Ser Jeng, Pi-Tai Chou, Chiu-Hun Su, Wei-Ju Shih, Yu-Chun Chen, Hwo-Shuenn Sheu, Ying-Huang Lai, Chih-Wei Lai |
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| Rok vydání: | 2008 |
| Předmět: |
Diffraction
Materials science Small-angle X-ray scattering Scattering Analytical chemistry Nanoparticle Synchrotron Cadmium telluride photovoltaics Surfaces Coatings and Films Electronic Optical and Magnetic Materials law.invention General Energy Quantum dot law Physical and Theoretical Chemistry Powder diffraction |
| Zdroj: | The Journal of Physical Chemistry C. 112:9617-9622 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp801384g |
| Popis: | Using synchrotron powder X-ray diffraction (PXRD) and small-angle X-ray scattering (SAXS), we have studied the structures of the two CdSe/CdTe and CdTe/CdSe type II quantum dots (QDs), including the crystalline structure, particle shape and size, as well as phase separation of the two components. The X-ray results suggest that the spherical CdTe/CdSe QDs of the size ∼8 nm, synthesized in a two-step procedure with CdTe nanoparticles (4 nm) as nuclides, have the structure of a CdTe-rich core enclosed by a CdSe shell. On the other hand, the spherical CdSe/CdTe QDs of the size ∼9 nm, synthesized via a similar two-step procedure but with CdSe nanoparticles (∼3 nm) as nuclides, show mainly one-phase structure with a relatively uniform distribution of CdSe and CdTe. The phase separation of the two components CdSe and CdTe inside each of the two QDs, a decisive factor in the photovoltaic applications, is furthermore examined using anomalous SAXS (ASAXS) for a consistent conclusion. For comparison, single-phase nanoparticles CdSe and CdTe are also examined. The correlation between the synthesis procedures and the corresponding structures of the QDs is discussed. |
| Databáze: | OpenAIRE |
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